United States
Environmental Protection
Agency
Municipal Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-81-224 Oct. 1981
Project Summary
Heavy Metal Sources and
Flows in a Municipal Sewage
System: Literature Survey and
Field Investigation of the
Kokomo, Indiana, Sewage
System
K. J. Yost, R. F. Wukasch, T. G. Adams, and B. Michalczyk
The mass flows of heavy metals (Cu,
Cr, Cd, Zn, Ni, Pb) and cyanide in the
Kokomo, Indiana, collection system
and wastewater treatment plant were
analyzed. The primary objectives were
to determine the relative contributions
of domestic and nondomestic sources
to the total pollutant load in the
system, and to assess the levels of
discharge control required for the
disposal of municipal sludge by landfill
or agricultural landspreading. Sampling
was conducted at point source loca-
tions, in major sewer trunklines and
feeder lines, and at the treatment
plant. Production and waste treatment
data were presented for point sources
sampled to characterize metal and
cyanide discharges as a function of
these parameters. A heavy metals
mass balance was attempted for the
treatment plant. Metal removal factors
were presented for various plant
operations.
With the exception of lead, metals
were found to be largely from non-
domestic sources. With the exception
of nickel, the Kokomo treatment plant
removed 80% to 90% of the influent
metals. Required reductions in non-
domestic sources of metals to meet
EPA landspreading guidelines for
sludge were 98% for cadmium, 84%
for zinc, and 42% for copper.
A simple statistical approach was
presented for the design of a cost-
effective sampling program for corre-
lating point source and trunkline
pollutant sampling. The purpose was
to minimize the amount of sampling
required to account for pollutants seen
in trunkline and treatment plant streams
in terms of discharges from specific
sources.
This Project Summary was devel-
oped by EPA's Municipal Environ-
mental Research Laboratory. Cincin-
nati, 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 disposal of municipal waste
treatment system sludges is a major
problem currently faced by many U.S.
cities. The presence of contaminants in
sludge, especially heavy metals, may
preclude the least costly disposal
alternative, e.g., landspreading. This
study addressed the problems associated
with the flow characterization and
identification of sources of heavy metals
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and cyanide in the Kokomo, Indiana,
wastewater collection and treatment
system. It was intended to be repre-
sentative of the type of survey and
analysis required to formulate source
control policies for reducing metals and
cyanide in municipal sludges to the
point that landspreading is feasible.
A major impediment to the conduct of
sewer system studies is the great cost
involved in source characterization.
This typically involves initial trunkline
sampling to identify segments of a
collection system carrying substantial
pollutant loads. Ideally, this is followed
by a series of simultaneous trunkline
and point source sampling to determine
whether or not suspected sources can
account for trunkline pollutant loads.
The resulting picture is often obscured
by infiltration of the collection system
following precipitation events and by
street runoff containing heavy metals
from rainstorms or snow melt. If
trunkline and source sampling data fail
to account for trunkline pollutant loads,
then simultaneous trunk and feeder line
sampling may be necessary to further
define source locations. If pursued to
the point of statistical certainty, such
source identification sampling programs
can become prohibitively expensive.
With the above in mind, the study
exemplifies a protocol to assist com-
munities in identifying, quantifying, and
formulating regulatory policies for
reducing heavy metal and cyanide
discharges to publicly owned treatment
works (POTW) to the point that land
disposal of sludge is feasible. This
protocol is discussed at length in the full
project report.
Sampling Procedure
The prototype community selected for
this study was Kokomo, Indiana. It is a
medium-sized city with a population of
42,000 with (from the sampling and
analysis point of view) a manageably
sized combined sanitary and storm
sewer treatment network that serves
well-defined residential areas and a
diverse industrial community. The
industrial and commercial makeup of
Kokomo includes such industrial cate-
gories as electroplating, metal fabricat-
ing, automotive manufacture, chemical
processing and food processing.
Trunkline sampling was conducted
from April 1978 to June 1979 at 12
locations in the Kokomo sewer network.
The locations were chosen to charac-
terize metal and cyanide input to the
treatment plant. Automatic sequential
samplers and continuous flow recorders
were used at each sampling location to
measure metal and cyanide mass flow
rates.
Samples were obtained for each
trunkline at 2-hour intervals for three
24-hour periods. Sampling was con-
ducted on a Monday through Thursday
schedule, when feasible, to avoid any
unusual fluctuations in flow or metal
and cyanide discharge due to variations
in industrial work schedules or increased
residential activity during the weekend.
Twelve known point sources of heavy
metals and cyanide identified by
Standard Industrial Classifications (SIC)
were sampled in the study over a 3-
month period in 1979.
Sampling at each source was con-
ducted at 2-hour intervals for 24 hours
over a consecutive 3-day period. Metal
and cyanide samples were collected
using an automatic sequential sampler.
The nature of the point sources is
summarized in Table 1.
Of the major collection system
trunklines sampled, 3, defined as
residential, served none of the 12 point
sources sampled. Conversely, four of
the major trunks served at least one of
the point sources sampled; these are
defined to be "nonresidential." The
pollutant mass flows in the residential
and nonresidential trunks are given in
Table 2 with pollutant mass flows in the
treatment plant influent. Note that for
cadmium, the "nonresidential" trunkline
metal flows are more than a factor of ten
larger than the residential flows and
that the sum of nonresidential and
residential is lower by a factor of three
than that seen in the treatment plant
influent. For all other metals, the sum of
the trunkline metal flows range from
virtually as large to substantially larger
than those detected in treatment plant
influent. The lack of "balances" among
the point source, trunkline, and treat-
ment plant metal flows probably results
from the nonsimultaneous sampling of
trunklines and treatment plant influent
as well as from infiltration and street
runoff, especially for lead. It appears
that the 12 point sources sampled are
reasonably sufficient to acount for the
loading of all metals in treatment plant
influent except cadmium.
A 60 sampling program was conducted
in the wastewater treatment plant to
assess the flow of heavy metals among
the various processes. The plant is a 30
mgd activated sludge-multi-media
gravity filter facility. Table 3 gives metal
concentrations in plant influent, sec-
ondary effluent, and plant effluent
streams. For Kokomo sludge to be
suitable for landspreading, substantial
reductions in nonresidential sources of
Cd, Cu, and Zn are necessary. The
situation is portrayed in Table 4 where
specific reductions necessary to achieve
EPA sludge landspreading guidelines
are indicated.
Results of the study confirm that
accurate mass balances on sources of
heavy metals and resulting flows in
municipal wastewater collection sys-
tems require simultaneous long-term
sampling. Such a program would,
however, be prohibitively expensive for
many medium-sized communities. An
alternative proposed in the present
work involves the analysis of data from
short-term, nonsimultaneous source,
and trunkline sampling. The method of
analysis provides a basis for accounting
for trunkline pollutants in terms of point
source discharges. The study also
suggests that a 60-day sampling period
is sufficient to conduct a heavy metal
balance for a municipal wastewater
treatment plant.
Table 1.
No.
1
2
3
4
5
6
7
8
9
10
11
12
Point Source Inputs
Type
Transmission and Die Casting
Circuit Board Plating
Radio and Semiconductor
Automotive
Rack and Barrel Plating
Wire Mill
Hot Dip Galvanized Fence
Architectural Aluminum
Alloys
Metal Fabrication
Industrial Laundry
Printing
Pretreatment
Batch
Batch
Batch
Batch
None
Continuous
Batch
Batch
Batch
None
None
None
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Conclusions
The Kokomo treatment plant removed
80% to 90% of the Cd, Cr, Cu,Zn, and Pb
in the plant influent, whereas only 30%
of the Ni was removed. The gravity
filters reduced the Cd, Cr, Cu, Zn, and Pb
in the secondary effluent by approx-
imately 50%, with a Ni reduction of 18%.
The sludge heat treatment and vacuum
filtration recycle streams did not
increase metal concentrations in plant
effluent. Finally, with only the domestic
source of metals to the treatment
system, Kokomo sludge could be applied
to cropland at rates limited only by
nitrogen addition tocropsoil, i.e., metals
would not be a limiting factor.
The full report was submitted in
fulfillment of Grant No. R805361-01 by
Purdue University, West Lafayette,
Indiana 47907 under the sponsorship of
the U.S. Environmental Protection
Agency.
Table 2. Summary of Inputs
Metal
Cd
Cr
Cu
Ni
Zn
Pb
Residential
kg/day
0.054
0.604
5.37
3.89
6.82
0.90
Nonresidential
kg/day
0.630
44.4
10.8
6.94
278.
0.73
Total
Residential
Nonresidential
kg/day
0.684
45.4
16.2
10.8
285.
1.63
Treatment Plant
Influent
kg/day
2.15
51.8
11.0
7.58
136.
0.588
Table 3. Metal Concentrations in Treatment Plant Input and Output Streams
Metal
Cd
Cr
Cu
Ni
Zn
Pb
Fe
Plant
Influent
mg/l
0.033
0.786
0.168
0.115
2.07
0.051
17.3
Secondary
Effluent
mg/l
0.0124
0.0773
0.0574
0.0988
0.488
0.0053
1.75
Plant EPA Interim Primary
Effluent Drinking Water Stds.
mg/l mg/l
0.0063
0.0167
0.0252
0.0812
0.233
0.0026
0.335
0.01
0.05
0.05
Table 4. Reductions in Nonresidential Sources of Metals Necessary to Achieve
Compliance of Kokomo Sludge with EPA Landspreading Guidelines
Metal
Cd
Cr
Cu
Ni
Zn
Pb
Permissible
Application
kg/ha
1
25
10
50
100
Permissible Required Reduction
by EPA Total in Residential in Nonresidential
Guidelines Sludge Contribution Sources
mg/kg mg/kg mg/kg %
56
1400
560
2800
5600
377
1060
1790
533
13600
94
10
12
870
273
680
143
87
42
0
84
0
K. J. Yost, R. F. Wukasch, T. G. Adams, and B. Michalczyk are with Purdue
University, West Lafayette, IN 479O7.
Sidney A. Hannah is the EPA Project Officer (see below).
The complete report, entitled "Heavy Metal Sources and Flows in a Municipal
Sewage System: Literature Survey and Field Investigation of the Kokomo,
Indiana, Sewage System,"{OrderNo. PB82-108366;Cost:$21.50, subjectto
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
tt US GOVERNMENT PRINTING OFFICE 1981—559-017/7399
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