THE DESIGN OF WASTEWATER TREATMENT FACILITIES
TO MEET POWER PLANT EFFLUENT GUIDELINES
ROBERT M. ROSAIN, Senior Associate Chemical Engineer
Gilbert/Commonwealth, Inc.
Jackson, Michigan 49201
INTRODUCTION
The purpose of this paper is to discuss the thermal and chemical wastes generated in a
fossil-fueled steam-electric power plant and to provide alternative treatment solutions for
these wastes. The subject of power plant wastewater treatment has been amplified and expanded in direct response to the federal effluent guidelines promulgated for the steam-
electric power industry and administered under the National Pollutant Discharge Elimination
System (NPDES). This paper will present treatment solutions capable of meeting these
federal limitations.
As is the case with all major industrial point source dischargers, the Federal Water Pollution
Control Act Amendments of 1972 (PL 92-500) specify that existing dischargers must meet
the "Best Practical Control Technology Currently Available" (BPCTCA) by July 1, 1977,
and the "Best Available Technology Economically Achievable" (BATEA) by July 1, 1983.
New plants must meet "Standards of Performance for New Sources."
THERMAL DISCHARGES
The largest source of thermal wastes generated in a power plant is that from the main
steam condensers. Here, exhausted steam from the turbine generator, sapped of all its usable
work, is condensed back to water and is routed back to the steam generator to continue the
cycle. Cooling water is normally drawn from an available natural water system.  It is this
heated cooling water that the EPA had in mind when they established the thermal discharge
regulation.
The federal thermal standards state that no generating unit placed into operation before
January 1, 1970, will be required to meet any limitations on the discharge of heat. For
units placed into operation between January 1, 1970, and January 1, 1974, only the largest
baseload units (ue., those of 500 MWe capacity or greater) will be subject to thermal control.
All other units and all New Sources will be subject to thermal control. For these units requiring thermal control, recirculating condenser cooling water systems must be installed
and operating by July 1, 1981.
In addition to the mentioned thermal discharge exemption for old and small units, four
other exemptions to thermal control were allowed by the EPA under certain conditions:
1. If the utility can demonstrate that insufficient land is available for the construction and
operation of mechanical draft cooling towers. "Sufficient land" is defined as 1100 ft   or
more per megawatt of name plate generating capacity.
2. If the utility can demonstrate that the total dissolved solids concentration (TDS) in the
cooling system blowdown would exceed 30,000 mg/1, and land not owned or controlled
by the utility is located within 500 ft in the prevailing downwind direction of every
practical location for mechanical draft towers.
3. If the utility can demonstrate that the plume from a cooling tower would cause a substantial hazard to commercial aviation. The utility must include a finding to this effect
by the Federal Aviation Administration.
4. If the utility can successfully demonstrate that the thermal discharge from its plant
will not harm the balanced indigenous community of shellfish, fish and wildlife in
or on the body of water into which the discharge is made. This demonstration is
allowed by Section 316(a) of the Act.
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