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Pollution Prevention and Control Technologies for Plating Operations

Section 2 - General Waste Reduction Practices


2.3.2 Chemical Tracking and Record Keeping

The major sources of pollution from plating operations are process chemicals. Process chemicals become pollution through both use and misuse, resulting in wastewater generation, spills/leaks, spent solutions, sludge and air emissions. To be fully effective, a pollution prevention and control program must track and record chemical purchases, chemical use, and waste generation. The following is a list of chemical and waste data that merit consideration for record keeping:

  • Chemical purchases
  • Chemical inventory
  • Bath analyses (see Section 2.3.3)
  • Process (tank) reformulations and chemical additions
  • Partial tank discharges (i.e., decanting) and total tank discharges (i.e., batch dumps)
  • Water use per rinse tank or plating line (see Section
  • Total wastewater flow
  • Wastewater treatment chemical use
  • Spent process solution analyses
  • Waste treatment sludge analyses
  • Waste location

To increase the utility of the chemical use and waste generation data, corresponding production data should also be collected and recorded. These data can be used to identify decreases or increases in chemical use and waste generation that are due to production changes rather than operational practices.

The chemical data can also be used to develop material balances for individual processes, a sequence of processes or an entire facility. A material balance, which is often shown as a block diagram, indicates the material inputs and outputs for the selected operation. Creating a material balance for a process such as chromium plating forces one to consider the various chemical inputs and losses such as chromic acid additions, emissions, drag-out, chromium plated onto parts, bath maintenance losses, etc. A material balance for chromium use at the Tinker AFB plating shop is shown in Exhibit 2-8.

Several questions in the Users Survey were related to chemical tracking and record keeping. These include questions 4, 6 and 7 of Exhibit 2-6 and question 8 of Exhibit 2-16. The response to question 4 showed that 207 shops (or 65.1%) have instituted strict chemical inventory control. The response to questions 6 and 7 indicate that 393 shops (or 92.1%) perform routine bath analysis and 273 shops (or 85.8%) maintain bath analyses and/or tank addition logs. The response to question 4 (Exhibit 2-16) indicates that 37 shops (or 11.6%) use water flow meters and/or accumulators to track fresh water use at each tank or plating line. Of these various pollution prevention options, the use of routine bath analyses and maintaining logs had the highest success ratings (4.37 and 4.35 respectively).

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