United States
Environmental Protection
Agency
Water Engineering
Research Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/S2-86/005 Mar. 1986
&EPA Project Summary
Ultraviolet Disinfection of
Wastewaters from Secondary
Effluent and Combined Sewer
Overflows
0. Karl Scheible, Maureen C. Casey, and Angelika Forndran
A 2-year, pilot-scale investigation
was conducted at New York City's Port
Richmond Water Pollution Control
Plant to demonstrate the application of
ultraviolet (UV) disinfection to second-
ary wastewater effluent and to deter-
mine the feasibility of applying UV
radiation to the disinfection of a waste-
water similar to combined sewer over-
flow (CSO). Three systems were op-
erated: Two were submerged quartz
units that differed only in the spacing of
the lamps; the third used Teflon* tubes
to carry the liquid, with the UV lamps
surrounding the tubes.
The UV process was very effective
in the disinfection of secondary efflu-
ent. The performance of the process
could be described empirically by the
initial coliform density, the suspended
solids, the UV absorbance coefficient,
and the system loading rate, as defined
by Q/W, the ratio of the flow to the
actual UV output of the system. Over-
all, the study demonstrated that log
survival ratios of -3 to -4 could be
achieved consistently at practical sys-
tem loadings. Similarly, the study
showed that a log survival ratio of as
low as -3 could be achieved with
primary effluent.
A mathematical expression was
developed and was found to respond
correctly to the variables associated
with the UV process. The study demon-
strated that coliforms, which are oc-
cluded by suspended particles, are not
•Mention of trade names or commercial products
does not constitute endorsement or recommendation
for use
affected by UV light and, in effect, set
the limiting final density. The inactiva-
tion rate of the coliform was related to
the calculated intensity of the UV
reactor.
Suggestions are made with regard to
the maintenance and monitoring of the
system to enhance the efficiency and
cost effectiveness of the process. A
cost analysis of the system shows it to
be cost effective and competitive with
chlori nation.
This Project Summary was devel-
oped by EPA's Water Engineering Re-
search Laboratory, Cincinnati. OH. to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
The use of ultraviolet (UV) radiation
for the disinfection of wastewaters is
accepted as an effective and economi-
cally attractive alternative to the use of
chlorine or ozone. As with any newly
emerging technology, however, direct
field experience is limited, and system
designs have generally relied on empiri-
cal information. The primary objectives of
this study related to design considera-
tions for UV systems. The study was to
establish and demonstrate a design ap-
proach that would account for the major
process variables and that would be
generically applicable to alternative
equipment configurations and waste-
water applications. The program also
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addressed the water quality parameters
appropriate to UV disinfection. Operation
and maintenance (O&M) requirements
were assessed, with particular regard
to those tasks needed to maintain effec-
tive long-term performance. Finally, an
analysis of capital and O&M costs was
conducted.
Facilities and Experimental
Program
Facilities
Port Richmond, located on the north
shore of Staten Island, is 1 of 12 waste-
water treatment plants owned and op-
erated by the New York City Department
of Environmental Protection. This step-
aeration, activated-sludge facility has a
design capacity for the secondary system
of 227 million L/day (60 mgd). Excess
primary effluent can be bypassed around
the secondary portion of the plant. The
pilot facility was located so that there
was convenient access to both the sec-
ondary effluent and the bypassed pri-
mary effluent. A layout of the pilot facility
is presented in Figure 1. Either secondary
or primary effluent would be pumped to a
constant-head tank, with the overflow
returned to the plant bypass channel.
Flow would then be directed by gravity
to the UV units.
Units 1 and 2 were submerged quartz
systems. Each had 100 lamps in a sym-
metrical (10 by 10) array perpendicular to
flow. The lamps were Voltarc 40 Watt
(nominal) G36T6VH. They were 0.9 m
long and had an arc length of 0.75m. The
rated output for each lamp at 253.7 nm is
14W nominal. Each lamp was sheathed
in a quartz sleeve with a 2.3-cm di-
ameter. The only difference between the
two systems was that the spacing be-
tween the quartz surfaces was 5.0 cm for
Unit 1 (7.3-cm centerline spacing) and
1.25 cm for Unit 2 (3.55-cm centerline
spacing). Each of the quartz units was
equipped with mechanical wipers to
maintain the outer quartz surfaces. The
units were tested at flow rates between
800 and 2500 L/M; residence times
were generally between 1 and 20 sec.
Unit 3 used Teflon tubes to carry the
liquid. The test compartment of Unit 3
contained eight Teflon tubes, each 3 m
long and 8.9 cm in diameter. The tubes
were on 15-cm centerlines. The lamps
were placed on the outside of the Teflon
tubes. Two lamps were required to ex-
tend the length of the Teflon. The lamps,
each with an effective a re length of 1.5 m,
were also placed on 15-cm centerlines
parallel to the Teflon tube.
Unit 3
Unit
1
Meters
Power Panel
5. cm i
Units
—: 1.25 cm
Eff. Tanks--'
g - Butterfly Valves -
Inf. Tanks
U.V.
Unit
2
Power Supply
Lighting Supply
From Feed Pumps
—»~ To
Bypass
To Bypass
-. Palmer-Bowk
Flumes
Units 1 and 2
Effluent
Figure 1. Schematic layout of UV pilot facility at the Port Richmond Water Pollution Contr
Plant, Staten Island. New York.
Experimental Program
The Field program was initiated in
December 1981 with the startup of the
two quartz systems. The Teflon unit was
in place by August 1982. The operational
period for testing the units extended
through September 1983. The experi-
mental program was designed to monitor
system performance over a wide range of
loading conditions. The operational vari-
ables imposed on the units were the rate
of flow and the number of lamps in
operation.
Influent and effluent samples were
enumerated for total and fecal coliform
densities by direct membrane filter (MF)
techniques. Influent samples were
analyzed for suspended solids, turbidity,
pH, temperature, and UV absorbance
(total and filtered) and chemical oxygen
demand. The UV absorbance measure-
ment was conducted by standard spec-
trophotometric procedures and by a
procedure that corrected for the scat-
tering of light. Special studies that were
incorporated into the experimental pro-
gram included detailed hydraulic tracer
analyses, photoreactivation by the stati
light and dark bottle procedure, an
specific procedures to monitor direct!
the transmissibility of the quartz an
Teflon enclosures and the UV output c
the lamps.
Results and Discussion
The total and fecal coliforms average
(geometric mean) 1.02 x 106 and 3.61
10B colonies/100 mL for the 2-ye<
period, respectively. Relatively littl
seasonal variation occurred for the col
form densities; significant variatior
were seen, however, in the routine wati
quality parameters such as the CO
(average = 44.5 mg/L) and suspend*
solids (average = 14.3 mg/L). These vari
tions were generally seasonal in natur
the higher-quality effluent occurre
during the warmer summer month
when nitrification was typically ai
complished at the plant.
The UV absorbance coefficients (ba:
e) were determined by two measun
ment techniques for both total ar
filtered samples. The first method w<
-------
simply a spectrophotometric measure-
ment of the absorbance of a direct beam
of light (at a wavelength of 253.7 nm)
that is passed through a quartz cell with
a 1-cm pathlength. By this method, light
that does not pass directly through the
cell and reach the detector \s considered
to be absorbed. The second method in-
corporates an integrating sphere and
accounts for light that is scattered and
still available for germicidal activity. The
spherical method is, in effect, a more
accurate measure of the true absorbance
than is the direct method.
The direct absorbance measurements
were always higher than the spherical
absorbance measurements, indicating
that the more routinely practiced direct
method overestimates the loss of energy
in the liquid. The direct UV absorbance
coefficient averaged 0.466 cm"1 and
0.404"1 for the total and filtered samples,
respectively. Average total and filtered
UV coefficients of 0.372 cm"1 and 0.358
cm"1, respectively, were measured by
the spherical method. The direct method
measures an absorbance for the total
sample that is approximately 17 percent
higher than that measured by the spheri-
cal method. A reasonable approximation
can be made by using the direct method
on a filtered sample; this approach could
be used in cases where the instrumenta-
tion is not available to correct for scat-
tering effects.
Tests were conducted over 2 weeks
using primary effluent as the feed to the
UV systems. The total and fecal coliforms
averaged 3.17 x 107 and 1.25 x 107
colonies/100 mL, respectively. The
average suspended solids were 80.9
mg/L; the UV absorbance coefficients
averaged 0.865 and 0.747 cm"1 for the
direct method, total and filtered, re-
spectively, and 0.593 and 0.533 cm"1 for
the spherical method, total and filtered,
respectively.
Hydraulic Characterization
A procedure was demonstrated for
experimentally constructing a residence
time distribution (RTD)fortheopen chan-
nel quartz systems. This procedure in-
volved the steady-state injection of a
tracer upstream of the unit; the injection
would be discontinued, and the die-away
to a second steady-state level (back-
ground) would be measured downstream
of the unit. The derivative of this curve
would then be determined and plotted
with time to yield the RTD curve.
A series of RTD curves was developed
and analyzed to estimate the dispersion
coefficient, E, of the system. This coeffi-
cient measures the spread of the RTD
curve and indicates the unit's hydraulic
behavior with regard to plug flow (E ap-
proaches zero) and complete mix (E ap-
proaches infinity) conditions. The values
of E for the two quart systems were esti-
mated to be 1.5 cm2/sec and 15 cmVsec
for Units 1 and 2, respectively. By calcu-
lation, the Teflon unit was shown to
approximate a plug flow reactor. Data
were also presented to demonstrate
turbulence for all three reactors.
Estimation of Available
UV Energy
An important element in evaluating
a UV system's performance or in the
design of a system is the actual energy
available in the germicidal range. The key
is to understand how efficiently the
253.7-nm energy of the low pressure
mercury arc lamp is being used and,
conversely, how it is being lost. A con-
siderable effort was expended during the
study to directly monitor the output of the
lamps and to quantify the amount of
energy available for disinfection. A sum-
mary of these data for the quartz systems
is presented in Figure 2, which estimates
the average UV output of the lamps with
I
IS
-------
The energy loss resulting from the
fouling of surfaces through which the UV
radiation must pass was measured under
varying conditions and after specific
cleaning exercises. With regard to the
quartz systems, this fouling occurred on
both the inner and outer surfaces of the
quartz. Cleaning was generally accom-
plished by a combined acidic/detergent
solution. The Teflon surfaces also be-
came dirty, and estimates were made of
the tube transmittance with time. The
lower line in Figure 2 is therefore an
estimate of the actual output being used,
which can be as low as 30 to 40 percent
of the nominal output. This information is
used to estimate the total wattage at
253.7 nm being transferred to the liquid
at the time of a given sampling.
Empirical Analysis of Process
Performance
The performances of the UV units
were empirically evaluated by a series of
multiple linear regression analyses.
These correlated performance with the
operation of the units and with thequality
of the Port Richmond secondary and
primary effluents. The least squares
method was used; the regression is cal-
culated stepwise, ordering the indepen-
dent variants by decreasing degree of
significance. The dependent variable in
all cases was the log of the survival ratio
(Log L/Lo) for either total or fecal coli-
forms. The independent variables that
were tested to reflect wastewater quality
were the suspended solids, turbidity, and
either the direct or the spherical UV ab-
sorbance coefficients. The variant se-
lected to represent the operating condi-
tion of the particular unit was the ratio of
the flow rate to the estimated total UV
output at 253.7 nm at the time of sam-
pling. This ratio, Q/W, is measured in
L/min per watt. The UV output, W, is
estimated from the number of lamps in
operation at the time of sampling and the
estimated average lamp output at the
time (Figure 2).
Performance was best predicted by
the ratio Q/W, the suspended solids con-
centration, and the spherical UV ab-
sorbance coefficient. An example of
solutions to the regression equations for
Units 1 and 2 is presented in Figure 3.
This figure shows the loading to the
system (as defined by the ratio Q/W), as
a function of the UV absorbance coef-
ficient and the suspended solids to
achieve log fecal coliform survival ratios
of -3 and -4.
Application of the Proposed
Disinfection Model
A mathematical model was developed
as part of the Port Richmond project to
describe the process performance of a UV
disinfection system. The expression is
written:
L = Lo exp [ ux{
2E
+ Lparticulate
+ 4KE)1/2}]
U2
(1 )
where:
L = the bacterial density re-
maining after exposure
to UV (coliforms/100
ml)
Lo = the initial bacterial den-
sity measured immedi-
ately before entry into
the UV reactor (coli-
forms/100 mL)
x = the distance traveled b\
an element of watei
while under direct ex
posure to UV light (cm)
u = the velocity of the waste
water as it travels through
the UV reactor (cm/sec)
This quantity is calculate*
as:
u = x/(Vv/Q)
where Q is the flow rat(
(L/sec) and V» is the re
actor void volume (L)
E = the dispersion coeffici
ent (cmVsec)
K = the rate coefficient fo
the inactivation of coli
forms (sec"1).
iate = the bacterial density as
sociated with the par
ticulates in the waste
water (coliforms/10<
mL)
r-SS{mg/l)
'
Unit 2
Fecal Coliform
L -3.0
0.2
0.8
8.0
6.0
x
Q.
. 4.O
a
2.0
SS (mg/l)
Unit 1
Fecal Coliform
Log = -4.0
1-0
0.4
0.6
8.0
6.0
4.0
2.0
0
1.0 O
Unit 2
Fecal Coliform
Log — = -4.0
f-o
SS Img/l)
I
I
0.2
0.8
a, (cm'1)
Unit 1, Fecal Coliform — Secondary Effluent
Log
-L = 0.3/5 (Q/W) + 0.032 (SS)
L° + 2.44 (crj - 5.59
0.4 0.6
Us (cm''1)
Unit 2, Fecal Conform—Secondary Eff.
Log — = 0.321 (Q/W) + 0.029 (SS)
L° + 2.52 (ctj - 5.56
Figure 3. Sizing requirements for the quartz units to achieve fecal coliform logL/L0of-3 and-
in a secondryeffluent as a function of suspended solids and absorbance coefficier
-------
Thus aside from knowing (or estab-
lishing) the physical dimensions of the
system (x, Vv) and the system loading
conditions (Q and L0), the model requires
knowledge of the hydraulics of the sys-
tem (E), the sensitivity of the coliforms to
UV (K), and the characteristics of the
wastewater (coliform occlusion in the
participates, and, as will be discussed
shortly, the UV absorption properties of
the fluid). The dispersion coefficient of
the two units (quartz) has been dis-
cussed. The inactivation rate is estimated
as a function of the intensity within the
UV reactor. Thus it is important that the
intensity be quantified for a given system
configuration.
UV Intensity
Complex, multi-lamp systems do not
allow for the direct measurement of the
actual UV intensity at any point within a
reactor. A microorganism moving through
a complex lamp system will'be exposed to
radiation from all directions; current
detector systems are not capable of
adequately accounting for all energy
under such conditions. However, a com-
putational method has been developed to
approximate the light intensity within a
system on the basis of the physical prop-
erties of the UV lamps, the configuration
of the multi-lamp reactors, and the prop-
erties of the aqueous medium. This
method is based on the point source
summation technique, which presumes
the lamp to be a finite series of point
sources that radiate energy radially in all
directions. The intensity at a given point
in a reactor is, then, the sum of intensi-
ties from each of these point sources. The
full report presents the computational
framework for the method.
The final product of the intensity
computation is the average nominal in-
tensity in a reactor as a function of the UV
absorbance coefficient of the liquid. This
product is presented in Figure 4 for each
of the units operated at Port Richmond.
An important note applies to these solu-
tions: The intensity is calculated at the
nominal output of the lamp and assumes
that the quartz and Teflon enclosures will
transmit 100 percent of the energy. Thus
to estimate the actual intensity under a
given set of conditions, it is necessary to
adjust the nominal average intensity:
Average intensity = (nominal average
intensity)
x (output fraction relative to nominal
lamp output)
x (transmittance relative to nominal
enclosure transmittance)
5
X
CM
5
•5! 4
<2
I
S 3
8
I i
I
Low Pressure Mercury Arc
Rated Nominal Output ~
18.2 Watts/m arc
(at 253.7 nm)
Unit 2
Unit 3
5: 0 0.2 0.4 0.6 0.8 1.0
•^
UV Absorbance Coefficient at
253.7nm, asfcm'^i
Figure 4. Solutions of intensity model for
units 1, 2, and 3 as a function of
the UV absorbance coefficient.
Estimate of Coliform Density
Associated with Particulates
Coliforms that are heavily aggregated
or are retained in the suspended matter
typical of primary or secondary effluents
will not be affected by the UV radiation. A
select set of Port Richmond data were
analyzed to estimate the densities as-
sociated with the particulates, as defined
by the suspended solids concentration.
The samplings were those conducted
under very high-dose conditions (Q/W
very low). The rationale was that any
coliforms measured after such exposure
would be attributable to the coliforms
retained in the particulates. A linear
regression of the log of the effluent fecal
coliforms as a function of the log of the
suspended solids, when transformed,
yields an expression in the form,
Lparticulate — C Oo
where SS is the suspended solids
(mg/L); in this case, c and d were deter-
mined to be 0.26 and 1.96, respectively.
Estimate of the Inactivation
Rate as a Function of the
Intensity
Insimilarfashion, a subset of data was
selected to estimate the inactivation rate.
In this case, the samplings are those in
which the dose was low enough that a
significant coliform density would re-
main in the exposed effluent. The rate
was estimated for each sampling by
manipulating the model equation and
solving for K. The correlation of the Log K
as a function of the Log (average was found
to be linear; the data for fecal coliforms
are presented in Figure 5. The trans-
formed expression has the form,
K = a lb average
where (average has the units /uW/cm2. The
coefficients were determined to be
0.0000145 and 1.3 for a and b, respec-
tively.
Calibrated Disinfect/on Model
The foregoing discussions presented
the analyses required to determine the
appropriate model coefficients. These
were a and b to describe Kas a function of
the intensity, c and d to describe the
Lparticuiate as a function of the suspended
solids, and the dispersion coefficient, E.
These coefficients can now be used in the
calibrated model to predict performance.
The predicted values were compared to
the observed values as a test of the
validity of the model expression. These
analyses, which are presented in detail in
the report, showed the model expression
to respond correctly to the variables
associated with UV design.
Model solutions were developed as
part of the study to demonstrate the
utility of the model for design and for the
evaluation of existing systems. An exam-
ple is provided in Figure 6, which pre-
sents the predicted performance of each
of the three system configurations as a
function of the system loading and the
calculated intensity. Note that these do
not account for the effect of the coliform
density associated with solids; the latter
would be additive to the levels predicted
by Figure 6. Several design examples are
presented to demonstrate the use of the
model for estimating design sizing for
varying wastewater and operating con-
ditions.
Cost Analysis
A detailed cost analysis was con-
ducted to determine current capital and
O&M costs for the UV process. The
capital costs are presented on the basis of
both equipment and installed costs; also
included is a discussion of the facilities
required to support the process. The
O&M is broken down to several cost
elements, including labor, energy, ma-
terials, and system replacement parts.
The details of the cost evaluation cannot
be presented within the context of this
summary, but it is critical that these
details be understood before the reader
can make effective use of the cost curves
presented in the report. For this reason,
we refer to the full report only for a
discussion of the costs. The following
figures can be used as preliminary
-------
20.0
u
01
I
I
10.0
8.0
6.0
4.0
2.0
1.0
0.8
0.6
0.4
0.2
Fecal Coliform
(Effluent Density Corrected for SS)
Unit 1 O
Unit 2 •
~ LogK-1.3Loglmr4.84
[K = 0.0000145 /»,a13]
r = 0.914
\
\
\
\ \
J \
600 WOO
2000 4000 6000
Average Intensity, l^
10,000 20,000
60.000
Figure 5. Estimation of the inactivation rate for fecal conforms as a function of the calculated
average intensity.
screening factors in estimating the costs
associated with UV disinfection.
The equipment costs (reactor, ancil-
lary equipment, and replacement parts)
will range from $4800/kW for the larger
systems (greater than 400 lamps) to
$7900/kW for the smaller systems (less
than 20 lamps). Note that these are 1984
costs; kW is total wattage (generally use
80 watts/lamp). The installation cost is
1.5 to 2.0 times the equipment cost
(housing, piping, electrical, engineering,
etc.). A ballpark figure of $15,000/kW
can be used as an estimate of installed
cost.
Exclusive of capital amortization,
annual O&M costs are between $1200
and $1700/kW for the smaller systems
(less than lOkW) and between $600and
$800/kW for the larger systems (greater
than 300 kW). Setting the trend from
smaller to larger systems, the materials
cost accounts for 20 to 40 percent of the
annual O&M costs (75 percent of which
is the replacement of lamps), power ac-
counts for 10 to 30 percent, and labor 70
to 30 percent.
6
Conclusions
The mathematical model expression
developed as part of this project correctly
responds to the major UV process and
equipment variables. When calibrated to
a specific wastewater application, the
model can be used to develop design
curves for specific equipment configura-
tions, and it can be used to describe the
operations of a system. The critical
wastewater parameters required are the
design flow, suspended solids, UV ab-
sorption coefficient, and the initial
density.
The ideal hydraulic design of a UV
reactor is one with radially turbulent plug
flow. These conditions can be achieved:
(1) by designing for effective approach
and exit conditions to yield an even dis-
tribution of flow across the entire lamp
reactor, (2) by designing at higher veloci-
ties to encourage turbulence, and (3) by
having high aspect ratios (length to
hydraulic radius).
The average intensity of UV radiation
in a reactor can be calculated by the point
source summation method and described
as a function of the absorbance coef-
ficients of the wastewater. This estimate
must then take into account the actual
output of the UV source and the trans-
missibility of the enclosures separating
the source from the liquid.
An effective parameter in describing
the sizing of a system is the radio of the
flow rate to the system's UV output,
Q/W. This ratio can be used empirically
and as an output parameter for the dis-
infection model. The wattage must ac-
count for the losses associated with the
aging of the lamps and the degradation ol
the enclosure surfaces. Performance ol
the Port Richmond units was best de-
scribed by this ratio coupled with the
suspended solids and the UV absorbance
coefficient.
Log survival ratios greater than -5 car
be achieved for secondary effluents; the
effect of the solids, however, will be add!
live. Thus if the solids contribute densi
ties equal to 1 to 2 logs, then the actua
performances that can be achieved are
between -3 and -4; this level is generally
sufficient for secondary effluents. U\
radiation is also effective in thedisinfec
tion of primary effluents, achieving lo(
survival ratios as low as -3 at initia
densities greater than 107 colonies/10(
ml. Much of the residual density will b<
associated with the suspended solids ir
the effluent, and the hydraulic loading;
are relatively low because of the higt
absorbance characteristics of the waste
water.
The quartz systems were most ef
ficient than the Teflon system, based or
the level of energy required to achieve
equivalent levels of performance. Nc
significant performance difference;
were found between the two quart;
systems, which differed only in th<
spacing between the quartz surfaces.
Essential to the proper design ant
operation of the system is a very clea
understanding of the UV output of thi
reactor and the transmissibility of thi
quartz and Teflon enclosures. Carefu
control of the average lamp output am
the transmittance can affect the costs fo
O&M of the system.
With regard to the UV equipment, thi
process lends itself to simplicity an<
flexibility, attributes that should be main
tained in the fabrication of the equip
ment. The reactor should be accessibl
for easy maintenance and/or replace
ment of the lamps and quartz/Teflo
enclosures. Proper mating of the lamp
and ballasts is critical, and adequat
ventilation of the power panel should b
provided to protect the ballasts from ovei
heating.
-------
W/cm2)
10,000
Quartz (Unit 1)
Spacing 5.0 cm
5000
10.000
15.000
20.000
Quartz (Unit 2)
Spacing 1.25 cm
70,000 Assumes 1.1 meters arc
per meter tube
18.2 Wn/m arc
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
1 pm/U. V.
(1) L = L0exp
,
'
Figure 6.
L 2E ° J
where a - 0.0000145 and b = 1.3
(2) L,a would be additive.
(3) Assumes velocity is greater minimum velocity.
Design solutions for three Port Richmond system configurations showing per-
formance as a function of loading and intensity.
The full report, prepared by Hydro-
Qual, Inc., was submitted by the New
York City Department of Environmental
Protection in fulfillment of Cooperative
Agreement No. CR 807556 under the
partial sponsorship of the U.S. Environ-
mental Protection Agency.
"A" U. S. GOVERNMENT PRINTING OFFICE:! 986/646-116/20785
-------
0. Karl Scheible and Maureen C. Casey are with HydroQual. Inc., Mahwah. NJ
07430; and Angelika Forndran is with New York City Department of Environ-
mental Protection. Wards Island, NY 10035.
Albert D. Venosa is the EPA Project Officer (see below).
The complete report, entitled "Ultraviolet Disinfection of Wastewaters from
Secondary Effluent and Combined Sewer Overflows," (Order No. PB 86-145
182/AS; Cost: $34.95, 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:
Water Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
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