Treating Navy Wastewaters Using High-Shear Rotary and Tubular Membrane Systems

Abstract

Membrane filtration systems can handle varying wastewaters with simple and robust operation. However, current low permeate flux rates attributed to solids accumulation at the membrane surface limit more widespread technology use. This work seeks a better understanding of flux performance relative to solids concentration and transmembrane pressure coupled with potential flux enhancements. Enhancements revolve around disturbing solids accumulation at the membrane surface by physical cleaning or periodic flow reversal. Results indicate both rotary and tubular membranes produce consistent particle-free, low-turbidity permeate at varying levels of feed solids concentrations. Rotary membranes may produce only slightly greater permeate flux rates than tubular membranes at low feed solids concentration, but the difference increases drastically as feed solids concentration increases. Rotary membrane systems can concentrate wastewaters to greater than 40% solids, but the greater the feed solids, the less additional pressure increases flux. Membrane surface cleaning by continually cleaning via nylon brushes contacting the membrane surface, periodic sponge ball surface cleanings, or periodic flow reversal can significantly increase permeate flux rates (2 to 20 times).