RESTRICTED 
WAR DEPARTMENT 
Report 834 
EFFICIENCY OF STANDARD ARMY WATER PURIFICATION 
EQUIPMENT AND OF DIATOMITE FILTERS IN REMOVING 
CYSTS OF ENDAMOEBA HISTOLYTICA FROM WATER 
3 July 1944- 
TECHNICAL STAFF 
THE ENGINEER BOARD 
Corps of Engineers, U. S. Army 
Fort Belvoir, Virginia 
RESTRICTED 
laiiHtr ItMii F*rt Btlvtir, li.  
Report G34 
EFFICIENCY OF STANDARD ARMY WATER PURIFICATION EQUIPMENT 
AND OF DIATOM ITS FILTERS IN REMOVING- CYSTS 
OF ENDAMOEEA HISTOLYTICA FROM WATER 
Project WSS 34S 
3 July 1944 
Submitted to 
THE ENGINEER BOARD 
Fort Belvoir., Virginia 
and/or 
The Chief of Engineers 
U* So Army 
Washington* Do 0, 
FOR OFFICIAL ACTION 
*>y 
Water Supply Equipment Branoh 
Technical Division III 
The Engineer Board 
Fort Belvoir, Virginia 
and 
National institute of Health 
U* S. Public Health Service 
This document contains information affecting the 
national defense of the United States within the meaning 
of the Espionage Act,, 50 U. S« C.9 31 and 32, as amended. 
Its transmission or the revelation of its contents in any 
manner to an unauthorised person is prohibited by law. 
RESTRICTED TABLE OF CONTENTS 
Section Tltlft Pej^a 
SYLLABUS V 
I SUBJECT 1 
I o So-opa I 
II AUTHORITY l 
2. Authority ?. 
Ill INVESTIGATION 1 
3, Introduction 1 
4„ Equipment and Apparatus 2 
5, Tasto 4 
IV DISCUSSION 16 
6? Cojactive 16 
?• Bo.o>; p ound 13 
8« Tout's with Standojrd Equipae*- r. 13 
9* with, pi *toai: ta Filters 24 
Y 23 
10c Conclusions 23 
VI EEC EMENDATIONS 28 
lla Recoinrr.enC afcions 28 
Appendin 
A AUTHORITY 31 
B TEST RESULTS DATA SHEETS 37 
C SAND ANALYSIS 85 SYLLABUS 
1. Scope* 
a* Introduoticnc This report covers a study of the re- 
moval of tlie cysts’ of "EndamoGba hictolybica from water by pressure 
type filtration# The work was conductoa~Tn cooperation with the 
National Institute of Health, United States Public Health Service# 
b# Equipment# The study treated herein was divided into 
two major phas'd si 
(1) Tests using the U# S# Army Portable Water Purifi* 
cation Unit, Model 1940, both with and without pretreatment 
of the raw water# 
(2) Tests using several types of diatomaceous silica 
filters inducing the U, Sc Army Portable Water Purification 
Unit converted for use with diatomaceous silica# 
2* Results# The results of this study show that; 
a. The complete removal of cyr-is of Endamoeba histolytica 
is not accomplished with tno sand filter Array’portable 
Water Purification Unit when operated at flow rates practical for 
field use-, 
Jb# Sedimentation alone for short periods is not effective 
in removing cysts from water# 
c# The total number of cysts in a quantity of water is 
reduced by good coagulation and sedimentation« 
d. Pressure type filters using any of the diatomaceous 
silica filter aids considered in the study will remove cysts of 
Endamoeba histo3 yt3ca« 
e. The combination of • pretreatment, ;sedimentation., ,-and 
filtration gives results considerably.better -than^filtration 
• -alone a 
3. Reoommendation0 > Tn view of the findings of this study of 
the removal of* cysts’ oFlwidaraoeba his col ytica from water., it is 
recommended that; 
ja# The output of the U* S* Army Portable Water Purifica- 
tion Unit Model 1940 be reduced from .15 gallons per minute to 10 gallons per minute as a maximum, and that this output be 
further reduced to not greater than 7.5 gallons per minute 
whenever possible. 
b. The output of the U. S. Army Mobile Water Purification 
Unit, Model 1940, be reduced from 75 gallons per minute to 60 
gallons per minute as a maximum, and that this output be further 
reduced to not greater than 45 gallons per minute whenever possible. 
(it must be understood that this reduction in output, while 
increasing the factor of safety, does not mean that complete re- 
moval of the cysts of Endamoeba histolytica is assured by adherence 
to the procedure recommended above.) 
o. One hour of detention be provided for coagulating, 
settling and prechlorinating all raw water without exception 
prior to filtration through either of the sanci units. 
cU Field water quality control equipment be supplied to 
all units in the field, which shall, among other things, provide 
equipment for conducting jar tests and for the evaluation of the 
efficiency of filtration in terms of turbidity removal. 
©• The study of diatomaceous silica now being conducted 
by the Engineer Board be continued to the end of determining the 
feasibility of the adoption of diatomaceous silica filtration 
equipment to replace the sand filters now in use. 
.£• Studies of the epidemiology of amoebic dysentery in 
the armed forces of the United Nations be encouraged, and the 
reports from the field be examined to determine the magnitude 
of the part that water may be playing in the dissemination of 
amoebic dysentery* R E S T R I,C T ED 
EFFICIENCY' OF STANDARD ARMY WATER PUR IF ICATI’ONEQUIPMENT 
“AND OF DIATOM ITE FILTERS BI IkOVlNG CYSTS 
OF ENDAMOEBA HISTOLYTICA FROM WATER.. , '■ 
ini — — ■■■■ - 
I. SUBJECT.’ 
1* Scope. This report covers a study of'the efficiency of 
standard Army water purification equipment and of diatomite filters 
in removing cysts of Endamoeba histolytica from water. Included is a 
summary Of the work completed to date, descriptions'and photographs of 
the equipment used, and recommendations relative both to the develop- 
ment of new equipment and to changes in the techniques of operating 
existing equipment.• 
II. AUTHORITY 
2. Authority. Authority for initiating a study of the effi- 
ciency'of filtration in removing cysts of Endaitfoebe. histolytica from 
water is contained in' a letter from the Chief of Engineers to the 
Engineer’ Board dated 19 March 1943, file SPESD, subjects Study of 
Effectiveness of Army Purification Methods in Removing Cysts of 
Endamoeba histolytica. In this letter the Board was directed to 
cooperate with tiie Surgeon Generalfs Office and the National Institute 
of Health in a program for the study of the, removal of the cysts of 
Endamoeba histolytica. A copy of’ this letter is contained in Appendix A. 
III. INVESTIGATION 
3. Introduction. -There is no record in the technical litera- 
ture of a previousstudy of the removal of cysts of Endamoeba histolytica 
from water by pressure type filtration. Filtration studies of this 
general type have been conducted by Baylis, Gullans, and Speotor , but 
their work was confined to gravity head filters and operation at lower 
filtration rates than those‘covered in this study. The’work done in 
this study with diatoraaceous silica has no precedent. This study was 
initiated after work by Brady/ Jones, and as well as other 
1 J. R. Baylis, 0. Gullans, and B. K. Speotor, ’’The Efficiency of 
Rapid Sand Filters in Removing the Cysts of the Amoebic Dysentery Or- 
ganisms, from Water,” Public Health Report 51 (Nov. 13, 1936), 1567-1576j 
B.K.. Speotor, J.R. Baylis, -and 0. Gullans, ”Effectiveness of Filtration 
in Removing from Water,- and of Chlorine in Killing, the Causative Orga- 
nism of Amoebic Dysentery,” Public Health1Report 49 (July 6,1934),766-800. 
2 F. J. Brady, Myrna F, Jones, and W. L. Newton, "Effect of Chlori- 
nation of Water on Viability of Cysts of Endamoeba Histolytica," War 
Medicine, III-(April, 1943), 409-419.: ' 
R E ST R I C T E D investigators had indicated that normal dosages of chlorine cannot 
be depended upon to destroy amoebic cysts. It was desired to de- 
termine the efficiency of standard Army water purification processes 
and equipment in removing cysts of’ Endamoeba histolytica from water. 
4. Equipment and Apparatus. 
a. Sand Filter. The sand filter unit used in the tests 
hereinafter described is a U. S. Army Portable Water Purifica- 
tion Unit, Model 1940, Essentially, the unit consists of a 
gasoline engine-driven centrifugal pump, a pressure filter, a 
belt-driven hypochlorinator, an alum and soda ash feed assembly, 
and necessary hose with fittings (Figure 1). The filter con- 
sists of an inclosed monel metal tank (17-inch inside diameter), 
outlet piping, control valves, pressure gages, and an internal 
collecting and distributing system. The filter bed consists of 
18 inches of graded sand, effective size' of 0,36 mm, uniformity 
coefficient of 1.35, resting on four inches of fine gravel. An 
analysis of the sand used is shown in Figure 54, Appendix C, 
. while the characteristics of the sand as specified are given in 
Figure 55, Appendix C. A perforated monel plate separates the 
sand and gravel. For these tests the filter bed of 1*57 square 
feet of surface was replaced for each test with new sand. The 
coagulants of ammonium alum and soda ash are fed into the raw 
water at the pump suction from two differential pressure pots 
operating across a venturi throat. The chlorinator was used 
during these tests as a constant feeding .device for the feed- 
ing of cysts to the raw water. No chlorine was used in any of 
the tests. A 1/4-inch line was tapped into the pump suction 
and equipped with a quick-opening petcock for batch application 
of cysts. 
_h« Diatomaceous Silica Filters. The following diatomaceous 
silica filters were used in this study; 
(1) Stoneheart Engineering Company, Model SF-1, 0.125 
gpm« This unit consists of a reservoir and a pressure 
filter containing a Stoneheart porous filter element 0,125 
square feet in area (Figure 2). The filter is suspended from 
the reservoir by 30 inches of l/4-inch plastic-coated fabric 
hose equipped with a shut-off clomp. The unit utilizes the 
static head to force the water from the reservoir through the 
filter, 
(2) ’Wallace and Tiernan Company, Incorporated, Model 
G2, 40 gph. This unitis likewise of the gravity type, being 
so constructed as to provide a maximum head of 5 feet (Figure 
3). The filter element used in this unit is a monel metal 
• c . • screen, 
(3) S. F. Bowser and Company, Incorporated, Model 2MS» 
60-100 gph. This filter consists of a filter shell containing a wire screen element 2 square feet in area, a hand- 
operated pump mounted on the filter head, and a body feed 
assembly (Figure 4). Provision is made for recirculating 
the water used to precoat the unit. 
(4) S. F. Bowser and Company, Incorporated, Model 
1.5C, 60-100 gph. This unit is identical with the earlier 
model 2MS with the exception of the element, which in this 
case is a porous carbon element 1.5 square feet in area. 
(5) International Filter Company, Incorporated, Model 
SW l/8, 0.375 gpm. The model SW 1/8 is a laboratory test 
assembly consisting of a glass filter shell containing a 
Stellar element 0,125 square feet in area and a small elec- 
tric motor-driven pump (Figure 5). The Stellar element used 
is identical in design and construction with elements in 
diatomaceous silica filters used by the British Army, 
(6) Naval Medical Research Institute Experimental Model. 
This gravity type unit consists of a vinylite bag in which is 
mounted a porous carbon disc of 8 square inches in area. The 
unit may be rolled up and carried in one's pocket. 
(7) Stoneheart Engineering Company, Model SF-Xl, 20 
gpm, This unit consists of a filter shell and head assembly, 
four Stoneheart ceramic filter elements totaling 8.8 square 
feet in area, a gasoline-engine-driven centrifugal pump, a 
turbine pump connected to the same engine, an electrically- 
driven body feed pump, a precoat tank and a hypochlorinator 
(Figure 6), In this study, only the filter section and pre- 
coat tank were used. The treatment section of a U, S, Army 
Portable Water Purification Unit was used to pump the raw 
water. 
(8) Uo S. Army Portable Water Purification Unit, Model 
1940, Converted for Use with Diatomaceous Silica, A filter 
of the same type as used in the tests with sand was converted 
for use with diatomaceous silica (Figure 7)« This unit con- 
tained 6,6 square feet of filtering surface consisting of 
three aluminum oxide filter elements. The body treatment 
was added through the pump suction and was controlled by a 
simple valve and sight glass assembly. 
c» Settling Tanks, Two sizes of sedimentation tanks were 
used in this study: first, a 2500-gallon steel tank measuring 
8 feet in diameterj and, second, a U. Sc Army 3000-gallon canvas 
tank measuring 11,25 feet in diameter. The latter tank is stan- 
dard issue with all purification units in the field (Figure 8), 
d. Metering and Sampling, A Pittsburgh water meter (No. 
3399304) was used to determine all' output rates above 5 gallons per minute* and a system of outlet taps installed in the dis- 
charge line permitted the simultaneous collection of the 
several samples* 
e# Chemical Analyses. The pH determinations at the 
filte7 were made with a standard comparator supplied with the 
U. S. Army Portable Water Purification Unit. The pH determina- 
tions in the laboratory were made with a Beckmann pH meter. 
All chemical analyses were conducted in accordance with standard 
methods• 
f, Preparation of and Examination for the Organism. The 
HRS strain of Endamoeba histolytica was used •throughout these 
tests because cysts could be prepared with relative ease and be- 
cause its size, averaging 15.2 ju - 2 ji, corresponds to the large, 
more pathogenic strain of E. histolytica. To procure the cysts, 
amoebae maintained on egg slant cultures with an overlay of 
Stone’s modification of Locke’s solution were transferred to 
tubes of a similar medium containing a small amount of rice 
starch. After 72 hours of incubation with this medium, the 
cysts were harvested, washed in distilled water, and stored in 
the refrigerator at least 24 hours before use. Estimates of 
the numbers of cysts were made with the use of the Fuchs-Rosenthal 
counting chamber, while the identification and counting of the 
cysts present in the effluent samples were made in a Scdgvdck- 
Rafter counting cell. 
5. Tests. The tests covered by this report consisted essen- 
tially of introducing a predetermined number of cysts of the HRS 
strain into the raw water, passing this water through filters, and 
collecting samples of the effluent at regular intervals for mioro- 
soopio examination. When preliminary treatment consisting of coagu- 
lation and sedimentation was employed, a uniform suspension of oysts 
in the water to be treated was obtained by introducing the organism 
into the water at a constant rate during the period that the settling 
tank was being filled. Chemical and bacterial analyses of the influent 
and effluent of a number of tests were made as an additional control. 
Operation of equipment and chemical analyses were performed by the 
Technical Staff of the Engineer Board 'Water Supply Equipment Branch; 
the incubation and harvesting of the cysts and the microscopic exami- 
nation were performed at the National Institute of Health. 
In general, the method used for the examinations of water 
samples for cysts was as follows* Samples of effluent waters were 
allowed to settle in a cool place for 18 to 24 hours. The super- 
natant was then gently siphoned off and the remainder placed in 
smaller bottles. To these containers, ammonium alum and soda ash 
were added, and the containers were left in the cold room over night. 
The supernatant was again siphoned off and the remainder placed in 
50-oc centrifuge tubes. By centrifugation, the sediment from each 
tube was again concentrated. One or two Owvlc centimeters of M/lO 
oxalic acid were added to redissolve the coagulum and the volume FIG. 1. U. S. ARMY PORTABLE WATER PURIFICATION UNIT, MODEL 1940. Assembled for operation. FIG, 2m GRAVITY TYPE DIATOMITE 
FILTER. Stoneheart Engineering 
Company, Model SF-1, 
FIG. 3. GRAVITY TYPE DIATOMITE 
FILTER, Wallace and Tieman 
Company, Model G-2, FIG. U. HAND-OPERATED DIATOMITE FILTER. S. F. Bowser and 
Company, Inc,, Model 2MS. 
FIG. 5. STELLAR DIATOMITE FILTER. Infilco Inc., Model SW 1/8.. FIG, 6, SKID-MOUNTED DIATOMITE FILTER, Stoneheart Engineering Company, Model SF-H. FIG. 7. U. S. ARMY PORTABLE WATER PURIFICATION UNIT, MODEL 194-0. Converted for use with diatomaceous silica. FIG. 8. STANDARD 3000-GALL0N CANVAS TANK WITH COVER. was made up to 5 or 10 cc with distilled water* One-cc samples from 
these tubes were taken and mixed with one drop of one percent iodine 
in a Sedgwick-Rafter counting cell. The area of the chamber was 
examined by the use of the low (lOx) and intermediate power (20x) 
objectives of a compound microscope. The amount of material examined 
was determined to a great extent by the amount of sediment present. 
All doubtful objects were recorded as cysts only when two observers 
were agreed as to their being cysts. 
The testing program was scheduled as follows; 
ja. Tests with Standard Equipment 
(1) Operation of U. S. Amy Portable Water Purifica- 
tion Unit, Model 1940, at 15 gpm without Pretreatment- The 
first group of three tests was conducted on the portable 
sand filter to determine its efficiency in the removal of 
the amoebic cysts under several conditions of operation. 
An initial output of 15 gpm, representing a flow rate of 
9.6 gpm per square foot of area, was used throughout this 
first group of tests. The three conditions represented 
were as follows? 
(a) Filtration without treatment. 
(b) Filtration with insufficient or improper 
coagulation, 
(c) Filtration with good coagu3.ation. 
In each of these tests, the filter was operated until a 
schmutzdecke had been formed before the cysts were intro- 
duced in a batch through the pump suction. The period 
required to introduce the cysts and wash down the intake 
funnel did not exceed 30 seconds. The results show that, 
while the efficiency of the unit in removing amoebic cysts 
is somewhat proportional to the quality of the treatment, 
the removal of cysts of Endamoeba histolytica, even under 
ideal conditions, is not obtained when the unit is operated 
at 9.6 gpm per square foot. 
(2) Operation of tf. S* Army Portable Water Purification 
Unit, Model 1940, at 10 gpm without Pretreatment. The 
second series of tests consisted of two tests designed to 
determine the efficiency of the portable sand unit in re- 
moving amoebic cysts when operated at the output rate of 10 
gpm. This output represents a flow rate of 6.35 gpm per 
square foot. In this series of tests, every available con- 
trol was utilized to obtain ideal operating conditions for 
the tests. Cysts were introC’.wed in a batch in the first 
test, whereas they were fed -through the hypochlorinator at 
a uniform rate in the second tent. A marked improvement was noted in the efficiency of the unit in removing amoebic cysts 
ovbr the results obtained at the higher flow rates 
(3) Operation of U. S. Army Portable 'Water Purification 
Unit, Model 1940, at 10 gpm Following Coagulation and Sedi- 
mentation. The third and final series of tests conducted 
with the portable sand filter consisted of three tests de- 
signed to determine the efficiency of pretreatment, followed 
by filtration, in removing amoebic cysts from water. In the 
first of these tests, cysts were introduced in the raw water 
and the water was allowed to settle without coagulants for 
one hour. The supernatant wsls then passed through the port- 
able sand filter at the rate of 6.35 gpm per square foot. 
Microscopic examination of samples of both the settled water 
and the filter effluent indicated that settling for one hour 
without coagulants, while reducing the number of cysts pre- 
sent, does not remove cysts from water. The other tests of 
this series were conducted in like manner, with the exception 
that coagulants were employed, and in one case the detention 
period was extended to two hours. A marked reduction in the 
concentration of amoebic cysts by the process of coagulating 
and settling was noted. 
b. Experiments with Diatomite Filters 
(1) Experiment I-D, Stoneheart Engineering Company, 
Model SF-1. The purpose of this test was to determine the 
efficiency of diatomaceous silica in removing amoebic cysts 
from water. Because of the absence of previous studies of 
this material, the results could in no way be anticipated. 
Therefore, this test was in the nature of a trial run de- 
signed to act as a guide for further work with diatomaceous 
silica. For this test, 350,000 cysts of Fndamoeba histolytica 
were added to one gallon of tap water to which clay had been 
added, the water was passed through the filter, and the entire 
gallon of effluent was subjected to microscopic examination. 
A complete absence of amoebic cysts in the effluent was noted. 
A grade of diatomaceous silica sold under the trade name of 
Sorbo-Cel by Johns-Manville, Inc., was used in the amount of 
12.5 pounds per 100 square feet of filtering surface for the 
precoat. No slurry feed was used. 
(2) Experiment 2-D, Wallace and Tieman Company, Inc., 
Model G2. The filter-aid used in this test was a commercial 
product which had received a special treatment by tbe manu- 
facturer of the filter. A precoat of this material was 
applied in an amount equivalent to 10 pounds per 100 square 
feet of filtering surface. A concentration of 6000 cysts 
per gallon was prepared in 50 gallons of Potomac River water 
and a uniform suspension maintained by agitation. The pre- 
coat was applied with the contaminated water. From the six 
gallons of effluent examined, three cysts were recovered. (3) Experiment 3-D, S* F> Bowser and Company. Inc., 
Model 2MS> Using Potomac River water to which amoebic 
cysts had been added in the concentration of 6000 cy«its 
per gallon, a precoat of Johns-Manville Cel it e Super--Cel 
was applied by recirculating the preooat water for a period 
of two minutes. The precoat of 3 ounces of the filter-aid 
was computed on the basis of 9.38 pounds per 100 square feet 
of filtering surface, while the body treatment was applied 
at the rate of 20 ppm, equivalent to 1 ppm of filter aid for 
each part of turbidity. A ’’break through" occurred after 
8.25 minutes of filtering, following the loss of the pump 
suction. This allowed the flow to cease momentarily, thus 
dropping the cake. Subsequent testing, which is not a pert 
of the work covered by this report, indicated that wire 
cloth elements such as are used in this unit are not 
generally satisfactory for the filtration of water. Prior 
to the "break through", no cysts were recovered from the 
effluent samples. 
(4) Experiment 4-D, S. F» Bowser and Company, Inc., 
Model lo5C* Tap water to which 25 ppm of chlorine had 
been added was recirculated through the unit for two 
minutes. The filter and water was then dechlorinated with 
sodium thiosulphate, Using this water, a preccat of Johns- 
Manville Sorbo-Cel was applied over a two-minute period. 
The precoat was computed on the basis of 10 pounds per 100 
square feet of filtering surface. No body treatment was 
used. After precoating, the suction hose was changed to a 
tank of potomao River v/ater containing .10,000 cysts per • 
gallon and the filtering cycle begun, .ifter 11 minutes 
of filtering, the pump was stopped, and a slight back flow 
was introduced to facilitate the dropping of the precoat. 
Pumping was then resumed and the effluent discharged to 
waste for 50 seconds, at which time the effluent was again 
clear. No cysts were recovered from the effluent samples, 
(5) Experiment 5-D, International Filter Company, 
Inc., Model SW l/8. Using Potomac River water containing 
6000 cysts per gallon, a precoat of Johns-Manville Sorbo- 
Cel was applied in the amount of 15 pounds per 100 square 
feet of filtering surface. After filtering for approxi- 
mately 27 minutes at the initial rate of 2 gpra per square 
foot, the pump was stopped and the cake allowed to drop 
from the element. The pump was then restarted and the 
filter operated to waste for one minute. The flow rate 
was set at 4 gpm per square foct for this second phase of 
the test. No cysts were recovered from the effluent samples. 
(6) Experiment 6-D, Nava' Medical Research Institute, 
Model Xp A precoat of Johns -Mi-jville Strbo-Ccl in the 
amount of 36 pounds per 100 square feet was applied, using 
uncontaminated tap water. After precoating, 4110 cc of Potomac River water, containing 10,000 to 12,000 cysts per 
gallon, were filtered. All of the effluent was collected 
and examined. No cysts were recovered. The procedure was 
repeated, using activated silver filter-aid in the amount of 
15 pounds per 100 square feet. No cysts were recovered. 
(7) Experiment 7-D, Stoneheart Engineering Company 
Model SF-XI. In view of the excellent results obtained with 
small units, tests on a larger scale were attempted. For 
this purpose the filter and precoat sections of the Model 
SF-XI were used in conjunction with the pumping section of 
a U«- S* Army Portable Water Purification Unit. The precoat 
of Johns-Manville Sorbo-Cel was computed on the basis of 17 
pounds per 100 square feet of filtering surface, and was 
applied by recirculating Potomac River water to which 225,000 
cysts had been added. The amount of 'water required to fill 
the unit for recirculation was 35 gallons. Body treatment 
was applied during the run at the constant rate of 170 ppm, 
this rate being equivalent to 2,5 ppm of body treatment for 
each part of raw water turbidity. Cysts were applied through 
the hypochlorinator at the constant rate of 4500 cysts per 
gallon of influent. The engine stopped for no apparent reason 
after six minutes of filtering. Although the engine was re- 
started almost immediately, the presence of a quantity of 
diatomaceous silica in the effluent for approximately one 
minute after restarting indicated that some of the precoat 
had been disturbed by the slight reverse flow set up when the 
engine stoppeds Of the 17 gallons of effluent examined, 
seven cysts were found in the samples taken during the early 
portion of the rim. 
(8) Experiment 8-D, U. S. Army Portable Water purificar 
tion Unit, Model 1940 Converted for Use with Diatomaceous 
Silica, (E. B. Model SFC-1). This unit was converted from 
a standard sand filter by personnel of the Engineer Board 
following, in general, the fundamental principles of the 
Stoneheart Engineering Company unit. Model SF-Xl. For this 
test a precoat of Johns-Manville Celite Sorbo-Cel was applied 
over a 3-minute period by recirculating 30 gallons of Potomac 
River water to which no cysts had been added. A secondary 
precoat consisting of one-half pound of Sorbo-Cel and one- 
quarter pound of Nuchar FcA.N, was then applied in like 
manner over a period of two minutes. The original precoat 
was computed on the basis of 15 pounds of filter-aid per 100 
square feet of filtering surface. The body feed was regu- 
lated to give a constant addition of 120 ppm of filter aid, 
this being equivalent to 6 parts of body treatment for each 
part of raw water turbidity. The precoat was applied at the 
rate of 4,1 gpm per square foot of filtering surface while 
the filtering rate over the 25-minvto run varied between 3*68 
and 2.55 gpm per square foot. The cysts were applied at a 
constant rate of 3600 cysts per gallon. In the six gallons of effluent examined, one cyst was found; this cyst 
appeared in the first five gallons of effluent. 
(9) Experiment 9-D, U. S. Army Portable Water Purifi- 
cation Unit, Model 1940 Converted for Use with Diatomaceous 
Silica (e. B. Model SFC-1). This test was quite similar to 
Experiment 8-D, described above. A precoat of Johns- 
Manville Celite Sorbo-Cel was applied by recirculating 30 
gallons of Potomac River water to which no cysts had been 
added. The precoat of one pound of filter-aid was calcu- 
lated on the basis of 15 pounds of filter-aid per 100 
square feet of filtering surface, and was applied at the 
rate of 2.5 gpm per square foot, while the filtering rate 
over the 25-minute run varied between 4.2 and 3*6 gpm per 
square foot. The body feed was regulated to maintain a 
minimum rate of pressure rise, 0»65 pound being used in 
the 25 minutes of operating time. The cysts were added at 
a constant rate of 1935 cysts per gallon of influent over 
the first 18 minutes of this operation, at the end of which 
time the supply of the organism was exhausted. In the six 
gallons of effluent examined, no cysts of Endamoba histolytica 
were recovered. 
(10) Experiments 10-D through 13-D, Inclusive, U« S. 
Army portable water Purification Unit, Model 1940. Converted 
for Use with Diatomaceous Silica (E. B. Model SFC-1)• The 
majority of the tests with diatomaceous silica as outlined 
above were conducted with a grade of filter-aid sold by 
Johns-Manville under the trade name of Celite Sorbo-Cel. 
The purpose of these tests was to determine if the removal 
of amoebic cysts from water can be accomplished with all 
grades of material including the highest flow rate filter- 
aids available. The four filter-aids considered were 
Celite Super-cel, Hyflo Super-cel, Celite Sorbo-Cel and 
Celite 545 was processed by John s-Manvi lie• Both Celite 
Super-cel and Celite Sorbo-Cel were used in some of the 
tests previously discussed, Hyflo Super-cel is currently 
used by the British Army, and Celite 545 is one of the two 
highest flow rate materials available. With each filter- 
aid in turn, the precoat was applied at the rate of 15 
pounds per 100 square feet of filtering surface. After 
precoating, the unit was then sterilized in each instance 
with sufficient chlorine to give an orthotolidine reading 
in excess of 100 ppm in the precoat water, dechlorinated 
with sodium thiosulphate, and checked for residual chlorine 
with orthotolidine. Filtration was then started, the cysts 
being added in a batch through the pump suction over a 
period of 30 seconds at the beginning of the filtering 
operation. One cyst was recovered from the effluent samples 
of each of the tests with and with Hyflo Super-cel, 
whereas the results of the tes'cs with Super-cel and with 
Celite 545 show that no cysts were recovered from the effluent samples. It was noted that Celite 545 removed the cysts of 
Endamoeba histolycjoa notwithstanding the foot that the 
mvlTriaT'’is so Toarse as to permit the passage of a con- 
siderable amount of turbidity. 
IV. DISCUSSION 
6* Objective* The objective of this study was to determine 
the efficiency of standard Army water purification equipment in re- 
moval of cysts of End amoeba histolytica from water, and, in the 
event that present equipment proved unsatisfactory, to invest!gate 
the effectiveness of both new operating procedures and new typos of 
equipment in removing amoebic cysts from water* 
7, Background* Data are not available which permit an evalu- 
ation of tne"relative importance of water, as compared with other 
modes of transmission in the dissemination of amoebio dysentery* 
In the Ifriited States, outbreaks of water-borne amoebiasis were re- 
corded a decade ago. However., the absence of da ha in no way excludes 
the possibility of water being on important medium of transmission of 
amoebic dysentery under certain favorable conditions* The largest 
outbreak of amoebiasis known to have occurred was that in Chicago in 
1933, It was thought that 160,,000 persons were exposed to the in- 
fection by means of a contaminated drinking water supply} of this 
number it is known, that 1,409 oases of the disease developed, with 
98 fatalities. No concurrent cases of other infectious enteric 
diseases occurred in the exposed group, apparent'1 y because an ade- 
quate chlorine residual was maintained in the contaminated water 
supply to kill the pathogenic enteric bacteria. This water-borne 
epidemic shows clearly that severe infections can be acquired from 
the consumption of water lacking a noticeably disagreeable taste and 
odor. Bunker shows a hypothetical case that a chlorinated but un- 
filtered municipal water in Bogota, Colombia, might contain over 
1,000 cysts of Endomueba histolytica in each liber of distributed 
water. Thus a chlorinated water regarded as potable by the usual 
physical standards and bacteriological examinations can be responsible 
for infections with J), histolytica. The inherent difficulties of cul- 
turing E, histolytica ©nd~Ox differantiating it from free living amoebae 
have prohibT.ted’ t,ne~ isolation and, therefore, the enumeration of these 
organisms in raw water. 
The degree of hazard of acquiring omoebiasis among troops 
cannot be evaluated at this time. It would appear that such an evalu- 
ation oould be made only by detailed epidemiological methods that are 
difficult to use under combat conditions. Peacetime experience has 
taught that the strains of amoebae occurring in the Pacific and India- 
Burma-China theatres are particularly virulent, and that these amoebae 
are harbored by high proportions of the natives. The cysts must 
commonly be present in the surface v/aters of these areas, Tne poten- 
tial threat of water-borne amoebiasis is further emphasised by the 
recent work of Brady, Jones, and Newton shewing that practical dosages of chlorine do not necessarily destroy the cysts of E« histolytica. 
One of the most important requirements that a water puri- 
fication unit must meet to be satisfactory for military use in the 
field is that the ratio of the quantity of water produced to the 
weight of the unit must be high. Of equal, and perhaps of greater, 
importance is the uncontested requirements that the water produced 
be both palatable and safe. With the use of sand as the filtering 
medium, experience has shown that the two requirements above are 
uncompromisingly opposed, one to the other, With few exceptions, 
the ratio of the weight of a sand filter to its filtering area is a 
fixed quantity of considerable magnitude. It is therefore necessary 
to resort to high flow rates to obtain a satisfactory ratio of output 
to weight. In civilian practice it has been found that flow rates of 
from two to three gallons per minute per square foot of filtering 
surface represent the maximum rates for satisfactory results. It 
will be noted that these flow rates are used only after carefully 
controlled pretreatment of the raw water, present sand filters 
used by the armed forces of the United States are operated at flow 
rates varying between 6 and 10 gpm per square foot of filtering sur- 
face while handling raw water which has received inadequate pretreat- 
ment. It has been necessary with the use of sand, therefore, to 
sacrifice quality for greater output. The wisdom of permitting high 
flow rates in the sand filters now in use has been open to question 
for some time., but little or no testing has teen previously conducted 
to evaluate the effect of these high flow rates on the quality of the 
water produced. 
The use of diatomaceous silica as a filtering medium for 
water does not represent a new basic idea* Equipment for water fil- 
tration using Kieselguhr, an unrefined form of diatomaceous silica, 
was tested by the United States Army at Carlisle Barracks in 1938. 
The equipment at that time consisted of a canvas duck element on 
which the Kieselguhr was deposited. Both the Kieselguhr and the 
element available were not suitable for water filtration; hence, 
the equipment tested was not satisfactory. Since 1930, great strides 
have been made in the processing of diatomite. Methods have been 
developed to obtain filter aids having almost any desired characteris- 
tic, and at the same time increasing both the efficiency and flexi- 
bility of the material far beyond anything obtained with the original 
Kieselguhr. These materials are today being used in the filtration of 
such commercial products as paint, oil, sugar and alcoholic beverages. 
However, except in rare instances where filter-aid has been used to 
’’polish" tap water, diatomaceous silica has not been used extensively, 
for water filtration. One of the contributing factors to this condi- 
tion has been the difficulty of obtaining an element possessing the 
necessary permeability, porosity, strength, and backwash characteris- 
tics for water filtration. Early in 1943* the Stoneheart Engineering 
Company (now merged with Titeflex, Incorporated) presented a pilot 
model filtering unit to the Engineer Bog'd which apparently was rea- 
sonably satisfactory for water filtration. Using a special filter aid 
processed by Johns-Manvilie, this unit was tested at the laboratories of the Engineer Beard at Fort Belvcir, Virginia. This unit* among 
others, was used in the tests covered by this report. 
Of particular interest is the development of diatomaceous 
silica filtration equipment overseas. Within the past decade, a unit 
known as the Stellar filter has been developed in England. This dia- 
tciiiaceous silica unit, constructed in several sizes, is now standard 
equipment in the British Army. There are indications that some of 
these units have been operated by American forces stationed in England* 
The Italians purchased some of the early units built in England, and it 
is possible that the equipment was used in the Ethiopian campaign. 
Stellar units, operated by Australian forces, have been used in the 
Southwest Pacific Area. Diatomaceous silica filtration equipment is 
used by both Canadian and New Zealand troops, Canadian troops have 
also used sand filters similar to the U. $• Array Portable Water Puri- 
fication Unit, Model 1940, Filter aids used by the British are pur- 
chased in this country from Johns-Manville and from the Dicalit© 
Company. 
Because of the unprecedented requirements for filtration 
equipment for our widely dispersed forces in the Southwest Pacific 
Area, e. number of diatomaceous silica units have been supplied to our 
forces. This filter, known as the Mollinito Filter, Model was 
developed by the Fletcher Chemical Company (Au>;t.»), pty, Ltd., 
Victoria, Australia. While it is understood that this unit produces 
relatively good results, further development of the mechanical details 
appears to be neceacary before the unit can be considered satisfactory 
for general field use. 
8c Tests with Standard Equipment, The U< 3* Army Portable Water 
Purification Unit., Model 1940* was used in the experiments conducted 
with sand filtration. It is logically assumed that the results obtained 
also apply to the U. S. Army Mobile Water Purification Unit.* Model 1940, 
which, except in size, is similar to the smaller unit. The reoommende.- 
tions of th*s rep03',t relative to the mobile unit are based on this 
assumption. 
Test T. Operation at Rated Capacity without Coagulants* 
(See Figure & significance’of this test lies in thefao¥"~ 
thac cysts passed the filter in very large showing con- 
clusively that the sand bed alone cannot be expected to remove 
cysts with operation at rated capacity. The water used in this 
test was obtained from the Fort Belvoir water supply and contained 
considerable iron from corroding mains, 
s~k T-» Operation at Rated Capacity with Coagulants. 
(See Figures .(0 and 1.1,; This test was conducted in such manner 
as to parallel methods currently used in the field. Weter was 
pumped through the filter with the addition of coagulants in 
sufficient quantity to produce a "clear" effluent. The effluent 
pH was than determined and this pH ma-.,:- tained throughout the 
operation. A reasonably clear effluent was obtained, but the total amount of water produced was low because the filter 
plugged rapidly. An after-floc was visible in the effluent 
during more than half of the operation, and the pH control was 
extremely difficult* The raw water, having very little buffer- 
ing action, added to the difficulties in the use of color stan- 
dards for pH control. It will be noted that cysts passed the 
filter during the first part of the operation in the same general 
order as in Test I, when no coagulants were used. No cysts were 
recovered at flow rates below 3 gpm per square foot. Cysts 
passed the filter with considerable ease while the effluent re- 
mained relatively clear. It is therefore apparent that removal 
of cysts is not necessarily a function of turbidity removal, 
o. Test III, Operation at Rated Capacity with Coagulants, 
(See Figures l2, 1&, and 14,) Every control feasible for field 
operation was employed in this test. The raw water was obtained 
from the Potomac River just prior to the test; jar tests were 
conducted to obtain the optimum coagulant dosage; pH determina- 
tions were made at one minute intervals; and the pump speed was 
not changed during the operation. Notwithstanding the attempt 
to provide ideal operating conditions and controls,-, cysts passed 
the filter. The increased turbidity and high plate counts in 
Samples 31, 32, and 33 indicate a break through of the filter 
bed after 25 minutes of the test operation, A close correlation 
is noted between effluent turbidity and bacterial removal, while 
cysts passed the filter in the greatest number when the effluent 
turbidity was lowest. The presence of after floe in Samples 31, 
32, and 33 was due to insufficient time for complete flocculation 
ahead of the filter. At the output rate of 15 gpm, slightly more 
than one minute is available for floe formation before the water 
reaches the portable sand filter. The bacterial analysis shows 
that the quality of the effluent deteriorated throughout the 
operation with Sample 33 producing results not unlike the raw 
water. The effluent turbidity did not exceed 3 ppm at the filter. 
However, cysts passed the filter with ease and the bacterial 
analysis shows that nothing better than a crude straining job was 
accomplished. 
d, Test IV, Operation at Reduoed Rate with Coagulants*. 
(See figures 15, 16, and 17.) This test was conducted at the 
reduced rate of 10 gpm, equivalent to 6,35 gpm per square foot 
of filtering surface. The cysts were introduced in two batches, 
the first at the start of the operation and the second after 30 
minutes. Cysts passed the filter, but the numbers passing were 
considerably changed from the results obtained in tests at rated 
capacity. At the time the second batch of cysts was applied, a 
Schmutzdecke of as much as one-halfpound of clay and coagulants 
had been built up on the filter. Cysts passed the filter at this 
time in equal or greater numbers then at the beginning of the test. 
Attention is called to the wide range of the pH values obtained 
with the Beckman instrument as compared with the values obtained 
with the color indicator at the unit# A comparison of effluent turbidities at the unit and after 24 hours shows a considerable 
increase in effluent turbidity after standing* For the most 
part, this increase was due entirely to after floe. The pre- 
sence of clay particles in Samples 38 and 39 indicated a break 
through in the filter bed. A marked increase in bacteria passing 
the filter accompanied this turbidity rise, while the number of 
cysts passing the filter was not materially changed. Here, as 
in previous tests, a reasonable effluent was maintained, bacteria 
removed to some degree, and a satisfactory output rate maintained,, 
but cysts passed the filter with monotonous regularity. 
e>. Test V. Operation at Reduced Rate with Ccagulantso 
(See Figures 18, 19, 20, and 21.) The purpose of this test was 
to determine the effect of adding the cysts continuously to the 
filter, and to determine the effectiveness of backwash in removing 
entrapped cysts from the unit. This test shows that the number of 
cysts passing the filter was changed somewhat by substituting con- 
tinuous feed for batch application of the cysts. Samples 55, 66, 
and 57 are extremely interesting. After 2C minutes of the test, 
it was found that the output had fallen to slightly below 10 
gallons per minute. The prmp speed was increased slightly, re- 
sulting in an output of approximately 11 gallons per minute. 
This operation was carefully executed to minimise sudden impulses 
on the filter bed* Notwithstanding, a decided break through 
occurred immediately following this flow adjustment, with an in- 
crease in effluent turbidity, a sharp rise in bacteria, and, in 
this case, a rise in the number of cysts passing the filter being 
noted. The unit was backwashed with river water, to which no 
cysts had been added, for a period of five minutes at the rate 
of 20 gpm. Filtration was resumed as before with no additional 
cysts being applied. Sample 59, taken after eight minutes of 
filtering, contained 2.0 cysts per gallon of effluent. It is 
obvious that backwashing should be done with filtered water inas- 
much as cysts in the backwash water can be caught within the sand 
bed during the operation. The rate of backwash should be the 
highest at which the sand does not escape the filter, probably 
about 25 gallons per minute. 
f• Test VI-A. Sedimentation without Coagulants. (See 
Figures 22 and 237) The purpose of this test was to detenuine 
the effectiveness of sedimentation without coagulants in removing 
cysts from water. It shows that while the total number of cysts 
per gallon of water is reduced, sedimentation for 90 minutes is 
not effective in removing either cysts or bacteria from water. 
Attention is directed to the fact that the effectiveness of sedi- 
mentation was based on the top portion of the settled water. 
(See Test VI-B.) 
J> Test VI-B« Operation at Reduced Rate without Coagulants. 
(See Figures 24, 25, and 2£>.) TKis test parallels "to sane degree 
Test I in that water containing cysts was pumped onto the filter 
without coagulants. It differs in that the supernatant used from Test VI-A contained a reasonably uniform number of cysts, 
while batch application of the cysts was used in the first 
test. In addition, it is possible that the cysts remaining 
in the supernatant of Test VI-A and used here contained only 
the smaller cysts. Cysts passed the filter in this test at 
a fairly uniform rate. The reduced flow rate of 6<,35 
was used in this test, whereas the unit was operated at rated 
capacity in the earlier test. The row water used was obtained 
from the Potomac River. This water contained an unusual tur- 
bidity composed of a very light, nonsettling material similar 
in appearance to undissolved lime particles. The pH was above 
the average for the stream. 
h. Test VII-A. Coagulation, 2-Hour Settling. (See 
Figures 27r"ond 28.) it was the purpose of this test to coagu- 
late and settle following, in general, methods used in the 
field, namely* determination of optimum coagulant dosage by a 
modified jar test and the addition of the coagulants to the 
water while pumping with use of the alum feed pot. The modified 
jar test used consists of filling a bottle or other container 
with raw water, adding a small amount of alum dissolved in water, 
and shaking violently for about one minute. Additional alum is 
added until a satisfactory floo is formed. At this point, the 
pH of the sample is determined. Pumping is then begun, with 
alum being applied through the feed pot in sufficient quantity 
to produce the some pH reading as was obtained in the jar test. 
This procedure was followed in this test with most unsatisfactory 
results. With approximately three feet of suction lift the 
coagulant feed through the unit was hopelessly erratic. After 
pumping 1288 gallons, it was found that 5*1 gr/gal of alum had 
been applied while the desired dosage was 10 gr/gal. The dosage 
applied would have been considerably lower if the second feet pot 
had not been used during a part of the operation. Since the floe 
formed was extremely fine, little or no settling occurred during 
the 60 minutes provided. A standard jar test was then conducted 
which showed that the dosage of 10 gr/gal of alum was satisfactory, 
but that 6 gr/gal of soda ash in addition considerably improved 
the size and settling quality of the floe. Hence 5 gr/gal of alum 
and 5 gr/gal of soda ash were dissolved in water and added to the 
tank of previously treated water. The soda ash and the alum were 
added in turn and distributed throughout the tank by agitation 
with a paddle. An excellent floo was formed as indicated by the 
settled water turbidity value of 2 ppm after 60 minutes of settling. 
Figure 27, Test VII-A, shows that better removal of cysts was 
accomplished in this test with coagulation and sedimentation than 
was accomplished by filtration at rated capacity in Tests II and 
III. It is to be noted, however, that samples 79 through 86 were 
taken from supernatant and that not more than 25 percent of the 
water depth was used in the subsequent filtration in Test VII-B. 
The results of Test VII-A are somewhat difficult to interpret 
because of the difficulty encountered in obtaining a satisfactory 
floo at the start of the operation. It is of considerable interest. however, in view of the high degree of clarification accomplished, 
that cysts were found in each of eight small samples collected 
from* the supernatant* 
i. Test VI1-3, Operation at Reduced Rate Folio-wing Coagu- 
lation and Sedimentation* *TSee Figures 2§ and 30*") In this test 
the water which had been coagulated and settled in Test VII-A was 
pumped through the filter at the reduced rate of 6*35 gpm per 
square foot* The finding of several cysts in three of eight 
filter effluent samples shoves that the efficiency of the unit in 
removing cysts from water is greatly improved by pretreatment of 
the raw water* Attention is directed to the clarity of the 
effluent which was consistently below 0*5 ppm and further that 
an output of 10 gpm was maintained without any increase in head 
less* 
Test VIIJCpA* Coagulation, 75-mlnute Settling* (See 
Figure 31,*J tFTTs test was conducted for the purpose of deter- 
mining the efficiency of coagulation and sedimentation in re- 
moving cysts from water* The method followed was one that 
could be followed in the field, A CO-galIon metal drum was 
placed upright in a 3000-gallcn canvas tank and the water pumped 
into the drum, The coagulants were dissolved, in viator and these 
solutions introduced continually during pumping* Cysts were 
pumped through the hypochlorinator at a constant rate cf -1300 
cysts per gallon of water pumped* Using the metal drum as a 
flash mixer, on excellent flee was formed, which settled rapidly* 
Reduction in cysts due to coagulation Laid sedimentation for 75 
minutes was reasonably good, the number per gallon being reduced 
from 4300 to less than ICO, The results of this test show that 
while the number of cysts present in a quantity of water are 
materially reduced by a method of coagulation and sedimentation, 
suitable for field use, complete removal is not accomplished* 
k* Test VIII-B* Operation at Reduced Rate Following 
Coagulation and Sediment avion * FigvwftToirTJ -"in this test 
the water treated and settled in Test VIII-A was pumped through 
the portable sand filter at the reduced rate of 6,35 gpm per 
square foot. It is apparent from Figure 32 that the procedure 
followed produced excellent results in removing turbidity. The 
passage of cysts through the filter in water containing only 0*1 
pp.m turbidity emphasizes the apparent impossibility of removing 
cysts with the sand filter when operated at rates practical for 
field use, 
JU Summary of the Xndirated Number of Cysts Removed by 
the Portable Sand Filter under Several ConditionsT TSee Figure 
It wiYl be noted that the efficiency of the unit varies 
somewhat proportionately with the coagulation achieved, the 
efficiency of the unit being highest when the control cf the 
coagulation is best. The coagulant used in this equipment was 
ammonium alum applied through a differential pressure pot. The contact time for floe formation ahead of the filter was quite 
short, there being but 10 feet of hose connecting the pump to 
the filter. The instructions for operating state that coagu- 
lants should be applied in sufficient quantity to produce a 
clear or satisfactory effluent. The result is that quite fre- 
quently a heavy after-floo forms in the effluent, while insuf- 
ficient flocculation is obtained ahead of the filter. At present, 
"clear water" is determined by observation on the part of the 
operator. Experience dictates that equipment for making a jar 
test and a turbidimeter for checking the quality of the effluent 
should be a part of this equipment. 
It will be noted from Figure 33 that two experiments 
were conducted using no coagulants. The results of these two 
experiments are not directly comparable because in the second 
experiment the filtration had been preceded by sedimentation 
and conceivably only the smaller cysts were present in the filter 
influent. The presence of considerable iron in the raw water 
of the first experiment may have acted as a floe, and assisted 
in the reduction of the number of cysts passing the filter. The 
significant feature of these two experiments is that it is con- 
vincingly demonstrated that sand alone does not remove the cysts 
of Endamoeba histolytica even at the reduced rate of 6.35 gpm 
per square foot, Hence*7 it follows that if cysts are to be re- 
moved from water with the portable sand filter, the removal must 
be accomplished by the coagulants alone or in combination with 
the sand. 
A comparison of the experiments in which careful control 
of the coagulants was maintained shows that the reduction of the 
rate of flow by one third materially aided in the removal of cysts. 
Thus the number of cysts passing the filter was reduced from 3900 
to 900 and 1400, respectively, in two experiments in which the 
rate of flow was reduced from 9.5 to 6.35 gpm per square foot. 
This reduction represents a fourfold increase in the efficiency 
of cyst removal. This reduction is consistent with the work of 
Baylis, Gullans, and Spector performed with a municipal type 
filter in which practically no cysts were found at the rate of 
2.0 gpm per square foot. The microscopic examination of the 
effluent samples after sand filtration showed in each case that 
objects of sizes considerably larger than cysts passed the filter. 
m. Results with coagulation and Sedimentation. (See 
Figure The results of experiments with pretreated water 
listed in Figure 34 show that the number of cysts in a given 
quantity of water is materially reduced by good coagulation and 
sedimentation, but that sedimentation alone for practical periods 
of time is of little value. It is obvious, therefore, that coagu- 
lation and sedimentation of the raw water is highly desirable be- 
fore filtration through the sand filters. A second feature of 
coagulating and settling the raw waver is that the resulting re- 
duction in raw water turbidity materially reduces the tendency of the filter to "break through" at frequent intervals. Prechlori- 
nating the raw water prior to the addition of the coagulants 
tends to reduce tastes and odors, and generally enhances the 
possibility of producing a safe water. 
9, Experiments with Diatomite Filters. The diatomite filters 
used in this study were experimental models, eight different units 
being used in all. It was anticipated that the numbers of cysts 
found in the effluent waters would provide a criterion for assessing 
the filtering efficiency of the types of equipment and filter aid 
tested. However, the results showed that with all equipment and 
filter aid tested, cysts were rarely found in the effluent water. 
It appears from these experiments that diatomaceous silica filtra- 
tton is much more effective than sand filtration for the removal of 
cysts. This is further confirmed by the microscopic examination of 
the filtered water, in which it was very rare to find particles 
larger than 2 or 3 micra in diameter. Experiments I-D through VI-D 
were conducted with small units for the purpose of obtaining data 
concerning the general characteristics of diatomaceous silica filters 
in removing cysts from water, while the objective of the remainder 
of the experiments was to determine the efficiency of the material 
and equipment under conditions similar to those encountered in the 
field. The experiments conducted were as follows: 
a. Experiment I~D0 Stoneheart Engineering Company Model 
SF-1.-” (See Figure 35,) In”this 'experiment, low pressure and 
flow rate was used? in general,, the results were inconclusive. 
However, attention is directed to the high concentration of cysts 
used in the re.w water and to the fact that from all of the 
effluent, no cysts were recovered. Since all of the water used 
was filtered, the filter was emptied with the fourth quart of 
water filtered, leaving the filter cake dry. The cake did not 
drop from the element when the flow ceased, 
b. Experiment 2-D. 'Wallace and Tiernan Company, Inc-, 
Model G2. "(See Figure 36,) This experiment was conducted with 
a gravity filter equipped with a wire screen element. Good 
clarification was obtained, but a few cysts passed the filter. 
, The element was observed to "breathe" under the influence of 
pressure variations* It is possible that the presence of cysts 
in samples 109 and 111 was caused by breaks in the cake because 
of slight pressure variations. However, the total number of 
cysts present was so small that the results obtained are incon- 
clusive. During the experiment it was observed that a gravity 
type filter of this general type permits raw water to spill over 
in filling the reservoir, thus providing a possible means of 
contaminating the filter effluent as well as of bringing the 
operator in contact with the raw water. 
_c« Experiment 3-D, S. F. Bowser and Company, Inc,, Model 
2MS. (See Figure 37, It will bo note’, from Figure 37 that no 
cysts were recovered from samples 112, 113, and 114 while a large number were present in sample 115. This unit was equipped 
with a very short length of suction hose which was most difficult 
to keep submerged during the experiment. Just prior to collecting 
sample 115, air entered the suction hose for several seconds9 The 
pump suction was thus momentarily interrupted, which interruption 
permitted the coke to break from the soreai element* Subsequent 
filtering did not appear to replace the filter aid satisfactorily* 
It was noted that the differential pot slurry feeder supp?vied with 
this unit tended to clog at intervals* 
d.* Experiment 4-D, S* F* Bowser or.d Company,, Inc.. Model 
1 *5C. (See Figure- 38*7 This experiment was quite similar to 
Experiment 3-D. In Experiment 4«D the preooat was applied with- 
out recirculation by discharging the effluent to waste. Sample 
117, collected after 1.6 minutes of operation,, contained a small 
number of cysts, while sample 118r taken after 1*55 minutes, con- 
tained no oyets* This result indicates that preooating is accom- 
plished with this un.it in less than two minutes. With modifica- 
tions in the inlet system used in Experiment 3-D,, it will be noted 
that the cake was replaced without difficulty after it hod been 
permitted to drop from the clement, A comparison of the action 
of the carbon element to that of the wire screen element used 
in Experiment 3-D showed that the carbon element retained the 
cake better than the wire screen element* This may indicate that 
the carbon element would be the better of the two whore variations 
3n pressure., momentary shut-down and other disturbances are 
expected. 
jp. Experiment 5-TV, International Filter Company, Inc*, 
Model gW-lT&V 7Soe”Figur'e”39“ f~lh. il equipment used‘~in 
this experiment was a laboratory model. the results of this ex- 
periment should be interpreted with caution. The absence of 
cysts in the influent is significant* 
f. Experiment 6-D»Naval Medical Research Institute. Model X* 
(See Tigures"40 and 41.) The significance of*this experiment is 
that it emphasizes the apparent ease with which cysts may be re- 
moved with simple devices employing diatomaoeous silica as the 
filtering medium. Attention is directed to the second phase of 
this experiment in which activated silver filter-aid was used. 
It will be seen in Figure 40 that a marked reduction in bacterial 
count was accomplished with the special filter aid, but that IB. 
ooli was present in the effluent samples even when the plate count 
was sterile for 0,1 oc. 
g. Experiment 7-D<Stoneheart Eng3neering Company, Model 
SF-XlV (See Figures 42j 43, and 44*”)”* In this experiment the 
precoat was applied with water containing a large number of cysts. 
While the results obtained are inconclusive. Figure 42 shows that 
cysts are removed by equipment having sufficient capacity to be 
used in the field* Cysts wore fo n.d in samples 129 end 130f 
thereafter, no cysts wore recovered * The filter used in this experiment was not constructed in a manner to permit easy venting 
of the air, with the result that the tubes did not properly pre- 
coat at the top* In addition, the engine stopped at time six 
minutes with some disturbance of the cake* as evidenced by the 
presence of silica in the effluent. Attention is directed to the 
increase in engine speed near the end of the operation. It was 
found that increasing the engine speed with the portable sand 
filter resulted in a Mbreak through” of the filter media, while 
no difficulty was encountered with the diatomite unit because of 
pressure changes. Slurry was introduced through the pump suction 
during the operation. 
h. Experiment 8-Do U. S. Army portable Water Purification 
Unitf1'iiode 1 1940, Converted for Use with Diatcmaceous Silica 
TEBiroTeT-SFG"!:'-'1 (§e~ Figures 45~and 46,,) This experiment 
was conducted with a standard sand unit converted by substituting 
three aloxite elements for the sand. The converted unit weighed 
165 pounds as compared to 435 pounds for the sand filter. The 
results tabulated in Figure 45 show that no cysts were recovered 
except in the first sample. Since the effluent hose was used in 
precoating, the presence of cysts in the first sample may have 
been due to contamination of the effluent hose rather than to 
cysts passing the filter after the precoat was in place. Atten- 
tion is directed to the use of carbon in this experiment. Be- 
cause of the presence of considerable color in the water, a 
secondary precoat of carbon was applied at the start of the 
operation. Figure 46 shows that the carbon was retained on the 
original precnaty and the absence of any appreciable increase 
in turbidity after 24 hours shows that the color was removed 
satisfactorily. The influent pressure was maintained at eight 
pounds per square inch during the operation, with the exception 
of the last three minutes of the filter run when the influent 
pressure was increased to 13,5 pounds per square inch. The 
sudden rise in pressure did not disturb the operation in any 
manner. It will be noted that the average output during the 
operation was approximately 19,5 gpm. 
_i. Experiment 9-D. U« S. Army Portable 'water Purification 
Unit. Model 1940, Converted for Use with piatomaceous Silica 
TEB Model SFC-1). TSee Figures 47 and 46.) This experiment’ 
differed from Experiment 8-D only in that activated carbon was 
omitted and that the pump was operated at full capacity from 
the beginning of the operation. The results tabulated show 
that the omission of carbon on the filter reduced the resistance 
and permitted higher flow rates* However, the marked increase 
in effluent turbidity after 24 hours indicates that color is 
not removed by the filter alone. The results show that total 
removal of cysts was accomplished during the operation at an 
average output of 25.9 gpm. 
• Experiments 10-D Through 13-P_Inclusive. U? Se Army 
Portable Fater Purification Unit, Model 1940, Converted for Use With Diatomaoeous Silica. (See Figures 49, 50, 51, and 52.) 
The 'purpose of this series of tests was to determine the effect 
tiveness of various grades of diatomaoeous silica in the removal 
of cysts, from water. Attention is directed to the absence of 
cysts in quantity in the effluent from all of the materials 
tested. Since cysts were removed by all of the materials tested, 
the significant feature of these tests is that no cysts passed 
the unit in Experiment 13-D. The filter aid used in the experi- 
ment was Johns-Manvilie Celite 545, which is too coarse for water 
filtration. Notwithstanding the passage of turbidity in excess 
of 10 ppm no cysts were found in the effluent samples. Bacterial 
removal with the several grades of filter-aid tested is shown in 
Figure 53. It appears, therefore, that any currently manufactured 
filter-aid in the range of the materials tested will produce 
satisfactory results. 
The test results indicate that diatomaoeous silica filtra- 
tion is much more effective than sand filtration for the removal of 
amoebic cysts. A filtration unit properly designed and operated 
would be expected to remove completely the cysts of Endamoeba histolytica^ 
It was not the objective of this study to develop diatomaoeous 
silica filters, but rather to determine the efficiency of the material 
in removing cysts from water. However, during the tests the following 
design features were recognized as being essential for best resultss 
a. It appears that all diatomite filters should be pro- 
vided with an air release cock which should be left open until 
the filter shell is entirely full of water at the start of the 
precoat operation. 
b. In order to obtain an evenly distributed precoat, to 
obtain good initial clarity, and to prevent plugging the element 
with dirt, the elements should be so mounted as to permit the 
water in the filter to rise at least one inch above the top of 
the elements. 
c. If the filter is precoated by recirculating a quantity 
of wa*ter, the water used should be filtered water and the piping 
arrangement should permit the change from preooating to filtering 
without interrupting the continuous flow of water. If recircula- 
tion is not employed, the precoat charge should be introduced 
directly into the filter shell. 
d. There appears to be no definite relationship between 
the optimum rate of slurry feed and the turbidity (ppm) of the 
water filtered. The controlling factor in slurry feeding appears 
to be the nature of the raw water turbidity, water containing 
organic slimes requiring much more slurry than water containing 
only hard non-compressible particles. e. Since the quality of the effluent from a diatomite 
filter is not necessarily a function of the pressure employed, 
it would appear that greatest efficiency would be realized when 
using pressures considerably in excess of those employed with ' 
sand filters. 
£, The spent cake may be contaminated with amoebic cysts, 
oercariae, and other such organisms; hence, a cleaning or back- 
wash method which does not bring the operator in direct contact, 
with the waste material is necessary. The use of any but filtered 
water in backwashing should be prohibited, and the method used 
should not require the placing of the suction hose in the filtered 
water tank. 
V. CONCLUSIONS 
10* Conclusions. As a result of the study of the efficiency of 
standard army water purification equipment and of diatomite filters 
in removing cysts of Endamoeba histolytica from water, it is concluded 
that: 
a. The complete removal of the Cysts of Endamoeba histolytica 
is not accomplished with the sand filter cf tho~Tf, S*. Army Portable 
Water Purification Unit when operated at flow rates practical for 
field use, and it may be logically assumed that this condition 
applies also to the U. S. Army Mobile Water Purification Unit. 
b. Sedimentation alone for short periods is not effective 
in removing amoebic cysts from water* 
The total number of cysts in a given quantity of water 
is reduced by good coagulation end sedimentation. 
d. Pressure type filters using diatomaceous silica as the 
filter medium will remove cysts of Endamoeba histolytica, pro- 
vided the retaining membrane or element /"as well as the filter 
shell, is correctly designed. 
£• The combination of pretreatment, sedimentation, and 
filtration gives results considerably better than filtration 
alone. 
VI. RECOMMEND AT IONS 
11* Recommendations. In view of the findings of this study of 
removal of cysts of Endamoeba histolytica from water, it is recommended 
that: 
a. The output of the U. S. Amy Portable Water Purification 
Unit, Model 1940, be reduced from 15 gallons per minute to 10 gallons per minute as a maximum, and that this output be.further 
reduced to not greater than 7,5 gallons per minute whenever 
possible. 
b. The output of the U, S, Army Mobile Water Purifica- 
tion Unit, Model 194-0, be reduced from 75 gallons per minute 
to 60 gallons per minute as a maximum, and that this output be 
further reduced to not greater than 45 gallons per minute when- 
ever possible, 
(it must be understood that this reduction in output rates 
is of an emergency nature and, while increasing the factor of 
safety, does not imply that complete removal of the cysts of 
Endamoeba histolytica is assured by adherence to the action 
recommended above.) 
c. One hour of detention be provided for coagulating, 
settling and prechlorinating all raw water without exception 
prior to filtration through either of the sand units, 
d. Field water quality control equipment be provided to 
all units in the field, which shall, among other things, pro- 
vide equipment for conducting jar tests and for the evaluation 
of the overall efficiency of the filtration in terms of turbidity 
removal. 
e. The study of diatomaceous silica now being conducted 
by the Engineer Board be continued to the end of determining the 
feasibility of the adoption of diatomaceous silica filtration 
equipment to replace the sand filters now in use, 
f. Studies of the epidemiology of amoebic dysentery in 
the armed forces of the United Nations be encouraged, and reports 
from the field be examined to determine the magnitude of the part 
that water may be playing in the dissemination of amoebic dysentery. 
Submitted by* 
nArry N. ybyre, Jr, 
Assistant' Engineer, Sanitary 
Water Supply Equipment Branch 
Frederick J. Brady 
Surgeon, Zoology Laboratory 
National Institute of Health 
U. S. Public Health Service Myjrha Jones' j 
Zqplogist, Zoology Laborato 
National Institute of Heart 
U, S. Public Health Service 
W. H*s Wright 
Chief, Zoology Laboratory 
National Institute of Health 
U. S, Public Health Service 
Hayse b,/Slack 
Captain,(dorps of Engineers 
Chief, Water Supply Equipment Branch 
The Engineer Board 
f Forwarded^ 
Karl F. Eklund 
Lt. Colonel, Corps of Engineers 
Director, Technical Division III 
The Engineer Board ' ACKNOWLEDGMENT 
The authors are indebted to past Assistant Surgeon 
Carl Larson for that part of the bacteriological work that was 
performed at the National Institute of Health, to Junior Zoolo- 
gist Walter L. Newton and Assistant Zoologist John Tobie for 
their aid in the examination of the water samples for amoeba 
cysts, and to Assistant Sanitary Engineer Ernest He Sieveka and 
Mr, F* R. LeNormandie of the Engineer Board Laboratory for the 
chemical analyses. .APPENDIX A 
AUTHORITY WAR DEPARTMENT 
OFFICE OF THE CHIEF OF ENGINEERS 
WASHINGTON 
SPESD March 19, 1943 
Subjects Study of the Effectiveness of Army Purification Methods 
in Removing Cysts of Endomoeba histolytica 
To: The President, 
The Engineer Boards 
Fort Belvoir, Virginia 
1. The Office of the Surgeon General has requested the Chief 
of Engineers to cooperate with the Rational Institute of Health in 
the study of the removal of the Cysts of Endomoeba histolytica from 
drinking water by means of standard Army purification equipment. This 
request has been approved with permission to contact the Engineer 
Board directly in this matter. 
2. The Office of the Surgeon General has made an arrangement 
with the Rational Institute of Health to carry On certain studies of 
the epidemiology of amebiasis. This was done in accordance with a 
directive file number GPRMD 720,21, dated January 29, 1943 issued by 
the Commanding General., Services of Supply to the Medical Department. 
A copy of this directive has previously been sent to the Engineer 
Board. 
3. It is therefore directed that the Engineer Board cooperate 
with the Surgeon GeneralJs office and the Rational Institute of Health 
in the program set up by them for the study of the Removal of the 
Cysts of Endamoeba histolytica. The cooperation of the Engineer Board 
is to be TimiYod'tV that necessary to furnish properly filtered water 
as requested by the Rational Institute of Health. 
By order of the Chief of Engineers: 
/%/ £• L« Knutson, 
/V E. L. KNUTSON, 
Captain, Corps of Engineers, 
Assistant, Engineering and Development Branch, 
Supply Division. 
larger :bg 
EXT. 76271 APPENDIX B 
TEST RESULTS DATA, SHEETS 
7 ” Test Number I 
Sheet 1 of 1 
March 30 
, 1943 
Sample Elapsed 
Number Time 
Min. 
Output 
G.P.M. 
Infl. 
Press 
psi 
Effl. 
Press 
psi 
Effl. 
Turb. 
PPm . 
Cysts Recovered 
Per Gallon Per 
Million Applied 
Operation 
Remarks 
- 
0-20 
12-15 
- 
Filtering 
- 
0 
15 
5 
2 
- 
- 
M 
1,4 million cysts applied in 
1 
2 
1.0 
1.790 
M 
a batch through the 
pump 
2 
5 
1.0 
540 
H 
suction. 
3 
10 
1.0 
117 
II 
4 
15 
14.5 
5 
2 
1.0 
191 
It 
Gradual decrease in 
output 
5 
20 
< 
1.0 
60 
II 
noted 
6 
25 
1.0 
83 
II 
7 
30 
1.0 
21 
It 
8 
35 
1.0 
12 
It 
9 
A0 
1.0 
12 
It 
10 
45 
1.0 
5 
It 
11 
50 
11 
5 
1.5 
1.0 
34 
II 
Raw Water: 
Source: Belvoir Tap* 
Turbidity: 10/ 
p.p.m. pH: 7.6, Temperature: 52°F. 
Treatment: 
Alum Applied: 
None* 
Soda Ash Applied 
: None* Other 
Treatment: None. 
Procedure 
and Remarks: After operating the 
filter 
for 20 minutes. 
the output of 
the unit was adjusted 
to 15 gallons per minute. 
1.4 million cysts of E. 
histolvtica were 
then applied 
in a batch through 
the pump suction 
over a period of 30 seconds. The 
turbidity of the tap water used was due almost 
entirely to iron 
which may 
have acted as a 
floe, restricting the flow after 15 minutes of the test 
operation. 
The pump was set to maintain a 
constant discharge pressure throughout the operation. 
Total wate 
r filtered: 666 gallons 
• 
Fig. 9 
Army Portable Water Purification Unit 
Cyst Removal With Operation At Rated Capacity Without Coagulants 
The Engineer Board and United States Public Health Service Test Number II 
Sheet 1 
of 2 
April 9, 1943 
Sample 
Elapsed 
Output 
Infl. Effl. 
Effl. 
Effl. Cysts Recovered 
Number 
Time 
G.P.M. 
Press Press 
pH 
Turb. Per Gallon Per Operation 
Remarks 
Min. 
osi osi 
ppm Million Applied 
- 
0-40 
15-18 
6.6 
6.6 
6.6 
1,0/ 
1.0/ 
1.0/ 
1.0/ 
2.0 
2.0/ 
2.0 
2.0 
2.0 
1.0 
- Backwash 
Backwash with raw 
12 
13 
14 
15 
16 
17 
18 
19 
20 
0-20 
0 
1 
12-15 
15 
5 2 
Filtering 
. t» 
398 " 
water. 
2 million cysts 
applied in a batch. 
3 
5 
10 
15 
20 
25 
30 
34 
10 
8.5 
5.7 
5 
8 0 
12 0 
6,6 
6.6 
6.6 
6.6 
6,6 
6.6 
1,322 » 
286 " 
232 " 
10 » 
2 " 
2 " 
1 " 
Effluent slightly 
milky. 
Difficulty noted in 
maintaining a constant 
treated water pH, The 
pH was adjusted to 6,6 
just prior to the 
/ 
6.6 
1.0- 
0 « 
taking of each sample. 
21 
22 
*4- 
•• 
** 
•• It 
while variations 
40 
50 
3 
2.7 
14.5 0 
6.6 
6,6 
1.0- 
1.0- 
0 " 
0 " 
between 6.4 to 6,8/ 
were noted. 
Raw Waters Source: Belvoir Tap nnd Olay, 
Turbidity: 50 
ppm. pH: 7.5* Temperature: 53°F. 
Treatment! Alum Applied: 
1.6-1.7 gr/gal. 
. Soda 
Ash Applied: 1 gr./gal, (Discontinued 
i after 5 min.) 
i begun; the 
soda ash 
coagulants being varied until a. satisfactory effluent was obtained. In that the use 
of 
did not improve the effluent, its use was 
discontinued at time 0-15 (elapsed time). 
The pH with 
the use 
of alum alone was 
found to be 6.6. 
Two mill ion cysts of E. histolytica were 
applied in a 
oaten tnrough the pump suction at zero minutes over a period 
•of 30 seconds. Total water 
filtered: 315 gallons. 
Fig. 10 
Army Portable Water Purification Unit 
Cyst Removal With Operation At Rated Capacity With Coagulant 
The Engineer Board and United States Public Health Service Test Number 
Sheet 2 of 
II 
2 
April 9, 1943 
Sample 
Number 
pH 
Turbidity 
Alkalinity 
M0 
ppm 
Sulphates 
SO^ 
ppm 
Alum Dosage(Gr./Gal.) 
Appearance 
of 
Effluent 
Sediment 
After 24 
HrsT 
At Unit 
. ppm 
24 Hrs. 
ppm 
Calc. From 
Alkalinity 
Calj. Prom 
Sulphates 
Raw 
7.5 
50 
50 
19.0 
8.1 
- 
• 
12 
7.3 
1.0/ 
2.0 
17.8 
11.1 
0.2 
0.3 
Slightly Very slight 
13 
7.0 
1.0/ 
1.5 
10.0 
20,3 
1.8 
1.6 
Clear 
None 
U 
6.8 
2.0 
3.0 
6.8 
27.6 
2.4 
2.7 
Slightly milky Moderate 
15 
6.8 
2.0/ 
4.0 
6,4 
26.6 
2.4 
2.7 
11 11 
n 
16 
6.9 
2.0 
3.0 
9.4 
19.7 
1.9 
1,6 
« »» 
rt 
17 
6,8 
2.0 
4.0 
6.2 
25.2 
2.5 
2.4 
n tt 
n 
18 
6.9 
2.0 
3.0 
9.0 
18.8 
2.0 
1.4 
n n 
it 
19 
7.0 
1.0 
1.5 
11.6 
17.0 
1.4 
1.2 
Clear 
Slight 
20 
7.2 
1.0- 
1.0 
12.2 
14.6 
1.3 
0.9 
Clear 
None 
21 
7.2 
1.0- 
1.0- 
12.2 
15.2 
1.3 
0.9 
n 
None 
22 
7.2 
1.0- 
1.0- 
12.8 
22,4 
1*4 
1.9 
it 
None 
Av. 1.7 
Av.1.6 
Remarks: The alkalinity values tabulated 
above show 
that the effluent approached distilled 
water 
in its carbonate and bicarbonate content. This 
1 water would 
have very little buffering 
action 
and may account, in part, for 
the difference between 
the Beckman pH readings * 
bove and the readings 
with Bromthymol Blue 
made at - 
the unit (Figure 10). 
Fig. 11 
Army Portable Water Purification Unit 
Cyst Removal With Operation At Rated Capacity With Coagulants 
The Engineer Board and United States Public Health Service Test Number III 
Sheet 1 of 3 
April 16, 1943 
Sample Elapsed 
Number Time 
Min. 
Output 
G.P.M. 
Infl. 
Press 
psi 
Em. 
Press 
nsi 
Effl, 
pH 
Effl. 
Turb. 
ppm 
Cysts Recovered 
Per Gallon Per 
Million Applied 
Operation 
Remarks 
- 
0-11 
16 
8 
0 
- 
- 
Backwash 
Discharged to waste. 
- 
0-8 
15 
5 
2 
6.4 
- 
- 
Filtering 
1.5 M cysts applied. 
- 
0 
15 
5 
2 
6,4 
1- 
- 
n 
Few particles of fine 
23 
3A 
15 
5 
2 
6.4 
1- 
77 
it 
sand noted in effluent. 
24 
2 
14.5 
5 
2 
6.4 
1- 
50 
tt 
2$ 
3 
14.5 
5 
2 
6,4 
1- 
10 
ti 
26 
5 
14 
5 
2 
6.4 
1- 
8 
M 
27 
10 
14 
5 
2 
6.4 
1- 
3 
tt 
28 
15 
14 
5 
2 
6.4 
1.0 
0 
it 
29 
20 
13 
5 
2 
6.4 
1.0 
3 
n 
30 
25 
13 
5 
2 
6.4 
1.0 
5 
it 
31 
30 
13 
5 
2 
6.4 
2/ 
0 
tt 
Effluent cloudy 
32 
40 
13 
5 
2 
6,4 
2.0 
0 
tt 
it it 
33 
50 
12 
5 
2 
6,4 
1-2 
0 
tt 
After floe noted 
- 
60 
12 
5 
2 
6.4 
3/ 
• 
tt 
it n n 
— 
61 
17 
8 
0 
* 
- 
Backwash 
Raw Water* Source: Potomac River, 
Turbidity; 
50 p.p.m. 
pH: 7.2. Temperature; 48°F. 
Treatment; *0ptimum Coagulant Dosage: 2 
gr./gal 
, (alum)# 
Alum Applied; 2, 
0 - 2.2 gr./gal. 
Procedure and Remarks; *Determined by standard 1ar test. 
The unit was backwashed and then operated 
with the addition 
of the coagulant for eight minutes during which time the effluent was run 
to waste. 
The output was then adjusted to 15 G.P.M. 
and 1.5 million cysts of E. histolytica were applied through 
the 
pump suction over a period of 30 seconds. Considerable 
care was exercised 
to maintain the pH of 
the 
treated water 
at the 
value of 6,4; readings and adjustments being made at 
one-minute intervals. 
Total water filtered; 64-7 gallons. 
Fig. 12 
Army Portable 7fater Purification Unit 
Cyst Removal With Operation At Rated Capacity With Coagulants 
The Engineer. Board and United States Public Health Service Test Number III 
Sheet 2 of 3 
April 16, 1943 
Sample 
Turbidity 
Alka.l inity 
Sulphates 
Alum Dosage (Gr./GaT.) 
Appearance 
Sedime nt 
Number 
pH At Unit 
24 Hrs. 
M0 
S0£ 
Calc. From 
Calc. From 
of 
After 
ppm 
ppm 
ppm 
ppm 
Alkalinity 
Sulphates 
Effluent 
24 Hours 
Raw 
7.2 
50 
50 
37.2 
9.1 
- 
- 
- 
Fine, flaky particles 
23 
6.9 
1- 
3.0 
27.4 
22.5 
2.1 
1.8 
Clear 
Small amount of sand 
24 
6,8 
1- 
1.0 
24.8 
24.6 
2.3 
2.1 
it 
ti 11 it it 
25 
6,8 
3- 
1.0 
26,4 
* 
* 
* 
11 
rt it n n 
26 
6.7 
1- 
1.0 
25.8 
19.6 
1.8 
1.5 
tt 
None 
27 
6.7 
1*- 
1.0 
27.2 
25.1 
2.2 * 
2.1 
11 
Slight 
28 
6.8 
1 
1.5 
25.8 
29.9 
2.3 
2.9 
t» 
Slight 
29 
6.7 
1 
3.5 
26.2 
29.7 
1.9 
2. 8 
n 
Moderate 
30 
6.8 
1 
2.0 
26 .4 
26.5 
2.2 
2.4 
ti 
Moderate 
31 
6.7 
2/ 
3.0 
28.4, 
27.9 
1.9 
2.6 
Cloudy 
Much 
32 
6.9 
2 
3.0 
28.2 
25.0 
2.0 
2.1 
it 
Much 
33 
6.9 
1/ 
3.0 
30.6 
24.1 
1.8 
2.1 
ti 
Av. 2.0 Av. 
2.2 
Remarks 
j broken. The appearance of 
the sediment after 24 hours found in 
samples 31, 
32 and 33 
indicated that 
a slight breakthrough had occurred. Attention is called 
to the increase in turbidity 
values 
both at 
the unit 
and after 24 hours in these sample 
s. In addition to turbidity some after 
floe was noted 
in sample 31, 32, 
33. 
FiG. 13 
Army Portable Water Purification Unit 
Cyst Removal With Operation At Rated Capacity With Coagulants 
The Engineer Board and United States Public Health Service Test Number III 
Sheet 3 
of 3 
April 16, 1943 
Sample 
Plate Count 
Turbidity At 
Number 
Nutrient 
LACTOSE BROTH 
Unit 
Agar 20°0 
10 ml 
1 
ml 
1/10 ml 1/100 ml 
1/1000 ml (from Sheet 2) 
EtW 
A 
12,000 
4 
4 
4 
50 
B 
32,000 
■k 
4 
— 
0 
30,000 
4 
4 
mm 
50 
D 
18,000 
4 
4 
4 
B 
20,000 
4 
4 
<-4) 
_ 
50 
r 
16,500 
4 
4 
mm 
a 
24,000 
4 
4 
mm . 
(V) 
50 
E 
20.000 
4 
- 
w 
- 
Av, 
, 21,500 
23 
24,000 
WWW 
mm 
1- 
24 
2,600 
— — «. 
mm 
mm 
<a» mm 
IM 
1- 
25 
3,800 
- - U) 
mm 
mrn 
mm 
mm mm mrn 
1- 
26 
2,1+00 
_ _ 
mm 
mm 
(4) 
mm mm mm 
1- 
27 
28 
3.300 
2,100 
- 
- 
- - - 
- 
1- 
1 
29 
2,000 
W)«) 4 
— 
— 
M — •» 
1 
30 
3.300 
(4) 44 
i4U4n4) 
4 mm mm mm 
1 
31 
4,500 
i4)i4H4) 
_ _ _ 
2-4 
32 
7,600 
4 4 4 
U)U)U) 
- (V) 
2 
33 
20,000 
4 4 4 
4 
4 
4 
- tf) 7 
u 
Remarks! 
Samoles A through H above reuresent samples taken from the 
raw water source at intervals 
during the 
operation. 
Samoles 
marked thus (•/) were negative after 24 hours but positive 
after 48 hours. 
« 
Fig. 1U 
Army Portable Water Purification Unit 
Cyst Removal With Operation At Rated Capacity With Coagulant 
The Sngineer Board and United States Public Health Service Test Number IV 
Sheet 1 of 3 
April 27, 1943 
Sample 
Number 
Elapsed 
Time 
Min. 
Output 
G.P.M. 
Infl. 
Press 
psi 
Effl. 
Press 
psi 
Effl. 
pH 
Effl. Cysts Recovered 
Turb. Per Galloii Per Operation 
ppm Million Applied 
Remarks 
- 
0-20 
18 
6.5 
1.0 
— 
- Backwashing 
Raw water used with 
- 
0-10 
10 
2.5 
1.0 
6.4 
5.0 
Filtering 
no cysts added. 
- 
0 
10 
3.5 
1.5 
6.5 
1.0- 
_ it 
2.5 million cysts 
34 
3/4 
10 
3.5 
1.5 
6.3 
1.0- 
0.8 " 
applied in a batch. 
35 
2 
10 
3.5 
1.5 
6.5 
1.0- 
1,6 " 
36 
3 
10 
3.5 
1.5- 
6.5 
1.0- 
2.4 " 
37 
5 
10 
3.5 
1.5 
6.5 
0.8 
3.2 " 
38 
10 
10 
3.5 
1.5 
6.5 
2 
1,6 " 
39 
15 
10.5 
3.5 
1.5 
6.4/ 
4 
3.2 ,f 
Alum dosage increased 
40 
20 
10 
3.5 
1.5 
6.4 
0.5- 
1.6 ” 
slightly to correct 
41 
30 
9.5 
3.5 
1.5 
6.4 
1.0 
0.0 " 
increasing amount of 
- 
- 
- 
- 
- 
m 
- 11 
effluent turbidity. 
42 
32 
9.2 
3.5 
1.5 
6.4 
1.0 
n.O " 
2,5 million cysts 
43 
32-3/4 
9.2 
3.5 
1.5 
6.4 
2.0 
8.0 " 
applied in a batch. 
44 
34 
9 
3.5 
1.5 
6.4 
1.0- 
3.2 " 
45 
35 
9 
3.5 
1.5 
6,4 
1.5 
1.6 " 
46 
37 
9 
3.5 
1.5 
6.4 
1.5 
9.6 11 
Raw Waters Source: Potomac Riverr 
Turbidity: 165 p.p.m. 
pH: 7.1, Temperature; 59°F, 
Treatment: *0ptimum Coagulant Dosage: 2. 
5 gr./gal 
. (alum)# 
Alum Applied: 2.8 - 3.2 gr 
./gal. 
Procedure and Remarks; -^Determined 
by standard jar 
test. After backwashing, the unit was 
operated for ten 
minutes 
at 10 G.P 
,M. 2,5 million 
cysts of E. histolytica were 
then applied through the pump suction over 
a period of 30 seconds. At 
32 minutes, 2, 
5 million cysts v;ere 
applied in a through 
the pump suction 
in like 
manner to 
the first batch applied at the beginning of the test. Note: Turbidity 
of raw water due 
to a heavy rain. 
The turbidity for 
the most part consisted of 
relatively large particles. 
Total water 
filtered: 475 gallons. 
Fig. 15 
Army Portable Water Purification Unit 
Cyst Removal 7/ith Operation At Reduced Rate With Coagulants 
The Engineer Board and United States Public Health Service Test Number IV 
Sheet 2 of 3 
April 27, 1943 
Sample 
Turbidity 
Alkalinity 
Sulphates Alum Dosage (Gr./Gal.) 
Appearance 
Sediment 
Number pH 
At Unit 
24 Hrs. 
M0 
SO/ 
Calc, From 
Calc. From 
of 
After 
ppm 
ppm 
ppm 
ppm 
A1kalinity 
Sulphates 
Ef fluent 
24 Hours 
Raw 
7.4 
165 
165 
43 
14.8 
- 
- 
- 
Very heavy 
0 
6.8 
1.0- 
- 
20 
45.4 
4.4 
3.7 
Clear 
Heavy after floe 
34 
6.7 
1.0- 
1.5 
29 
34.9 
2.8 
2.7 
it 
Slight 
35 
6,8 
1.0- 
1.5 
32 
25.7 
2.2 
1.4 
n 
Nil 
36 
6.9. 
1.0- 
1.0 
36 
22.9 
1.4 
1.0 
n 
Slight 
37 
7.0 
0.8 
2.0 
36 
21.4 
1.4 
0,8 
ti 
Slight 
38 
7.1 
2.0 
4.5 
36 
23.9 
1.4 
1.1 
Milky 
Moderate 
39 
- 
4.0 
8.0 
16 
54.3 
5.4 
4.8 
ii 
Heavy 
40 
6.7 
0.5- 
1.5 
18 
50.1 
4.6 
4.2 
Cloudy 
Slight 
41 
7.0 
1.0 
2.0 
32 
29.9 
2.2 
2.1 
it 
Moderate 
42 
7.0 
1.0 
2.5 
27 
37.9 
3.2 
3.1 
rt 
Slight 
43 
6.9 
2.0 
3.0 
23 
41.9 
4.0 
3.6 
it 
Moderate 
44 
6,8 
1.0- 
3.0 
21 
45.0 
4.4 
4.0 
it 
Moderate 
45 
6.8 
1.5 
2.5 
21 
44.5 
4.4 
4.0 
it 
Moderate 
46 
6.7 
1.5 
2.5 
24 
40.1 
H 
Moderate 
Av. 3.2 Av, 2,8 
Remarks; Attention is 
called to the range of 
the pH values above obtained with a 
Beckman instrument 
as compared 
with the pH values 
obtained at the 
f unit 
(Figure 15) with the standard Brorathymol 
B1 ue 
color ( 
disc. The jar test 
conducted prior 
• to this operation showed that 2 gr./gal. of alum 
gave 
a pinpoint ; 
floe while 3 
gr./gal 
. gave a heavy floe. 
Attention is directed to the 
presence of after 
floe 
in the 
effluent notwithstanding the reduced flo^j 
t rate. 
Fig. 16 
Array Portable Water Purification Unit 
Cyst Removal With Operation At Reduced Rate With Coagulants 
The Engineer Board and United States Public Health Service Test Number IV 
Sheet 3 of 3 
Bacterial Analysis 
April 27, 1943 
Sample 
Bacterial Count 
Smallest Quantity 
* 
Number 
Per c.c. 
Positive For 
°C 
B. Coli 
Raw 0f 
250 
0.1 
c.c. 
Raw 10' 
270 
0.01 
c.c. 
Raw 20' 
380 
0.1 
c.c. 
Raw 30* 
320 
0.1 
c.c. 
0* 
106 
10.0 
c.c. 
34 
10 
0.1 
c.c. 
35 
26 
1.0 
c.c. 
36 
24 
1.0 
c.c. 
37 
24 
1.0 
c.c. 
3* 
188 
1.0 
c.c. 
39 
222 
1.0 
c.c. 
4-0 
14 
10.0 
c.c. 
41 
36 
0.1 
c.c. 
42 
43 
0.1 
c.c. 
43 
87 
0.1 
c.c. 
44 
165 
1.0 
c.c. 
45 
80 
1.0 
c.c. 
46 
325 
1.0 
c.c. 
Fig. 17 
Army Portable Water Purification Unit 
Cyst Removal With Operation at Reduced Rate With Coagulants 
The Engineer Board and United States Public Health Service Test Number V 
Sheet 1 of A 
May 4, 1943 
Sample 
Number 
Elapsed 
Time 
Min. 
Output 
G.P.M. 
Infl. 
Press 
psi 
Effl. 
Press 
psi 
Effl. 
pH 
Effl. 
Turb, 
ppm 
Cysts Recovered 
Per Gallon Per 
Mill ion Applied 
Opera tion 
Remarks 
0-16 
20 
5 
2 
Backwashing 
Raw water used 
- 
0-11 
10 
4 
2 
- 
1/ 
- 
Filtering 
containing no cysts. 
47 
0 
10 
3.2$ 
1 
6,8 
o.$ 
0.0 
n 
Addition of cysts 
48 
3/4 
10 
3.25 
1 
6,8 
0.5- 
0.0 
it 
through hypo- 
49 
2 
10 
3.2$ 
1 
6.8 
o.$- 
22.8 
H 
chlorinator begun. 
' $0 
3 
10 
3.2$ 
1 
6.8 
o.$- 
0.0 
It 
51 
5 
10 
3.2$ 
1 
6.8 
o.$- 
0.0 
It 
52 
10 
10 
3.2$ 
1 
6,8 
o.$- 
0.0 
It 
53 
15 
10 
3.2$ 
1 
6.8 
o.$- 
1.8 
tt 
54 
20 
9.5 
4 
1 
6.6 
0.5 
1.4 
It 
Pump speed increased 
55 
30 
11 
4 
1 
6,8 
4 
3.7 
M 
to maintain flow at 
56 
40 
10 
3.5 
1 
6.7 
3 
9.9 
tt 
10 g.p.m. Effluent 
31 57 
50 
10 
4 
1 
6.7 
5 
10.1 
tt 
cloudy in samples 
- 
• 
- 
- 
- 
- 
30,40, and $0. 
- 
0-5 
20 
5 
2 
_ 
_ 
Backwashing 
Raw water used 
58 
0 
6.5 
o.$ 
0 
7.1 
5/ 
0.0 
Filtering 
containing no cysts 
59 
8 
9.5 
2.75 
1 
6.7 
1/ 
2.0* 
tt 
*2,0 cysts per gal. 
60 
9 
9.5 
2.75 
1 
6.7 
1/ 
0.0 
it 
Not cysts per gal. 
■ 61 
10 
10 
2,75 
1 
6.8 
1- 
0.0 
n 
per million applied 
62 
11 
11 
3 
1 
6,8 
1- 
0.0 
it 
since none added 
after sample #$7 
Continued on Sheet 2, 
Fig. 18 
Army Portable Water Purification Unit 
Cyst Removal With Operation At Reduced Rate With Coagulants 
The Engineer Board and United States PuWLic Health Service Fig. 19 
Army Portable Water Purification Unit 
Cyst Removal With Operation At Reduced Rate With Coagulants 
The Engineer Board and United States Public Health Service 
Test Number V 
Sheet 2 of U May U, 194-3 
Raw Water: Source: Potomac River, Turbidity; 120 p.p.ra,, pH: 7.1, Temperature: 5&°F 
Treatment; ** Optimum Coagulant Dosage: 2 gr./gal. (alum): Alum Applied: 2,3-2,4- gr./gal. 
Procedure and Remarks: The unit was backwashed with raw water and than operated with alum for 11 minutes. 
Cysts of E, histolytica were applied through the hypochlorinator at the rate of 7,000 per gallon of effluent 
starting at zero minutes (Elapsed Time), After $0 minutes of operation, the unit was shut down, 
backwashed with river water to which no cysts had been added and operation resumed with no further addition 
of cysts. Samples were collected at intervals. ** Determined by standard jar test. Totaled water 
filtered: 50/r gallons. Test Number V 
Sheet 3 of 4. 
May 4, 1943 
Sample 
Turbidity 
Alkalinity 
Sulphates 
Alum Dosage 
(Or./Gal.1) 
Appearance 
Sediment 
Number 
PH 
At Unit 
ppm 
24 Hours 
ppm 
M0 
ppm 
S04 
ppm 
Calc. From 
Alkalinity 
Calc. From 
Sulphates 
Of 
Effluent 
After- 
24 Hours 
Raw 
7.1* 
120 
49.3 
15.7 
47 
7.0 
0.5 
2.5 
38.8 
36.2 
2.1 
2.8 
Clear 
Slight 
4-8 
7.1 
0.5- 
1.0 
40.4 
26.1 
1.7 
1.2 
M 
None 
49 
7.1 
0.5- 
1,0 
39.1 
33.7 
2.0 
2.5 
It 
n 
50 
7.1 
0.5- 
1.0- 
38.8 
31.5 
2.1 
2.0 
II 
it 
51 
7.1 
0.5- 
1.0- 
38.9 
29.9 
2.1 
1.9 
It 
it 
52 
6.9 
0.5- 
1.0- 
34.1 
37.3 
3.0 
2,9 
II 
it 
53 
7.0 
0.5- 
1.0- 
3A.6 
32.1 
2.9 
2.1 
It 
it 
54 
7.0 
0.5 
1.0 
34.7 
33.3 
2.9 
2.4 
II 
it 
55 
7.1 
4 
5.0 
37.1 
32.0 
2.4 
2.2 
Milky 
Moderate 
56 
7.1 
3 
4.5 
37.3 
34.8 
2.4 
2.6 
n 
Slight 
57 
7.0 
5 
7.5 
35.0 
35.6 
Av. 
2.8 
2.4 Av. 
2.8 
. 2.3 
Dirty 
Heavy 
Remarks: *r>H reading with Bromthymol Blue. 
"Break-through11 of filter bed. 
Turbidity in 
samples Nos. 
55, 56, and 
57 indicates definite 
Fig. 20 
Army Portable Water Purification Unit 
Cyst Removal With Operation At Reduced Rate With Coagulants 
The Engineer Board and United States Public Health Service Test Number V 
Sheet 4 of 4 
Bacterial Analysis 
May 4, 1943 
Sample 
Number 
*Bacterial 
Per c 
°C 
Count 
.c. 
Smallest Quantity 
Positive For 
B. Coli. 
Raw 0* 
180 
0.1 
c.c. 
Raw 10* 
4,300 
0.1 
c.c. 
Raw 301 
5,000 
0.1 
c.c. 
Raw 50* 
2,400 
0.1 
c.c. 
47 
22 
(absent) 
10.0 
c.c. 
48 
23 
10.0 
c.c. 
49 
25 
(absent) 
10.0 
c.c. 
50 
20 
(absent) 
10,0 
c.c. 
51 
42 
(absent) 
10.0 
c.c. 
52 
190 
10.0 
c.c. 
53 
26 
1.0 
c.c. 
54 
38 
1.0 
c.c. 
55 
223 
1.0 
c.c. 
56 
102 
0.1 
c.c. 
57 
146 
0.1 
c.c. 
♦ Agar count unreliable due to cloudy media. 
Fig- 21 
Army Portable Water Purification Unit 
Cyst RemovaI With Operation At Reduced Rate With Coagulants 
The Engineer Board and United States Public Health Service Test Number VI-A 
May 18, 194-3 
Sheet 1 
of 2 
Sample 
Elapsed 
Cysts Recovered 
Number 
Time 
Min. 
Per Gallon of 
Supernatant 
Operation 
Remarks 
- 
0-4.1 
10,000* 
Pumping 
Water being pumped into tank for 
- 
0-21 
10,000 
n 
settling. Cysts applied through 
- 
0-1 
10,000 
it 
hypochlorinator at rate of 10,000 
- 
0 
A0 
- 
Settling 
n 
cysts per gallon pump^c 
• 
90 
- 
it 
End of settling period 
- 
90 
- 
Filtering 
63 
95 
557 
ii 
See Test No, VI-B for filtering data. 
U 
100 
1,552 
t> 
65 
105 
868 
n 
66 
110 
656 
it 
67 
115 
288 
it 
68 
120 
1,056 
it 
69 
130 
592 
it 
Less than half of the settled water had 
70 
uo 
1,232 
it 
been pumped through the filter at end of run 
Raw Water; Source; Potomac River* Turbidity 
; 50 p.p.m. 
pH; 7.8f Temperature: 70°F. 
Treatment; Coagulants; 
None applied. Settled After Addition of Cysts; 90 minutes. 
Procedure and Remarks; 
♦Calculated from the rate at which 
the cysts were applied to the water through the 
pump of 
the hypochlorinator, 1230 gallons of water was pumped into a tank with the continuous addition of 
cysts at the rate 
of approximately 10,000 cysts 
per gallon of water. This was allowed to settle without 
the addition of coagulants for 90 minutes. The water used 
had 
been taken from the Potomac River May 18 and 
allowed 
to settle 
until 
the tine of use. The turbidity of the 
water did not therefore decrease during 
the 90 minutes of 
settling used in this test. Attention is 
s called to the magnitude of the drawdown in the 
tank during the subsequent filtering operation^ 
the total being only 14- inches. 
Fig. 22 
Army Portable Water Purification Unit 
Cyst Removal By Sedimentation Without Use of Coagulants 
The Engineer Board and United States Public Health Service Test Number VI-A 
Sheet 2 of 2 
Bacterial Analysis 
18 May 1943 
Sample 
Number 
Bacterial Count 
Per c.c. 
°C 
Smallest Quantity 
Positive for 
B. Coll 
Raw O’ 
5,600 
0.1 
c.c. 
Raw 20' 
5,010 
1.0 
c.c. 
Raw 401 
1,540 
0.0001 
c.c. 
O' 
8,250 
0.01 
c.c. 
64 
2,800 
0.0001 
c.c. 
66 
3,200 
0.1 
c.c. 
68 
1,200 
0.1 
c.c. 
69 
2,420 
0.01 
c.c. 
70 
2,940 
0.001 
c.c. 
fig. 25 
Army Portable Water Purification Unit 
Cyst Removal By Sedimentation Without Coagulants 
The Engineer Board and United States Public Health Service Test Number VI-: 
Sheet 1 of 3 
B 
May 18, 19^3 
Sample 
Number 
Elapsed 
Time 
Mixu 
Output 
G.P.M. 
Infl* 
Press 
uai 
WfT, 
Press 
13 si 
nH 
Effl 
Turb, 
wm 
C/ysts Recovered 
Per Gallon of 
Effluent 
Operation 
Remarks 
m 
90 
10 
4.5 
2.5 
7.8 
10/ 
- 
Filtering 
Discharged to waste 
71 
95 
8 
4.0 
2.5 
7.8 
1.0 
36 
n 
72 
100 
11 
7.5 
4.5 
7.8 
2.0 
256 
it 
Engine missing slightly 
73 
105 
11 
7.0 
4.5 
7.8 
2.0 
176 
n 
Valve adjusted at Time 
74 
110 
10 
6.0 
4.0 
7.8 
1.0 
174 
n 
106 to maintain flow at 
75 
115 
10 
6.7 
4.5 
7.8 
1.0 
168 
it 
10 g.p.m. 
76 
120 
10 
6.7 
4.5 
7.8 
1.0- 
174 
n 
77 
130 
10 
6.7 
4.5 
7.8 
1.0 
166 
it 
78 
140 
10 
6,6 
4.,5 
7.8 
1.0 
198 
it 
End of test. 
Raw Water; Source: Potomac River (settled water from Test No. VI-A). 
Turbidity: 
50 p.p.m. pH: 7.8, 
Temperature: 
70OF# 
Treatment: Water settled for 90 minutes (see Test No. VI-A). Coagulants Aoolied: 
None. 
Procedure and Remarks: 
The filter was 
backwashed prior to the start of 
the run with Potomac River 
water to which 
no cysts had been added 
. Filtration 
was started without 
the use of coagulants at the 
output rate of 
10 G.P.M. 
Total 
water 
filtered; 498 gallons. 
Fig. 2h 
Army Portable Water Purification Unit 
Cyst Removal With Operation At Reduced Rate Without Coagulants 
The Engineer Board and United States Public Health Service Test Number VI-B 
Sheet 2 of 3 
May 18, 1943 
Sample 
Number 
pH 
Alkalinity 
MO 
nom 
Turbidity 
At 
Unit 
Anpearance 
Of 
Effluent 
Sediment 
After 
2L Hours 
Raw* 
7.8 
62.5 
50 
Milky 
71 
7.8 
60.0 
1.0 
n 
Slight 
72 
7.7 
60.0 
2.0 
« 
it 
73 
7.7 
60.0 
2.0 
it 
it 
U 
7.7 
60.0 
1.0 
N 
n 
75 
7.7 
60.0 
1.0 
N 
n 
76 
7.7 
60.0 
1.0- 
n 
it 
77 
7.7 
60.0 
1.0 
it 
H 
78 
7.8 
60.0 
1.0 
it 
Very slight 
Remarksi The turbidity of the water used was composed of very fine particles not unlike particles of 
lime. It will be noted 
that the alkalinity of the raw water is considerably above the 
average for the 
Potomac River at Gunston 
Cove, 
Average pH values for Potomac River water at this point 6,6 to 7.3. 
* Raw water sample from supply tank collected before pumping into settling tank. 
Fig. 25 
Army Portable Water Purification Unit 
Cyst Removal With Operation At Reduced Rate Without Coagulants 
The Engineer Board and United States Public Health Service Test Number VI-B 
Sheet 3 of 3 
Bacterial Analysis 
May 18, 194-3 
Sample 
Bacterial Count 
Smal1est Quantity 
Number 
Per c.c. 
Positive For 
°C 
B. Coli 
0 
132,000 
0.01 
c.c. 
72 
110,000 
0.0001 
c.c. 
1U 
3,750 
0.1 
c.c. 
76 
29,000 
0.1 
c.c. 
77 
8,000 
0.01 
c.c. 
7ft 
9,500 
0.001 
c.c. 
Note? Attention is 
called to the very high counts in the 
effluent samples. This may be due to the filter becoming 
contaminated during 
the backwash operation. 
Fig, 26 
flrmy Portable Y/ater Purification Unit 
Cyst Renoval With Operation At Reduced Rate Y/ithout Coagulants 
The Engineer Board and United States Public Health Service Test Number VII-A 
Sheet 1 of 2 
May 11, 1943 
Sample 
Elapsed 
Cysts Recovered 
Number 
Time 
Per Gallon of 
Operation 
Remarks 
Min, 
Supernatant 
0-46 
3800 
Pumping 
Pumping was begun with the treatment section 
- 
0 
3800 
Settling begun. 
of the unit adding alum through the pot feeder. 
T60 
60 
- 
Settling 
Due to finess of floe which did not settle out, 
5 gr./gal, alum and 5 gr./gal. soda ash was 
added to the tank of water and stirred with a 
paddle. 
T120 
120 
- 
Filtering begi n 
Discharge to waste. 
- 
123 
- 
Filtering 
See Test Number VII-B for filtering data 
79 
128 
3.2 
n 
BO 
133 
9.6 
It 
81 
138 
6.4 
It 
82 
U3 
6.4 
R 
S3 
148 
1.6 
ft 
84 
153 
1.6 
It 
8$ 
163 
4.8 
It 
86 
173 
9.6 
tt 
Raw Water 
: Source: 
Potomac River, 
Turbidity: 50 ppm, pH: 
7.4, Temperature; 72°F, 
Treated Water: oH: 
7,0*, Average Turbidity: 2 ppm. 
Treatment 
s Coagulants: 5 gr./gal. alum followed in 60 minutes 
by an additional 5 gr./gal. alum 
and 5 gr./gal. soda ash. 
Water settled for total time of 120 minutes. 
Procedure and Remarks; 1288 gal]ons 
of water was pumped into a 
tank through a treatment section of the 
unit with 
the addition of approximately 5 gr./gal, of alum being fed through the feed pots. A very fine 
floe was ; 
formed, which did not settle 
out in 60 minutes. Additional coagulants were added and another hour 
of settling time provided. Cysts were added continuously during 
the pumping operation at the rateof 3800 
cysts per gallon of 
effluent. See Test No, VII-B for filtering data, *Bromthymol Blue reading. 
Fig. 2? 
Army Portable Water Purification Unit 
Cyst Removal By Coagulation and Sedimentation 
The Engineer Board and United States Public Health Service Test Nuirber VII-A 
Sheet 2 of 2 
May 11. 1943 
Sample 
Turb. 
Alkalinity 
Sulphates 
Alum Dosage (Gr./Gal) 
Number 
pH 
ppm 
M0 
SO^ 
Calc.From 
Calc.From 
Remarks 
. .PPm . 
_ .ppm 
Alkalinity Sulnhates 
Raw 
7.7 
50 
51.1 
26.2 
- 
- 
Both alkalinity and pH high for 
0-36 
6.5 
50 
27.0 
59.0 
4.8 
4.5 
Potomac River water. 
0-26 
6.5 
50 
28.2 
57.7 
4.5 
4.3 
0-16 
5.5 
50 
3.4 
102.2 
9.5 
10.4 
Alum dosage increased by use of 
0-6 
6.1 
50 
10,2 
84.4 
8.1 
8.0 
second pot. 
6.2 
50 
14.5 
79.5 
7.3 
7.2 
T 60 
8.5 
4-5 
71.6 
63.7 
- 
5.1 
5 gr./gal alum and 5 gr./gal soda 
T 120 
7.2 
2 
54.1 
103.2 
— 
10.6 
ash applied. 
Remarks: 
Samples Nos 
. 0-36 through 0 
-6 were taken 
from the discharge hose 
of the pump during the time of 
filling 
the tank for settling. When 
the additional alum and 
soda abh was added, the coagulants were first 
dissolved in 
water and applied to the 
top of the tank of water. The water 
was then agitated for 5 minutes 
with paddles. 
, Sample No, T 60 was collected iust prior to-the addition of 
5 gr./gal. of alum but after 
the addition 
of the soda ash. 
Fig. 28 
Army Portable Water Purification Unit 
Cyst Removal By Coagulation and Sedimentation 
The Engineer and United States Public Health Service Test Number VII-B 
Sheet 1 of 2 
May 11, 1943 
Sample 
Elapsed 
Output 
Infl. 
Effl. 
Effl. 
Cysts Recovered 
Number 
Time 
G.P.M. 
Press 
Press. 
Turb. 
Per Gallon of 
Operation 
Remarks 
Min. 
psi 
psi 
ppm 
Effluent 
T-120 
120 
10 
3.0 
0 
Filtering 
Discharge to waste. 
- 
123 
10 
2.8 
1 
0.5 
, 
tt 
87 
128 
9.5 
2.8 
1 
0.5 
0 
tt 
First sample collected. 
S8 
133 
10 
3.5 
1 
0.5 
2 
it 
Flow adjusted at Time 
89 
138 
10 
3.5 
1 
0.5 
2 
tt 
130 
90 
143 
10 
3.5 
1 
0.5 
0 
tt 
91 
148 
10 
3.5 
1 
0.5 
0 
1! 
92 
153 
10 
3.5 
1 
0.5 
0 
t» 
93 
163 
10 
3.5 
1 
0.5 
0 
tt 
94 
173 
10 
3.5 
1 
0.5 
4 
tt 
End of test. 
Raw Water 
; Source 
; Coagulated and 
Settled (Test No, 
VII-A)•, pH: 7 
.0, Turbidity 
; 2 p.p.m, (average). 
Treatment 
: See Te 
st Number VII-A 
Procedure 
and Remarks-; Potomac River water 
coagulated and settled in 
Test No. VII-A 
was pumped through 
the sand 
filter at 
the output rate of 10 g. 
p.m. Just 
prior to the operation, the filter was backwashed 
with tap 
water for 
five minutes at 
the rate 
of 20 g.p, 
,m. In that the 
treatment section of the unit 
was known 
to be contaminated, an auxiliary 
pump was used to supply the 
filter during 
the operation. 
Total Water Filtered; 495 
Gallons, 
Fig. 29 
Army Portable Water Purification Unit 
Cyst Removal With Operation At Reduced Rate Following Coagulation and Sedimentation 
The Engineer Board and United States Public Health Service Test Number VII-B 
Sheet 2 of 2 
May 11, 1943 
Sample 
Number 
pH 
Turbidity 
At After 
Unit 24 Mrs. 
Alkalinity 
MO 
ppm. . 
Appearance 
Of 
Effluent 
Sediment 
24 
Hours 
T-120 
7.2 
2 
- 
54.1 
- 
- 
87 
7.2 
0.5 
2 
53.9 
Cloudy 
Moderate* 
88 
7.2 
0.5 
0.5 
53.9 
Clear 
None 
89 
7.2 
0.5 
0.5 
53.9 
it 
it 
90 
- 
0.5 
0.5 
53.9 
n 
it 
91 
7.2 
0.5 
0.5 
53.9 
it 
it 
92 
- 
0.5 
0.5 
53.9 
ti 
it 
93 
7.2 
0.5 
0.5 
53.9 
it 
it 
94 
7.2 
0.5 
0.5 
53.9 
it 
it 
Remarks: *Sedimerit orobablv due to debris 
turbidity passing the filter. 
in lines rather than 
Fig. 50 
Army Portable Water Purification Unit 
Cyst Removal With Operation At Reduced Rate Following Coagulation and Sedimentation 
The Engineer Board and United States Public Health Service Test Number V1II-A 
Sheet 1 of 1 
June 29, 1943 
Semple Elapsed 
Cysts Recovered 
Number 
Time 
Per Gallon of 
Operation 
. Remarks 
Min, 
Supernatant 
- 
0-4-3 
4300 
Pumping 
Water being pumped into tank for coagulation. 
- 
0 
4300 
Settling 
Cysts applied continuously through hypochlorinator 
•* 
75 
it 
at rate of 4300 cysts per gallon of water pumped. 
TO 
75 
Filtering 
Discharged to waste. 
95 
77 
121 
it 
First sample collected. 
96 
87 
- 
tt 
See Test Number VIII-B for filtering data. 
97 
97 
57 
n 
98 
107 
- 
ti 
99 
117 
5 
it 
100 
127 
- 
it 
101 
14-7 
- 
it 
102 
14-9 
43* 
n 
103 
152 
- 
tt 
104- 
162 
43* 
n 
Total water filtered: 850 gallons. 
Raw Water 
; Source 
: Potomac River, 
Turbidity: 
30 p.p.m. pH: 7.4* Temperature: 74°F. 
Treated Water: pH 
: 6.7, Average Turbidity: 
ppm. 
Treatment 
: Coagulants: 10 gr./gal. 
alum and 5 gr./gal. soda ash. Settled after addition of cysts: 
75 Min 
• 
Procedure 
and Remarks: 2200 gals, of water ’-as 
pumped into a standard 3000-gallon canvas tank through 
the treatment section with the cysts being added continuously at rate of 4-300 through the hypochlorinator 
The pump < 
effluent 
was directed into j 
a drum set within the tank and the coagulants added continuously to 
the water 
. After 
the tank was full, 
the water was allowed to settle for 75 minutes before filtration 
was begun 
, ’♦‘Combined sample. 
Fig. 31 
Army Portable Fater Purification Unit 
Cyst Removal By Coagulation and Sedimentation 
The Engineer Board and United States Public Health Service Test Number VI11-B 
Sheet 1 of 
1 
June 29, 1943 
Sample Elapsed 
Output 
Infl. 
Effl. 
Effl. 
Cysts Recovered 
Number 
Time 
G.P.M. 
Press 
Press 
Turb. 
Per Gallon 
of 
Operation Remarks 
Min. 
psi 
psi 
ppm 
Effluent 
T-0 
75 
10.0 
- 
- 
Filtering Discharge to waste. 
95 
77 
10.0 
3.0 
2.0 
0.1 
5 
it 
96 
87 
9.7 
3.0 
2.0 
0.1 
4 
it 
97 
97 
9.2 
3.0 
2.0 
0.1 
2 
ii 
98 
107 
9.4- 
3.5 
2.0 
0.1 
0 
it 
99 
117 
10.2 
3.6 
2.0 
0.1 
1 
11 Rate adjusted at Time 109 
100 
127 
10.1 
3.8 
2.0 
0.1 
1 
" Suction hose lowered to 
101 
14-7 
9.8 
3.8 
2.0 
0.1 
5 
11 within 3 inches of tank 
102 
14-9 
- 
- 
- 
bottom at Time 143• 
103 
152 
9.8 
3.8 
2.0 
0.2 
1 
it 
104. 
162 
10.1 
3.8 
2.0 
0.1 
1 
it 
Raw Water: 
Source: 
Coagulated and 
Settled 
(Test VIII-A), pH: 
6,7, 
'Turbidity: 70 p.p.m. (Average) 
Treatment: 
See Test Number VII]-A 
Procedure and Remarks: Potomac River water 
coagulated and settled in 
Test No. VI11-A was pumped through 
the sand filter at 
the output rate 
of 10 g. 
p.m. Samples were collected for microscopic examination 
at intervals. Attention is 
called 
to the increase 
in the number of cysts passing the filter at Time 
14-7 following the lowering « 
of the suction hose in 
the tank at T 
ime 14-3. Just prior to this run, the 
filter was 
backwashed for 5 
minutes 
with tap water 
at the rate 
of 18 
g.p.m. Total water filtered: 
850 gallons 
i. 
Fig. 32 
Army Portable Water Purification Unit 
Cyst Removal ?/ith Operation At Reduced Rate Following Coagulation and Sedimentation 
The Engineer Board and United States Public Health Service Experiment 
Number 
Quality of 
Coagulation 
Filtration Rate 
GPF/ft,2 
Calc. Number 
of Cysts per 
Gal. Influent 
Calc. Number 
of Cysts per 
Gal. Effluent 
Cysts Passing Filter 
Per 
Million Applied 
I 
None 
9.5 
2100 
250 
119,000 
II 
Poor 
9.5 
6300 
240 
38,000 
111 
Good 
9.5 
2300 
9 
3,900 
IV 
Good 
•6.35 
5000 
4.5 
900 
V 
Good 
6.35 
7000 
10 
1,400 * 
VI-B 
None 
6.35 
838 
165 
197,500 
Fig. 33 
Army Portable Water Purification Unit 
Summary of The Results of Experiments With Operation Under Several Conditions 
The Engineer Board and United States Public Health Service Experiment 
Number 
Pretreatment 
Settling 
Time 
.. (Min,) . 
Filtration 
Rate 
GFM/ft2 
Calc, Number 
of cysts per 
Gal. Influent 
Calc. Number Cysts Passing 
of Cysts Per Filter Per 
Gal. Effluent Million Applied 
VI-A 
None 
90 
. 
10,000 
838 
83,800 
VI-B 
- 
- 
6.35 
838 
165 
197.500 
Combined 
Results 16,500 
VII-A 
Alum / Soda Ash 
120 
— 
3800 
5.4 
1400 
VI1-B 
- 
6.35 
5. U 
0.95 
176,000 
Combined 
Results 250 
VIII-A 
Alum / Soda Ash 
75 
3800 
56 
iU.700 
VIII-B 
6.35 
56 
2 
55.700 
Combined Results 526 
FiC. 3U 
Army Portable 7/ater Puri f ication Unit 
Surwry of the Results of Experiments with Operation 
At Reduced Rate Following Coagulation and Sedimentation 
The Engineer Board and United States Public Health Service Experiment Number 
Sheet 1 of 1 
1-D 
April 9, 1943 
Sample 
Number 
Elapsed 
Time 
Min. 
Output Infl. 
G.P.M, Press, 
psi 
Effl. 
Press. 
psi 
Effl. Cysts Recovered 
Turb Per Gallon Per 
ppm Million Applied 
Operation 
Remarks 
a* 
0-1.66 
0,15 0.4 
0.0 
- 
Precoating 
First quart of effluent 
— 
returned to reservoir for 
- 
refiltering. 
- 
0 
0.4 
0.0 
1-** 
Filtering 
105 
2.4-1 
0.104 0.4 
0.0 
1- 0.0 
ii 
First quart collected. 
106 
5.00 
0.050 0.3 
0.0 
1- 0.0 
it 
Second quart collected. 
107 
7.91 
0.031 0.3 
0.0 
1- 0.0 
it 
Third quart collected. 
108 
13.0 
0.019 0.2-0.0 
0.0 
1- 0.0 
n 
quart collected. 
Raw Water: Source: Belvoir tap and Clay* Turbidity: 50 p.p.m. pH: 
7.5, Temperature: 53°F. 
Treatment: Precoat: 0.25 oz, Sorbo- 
cel** Slurry feed: None, 
Procedure and Remarks; 350,000 cysts were added to one gallon of -ater. 
To about one quart of this 
suspension, 0.25 
ounces of diatoraaceous silica were added and this poured 
into the filter reservoir. 
The first quart of effluent was returned to the 
reservoir of the filter. 
The entire gallon was then 
filtered and the 
four quarts of effluent examined for cysts. *Precoat of 
' 0,25 ounces 
is equivalent 
to 12.5 
pounds of 
filteraid per 100 
square feet 
of filtering surface. Area of filter approximately 
0..125 square feet 
. ** Effluent turbidity of less than 1.0 p.p.m. is estimated. 
Fig. 53 
Diatomsceous Silica Filter, Model SF-1 
Cyst Removal with Gravity Type Silica Filter 
The Engineer Board and United States Public Health Service Experiment Number 2-H 
Sheet 1 
of 1 
June 22, 19^-3 
•rilspeed 
Total water inn, JEffl. 
uysts Recovered 
Sample 
Time 
filtered 
Press, Turb. 
Per Gallon of 
Number 
Min. 
Gallons 
psi ppm 
Effluent 
Operation 
Hemarks 
_ 
0J1 
— 
1.3 
- 
Precoating 
Effluent re- 
— 
0 
0 
1.3-1.0 0.5- 
- 
filtering 
turned to 
109 
3.5s 
5 
1.3-1.0 0.3 
0.5 
filtering 
reservoir until 
no 
9.33 
5 
1.3-1.0 0.2 
0.0 
filtering 
clear 
111 
17.66 
5 
1.3-1.0 0.2 
1.0 
filtering 
Total 15 
Haw Water: Source: Potomac Hirer. Turbidity: 20 ppm. pH: Temperature: 72°f 
Treatment: Precoat: Special filteraid (lO lb/100 Slurry Peed: None 
Procedure and Hemarka: The precoat was applied by recirculating contaminated water (6000 cysts/ 
gal) to which the filteraid was added. The rariations in influent 
pressure are due to changes in 
water level in the reservoir between the times of adding raw water 
from a bucket. 
Fig. 36 
Blatomaceous Silica filter. Model &-2 
Cyst Heaoval With Gravity Silica filter 
The Engineer Board and United States Public Health Service Experiment Number 3-® 
Sheet 1 of 1 
June 22, 19^3 
Length of Time 
Required to 
Sample Collect Sample 
Number (Min. & Sec.) 
Size of 
Sample 
(Gallons) 
Number of 
Cysts 
Recovered 
Calc, Number 
of Cysts Per 
Gallon (3ffl.) 
Operation 
2100 
- 
- 
- 
Precoating 
112 2:35 
5 
0 
. 0 
Filtering 
113 2:h0 
5 
0 
0 
Filtering 
llU 3:00 
5 
0 
0 
Filtering 
115 1:00 (approx.) 3*5 
2* 
11^ 
Filtering 
116 - 
3 
3.7 
Filtering 
Raw Water: Source: Potomac River^ 
Turbidity: 
20 ppmt pHj 
l.K 
Temperature: 
72°P. 
Treatment: Precoat: JM Suner-Cel,* 
Slurry Feed: Charge of 3 < 
3Z. 
Procedure and Remarks: 
The precoat 
was applied by recirculating contaminated 
water (6000 cysts 1 gal. 
) to which the filteraid had been added. 
*Air entered 
suction hose Just prior to taking this sample. 
A small amount of slurry feed 
was applied during the run in accordance with recommendations of the manufacturer. 
The slurry feed was in the amount of 
1 p.p.m, slurry per part of turbidity. 
Fig. 37 
Dlatonaceous Silica Filter, Model 2MS 
Cyst Removal With Hand Operated Silica Filter 
The Engineer Board and United States Public Health Service Experiment Number *J-D 
Sheet 1 of 1 
July 16, 19*& 
Sample 
Number 
Time at Beginning 
of Collection of 
Sample 
(Min. and Sec.) 
Size of 
Sample 
(Gals.) 
Number of 
Cysts 
Recovered 
Calc. Number 
of Cysts Per 
Gallon (Effl.) 
Operation 
0 
- 
- 
Discharge to waste 
117 
1*30 
1 
1 
5 
filtering 
llg 
1*57 
5 
0 
0 
Filtering 
119 
U:00 
5 
0 
0 
Filtering 
10:00 
- 
- 
- 
Dropped cake 
12:00 
— 
- 
Discharge to waste 
120 
13*50 
_5 
0 
0 
Filtering 
Haw Water: source* Potomac Rlver, 
Turbidity: lOOp.p.m., pH: 
7.**. 
Temperature! 7^°^ 
Treatment 
: Precoat: JM Sorbo-Cel (0.1 lb/100 Slurry Peed: None 
Procedure and Remarks! The precoat 
was applied with contaminated water (10,000 
cysts/gal.) by discharging the first 
effluent to 
waste. After filtering for 10 
minutes, 
the cake was dropped, replaced and filtering resumed. 
Fig. 38 
Dlatomaceoue Silica Filter, Model 1#5C 
Cyst Removal With Hand Operated Silica Filter 
The Engineer Board and United States Public Health Service Experiment Number 5-® 
Sheet 1 of 1 
June 22, 19^3 
Sample 
Number 
Length of Time 
Required to 
Collect Sample 
(Min. and Sec.) 
Size of 
Sample 
(Gailons) 
Number of 
Cysts 
Recovered 
Calc. Number 
of Cysts Per 
CalIon (Effl.) 
Operation 
_ 
2:00 
— 
— 
— 
Precoating 
121 
26:55 
5 
0 
0 
Filtering 
- 
- 
- 
- 
Propped cake 
2:00 
- 
- 
Filter to waste 
122 
7lll-5 
5 
0 
0 
Filtering 
Haw Water: Source: Potomac Hirer_ 
Turbidity: 20 ppm, pH; jb 
Temperature: 7?°^ 
Treatment: Precoat: JM 
Sorbo-Cel, 
Slurry Peed: 
None. 
Procedure and Remarks: 
The precoat 
was applied in the first instance by 
recirculating contaminated water (6000 cysts/gal. 
) for 2 minutes 
after which the 
■unit was operated for approximately 27 minutes at 
2 g.p.m./ft2. 
The unit was then 
shut down and the cake allowed to drop. The unit 
was started, the cake replaced 
and the unit operated until a second sample of 5 gallons had been 
. collected. 
Fig. 39 
Diatomaceous Silica filter. Model SW l/g 
Cyst Removal With Experimental Stellar Filter 
The Engineer Board and United States Public Health Service Experiment Number 6-B 
Sheet 1 of 2 
August 10, 19^3 
.me at Beginning of 
Size of Fraction of dumber of 
Smallest Quantity 
Sanrole 
Collection of Sample 
Sample Sanrole Cysts 
Bacterial Count 
Positive for B, 
Number 
Min. 
c.c. Examined Recovered 
ner c.c. 
Coll 
Haw 
— 
- — — 
kbOO 
0.1 c.c. 
Filtration with Sorbo-Cel 
123 
0.00 
**50 all 0 
— 
- 
125-B 
0.50 
- - - 
1900 
0.1 c.c. 
124 
1.00 
1950 all 0 
12U-B 
3.00 
— — _ 
2U0 
1.0 c.c. 
Further filtration after refilling bag 
125 
0.00 
410 all 0 
125-B 
0.50 
- - 
860 
0.1 c.c. 
126 
0.66 
2300 all 0 
- 
- 
126-B 
3.oo 
- — - 
9U0 
1.0 c.c. 
Raw Water: 
Source: Potomac River* Turbidity: 50 ppm* pH: J.U* Temperature: 
78°F, 
Procedure: 
The precoat of 0.2 pounds of Sorbo-Cel was applied by passing 3 quarts of clear tap water and 
filterald through the filter, 
followed by a small quantity of river water to which no 
cysts had been 
added. 
After precoating 3 quarts of river water containing 10,000 
- 12,000 cysts per gallon was filtered. 
The flow 
was started (zero minutes) and all water filtered was collected for examination. The bag was 
refilled with cyst-containing water and again all water filtered was collected for examination. 
Fig. 1*0 
Uiatomaceous Silica Filter, Model X 
Cyst Removal With Gravity Type Silica Filter 
The Engineer Board and United States Public Health Service Experiment Number 6-B 
Sheet 2 of 2 
August 10, 19^3 
Tim© at beginning of 
Sample Collection of Sample 
Number Hin. 
Size of fraction of 
Sample Sample 
c.c. Examined 
Number of 
Cysts Bacterial Count 
Recovered -per c.c. 
Smallest Quantity 
Positive for 
B. Coli 
Raw 
- 
- 
_ U'god 
0.01 c.c. 
127 
12S 
12£-B 
0.00 
1.00 
2.00 
Filtration with activated 
55 all 
750 all 
silver-f lit erald 
0 (Sterile 0.1 c, 
0 
10 
c.) 1.0 c.c. 
1.0 c.c. 
Raw Water: 
Source: Potomac River, Turbidity: 50 ppn, pH: Temperature: 
7goF. 
Procedure: 
combination 
examination. 
The apparatus was rinsed and 1 quart of water and O.U gma of the activated silver-filteraid 
were added. The unit was not precoated by recirculation, the first water being taken for 
Fig. Ul 
Diatomaceaus Silica Filter, Model X 
Cyst Removal With Gravity Type Silica Filter 
The Engineer Board and United States Public Health Service Experiment Number T-® 
Sheet 1 of 3 
May 25. 19^3 
Sample 
Number 
Elapsed 
Time Output 
Min. G.P.M. 
Infl, 
; Press 
usi 
Effl, Effl. 
Press Turb, 
vsi unm 
Cysts Recovered 
Per Gallon of 
Effluent 
Operation 
Remarks 
_ 
0-6 
24.5 
- 
- 
- 
Precoating 
Water recirculated. 
X29-A 
0 
23 
16 
3 
0.5- 
- 
Filtering 
Engine speed erratic. 
129 
5 
21 
16 
3 
0.5V 
1.0 
Filtering 
Engine stopped for 
130 
10 
15 
15.5 
0 
0.0/ 
1.7 
Filtering 
30 seconds at Time 6. 
131 
15 
12.5 
16 
0 
0.04 
0.0 
Filtering 
132 
20 
11 
16 
0 
0.04 
0.0 
Filtering 
133 
25 
11 
16 
0 
0.04 
0.0 
Filtering 
13^ 
30 
10.5 
17 
0 
0.04 
0.0 
Filtering 
Engine speed advanced 
135 
Uo 
lU 
21 
0 
0.64 
0.0 
Filtering 
at Time 32 min, and 
136 
50 
12 
25 
0 
0. 5- , 
0.0 . 
Filtering 
again at Time U5 min. 
Raw Water: 1 
Source: Potomac River. 
Turbidity: 65 p.p.m. pH: 7*6. Temperature: 6S°F, 
Treatment: Precoat; 1 
,.5 uounds Sorbo-Cel*. 
Slurry Peed: 170 u.p.m. 
Procedure and Remarks: 
2U ounces of 
Sorbo-Ci 
el and 225.000 cysts 
were added ■ 
bo 35 gallons of raw water. 
This suspension was recirculated through the unit for 6 minutes; 
at which time the effluent was relatively 
clear. 
Filtration was 
then started with the 
continuous addition of cysts and filteraid for a ueriod of 
50 minutes. 
The cysts were applied through the hypochlorlnator at the constant rate of 71,500 cysts 
per minute. 
Attention 
is called 'to 
the relatively high influent nressure at 
the start of the test. This 
was due 
to excessive losses in the piping rather than to high resistance through the filtering cake. 
Total water filtered: 
696 gallons. 
*Precoat of 1,5 pounds equivalent to 1J pounds per 100 square feet 
of filtering 
area. 
■Fie. hz 
Biatomaceous Silica Filter, Model SF-Xl 
Cyst Removal With Pressure Type Silica Filter 
The Engineer Board and United States Public Health Service Experiment Number 7-® 
Sheet 2 of 3 
May 25, 19U3 
Sample 
Number 
Effl. 
# 
Effluent 
St, Louis 
At 
Unit 
Turbidity 
i Baylie Tindall 
After After 
2U Hrs. Hrs. 
Alkalinity 
MO 
mm 
Raw 
7.6 
- 
- 
34.7 
129 
7.6 
o.5- 
1.0 
1.0/ 
3^-7 
130 
7.6 
0.54 
1.0 
1.0 
34.7 
131 
7.6 
o 4 
0.5- 
0.5 
34.7 
132 
7.6 
o 4 
0.5- 
O.U 
34,7 
133 
7.6 
o 
0.5- 
0.3 
3^.7 
134 
7.6 
o 
0.5- 
0.4 
34.7 
135 
7.6 
o 4 
0.5- 
0.3 
34,7 
126 
7.6 
o.5- 
—£•■£.,.. 
0.2 
3**.7 
_Fi_g. h3 
Uiatomaceous Silica filter. Modal SP-H 
Oyst Removal With Pressure Type Silica Pilter 
The Engineer Board and United States Public Health Service Fig. ItU 
Diatomaceous Silica filter. Model S7~X1 
Cyst Removal With Pressure Type Silica filter 
The Engineer Board and United States Public Health Service 
Experiment Number 7-® 
Sheet 3 of 3 
May 25. 19^3 
Bacterial Analysis 
Bacterial Count 
Smallest Quantity 
Sample 
Per c.o. 
Positive for 
Number 
37°® 
B. Coll 
Haw* 
1700 
0.1 cc 
129-^ 
29U00 
(absent)lO.O oe 
150 
k$20 
10.0 cc 
132 
moo 
10.0 cc 
13U 
2200 
1,0 cc 
135 
390 
(absent)l0,0 cc 
136 
765 
10,0 cc 
Remarks: 
*Average of 6 samples 
taken at 10-minute intervals. 
Effluent hose and piping was not sterilised prior 
to the operation. Experiment Number 
Sheet 1 of 2 
g-D 
June 8, I9U3 
Elapsed 
Infl, 
TPfi'.- 
Cysts Recovered 
Sample 
Time 
Output 
Press 
Press 
Turb. 
Per Gallon of 
Number 
Min. 
G-.P.M, 
psi 
P»1 
psi 
Effluent 
Operation 
Remarks 
_ 
0-10 
“573 
7 
k 
- 
- 
Precoot ing 
Water recirculated 
— 
0- 7 
27 
8 
k 
— 
.. 
Added carbon 
Water recirculated 
137 
0 
2U.5 
8 
k 
0/ 
1 
Filtering 
138 
5 
21 
8 
3 
0/ 
0 
Filtering 
139 
10 
18 
8 
3 
°/ 
0 
Filtering 
lUo 
15 
18 
8 
3 
0 
Filtering 
lUi 
2C 
ik 
8 
2 
<4 
0 
Filtering 
Pump speed increased 
1U2 
25 
17 
13.5 
3 
0/ 
0 , 
Filtering 
at Time 22 min. 
Raw Water; Source: Potomac River. 
Turbidity: 20 ppm. pH; g.; 
Temperature: 
7U°r. 
Treatment: Precoat: 1.0 pound Sorbo-Cel followed by O.* pound Sorbo-Cel mixed with 0.2*5 
pound activated carbon (Nuchar F.A,N,)t 
Slurry Peed: 
120 ppm (av,) 
Procedure and Remarks: The precoat 
of 1.0 pound of 
Sorbo-Cel (0.15 was applied by recirculating 
the precoat water 
to which no cysts 
had been added. 
The slurry and cysts were applied through the 
hypochlorinator. 
The water used contained very little suspended clay but contained ( 
considerable algae and 
color. 
Total water filtered; 485 gallons. 
Fi?. U5 
Biatomaceous Silica Filter, Model SFC-1 
Cyst Removal With Converted Portable Sand Filter 
The Engineer Board and United States Public Health Service Experiment Number 8-3 
Sheet 2 of 2 
Jtme 8, 19Uj 
Sample 
Number 
Effluent Turbidity tanm? 
St. touis Tindall Tindall 
Hffl. At At After 
t>H Unit Unit 2H Hrs. 
Baylis 
After 
2»t Hrs. 
Alkalinity 
MO 
pm .. 
Haw 
X2 
- 
- 
- 
• 
31.6 
137 
5.2 
0/ 
0.1 
0.1 
0.0/ 
9.9 
13* 
6.2 
0/ 
0.05 
o.U 
0.1 
2k.O 
139 
7.7 
0/ 
0.05- 
0.2- 
0.0/ 
25.0 
ibo 
7.* 
°/ 
0.05 
0.2— 
0.2 
86.9 
ibi 
7.9 
°/ 
0.05 
0.2- 
0.1 
27.0 
1U2 
7*9 
ol 
0.0*5- 
0.2- 
0.1 
27.^5 
Remarks: 
The low alkalinity value for Sample Ho 
.137 and the 
following rise in both alkalinity and pH oan be attributed to the 
presence of activated carbon in the preooat. 
Fig. h6 
Biatomaceous Silica filter t Model SPCLl 
Cyst Hemoral With Converted Portable Sand Pllter 
The Engineer Board and United States Public Health Service Experiment Number 
Sheet 1 of 2 
9-i> 
June 8, 19^3 
Elapsed 
Infl. 
1WtTT 
ttysts 
Recovered 
Sample 
Time 
Output 
Press 
Press. 
Turb, Per < 
Sallon of 
Number 
Min. 
G.P.M. 
psl 
psi 
ppm Effluent 
Operation 
Remarks 
— 
0-5 
15 
8 
3 
- 
- 
Precoating 
Water recirculated 
i*? 
0 
28 
10 
k 
0 
Filtering 
pump opened to 
ikk 
5 
27 
10.5 
k 
°/ 
0 
Filtering 
full capacity 
1U5 
10 
2k 
13 
k 
0^ 
0 
Filtering 
ike 
15 
2k 
13.5 
k 
0.1 
0 
Filtering 
Engine speed 
iki 
20 
2k 
i?.5 
k 
0.1 
0 
Filtering 
fluctuating 
Iks 
25 
2k 
lU 
k 
0.1 
0 
Filtering 
Raw Water: Source: Potomac River. 
Turbidity: 20 ppm# 
pH: 8.2„ 
Temperature: 
7k°F. 
Treatment: Precoat: 1.0 pound Sorbo-Cel 10.lb/ft^). 
Slurry feed: 120 ppm (av] 
1* 
Procedure and Remarks: The precoat 
was applied by recirculation of urecoat water to 
which no cysts had 
been added, *The 
slurry feed was adjusted continuously to maintain rate of pressure rise at a minimum 
throughout the operation. 
Cysts were applied continuously through the hypochlorlnator. Total water 
filtered: 6Ug gallons. 
Uiatomaceous Silica Filter, Model SFC-l 
Cyst Removal With Converted Portable Sand Filter 
The Engineer Board and United States Public Health Service Experiment Bomber 9-® 
Sheet 2 of 2 
Jtme 8. 19^3 
Effluent Turbidity 
ixmmj 
St. Louis 
Tindall 
Tindall 
Baylls 
Alkalinity 
Sample 
Bffl. 
At 
At 
After 
After 
MO 
Bomber 
oH 
Unit 
Unit 
2* Hr b. 
2b Hrs. 
ppm 
Haw 
S.2 
mm 
«. 
31.0 
i**3 
7.9 
0/ 
.05^ 
0.3 
0.2 
27.5 
ibb 
7.9 
0/ 
0.1 
0.7 
0.7 
27.5 
1U5 
7.9 
0/ 
o.jV 
0.6 
0.7 
27.5 
1U6 
7.9 
0.1 
.2 
0.7 
0.7 
27.5 
1*7 
7.9 
0.1 
.1 
0.5 
0.5 
27.5 
l*g 
7.9 
0.1 
.1 
0.5 
Q.3 
27.5 
Remarks: 
Increase in turbidity due in part to 
color which had coagulated. 
Turbidity of supernatant of samples after 2* hours was approximately the 
same as 
that found at the unit. 
Fig. U8 
Dlatomaoeous Silica Filter, Model SFC-1 
Cyst Removal With Converted Portable Sand Filter 
The ftigineer Board and United States Public Health Service Experimental Number 10-R 
Sheet 1 of U 
July 6, 19^3 
E1 speed 
I aft. ' 
Wfl. 
Jtffl. 
Cysts Recovered 
Sample 
Time 
Output 
Press 
Press 
Turb. 
Per Gallon of 
Number 
Mln. 
G.P.M. 
pel 
_ v si _ 
PPm 
Effluent 
Operation 
Remarks 
_ 
0-10 
20 
20 
2 
- 
Precoating 
Chlorine added to 
o-T 
— 
- 
- 
- 
- 
100 ppm 
0-2 
27-5 
22 
2 
- 
— 
Entering 
Rechlorinated 
IU9-A 
0 
— 
20 
2 
0.1- 
- 
Filtering 
Cysts applied 
1U9 
1-2 
2k 
20 
2 
0.1 
0 
Entering 
150 
2-3 
18 
22 
2 
0.1 
1 
Entering 
151 
3-H 
16 
22 
2 
0.1 
0 
Entering 
152 
k-3 
lU 
2k 
- 2 ..... 
0.2 
0 
Entering 
Raw Water: Source: 
Potomac River# 
Turbidity: 1 
50 ppm* pH: 7.6„ 
Temperature: 
72°E. 
Ir.gfltmiaak’ Precoat 
: 1.0 pound Sorbo-Cel (0,15 lb/ft2), Slurry Peed: 
None. 
Procedure and Remarks: The precoat 
was applied by recirculation of water containing 100 ppm chlorine. 
The unit was dechlorinated 
and the 
cysts 
applied in a batch. No slurry was used. 
Fig. U9 
Uiatomaceous Silica Filter, Model SFC-1 
Cyst Removal With Converted Portable Sand Filter 
The Engineer Board and United States Public Health Service Experiment Humber 
Sheet 2 of k 
11-D 
July 6, 19^3 
Elapsed 
Infl. 
Sffl. 
Effi. 
Cysts Recovered 
Sample Time 
Output 
Press. 
Press. 
Turb. 
Per Gallon of 
Humber Min. 
O.P.K. 
uai 
nsi 
unm 
Effluent 
Oneration 
Remarks 
0-12 
- 
- 
Precoating 
Chlorine added to 100 pnm 
0-10 
22 
2k 
2 
- 
— 
Rechlorinated 
153-* 0 
- 
- 
- 
0.1- 
— 
Entering 
Cysts added 
153 1-2 
17 
22 
2 
0.1- 
0 
Entering 
15U 2-3 
18 
2k 
2 
0.1- 
0 
Entering 
155 3-* 
13 
2k 
2 
0.1- 
0 
Entering 
156 U-5 
12 
25 
2 . 
0.1- 
0 
Entering 
Raw Waters Source 
s Potomac River, Turbiditys 50 ppm, pHs J,S9 
Temperatures 
72°r. 
Treatments Precoats 1.0 uound Super-Cel (0.1*5 Slurry feeds 
None. 
Procedure and Remarkss The precoat 
was spplied by recirculation of water containing 100 ppm chlorine. 
The unit was dechlorinated and the cysts applied in a batch. Ho slurry was used. 
Fig. 50 
Uiatomaceous Silica Filter, Model SFC-l 
Cyst Removal With Converted Portable Sand Filter 
The ]fingineer Board and United States Public Health Service Experiment Number 12-D 
Sheet 3 of U 
July 6, 19^3 
Elapsed 
Infl. 
Effl. 
Bffi. 
Cysts Recovered 
Sample 
Time 
Output Press 
Press 
Turb 
Per Gallon of 
Number 
Min. 
G.P.M. P.S.I. 
P.S.I. 
P.P.M. 
Effluent 
Operation 
Remarks 
0-9 
26.5 20 
2 
1*5/ 
Precoating 
Chlorine added 
• 
0-3 
- - 
- 
1.54 
- 
to 100 p.p.m. 
X57-* 
0 
25.0 20 
2 
1.5/ 
- 
Piltering 
Dechlorinated 
157 
1-2 
IS.5 22 
2 
1.5/ 
0 
Entering 
cysts applied 
158 
2-3 
16 22 
2 
1.5/ 
1 
Entering 
159 
3-tf 
22 
2 
1.5/ 
0 
Entering 
160 
£5 
13 23 
2 
—1.5/— 
0 
Entering 
Raw Water: Source: Potomac River* 
Turbidity: 50 p 
.p.m, pH: 7.6, 
Tenroerature: 72°E, 
Treatment: Precoat: 1.0 uound Hyflo Suner 
cel (0,15 lb/ft2)* Slurry Peed: None 
Procedure and Remarks: The rrecoat 
was applied by recirculation of water containing 100 p.p.m. 
chlorine. The unit was dechlorinated and the cysts applied in a batch. 
No slurry was used. 
Fig. 51 
Biatomaceous Silica Filter, Model SFC-l 
Cyst Eeaoval With Converted Portable Sand Filter 
The Engineer Board and United States Public Health Service Experiment Number 13-® 
Sheet U of U 
July 6. 19^3 
Elapsed 
Infl. 
Effl, 
Bffl. 
Cysts Recovered 
Sample 
Time Output 
Press, 
Press, 
Turb. 
Per Gallon of 
Hnraher 
Min. G.P.M. 
psi 
osl 
psi 
Effluent 
Ooeration 
Remarks 
- 
0-12 
mm 
„ 
mm 
Precoating 
Chlorine added to 
- 
0-3 
32 
20 
2 
1- 
100 ppm Reohlorinated 
l6l-A 
0 
29 
20 
2 
• 
— 
Entering 
cysts applied. 
l6l 
1-2 
26 
22 
2 
6-10 
0 
162 
2-3 
22 
22 
2 
10^ 
0 
if? 
20 
23 
2 
10/ 
0 
164 
J±5 
18 
25 
Q 
Raw Water: Source: 
Potomac Riyer. 
Turbidity: 50 ppm, pH: 7,6, 
Temperature: 
72°E. 
Treatment: Precoat: 
1.0 pound JM (0.15 lb/ft2) 
, Slurry Peed: 
None 
Pro cedur 
e and Remarks: The precoat 
1 was applied by recirculation of water containing 100 ppm chlorine. 
The unit 
was chlorinated and the cysts spoiled in a batch. No slurry 
was used. Note absence of cysts 
in presence of 10-15 ppm 
turbidity in effluent. 
Fig. 52 
Blatomaceous Silica filter. Model SFC-1 
Cyst Removal With Converted Portable Sand Filter 
The Engineer Board and United States Public Health Service Experiment Ho a, 10-2) & 13-2) 
Sheet 1 of 1 
July 6, 19^3 
Teat 
Ho. 
riltwald 
Ujtfa 
Sample 
Humber 
bacterial Count 
Per c, c. 
37°0 _ 
Smallest Quantity Positive 
Por Bt Oo^Li 
Haw* 
W5 
6.1 c.c. 
10-D 
Sorho-Cel 
1^9-A 
Bact. absent in 0.1 o.e. 
1.0 o.o. 
152 
Uo 
10 0.9. 
UJ 
Super-Cel 
153-A 
Uo 
(absent)10 o.e. 
156 
20 
(absent)lO c.c. 
12-D 
Hyflo 
157-A 
30 
1.0 c.c. 
160 
120 
1.0 c.c. 
X3_B 
*5^5 
161 
3U0 
.01 c.c. 
16H 
120 
1.0 c.c. 
Remarks: *Average of k samples. 
Fig. 53 
Biatoaaoeous Silica Filter, Model SFC-1 
Summary Bacterial Removal With Several Grades of Filteraid 
The Engineer Board and United States Public Health Service  
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