Removal of benzene in a hybrid bioreactor

A novel hybrid bioreactor was designed to remove volatile organic compounds from wastewater and its performance was investigated. The bioreactor was c omposed of a biofilter section and a bubble column bioreactor section. Benz ene was used as a model compound and the influent benzene was removed by im mobilized cells in a bubble column bioreactor. Gas phase benzene stripped b y air injection was removed in a biofilter. When the superficial air flow r ate was 21.1 m h(-1) (0.76 min of residence time in a biofilter), up to 2.2 ppm of benzene in gas phase was removed completely in a biofilter and the maximum removal rate was 4.71 mg day(-1) cm(-3). The concentration profile of benzene along the biofilter column was dependent on the superficial air flow rate and the degree of microbial adaptation. Air flow rate and residen ce time were found to be the most important operation parameters for the hy brid bioreactor. By manipulating these operational parameters, the removal efficiency and capacity of the hybrid bioreactor could be enhanced. The org anic load on the hybrid bioreactor could be shared by the biofilter and bub ble column bioreactors and the fluctuation of load on the hybrid bioreactor could be absorbed by changing the distribution of benzene between biofilte r and bubble column bioreactors. The maximum removal capacity of the hybrid bioreactor in the experimental range was obtained when the biofilter took 50.3% of influent benzene while 100% of removal efficiency was achieved whe n the biofilter took 72.3% of influent benzene. (C) 1999 Elsevier Science L td. All rights reserved.