MEMBRANE BIOREACTOR (MBR) FOR VOC EMISSION REDUCTION AND WASTEWATER REUSE IN THE CHEMICAL MANUFACTURING INDUSTRY

The organic chemical industry is ranked the third largest in volatile organic compound (VOC) emissions after the petroleum refining and ground transportation industries (EPA 2002). VOCs are a significant public health concern because of their health effects and atmospheric reactions to form ozone. This research investigated the performance of a membrane bioreactor (MBR) for treatment of VOC containing wastewater generated by the synthetic resin manufacturing industry. Operating conditions to maximize biodegradation and minimize volatilization of the VOCs to the atmosphere were investigated. The two-stage bench scale MBR system was operated with a wastewater containing acetaldehyde, butyraldehyde and vinyl acetate. The organic loading rate was varied from 1.1 to 2.0 kg COD m−3 d−1 at a constant solids residence time (SRT) of 100 days. More than 99.9% and 99.3% BOD5 and COD removal was achieved at all organic loading rates. In the case of VOCs, the overall removal efficiency was greater than 99.7% at steady state. Less than 12.5% of acetaldehyde, less than 2.0% of butyraldehyde and 6.2 to 14.0% of vinyl acetate introduced into MBR was released to the atmosphere through the headspace of bioreactors. Higher MLVSS concentrations resulted in increased viscosity and decreased initial and average permeate flux, independent of bioreactor soluble COD (SCOD). The permeate flux was inversely proportional to the viscosity and TOC concentration of bound extracellular polymeric substance (EPS) in the bioreactors.