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Section 7. COAL, COKE AND POWER PLANT WASTES ACHIEVING THE EPA EFFLUENT LIMITATIONS FOR POWER PLANTS: APPROACHES TAKEN BY UTILITIES IN WISCONSIN Robert Chiesa, Chemical Engineering Analyst Sargent and Lundy Engineers Chicago, Illinois 60603 Suzanne Bangert, Environmental Engineer Industrial Wastewater Section Wisconsin Depart, of Natural Resources Madison, Wisconsin 53707 INTRODUCTION In 1974 the DNR issued NPDES permits to all electric power utilities requiring achievement of the EPA BPT effluent guideline limitations by July 1, 1977. Although the guidelines require control of a number of pollutants in the discharges (including pH, oil and grease, chlorine, iron, and copper) the pollutant of major concern at these plants was total suspended solids (TSS). The effluent guideUnes require monthly average and daily maximum TSS of 30 and 100 mg/1, respectively, for all process wastewaters and a daily maximum of 50 mg/1 for area run-off. In response most of the utilities built new wastewater treatment systems (WWTS's) or substantially modified and improved their existing systems. Two basic approaches were taken depending on the amount of land available at each plant. Those plants with sufficient land available for large ash ponds used them as the core of the WWTS to meet the TSS Umitations. In several cases the ash ponds were already in use prior to 1974 so the WWTS's only required modifications and additions to meet the EPA limits, but in one case a completely new ash pond system was needed. Those plants with limited land available installed mechanical WWTS's. In several cases the plants had no treatment so completely new WWTS's (including extensive modifications to the plants' sewer systems) were needed. In other cases the existing WWTS's were extensively modified and upgraded. On July 1, 1977, 24 of the 25 steam-electric power plants in Wisconsin were in substantial compUance with the EPA BPT effluent guideline limits. The other plant completed its treatment system in October 1977. DESCRIPTION OF THE POWER PLANTS AU the plants discussed in this paper are coal-fired, and all generate low-volume wastewaters and bottom ash sluice wastewaters which are the main sources of process wastewater at coal-fired power plants. Table 1 lists information about each plant and the wastewaters treated by each plant's WWTS. However none of these plants treat boiler cleaning wastes (which are very difficult to treat): either the boilers are not cleaned or the boiler cleaning wastes are coUected and returned to the boilers for incineration. The three plants with mechanical WWTS's (A,B, and C) are located in urban areas where little space was available. The three plants with settUng pond WWTS's (X, Y, and Z) are located on the fringes of urban areas or in rural areas and have space available for large ash settling ponds. COMPARISON OF TREATMENT SYSTEM DESIGN Mechanical Systems As Table II shows, all the mechanical treatment systems have short detention times and high hydraulic loading rates, and all must use flocculants to increase the sohds settling rate. The need for proper flocculation makes the system susceptible to upsets when malfunctions 266
Object Description
Purdue Identification Number | ETRIWC198026 |
Title | Achieving the EPA effluent limitations for power plants : approaches taken by utilities in Wisconsin |
Author |
Chiesa, Robert Bangert, Suzanne |
Date of Original | 1980 |
Conference Title | Proceedings of the 35th Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://e-archives.lib.purdue.edu/u?/engext,31542 |
Extent of Original | p. 266-280 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Date Digitized | 2009-10-22 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 266 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Transcript | Section 7. COAL, COKE AND POWER PLANT WASTES ACHIEVING THE EPA EFFLUENT LIMITATIONS FOR POWER PLANTS: APPROACHES TAKEN BY UTILITIES IN WISCONSIN Robert Chiesa, Chemical Engineering Analyst Sargent and Lundy Engineers Chicago, Illinois 60603 Suzanne Bangert, Environmental Engineer Industrial Wastewater Section Wisconsin Depart, of Natural Resources Madison, Wisconsin 53707 INTRODUCTION In 1974 the DNR issued NPDES permits to all electric power utilities requiring achievement of the EPA BPT effluent guideline limitations by July 1, 1977. Although the guidelines require control of a number of pollutants in the discharges (including pH, oil and grease, chlorine, iron, and copper) the pollutant of major concern at these plants was total suspended solids (TSS). The effluent guideUnes require monthly average and daily maximum TSS of 30 and 100 mg/1, respectively, for all process wastewaters and a daily maximum of 50 mg/1 for area run-off. In response most of the utilities built new wastewater treatment systems (WWTS's) or substantially modified and improved their existing systems. Two basic approaches were taken depending on the amount of land available at each plant. Those plants with sufficient land available for large ash ponds used them as the core of the WWTS to meet the TSS Umitations. In several cases the ash ponds were already in use prior to 1974 so the WWTS's only required modifications and additions to meet the EPA limits, but in one case a completely new ash pond system was needed. Those plants with limited land available installed mechanical WWTS's. In several cases the plants had no treatment so completely new WWTS's (including extensive modifications to the plants' sewer systems) were needed. In other cases the existing WWTS's were extensively modified and upgraded. On July 1, 1977, 24 of the 25 steam-electric power plants in Wisconsin were in substantial compUance with the EPA BPT effluent guideline limits. The other plant completed its treatment system in October 1977. DESCRIPTION OF THE POWER PLANTS AU the plants discussed in this paper are coal-fired, and all generate low-volume wastewaters and bottom ash sluice wastewaters which are the main sources of process wastewater at coal-fired power plants. Table 1 lists information about each plant and the wastewaters treated by each plant's WWTS. However none of these plants treat boiler cleaning wastes (which are very difficult to treat): either the boilers are not cleaned or the boiler cleaning wastes are coUected and returned to the boilers for incineration. The three plants with mechanical WWTS's (A,B, and C) are located in urban areas where little space was available. The three plants with settUng pond WWTS's (X, Y, and Z) are located on the fringes of urban areas or in rural areas and have space available for large ash settling ponds. COMPARISON OF TREATMENT SYSTEM DESIGN Mechanical Systems As Table II shows, all the mechanical treatment systems have short detention times and high hydraulic loading rates, and all must use flocculants to increase the sohds settling rate. The need for proper flocculation makes the system susceptible to upsets when malfunctions 266 |
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