f/EPA
United States
Environmental Protection
Agency
Municipal Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-81-174 Oct. 1981
Project Summary
Effect of Halogens on
Giardia Cyst Viability
Ernest A. Meyer
The report summarized here de-
scribes the results of a study in which
the effect of halogens on the cysts of
Giardia lamblia was tested. Halogens
were applied under conditions com-
monly used in drinking water disinfec-
tion. The specific effect measured was
the ability of the Giardia cyst to
excyst, under controlled conditions
after exposure to halogen; this was
compared with the excystation ability
of untreated cysts from the same
source. Earlier studies of Giardia cyst
inactivation employed a dye exclusion
method; this has been shown to be a
less reliable indicator of Giardia cyst
viability than the excystation proce-
dure.
In one set of experiments, chlorine
was tested under a variety of condi-
tions including chlorine concentration,
temperature, pH, and chlorine-cyst
contact time. Within the range of
variables studied, the ability of cysts
to excyst after treatment was affected
by each of these variables. Percent
excystation decreased with (a) in-
creasing chlorine concentration, (b)
increasing temperature, (c) decreas-
ing pH, and (d) increasing chlorine-
cyst contact time.
In a second set of experiments, six
small-quantity water disinfection
methods were tesied. In every case,
directions recommended for the appli-
cation of the method were strictly
followed. Two water qualities (cloudy
and clear) and two water temperatures
(3° and 20°C) were employed. At
20°C, all of the methods proved
effective. At 3°C in cloudy water.
however, one method was less than
completely effective; and, in clear
water, four methods failed to inacti-
vate all of the cysts. The results of
these experiments underline the im-
portance of considering water tem-
perature, chlorine demand, contact
time, and pH when employing halo-
gens for the disinfection of drinking
water.
This Project Summary was developed
by EPA's Municipal Environmental
Research Laboratory, Cincinnati, OH.
to announce key findings of the
research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
introduction
Parasitic protozoan flagellates in the
genus Giardia are distributed worldwide
and are now the most commonly
reported human intestinal parasites in
the United States and Great Britain.
Host-to-host transmission of Giardia
occurs when viable cysts, excreted in
the feces of an infected host, are
ingested directly or in the food or water
of another host. The subsequent growth
of these organisms in the small intestine
frequently results in giardiasis, a
disease whose symptoms, including
diarrhea, malaise, abdominal cramps
and weight loss, may persist for a month
or more. Until a decade or so ago,
giardiasis was considered to be a
disease acquired by Americans outside
the United States in parts of the world
(particularly in tropical and subtropical
areas) where sanitary standards were in
-------
need of improvement. Travel to such
areas still is the most probable explana-
tion for a significant number of the
cases of giardiasis diagnosed in this
country.
Since about 1970, evidence has been
accumulating that giardiasis can be
spread in another way: in epidemic
form, in temperate and cold climates.
The vehicle for spreading epidemic
giardiasis is drinking water. Waterborne
giardiasis has now been reported from a
number of states in the United States
including New York, New Hampshire,
Pennsylvania, Colorado, California,
Utah, Oregon, and Washington. The
disease has been acquired by drinking
water from community supplies as well
as from untreated sources in recreation
areas. Evidence strongly suggests that
many giardiasis infections have been
acquired in Leningrad in the Soviet
Union by drinking the water in that city.
Humans are not the only hosts for
Giardia, which in nonhuman hosts are
morphologically indistinguishable from
those that parasitize humans. Although
organisms in this genus were long
considered to be strictly host-specific, it
is now known that this is not the case.
Available data suggest that Giardia
organisms from man are capable of
infecting lower animals. There is also
evidence to suggest that, conversely, at
least some of the Giardia parasitic in
lower animals can infect humans.
The existence of animal reservoirs of
these organisms capable of infecting
man simplifies the explanation of how
this disease is acquired (a) in areas far
from human activity and (b)from water
collected from watersheds from which
humans have been excluded.
Because Giardia cyst survival has
proven difficult to study, we don't know
how to treat water to ensure that any
Giardia cysts will be destroyed. The
presently used chemical methods of
water disinfection are based not on
killing Giardia but on killing Entamoeba
cysts. Recently, questions have arisen
concerning the ability of these recom-
mended chlorine concentrations to kill
Giardia cysts.
The development of a method to
induce the excystation of Giardia cysts
has made possible, for the first time, a
relatively simple, reliable method of
determining Giardia cyst viability and,
thus, the ability to determine whether a
given procedure kills these cysts. The
method has recently been used to
determine that in cold water, Giardia
cysts can remain viable for upwards of 2
months.
The report summarized here describes
the results of a study to determine the
effect on Giardia cyst viability.
Effect of Chlorine on Giardia
Cyst Viability
The variables employed in this study,
in addition to chlorine concentration,
were pH, contact time, and temperature.
By determining the percent of a given
Giardia cyst suspension capable of
excysting after different periods of
exposure to chlorine under a variety of
experimental conditions, and plotting
the resultant data, it was possible to
generate a number of curves that
describe the rate of Giardia cyst
inactivation under varying conditions.
Within the range of variables studied,
the percent of excystation decreased
with (a) increasing chlorine concentra-
tion, (b) increasing temperature, (c)
decreasing pH, and (d) increasing
chlorine-cyst contact time. These curves,
a more detailed description of these
experiments, and a discussion of the
significance of the results, were recently
published in a journal article to which
the interested reader is referred (Jarroll,
E.L, A.K. Bingham, and E.A. Meyer.
Effect of chlorine on Giardia lamblia cyst
viability. Applied and Environmental
Microbiology 47:483-487, 1981.).
Effect of Six Small-Quantity
Water Disinfection Methods on
Giardia Cyst Viability
Of the six disinfection methods
tested, two (Halazone* and bleach)
employed a form of chlorine, and four
(Globaline, EDWGT, and elemental
iodine in tincture and in saturated form)
involved some form of iodine. Because
the recommended amount of halogen to
be added, or the recommended contact
time, or both varied with some methods
according to the water turbidity or
temperature, cyst survival using each
method was determined using both
clear and cloudy water, at 3° and at
20°C.
Two of the methods, one chlorine-
based (Halazone) and one iodine-based
(EDWGT) inactivated all of the cysts
under all test conditions Three other
methods (bleach, Globaline, and tincture
of iodine) only failed to inactivate all
cysts under one set of experimental
conditions: in clear water at 3°C.
Finally, one method (saturated iodine]
inactivated all cysts in both water
samples at 20°C, but failed to inactivate
all of the cysts in either clear or cloudy
water at 3°C.
These results suggest that Giardia
cysts can be inactivated by halogen-
containing compounds under appro-
priate conditions; at low watertempera-
tures, however, increased contact time,
increased concentrations of halogen, or
both may be required.
Details of these experiments have
been published in two journal articlesto
which the reader is referred. (1) Jarroll,
E.L., A.K. Bingham, and E.A. Meyer.
Giardia cyst destruction: effectiveness
of six small-quantity water disinfection
methods. Am. J. Trop. Med. Hyg., 29, 8-
11,1980. (2) Jarroll, E.L, A.K. Bingham,
and E.A. Meyer. Inability of an iodination
method to destroy completely Giardia
cysts in cold water. West. J. Med.
132:567-569, 1980.
The full report was submitted in fulf ill-
ent of Grant No. R-806032 by the
University of Oregon Health Sciences
Center, Portland, OR 97201, under the
sponsorship of the U.S. Environmental
Protection Agency.
•Mention of trade names or commercial products
does not constitute endorsement or recommenda
tion for use.
-------
Ernest A. Meyer is with the University of Oregon Health Sciences Center,
Portland, OR 97201.
John C. Hot'f is the EPA Project Officer (see below).
The complete report, entitled "Effect of Halogens on Giardia Cyst Viability,"
(Order No. PB 82-102 294; Cost: $5.00, subject to change) will be available
only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
U S GOVERNMENT PRINTING OFFICE, 1981 — 559-01 7'7383
-------
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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&EPA
r
United States
Environmental Protection
Agency
Municipal Environmental Researc]^ w*
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-81-173 Oct 1981
Project Summary
Demonstration Physical
Chemical Sewage Treatment
Plant Utilizing Biological
Nitrification
James F Kreissl and Ronald F. Lewis
This study involved the design, con-
struction and operation of a hybrid
physical-chemical (P-C) biological
treatment facility. Evaluation of this
system was based on two factors: its
utility as a transportable facility for
interim high quality treatment of
wastewaters at different locations and
its value as a treatment concept to
incorporate the best attributes of both
methods (P-C and biological) of treat-
ment.
Although the system produced a
consistent, high quality effluent, its
utility as a transportable system was
only partially demonstrated and its
viability as a treatment sequence
could not be confidently stated due to
several design and operational prob-
lems.
This summary presents an overview
of this joint USEPA-DHUD project.
This Project Summary was devel-
oped by EPA's Municipal En viton men -
tal Research Laboratory, Cincinnati,
OH, to announce key findings of the
research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
Experience has shown that a need
exists for flexible and efficient sewage
treatment units able to meet the ever
more stringent regulations imposed by
government Urban fringe developments
are particular problem areas that
outstrip the service ability of urban
sewage authorities.
Small housing, commercial, and
public developments spring up beyond
the range of central sewage transport
systems and must have acceptable
sewage treatment on a permanent or
temporary basis. Often, the temporary
nature of the treatment facilities com-
pounds the problem, resulting m heavy
capital equipment outlays prorated over
relatively short time periods. The small
size and nature of such development
areas frequently provide flow variations
that are not conducive to effective
biological treatment. Daily, as well as
seasonal, fluctuations may be extreme
m both hydraulic and organic loadings
The need for treatment processes that
can be placed m servicequicklyand with
a minimum of delay to meet strict
effluent limitations has long been
recognized. Development areas on
urban fringes frequently discharge to
small streams with neither little dry
weather flow nor periodic high rainy
weather flow and effluent limitations
are generally based on the most
extreme low flow conditions.
This demonstration project was
conducted to show that wastewater
could be treated m a physical-chemical
wastewater treatment plant employing
a biological intermediate stage for
oxidation of nitrogenous material to
produce a high quality effluent and
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provide different treatment levels to
meet a variety of effluent requirements
The physical-chemical plant chosen
was of a modular design employing
high-rate processes which normally
facilitate a relatively speedy installation,
a minimum amount of lag time to
produce the desired effluent quality,
and ease of transport for relocation to
other critical areas when needed
The plant was located in the drainage
area of a planned residential develop-
ment known as Beechgrove Village in
the southern part of Kenton County,
Kentucky The wastewater was domestic
in nature, with no commercial or
industrial sources.
Facility Description
The facility consisted of a modular
physical-chemical (P-C) wastewater
treatment plant which was skid-mounted
for ease of transport, an intermediate
biological nitrification tower, an equali-
zation tank and a sludge holding tank.
Any of these ancillary units to the P-C
plant could be constructed of materials
which would facilitate relatively fast
startup at a new location Sizing of the
plant components was based on a flow
of 190 cu m/d (50,000 gallons per day).
The treatment process sequence con-
sisted of screening, flow equalization,
chemical flash mix, flocculation, clarifi-
cation, pH control, biological nitrifica-
tion, filtration, granular activated carbon
adsorbtion, and chlormation. Excess
sludge from the clarifler was periodically
transferred to the sludge holding tank
from which settled solids were occa-
sionally transported by truck to a
disposal site A treatment process flow
schematic of the demonstration plant is
shown in Figure 1.
Influent Flow Control
Wastewater for the demonstration
plant was taken from an existing man-
hole above the lift station serving the
Beechgrove Village development. A
diversion dam within the manhole
provided a flooded section from which
the demonstration plant was fed. In the
outlet pipe (0.2 m in diameter) an air-
activated pinch valve was located in the
flooded pipe which, when activated by
liquid level controls in the equalization
tank, opened and allowed diversion of
the wastewater to the demonstration
facility through the 845-m gravity line
The level controls were of the solid-rod
type located directly in the main
equalization basin. Signals from the
electrodes were transmitted via a
telephone circuit to a solid-state control
relay located near the pinch valve The
relay in turn controlled a 3-way solenoid
valve which was installed in an air pipe
between the pinch valve and an air
compressor The air pressure in turn
activated the pinch valve. Excess waste-
water flow was discharged to the
existing sewer from the manhole
overflow
Flow Equalization Tank and
Screening
A bar screen with approximately 25
mm (1-m) openings was located in the
influent structure of the flow equaliza-
tion tank to remove larger objects that
might damage the system The flow
equalization tank consisted of a rec-
tangular 75.7-cu m (20,000-gal) pre-
fabricated coated steel tank and in-
corporated a diffused-air system to
ensure solids suspension and mixing
and also to maintain aerobic conditions
during storage The buffer capacity of
this tank allowed continuous operation
during normal low flow conditions
encountered at night The tank also
received filter and adsorber spent back-
washes In addition to the influent flow
control liquid-level sensors, electrodes
were also installed to provide emergency
shut down of the remaining treatment
processes m the event of low level
conditions in the flow equalization tank.
The wastewater was pumped from the
flow equalization tank to the treatment
unit by a constant-speed, progressive-
cavity pump
Chemical Clarification
Chemical clarification was achieved
using hydrated line fed at a periodically
adjusted constant rate m a 10 percent
slurry form Lime slurries were made up
on a daily basis using commercial
hydrated lime in 22.7 kg (50 Ib) bags A
1.363-cu m (360 gal) plastic tank served
as the makeup and storage tank Con-
stant mixing of the lime tank was
provided to maintain the slurry using a
0.37 kw (0 5 hp) constant-speed mixer.
Lime slurry was fed to the 0.25-cu m
j(65-gal) flash-mix tank using a variable-
speed, diaphragm-type slurry metering
pump A constant-speed mixer provided
thorough mixing of the lime slurry with
the incoming wastewater from the
equalization tank. Theoretical detention
time within the flash mix unit was 1 87
minutes at the design flow rate of 1 90
cu m/d (50,000 gal/d)
Flocculation was provided in a square
shaped 2 16-cu m (570-gal) tan!
Agitation was carefully controlled usm
a variable-speed, vertical-shaft mixe
Theoretical detention time was 16.
minutes at design flow rate.
Flow from the flocculation tank wa
introduced to the 17.83-cu m (4,71 C
gal) circular clanfier through a distribu
lion box which channeled the flow to
peripheral-feed inlet near the bottom c
the clanfier A theoretical detentio
time of 1 35 minutes wasavailable in th'
clanfier at the design overflow rate of 2i
cu m/sq m/d (640 gal/sq ft/d). Th<
desiga overflow weir rate was 21 c
m/m/d (1,700 gal/ft/d). The clanfie
was equipped with motor-driven sludgi
raking and skimming and an effluen
"V-notch" weir around the circumfer
ence of the tank.
pH Control
A neutralization step was necessar
following lime clarification m order t<
prevent deposition of calcium carbonate
in subsequent processesandtofacilitatf
the biological nitrification process. Foi
large-scale systems this is often ac
complished by recarbonation of the higr
pH clarified wastewater with carbor
dioxide (CO2). For this facility, sulfurk
acid was used because of the capita
cost and space savings inherent in thi!
approach
Sulfuric acid was purchased in 49- oi
57-liter (13- or 15-gal) plastic carboys
and the required solution was made up
daily. A 0.3-cu m (80-gal) plastic tank
was used for mixing and storage of the
20% sulfunc acid solution. A smal
mixer was installed in this tank tc
ensure the initial blending of the watei
and acid. A variable-speed chemica
feed pump was used to transfer the
solution to the 0.19-cu m (50-gali
neutralization tank for the lime-clanfiec
effluent. Thorough mixing of the acid
feed solution and high-pH effluent was
provided. The tank was equipped with
electrodes for pH measurement which
provided signals to the pH control unit
which, in turn, controlled the off-on
operation of the acid feed pump. Experi-
ence demonstrated that acid added
directly into the clanfier effluent piping
upstream of the baffled neutralization
tank (baffled to separate the mixing and
sensing functions) were necessary to
obtain satisfactory operation. The
neutralization tank effluent was then
pumped to the nitrification towers
during most of the operational period,
even though flexibility was available to
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Chemical Feed
Effluent I Chlorine
Contact
Activated
Carbon
Columns
Figure 1. Demonstration plant process flow schematic
vary the sequence of all subsequent
processing steps.
Biological Nitrification
Three separate biological nitrification
towers were constructed from 1.85-m
(72-in) diameter concrete pipe sections
Overall height of each unit was 5.18-m
(17-ft), and they were packed to a depth
of 4 57-m (15-ft) with a high specific
surface plastic media which was light-
weight and provided 187 sq m/cu m
(57-sq ft/cu ft) of surface area with 93
percent void space and a bulk density of
64 kg/cu m (4 Ib/cu ft) by virtue of
random packing m the towers.
The three nitrification units were
designed for parallel operation, with
adjustable flow rates to each unit. The
system design allowed for total recycle
of "seed" sludge in order to obtain a
biological population capable of effecting
nitrification within a reasonable period
(4 to 6 weeks) after startup Rotary
distributor arms were used in each
tower to provide uniform surface
distribution The underdrams from each
tower discharged to a commom sump
for pumping to the subsequent process
Based on the 7 88 sq m (84 8 sq ft) of
surface area contained in the three
towers, the design surface loading rate
was 9 8 cu m/sq m/m (0.4 gal/sq
ft/m).
As with all processes following
clarification/neutralization steps, ef-
fluent from the nitrification towers
could be directed to the dual-media
filters or to the granular activated
carbon adsorption towers; the former
scheme was used throughout this
study System design was based on the
presumption from earlier pilot studies
that there would be a low net solids
production associated with the nitrifica-
tion towers so that intermediate clarifi-
cation prior to filtration would not be
required.
Dual-Media Filtration
The filter used was a downflow
pressure system employing the dual-
media concept, i.e , a 0 3-m (1 -ft) layer
of AWWA B 100 medium (0.45 to 0.55
mm effective size) sand overlain by a 0.3
m (1 ft) layer of anthracite, AWWA B 100
No. 1 (0.6 to 0.8 mm A 1.6-cu m) (424-
gal) surge tank preceded the pressure
filter and provided flow storage during
the filter backwash cycle. In addition,
the surge tank was equipped with liquid
level sensors that served as controls for
the pressure filter feed pump Flow rate
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through the 0.66-sq m (7.1-sq ft)
surface area filter was controlled by a
variable orifice, pressure-compensated
flow regulator at 12.2 cu m/sq m/h (5
gal/sq ft/m). Backwash operation was
automatic with intervals between back-
wash cycles being operator selectable
on a 24-hour time clock. The manu-
facturer suggested backwash initiation
at 28 to 35 k Pa (4 to 5 psig) pressure
differential across the pressure filter
This corresponds to a head loss of
between 2.8 and 35m (9.2 and 11.5 ft).
Flexibility also existed for controlling the
length of each backwash sequence The
chlorine contact tank served as the
backwash source, and backwashing
flow was regulated through a constant-
flow control valve at a rate of 43 cu
m/sq m/h (177 gal/sq ft/m). To
facilitate backwash efficiency, a pre-
backwash air source was provided.
Spent backwash was returned to the
flow equalization tank
Granular Activated Carbon
Columns
Two granular activated carbon columns
were used to provide removal of
dissolved organic matter. The two
columns were operated in series with
the first column being an upflow type
and the second being of downflow
design. Empty-bed contact time for each
column was approximately 21.6 minutes
Each 1.22-m (4-ft) diameter by 2.44-m
(8-ft) tall column contained approxi-
mately 1.22 m (4-ft) of granular activated
carbon (Calgon Filtrasorb 300) underlain
by a 0.3-m (1 -ft) layer of selected gravel.
Flow was introduced into the upflow
column via a perforated distributor
buried in the supporting gravel layer. In
order to maintain a fluidized condition m
the carbon bed at the liquid upflow rate
of 6.8 cu m/sq m/h (2.8 gal/sq ft/m), a
stream of air was also introduced at a
manually controlled rate through a
second perforated distributor within the
gravel layer. Overflow from the upflow
carbon column was screened prior to
overflow to the surface of the downflow
column. Backwash facilities similar to
those for mixed media filtration were
incorporated in the design of the down-
flow carbon column The backwash flow
rate was 19 5 cu m/sq m/h (8.0 gal/sq
ft/m), and a surface wash was provided
during the backwash cycle. The chlorine
contact tank also served as the backwash
water source for this operation, and
spent backwash was returned to the
equalization tank.
Effluent Subsystem
The effluent subsystem included a
water meter for recording plant effluent
flow and the chlormation facilities for
disinfection of the final effluent A4 46-
cu m (1,178-gal) chlorine contact tank
provided a theoretical contact time of
33.6 minutes at the design flow
Chlorine was fed from a 45.4 kg (100lb)
liquid chlorine cylinder using a solution-
feed, vacuum-operated gas chlorinator,
mounted directly on the cylinder The
operating vacuum was provided by a
hydraulic injector unit, with a close-
coupled diffuser attached to a sub-
mersible pump mounted on the contact
tank floor.
Sludge Handling Facilities
A 30 28-cu m (8,000 gal) rectangular
sludge storage tank was provided to
handle the excess lime sludge from the
chemical clarification unit As lime
sludges generally show good settling
properties, provisions were made in the
storage tank to gravity thicken the
sludge. Supernatant drawoff ports were
placed at selected elevations along the
upper section of the sludge storage tank
to allow decanting of the supernatant
during settling The decent was returned
to the flow equalization tank
A diff used-air system was installed to
prevent anaerobic conditions and ex-
cessive compacting and to facilitate
removal of the thickened sludge. Cou-
plings were installed at the bottom
sludge draw-off valve toallow tank truck
disposal of excess accumulated solids
The design and intent of the sludge
storage-thickening unit was to aerate
the sludge to prevent anaerobic condi-
tions and to periodically stop aeration to
permit thickening and subsequent
supernatant drawoff. Withdrawal of
thickened solids for disposal was
permitted only during the aeration cycle
to assist in fluidizmg the tank contents
for easier withdrawal.
Evaluation Factors
Sampling
Automatic composite samplers were
used for collecting samples from the
equalization tank (influent) and the
effluent from the carbon adsorbers prior
to chlorination (effluent). Also, periodic
grab samples were taken of the clarif ler
effluent, neutralization tank effluent,
nitrification tower effluent and filter
effluent. All samples were refrigerated
including samples for biochemic;
oxygen demand (BOD5) and suspende
solids (SS) Besides refngeratior
samples for chemical oxygen deman
(COD), total organic carbon (TOC), tot;
Kjeldahl nitrogen (TKN), ammom
nitrogen (NH3-N) nitrite nitrogen (NO;
N), nitrate nitrogen (NO3-N), acid
hydrolyzable phosphate (AHP), an
orthophosphate were further preserve
by the addition of 2 ml of H2SO4 per lite
of sample following collection A
testing was done m conformance wit
"Standard Methods for Examination c
Water and Wastewater," Fourteentl
Edition, 1975
Construction and Start Up
Project planning and plant design an
specifications were completed in Fet
ruary 1975 Due to the nature of th
project and the equipment required, tw
separate contracts were awarded. On
contract encompassed the skid-mounte
physical-chemical treatment systerr
while the other covered site worL
nitrification towers, the flow equalizatioi
tank, the sludge storage/thickene
tank, and other miscellaneous items. Al
bids for both contracts were considerabl'
in excess of the budget limits of thi
project Negotiations with the lov
bidders coupled with numerous desigl
changes resulted in the eventua
signing of both contracts within ths
original budget estimates The physical
chemical (P-C) plant was delivered ir
January 1976. The work scheduled ir
the second contract was to be completec
in late November 1975, but due tc
financial difficulties on the part of the
contractor and subsequent unantici
pated requirements resulting from this
problem, the construction phase anc
initial testing were not completed unti
late 1977
Numerous problems were encoun-
tered during the initial attempts to check
out the individual units in the system
and to verify their proper operation. The
treatment system was designed for
above ground operation to allow for a
short installation time and to facilitate
movement of the system to another
location, should the need arise. The P-C
system was delivered to the site in
January 1976. Because of the serious
delays m completion of the other
contract, this equipment was left at the
site, unused, for two years including
two winter seasons of unusually cold
weather. Proper precautions were not
taken to protect the units during this
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long period Numerous pipes, valves,
fittings, and pumps suffered substantial
damage, requiring replacement or
repair Breakdowns encountered with
pumps and motors continued to be a
major problem during the entire opera-
tional phase of the project, probably
caused by the long exposure
Results
Overall Removals
Prior to system design 10 twenty-four
hour composite samples of the raw
wastewater gave the results presented
in Table 1.
During the operational phase, the
average BOD5 of the equalization tank
samples average characteristics were
159 mg/l of BOD5, 368 mg/l of SS, and
435 mg/l of COD, as shown in Table 1 in
parentheses. The significance of the
differences between these values is not
clear, since some are lower and some
higher. Certainly, some changes could
be due to the aerated flow equalization
tank prior to the pumping to the
clarification unit. Since the theoretical
retention time in the equalization tank
was between 5 and 10 hours, some
biological oxidation could have occurred,
and the recycle of certain streams from
the treatment system to this tank would
also account for some variance.
A summary of the treatment efficien-
cies achieved with each of the units
(clanfier, nitrification tower, dual-media
filtration, and carbon columns) is
presented in Table 2. The percent of
removal of BOD5, COD, TOC, SS, acid-
hydrolyzable phosphorous, and total
nitrogen, is presented The data represent
paired samples where influent and
effluent samples were taken from each
unit and analyses performed Thus, the
percentage of removal within one unit is
calculated from the difference of the
influent and effluent of that unit The
percentage of cumulative removal is
calculated from the difference between
the clanfier influent and the effluent of
that unit. As can be seen, the removals
of BOD5, COD, TOC and SS were
excellent, with cumulative removals
ranging from 88 percent for COD to 97
percent for suspended solids. The
greatest amount of organic material and
suspended solids was removed during
the lime clarification.
Phosphorus removal from an influent
concentration average of 12.3 mg/l was
also excellent but the nitrogen removal
was rather low. The major portion of the
phosphorus was removed during the
lime clarification. High lime feed with a
higher pH (11.4 as compared to 10.7 for
the low lime feed) significantly increased
the removal of phosphorus, i.e., from 63
to 87 percent. Recycle or non-recycle of
clarifier sludge had little influence on
the removal of phosphorus
Nitrification never properly developed
during the course of the study, even
though nitrogen removals averaged 40
percent from the average influent con-
centration of 38 mg/l during the last
eight weeks of operation The overall
removal of nitrogen averaged 32 per-
cent, with losses nearly equally split
between the clarification, filtration, and
carbon adsorption processes In the first
two processes these removals can be
attributed to the organic nitrogen
content of the solids removed In the last
process nitrogen removal appears to
have been due to denitrification in the
carbon beds
Individual Process Performance
As noted in Table 2, the limeclanfica-
tion step accounted for the major
Table 1. Wastewater Characteristics*
portion of removal of all pollutants
measured From the standpoint of
defined secondary effluent quality, the
clanfier effluent nearly metthe BODs SS
requirement of 30:30, with actual
values of 46 21. Organics, as measured
by BOD5, COD and TOC were removed
by average rates of 66 to 77 percent,
while 82 percent of the acid-hydrolyzable
phosphorus was removed.
The nitrification tower, though seem-
ingly ineffective in its intended role as
measured by nitrogen series analysis,
did provide significant additional re-
movals of BOD5, TOC and COD. The
reasons for the apparent lack of nitrifi-
cation remain somewhat mystifying
based on earlier published data which
indicated that the designed system
should be able to oxidize 3.2 to 8 2 kg of
NH4-N/day (7 to 18 Ib/d) Since the
approximate loading was 5 0 kg of NH4-
N/day (11 0 Ib/day), the resulting
oxidation, as measured by NO2-N and
N03-N increase, of 0 27 kg/day (0 6
Ib/day) was disappointing This is
especially true in light of favorable
wastewater temperatures and BOD5/
BOD5 COD TS VTS SS VSS DS VDS pH Alkalinity
as CaC03
239 370 974 467 411 219 562 248 7.0 278
(159f (435f (368f
* all analyses in mg/l, except pH
+ operational phase averages
Table 2. Project Data Summary
Parameter Measured*
Subsystem
Clanfier
% Removal
% Cumulative
Nitrification
% Removal
% Cumulative
BODs
77
77
44
84
COD
73
73
13
76
TOC
66
66
42
80
SS
86
86
Neg.
85
AHP**
82
82
Neg
80
77V***
13
13
Neg.
11
Dual-Media Filter
% Removal — 40 5 71 17 11
% Cumulative 91 86 82 95 85 24
Carbon Columns
% Removal 33 15 20 39 Neg. 10
% Cumulative 93_ 88_ 86 57 80 32
* Data represents paired samples where influent and effluent analyses were
performed.
** Acid-Hydrolyzable phosphorus
*** Total Nitrogen
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TKN ratios. Initial attempts to provide
seeding to the nitrification towers were
unsuccessful due to hydraulic deficien-
cies in the plant, but sufficient operating
time was available for natural develop-
ment of mtnfiers The fact that no such
development took place would appear to
be due to either the unreliability of the
neutralization step and/or the lack of
recirculation
The dual-media performed well in
terms of solids removal and concomitant
removals of organics, TKN and AHP
associated with those solids Suspended
solids removals of 70 percent were
achieved, along with COD, TOC, TKN
and AHP removals of 40, 5, 11 and 17
percent, respectively However, the
media sizes were not well-suited to
handling the 44 mg/l of SS (average)
found in the filter influent. Therefore,
filter runs were frequently as short as
four hours, which represented a con-
siderable 0/M problem, because of the
fine coal size provided with the filter.
The activated carbon columns were
loaded very lightly during this study. The
COD removed by the adsorbtion process
had reached 018 Ib. of COD per Ib. of
activated carbon by the end of the
project, no apparent reduction in the
rate of COD removal verified that the
carbon had not been exhausted. The
system was designed with the capability
of removing spent carbon and adding
fresh carbon Denitrification of the
nitrate produced by the nitrification
towers did occur in the carbon columns,
and no hydrogen sulfide problem was
encountered.
Performance Reliability
In spite of the equipment and opera-
tional problems encountered, the hybrid
(physical-chemical/biological) treat-
ment plant, as designed, was able to
produce a consistent, high-quality
effluent, when compared to typical
biological systems used to treat waste-
waters from small communities. Figure
2 compares the reliability of this hybrid
system for the removal of BOD5 and SS
versus extended aeration plants in the
Cincinnati area. Since this hybrid plant
also removes phosphorous, other bio-
logical systems would require ancillary
treatment steps to provide comparable
performance characteristics
Operation and Maintenance
The normal operation and mainte-
nance of this plant was more time
consuming and complex than that
associated with most biological treat-
700
90
80
70
60
Q
2 50
OQ
0)
3
Uj
40
30
20
10
Cincinnati Area
Extended Aeration
Plants
Beechgrove
Demonstration
Plant
100
90
80
70
60
50
Oi
5
CO
c
Q)
40
30
20
10
0
2 5 10 20 30 40 50 60 70 80 90 95 98 99
Percent of Time Value was Less Than
Figure 2. Comparison of BOD5 and SS reliability
ment plants Some of the work involved
the sampling and laboratory testing
required at the site for the experiments
of this project and included sample
preparation and delivery and prepara-
tion of logs and records However, there
were a number of pumps, tanks, mixing
chambers, and backwash systems
which had to be cleaned, adjusted, and
occasionally repaired The mixing of
chemicals (lime slurry and acid neutral-
izer) required knowledge of the opera-
tions and caution to avoid chemical
burns. One full time operator was
required with additional manpower
required for any unusual problem.
Weekend coverage of the plant was also
provided.
In order to properly conceive of the
O/M requirements, it should be noted
that an extended aeration package plant
capable of handling the same design
flow normally requires approximately
0.5 person-years/year. Therefore, the
manpower required for the hybrid
system was approximately three times
that required for an extended aeration
system. Likewise, increased chemical
costs are inherent to the hybrid system
design The value of relatively instan-
taneous, high-quality effluent would
have to be weighed against these
increased O/M costs on a case-by-case
basis The question of initial cost
comparison is far more difficult because
of the transport-ability of the physical-
chemical portion of the hybrid plant.
Multiple use of such a system by a
public or private entity at different sites
would determine whether such a
system would be economical.
4
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Discussion
Two factors were intended for testing
in this study, the technical feasibility of
the treatment sequence and the concept
of transportability Although certain
shortcomings arose in the testing of
these factors, certain implications of the
study are relevant to each
The transportability concept is impor-
tant to agencies such as DHUD in that
the potential health and ecological
dangers which often result from natural
or man-made disasters might be mini-
mized through prompt response with
nearly instantaneous high quality treat-
ment capability to meet most water
quality limitations To a lesser degree,
an adjunct treatment capability for
"boom towns" or other sudden popula-
tion increases, which in recent times
have been associated with energy
development, could obviate the potential
impacts on a fragile ecology due to
sudden overload of existing sanitary
facilities and infrastructure
As noted earlier, the physical-chemi-
cal (P-C) portion of the hybrid treatment
plant was skid-mounted and trans-
portable from site-to-site by tractor
trailer The associated process needs,
i e , equalization and sludge handling,
could quickly be provided at almost any
site by excavation and lining or other-
wise sealing of the soil to prevent
seepage and/or introduction of debris
to the wastewater, if such tankage is not
already available Therefore, a complete
(P-C) unit could be quickly operable at
such locations, assuming necessary
power provisions at the plant site The
nitrification tower is an unlikely addition
in the event that a nitrogen standard
must be met, not because of its marginal
performance during this study, but
because its inherent lag time to reach
proper nitrification is inconsistent with
the otherwise quick startup potential of
the unit Therefore, the P-C system
alone would serve the transportability
function quite well if no nitrogen
standard were in effect and offer the
added benefits of phosphorus removal
and consistently high quality perform-
ance. Introduction of a nitrogen standard
would probably require the use of break-
point chlormation or stripping towers in
order to provide relatively instantaneous
nitrogen removal consistent with the
overall plant characteristics.
The technical feasibility of the hybrid
facility's processing sequence is a
separate issue. The concept of utilizing
biological nitrification with physical-
chemical processing was designed to
overcome two basic weaknesses in the
P-C treatment concept, i.e., high NH4-N
concentrations in the effluent and odors
associated with the carbon adsorbers
the perceptible nitrification was minimal,
the total system did remove about 30
percent of the nitrogen in the waste-
water, as opposed to the original
estimate of 36 percent. The major
The latter problem had been overcome
by the addition of NO3-N to the influent
of carbon adsorbers in sufficient quantity
to prevent H2S formation. The hybrid
facility was designed to utilize the
nitrogen already in the wastewater by
converting, all or part of, it to the NOs-
form prior to carbon adsorption. Although
difference in the actual vs estimated
effluent quality was the form of the
nitrogen, i e , NH4-N rather than NCb-N,
which could result in a significant
oxygen demand in the receiving stream
The overall acceptability of a waste-
water treatment system is based on a
variety of factors including capital and
0/M costs, labor requirements and
performance characteristics If one
assumes that the reasons for poor
nitrification tower performance can be
easily overcome through improved
neutralization and nitrification tower
design, the hybrid design studied (with
proper filter media) is capable of
producing a high-quality effluent un-
matched by either pure biological or
pure physical-chemical systems, incor-
porating the positive features of both
systems, eg , compact size, reliability,
resistance to toxic upset, improved
toxics removal, phosphorus removal,
non-odorous operation, and nrtrogen
reduction with ammonia removal
The EPA authors James F. Kreissl(a/so the EPA Project Officer, see below) and
Ronald F. Lewis are with the Municipal Environmental Research Laboratory,
Cincinnati, OH 45268
The complete report, entitled "Demonstration Physical Chemical Sewage Treat-
ment Plant Utilizing Biological Nitrification," was authored by E Brenton
Henson of the Sanitation District No 1 of Campbell and Kenton Counties,
Covmgton, KY 41011 (Order No PB 82-101 643, Cost $950. subject to
change) will be available only from
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone 703 487-4650
The EPA Project Officer can be contacted at
Municipal Environmental Research Laboratory
U S Environmental Protection Agency
Cincinnati, OH 45268
. S. GOVERNMENT PRINTING OFFICE- 1981/559-092/3321
-------
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Environmental Protection
Agency
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