During the aluminum etching process, aluminum is lost from the raw foil and contaminates the concentrated acid etch solution. When the etching solution becomes saturated, it must be replaced and disposed of at a high cost. Our customer wanted a zero discharge system designed to eliminate the disposal of the bath into neighboring ponds that did not have sufficient holding capacity.  Foster-Miller designed and fabricated a process system that recycled the acid bath for reuse through a process of ion exchange coupled with evaporation and distillation of the regenerated waste solution.

The aluminum ions in the acid etch solution were removed by a continuous ion exchange process and replaced with hydrogen ions to maintain the acidity of the solution. The aluminum was recovered as a dilute solution of aluminum chloride by regenerating the ion exchangers with hydrochloric acid. The aluminum chloride was further concentrated and purified by evaporation and distillation and was sold to a deodorant manufacturer. The sale of this product offset the treatment costs and solved the problem of disposing of the waste solution into the holding ponds. The modular system was designed and tested prior to installation in an aluminum etching facility in Tennessee. 

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