A Membrane Process for Industrial Water Treatment: From Bench to Pilot Demonstration

Abstract:

A rotary membrane filtration system was used to separate die lubricant from a manufacturing wastewater stream consisting of various oils, hydrocarbons, heavy metals, and silicones. The ultrafiltration membranes reduced organics from initial oil and grease contents by factors of 20 to 25, carbon oxygen demand by 1.5 to 2, and total organic carbon by 0.6, while the biological oxygen demand remained constant. The rotary membranes were not fouled as badly as static membranes, and the rotary membrane flux levels were consistently higher and more stable than those of the static membranes tested. Field testing demonstrated that the rotary ultrafilter can concentrate the die lubricant, remove the glycerin component, and produce a die lubricant suitable for in-plant recycling. The recycling system operated for 6 weeks with only seven cleaning cycles and no mechanical or electrical failures. Test data and quality records indicate that when recycled die lubricant was used, the die casting scrap was reduced from 8.4 to 7.8%. Rotary ultrafiltration presents significant opportunities that can be evaluated further.