Multiple Rinsing Tanks

3222 Multiple Rinsing Tanks. The use of multiple rinsing tanks is one of the most common rinsewater reduction techniques, and can dramatically reduce rinsewater requirements. In a typical counterflow three-tank rinsing system, the workpiece initially enters the first rinse tank, which has the most contaminated rinsewater. It is then moved to the second tank, and then to the last, where it contacts fresh rinsewater. Fresh rinsewater enters only the last (third) rinsing tank. The water from the third tank flows into the second tank and then into the first tank, from which it can be routed either into the plating tank as a make-up, or to the treatment system. 

It is preferable to route the rinse system effluent back into the plating bath, in order to prevent release of the chemicals they contain to the environment. One chrome plater (Foss 1988) whose shop was examined for this study accomplished this by lowering the flow through his counterflow system to 0.5 gal/min or less, and installing an evaporator on the plating tank capable of vaporizing up to 350 gal/day. 

A second wastewater reduction method with a high implementation potential is the reuse of rinsewater. Electroplating operations use rinsewater at several stages in the process, and it is often possible to use the same stream at more than one stage. The main problem with 

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Install multiple rinse tanks (including counterflow rinse tanks) after process baths to improve rinse efficiency and reduce water consumption. 

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