HAZARDOUS MATERIALS BALANCE APPROACH FOR SOURCE REDUCTION AND WASTE MINIMIZATION

A dual-level approach for conducting waste minimization assessments th at utilizes the material balance concept is presented and illustrated with case studies from the electronics manufacturing industry. In Leve l I of the strategy, basic data is collected in order to characterize the various waste streams according to quantity, source, nature, and c ost of handling, treatment,or disposal. An overall hazardous materials balance on individual target substances for the facility can be used to predict long-term environmental releases of difficult-to-track cont aminants such as volatile organic solvents. Level II of the assessment proceeds with detailed process investigations of priority waste steam s. This is illustrated by construction of a material balance model for a dual-countercurrent rinse system associated with chromium finishing processes. Process data is used to calibrate the model and obtain a q uantitative understanding of important system conditions such as drag- in/drag-out volumes and nonideal rinsing of parts. Once calibrated, th e model becomes a rational design and evaluation tool for source reduc tion and waste minimization options and can be used to predict the per formance of waste generating processes while avoiding costly continuou s monitoring. Because it is based on a fundamental principle, the appr oach is readily transferable to other waste generating processes.