At head of title: Project Summary. "EPA/600-SR-93-144." "September 1993."

Pollution prevention efforts studied in the report summarized here targeted the hazardous waste generated from a 5000-gal iron phosphating/degreasing bath used by a metal fabricator to clean and precondition steel parts for painting. When oil buildup in the bath began to sacrifice product quality and the discharge levels of oil and grease in the rinse water edged closer to the maximum allowable limit, all 5000 gal were dumped and replaced. Periodic dumping, about three times each year, resulted in at least 15,000 gal/yr of hazardous waste. Several waste minimization alternatives were considered, and ultrafiltration was selected as the most promising technology to recover and reuse the bath and to reduce the total amount of hazardous waste generated. This project was carried out in four stages: (1) initial assessment of the problem and evaluation of alternatives, (2) bench-scale screening of ultrafiltration membrane candidates, (3) pilot-scale study at the Illinois Hazardous Waste Research and Information Center (HWRIC), and (4) full-scale implementation and testing onsite at the company's facility. Full-scale testing integrated the new waste reduction scheme into the facility's production process by applying ultrafiltration directly to the 5000-gal iron phosphating/degreasing bath. Ultrafiltration successfully removed oil contamination from the bath and returned clean process solution back to the original 5000-gal tank. Ultrafiltration concentrated the hazardous component down to 10 gal of oily waste and reduced hazardous waste generation 99.8%. Permeate flux rates were high enough to compete with the constant input of oil from the production line, and concentrations of oil in the bath were maintained at acceptable operating levels. The estimated payback period associated with implementing ultrafiltration was only 6.9 mo.