Effect of acidogenic stage on aerobic toxic organic removal

A laboratory investigation explored treatment of wastewaters containing nitrobenzene, biphenyl, and polynuclear aromatic hydrocarbons (PAHs) by two aerobic reactors, with and without acidogenic pretreatment. A sequencing batch operation was adopted for both acidogenic-aerobic and aerobic systems. Results indicated that nitrobenzene, biphenyl, and PAHs such as naphthalene and anthracene could be effectively removed by the acidogenic-aerobic system with removal efficiencies of more than 98% for nitrobenzene, 97% for biphenyl, and 96% for the PAHs, with a hydraulic retention time of the acidogenic stage at as low as 8 h. The acidogenic-aerobic system was therefore found to be effective in treating wastewaters containing such complex organics. The relatively low hydraulic retention time required for the acidogenic stage makes the process a potentially cost-effective technology.