Hazardous materials balance approach for source reduction and waste minimization

Abstract

A dual‐level approach for conducting waste minimization assessments that utilizes the material balance concept is presented and illustrated with case studies from the electronics manufacturing industry. In Level I of the strategy, basic data is collected in order to characterize the various waste streams according to quantity, source, nature, and cost 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 contaminants such as volatile organic solvents. Level II of the assessment proceeds with detailed process investigations of priority waste steams. 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 quantitative understanding of important system conditions such as drag‐in/drag‐out volumes and non‐ideal rinsing of parts. Once calibrated, the model becomes a rational design and evaluation tool for source reduction and waste minimization options and can be used to predict the performance of waste generating processes while avoiding costly continuous monitoring. Because it is based on a fundamental principle, the approach is readily transferable to other waste generating processes.