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Pollution Prevention and Control Technologies for Plating Operations
Section 1 - Overview of Project Results
1.2 Overview of Users Survey Results
1.2.3 Wastewater and Discharge Characterization
Exhibit 1-8 provides an overview of the wastewater data contained in the Users Survey database. Column 1 shows the shop code. Column 2 indicates the type of wastewater discharge (direct-to a stream or river, indirect-to a publicly owned treatment works or POTW, or zero discharge-no wastewater discharge). Column 3 indicates the average discharge rate from the plating operations. The database also contains data for the maximum plating discharge and the average and maximum total industrial discharge. Column 4 indicates the amount of flow reduction that has been achieved through the implementation of pollution prevention techniques and methods. The next two columns indicate the type of effluent regulations that apply to each shop. These are shown as either standard or non-standard (i.e., CFR 413 or CFR 433) and aquatic-toxicity-based.
The majority of the respondents to the Users Survey are indirect dischargers. The percentage of shops that are either indirect, direct, both indirect and direct, and zero discharge are shown in Exhibit 1-9. These data indicate that captive shops are more likely to be direct dischargers than are job shops. EPA estimates in 1984 indicated a similar trend (ref. 517).
The electroplating discharge rates (average daily flows) of the survey respondents vary from 0 gpd to 420,000 gpd (some higher discharge rates were reported for combined plating and non-plating industrial discharges). The average and median plating discharge rates for respondents were 34,600 gpd and 14,000 gpd, respectively (see Exhibit 1-10 for a graphical summary of discharge data). Many shops indicated that they have made drastic progress in reducing wastewater flow rates, the most significant of which are listed in Section 2.
The respondents to the Users Survey are required to meet either CFR 413 (Electroplating Categorical Standards), CFR 433 (Metal Finishing Categorical Standards), or non-standard effluent limitations. Non-standard limitations are more stringent than the categorical standards for one or more pollutant parameters. Some of the non-standard limitations are written in terms of pollutant mass and flow rates (e.g., 0.37 lbs/day of chromium with a maximum flow of 40,000 gpd) rather than concentration limitations. The percentage of respondents that are required to meet each type of effluent limitation are as follows:
40 CFR 413: 28%
40 CFR 433: 8%
Non-Standard: 64%In addition to concentration or pollutant mass discharge standards, 16% of the respondents indicated that they are also subject to aquatic-toxicity-based effluent standards. These limits require that an industrial wastewater be sufficiently treated such that certain percentages of organisms (typically fish and water fleas) are able to survive in the effluent for a given time period.
More detailed data on regulations and the compliance experience for each shop are contained in the database. For example, the Users Survey asked platers to list the pollutant parameters for which they have compliance difficulty. A summary of their responses is shown in Exhibit 1-11.
