MEMBRANE BIOREACTOR FOR CONTROL OF VOLATILE ORGANIC-COMPOUND EMISSIONS

A membrane bioreactor system that overcomes many of the limitations of conventional compost biofilters is described. The system utilizes mic roporous hydrophobic hollow fiber membranes for mass transfer of volat ile organic compounds (VOCs) from the gas phase to a microbially activ e liquid phase. The reactor design provides a high biomass concentrati on, a method for wasting biomass, and a method for addition of pH buff ers, nutrients, cometabolites, and/or other amendments. A theoretical model is developed, describing mass transfer and biodegradation in the membrane bioreactor. Reactor performance was determined in a laborato ry scale membrane bioreactor over a range of gas loading rates using t oluene as a model VOC. Toluene removal efficiency was greater than 98% at an inlet concentration of 100 ppm, and a gas residence time of les s than 2 s. Factors controlling bioreactor performance were determined through both experiments and theoretical modeling to include: compoun d Henry's law constant, membrane specific surface area, gas and VOC lo ading rates, liquid phase turbulence, and biomass substrate utilizatio n rate.