Aqueous Cleaning System Design: Recycling

Introduction The current regulatory climate is causing both large and small companies to reconsider their existing cleaning methods. The use of chlorinated solvents in metal and electronics parts cleaning is no longer the primary method of choice. Over the last five to 10 years, the consequences of past usage of these cleaning systems have led to traumatic and expensive experiences of many companies, municipalities and government agencies.’ With heightened environmental awareness , more improvements a r e s t i l l r equ i r ed . The Environmental Protection Agency has declared that source reductions leading to pollution prevention will be the primary area of focus in environmental compliance over the next decade and beyond. In the realm of precision cleaning, aqueous cleaners are emerging as safe and effect ive al ternat ives to solvent degreasers. Switching to water-based cleaners, however, creates a new waste stream which tends to be high in oil and grease and potentially RCRA hazardous. An article appearing in this journal” described how one company, Hamil ton Standard, switched from a vapor degreaser to an aqueous cleaning technology. A more impressive example comes from R.B. White, which accomplished the same feat and has been using the same cleaning solution for four-and-a-half years without dumping its cleaning tank. This process of reclaiming and reusing spent solutions is the basis of closed-loop cleaning technologies. This article will discuss closed-looping of aqueous cleaning processes as a means to make them more economical and environmentally friendly. In support of this, we will present case studies exemplifying the process and documenting the results.