The performance of a hybrid reactor, comprising of trickling filter and activated sludge process, in treating
nitrobenzene wastewater was investigated.
Acetate induced cells of mixed consortia was acclimatized with gradual increase of
nitrobenzene concentration up to 90 mg/l in 100 days using
sodium acetate as co-substrate and considering COD and
nitrobenzene concentration as paramount parameters for assessing the growth of biofilm and acclimation. A removal of 60-95.80% COD and 80-90.23%
nitrobenzene was observed during acclimation. During hydraulic retention time (HRT) studies, the optimum HRT was found to be 29.55 h at which a maximum of 95.83% COD and 97.93%
nitrobenzene removal was observed. Other studies included optimization of C:N ratio, substrate:co-substrate ratio, effect of
shock loading and estimation of volatilization losses. The optimum C:N ratio was found to be 100:20 at which maximum 97.93% removal of
nitrobenzene was observed. At optimum HRT (29.55 h) and optimum C:N ratio (100:20) optimum substrate:co-substrate ratio was found to be 1:33. From the
shock load studies it can be concluded that the system can withstand
shock load up to two times of usual
nitrobenzene concentration. A loss of 9.44%
nitrobenzene was observed due to volatilization and mass balance gave an efficiency of 87.49%
biological removal of
nitrobenzene.