Comparative Evaluation of Ultrafiltration/Microfiltration Membranes for Removalof Nitrocellulose (NC) Fines from Wastewater

摘要

Nitrocellulose (NC) is a basic constituent for military gun propellants. NCwastewater is a byproduct of the NC manufacturing process. Crossflow microfiltration/ultrafiltration (MF/UF) may recover NC fines and allow the wastewater to be recycled. This bench-scale crossflow membrane filtration system was constructed to test the application of MF/UF technology to NC wastewater. This study was conducted in two phases. The results of Phase I were used to select a candidate membrane. In Phase II, a pilot-scale crossflow membrane filtration system was constructed to: (1) investigate the concentration polarization and fouling mechanism caused by NC fines during crossflow filtration of NC wastewater, (2) explore flux decline behavior of NC wastewater streams with various membranes, and (3) study the effects of operating parameters on flux decline behavior. This study found that: 1. UF membranes have a lower flux decline rate and a higher flux recovery than MF membranes, but UF membranes have a relatively low permeate production rate compared to MF membranes. 2. A critical membrane pore size of about 0.1 micron exists, at which point the worst flux performance occurs. 3. The cellulose-based hydrophilic membranes have the best flux performance.