Full Description

Disposal and treatment of nitrocellulose (NC) containing wastewaters is a major concern for the US Army. Ultrafiltration (UF) and microfiltration (MF) of NC wastewater samples from the Radford Army Ammunition Plant (RAAP), in Radford, Virginia, have been studied for various UF/MF membranes in a batch cell. The flux performance depends on NC wastewater characteristics as well as membrane properties such as membrane type, pore size, and base material. The major foulant in most NC wastewater samples was colloidal and supracolloidal NC fines. However, in addition to NC fines, dissolved organic matter in a wastewater sample from the poacher house caused serious fouling. Powdered activated carbon (PAC) pretreatment dramatically improved the flux performance for the poacher house sample by lowering reversible/irreversible fouling. UF membranes were more susceptible to organic fouling while MF membranes were more easily fouled by NC fines due to pore blocking/adsorption. A critical membrane pore size appeared to exist for the worst flux performance. The cellulose based UF/MF membranes showed the best flux performance among the membranes tested. The effects of transmembrane pressure (from 5 to 15 psi) and stirring were investigated with two selected UF/MF membranes. Although the flux decline rate increased with the transmembrane pressure, the actual permeate flux increased with the transmembrane pressure, showing that the flux was still in the pressure controlled region. Unexpectedly, the unstirred conditions produced higher flux performance than the stirred conditions. Microscopy and image analysis of cake samples showed that this was probably caused by the formation of a less dense cake at the membrane surface under unstirred conditions.

Product Details

Published: 01/01/1995 ISBN(s): 0898678153 Number of Pages: 16File Size: 1 file , 710 KB