3    MATERIAL SUBSTITUTION LOWERS INDUSTRIAL WASTE
TREATMENT COSTS
Gail E. Montgomery, Project Engineer
Bruce W. Long, Project Engineer
Black and Veatch Engineers-Architects
Kansas City, Missouri 64114
INTRODUCTION
The United States Environmental Protection Agency (EPA) has been moving toward the development and implementation of industrial pretreatment standards for both existing and new point
sources since the mid-1970's. The responsibility of imposing the pretreatment standards, in most
cases, has been assigned to municipalities following the development and adoption of a local industrial sewer use ordinance. Pollutant discharge limitations of the local ordinances vary from location to
location, and since the municipality must comply with its NPDES permit and ensure that the sludge
from its wastewater treatment plant is suitable for handling and disposal (including possible reuse),
the local ordinances are often more restrictive than the federally mandated standards.
Pretreatment standards have been promulgated on two different criteria, only one of which applies
to a given industrial category or subcategory. The first places a concentration limit on individual
pollutant parameters with no explicit limit on the volume of the process wastewater discharged. The
second limits the daily mass of a pollutant discharged to the sewer and bases the mass limitation on
some unit of the particular industry's production process, such as the surface area of parts cleaned or
plated or per unit mass of a particularly significant raw material used.
Industries can achieve compliance with mass-based standards by a combination of approaches,
such as reducing the volume of wastewater discharged and/or reducing the concentration of pollutants by appropriate treatment. Mass-based standards encourage use of water conservation measures,
for as the volume of wastewater discharged decreases, the concentration of pollutants allowable under
the EPA pretreatment standards increases. At some point, however, the allowable pollutant concentration may become limited by the local sewer use ordinance.
An example of the impact of flow reduction measures on allowable pollutant discharge concentrations is illustrated by the data in Table I.
These data apply to a midwestern manufacturing facility that will be required to meet pretreatment
standards for /inc. nickel, manganese, and mercury. The Table I data illustrate that reduction of the
plant's wastewater volume from 20,000 gallons per day (gpd) to 5.000 gpd would permit a four-fold
Table I. EPA Allowable Monthly Average Discharge Concentrations vs. Daily Flow
flow, lipd
Constituent. mg/L
20,000
15,000
10,000
5.000
2.000
0.08
0.11
0.16
0.32
0.80
0.12
0.16
0.24
0.48
1.20
0.41
0.55
0.82
1.64
4.10h
0.84
1.12
1.68
3.36
8.40'
0.07a
0.09*
0.14a
0.28a
0.70*
0.11
0.15
0.22
0.44d
I.10d
0.19
0.25
0.38
0.76
1.90
Cyanide
Chromium
Zinc
Nickel
Mercury
Silver
Manganese
•"Limited by city ordinance standard of 0.02 mg/L.
hLimited by city ordinance standard of 2.6 mg/L.
'Limited by city ordinance standard of 4.0 mg/L.
''limited by city ordinance standard of 0.40 mg/L.
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