Bio–reduction of para-chloronitrobenzene (p-CNB) in Drinking Water Using a Continuous Stirring Hollow Membrane Biofilm Reactor

para-chloronitrobenzene (p-CNB) is a compound that is particularly harmful and persistent in the environment and is one of the priority pollutants, which is widely used as intermediates for chemical syntheses of drugs, herbicides, dyes, etc. A feasible degradation pathway for para-chloronitrobenzene is bio-reduction with H2 as the electron donor. The proposed pathway involves two complete steps that lead to para-chloraniline (p-CAN) and aniline (AN). This study investigated the bio-reduction of p-CNB in a H2-based membrane biofilm reactor that also is active in nitrate and sulfate conditions. p-CNB was bio-reduced to p-CAN in major extent (at least 93% from day 105 to 110) and AN of 384 μg/L in MBfR in which the fluxes were dominate by nitrate and sulfate reductions. A good bio-reduction effect could be got by the new continuous stirred MBfR using PVC membranes, and the maximum p-CNB reduction rate achieved was at 3.57 g/m3·d. Denitrification was achieved nearly completely with 0.2 mg/L NO3--N in effluent, and sulfate reduction was limited by H2 with 37.4 mg/L in effluent. The results showed that the hollow membrane biofilm reactor is a feasible way for treatment of drinking water contaminated with p-CNB.