Control of chelator-based upsets in surface finishing shop wastewater treatment systems

Actual surface finishing shop examples are used to illustrate the use of pr ocess chemistry understanding and analyses to identify immediate, interim, and permanent response options for industrial wastewater treatment plant (I WTP) upset problems caused by chelating agents. There is economic and envir onmental compliance value to achieving such control, because it is difficul t to eliminate these upsets and their associated costs in actual plant prac tice. Chelating agents are required for baths operating at a pH sufficientl y high to cause metal hydroxide precipitation, or which need to maintain lo w metal ion activities for proper plated metal morphology. A methodology is offered to identify recovery and prevention solutions to such problems, wh ich uses readily available materials and procedures. Fifty-three such optio ns are offered.