MEMBRANE BIOREACTOR MODEL FOR REMOVAL OF ORGANICS FROM WASTE-WATER

The persistence of trace organics in wastewater effluent is a major en vironmental concern. Possible use of fixed microbial films in wastewat er treatment processes is currently an active area of research that ma y be able to address many of these problems. In the waste effluent, th e persistence of trace organics is attributed, in part, to the inabili ty of microbial populations to extract energy from dilute environments at a rate fast enough to sustain themselves. To address this problem, a novel wastewater treatment scheme is considered. On the basis of pr evious hollow fiber biomass growth studies, we believe that an anaerob ic biofilm supported by hollow fibers could achieve greater biomass de nsity than a film grown on traditional impermeable supports. This in t urn could lead to improved substrate removal efficiency in a reactor o f a given volume. Using this concept, we developed a mathematical mode l to test the potential of hollow fiber membrane reactors for biodegra dation of acetate solution. A computer simulation has shown that it wo uld be possible to remove about 90% from feed solutions containing 0.1 mg . cm(-3) acetate with biomass density 25 mg . cm(-3) in the hollow fiber supported biofilm. More concentrated feeds could be effectively treated if sufficiently high biomass density could be attained. This process, therefore, shows promise in wastewater treatment. The advanta ges of hollow fiber membrane bioreactors are their high surface-to-vol ume ratio, separation of cells from flow, and high cell concentration. All of these are essential requirements for optimum utilization of bi omass in wastewater treatment. The hollow fiber membrane bioreactor co ncept, therefore, may provide a new and unique approach to treating or ganics.