Biosorption and Bioreduction of Perchlorate Using the Nano-Fe3O4-Laden Quaternary-Ammonium Chinese Reed: Considering the Coexisting Nitrate and Nano-Fe3O4

Nano-Fe3O4-laden quaternary-ammonium Chinese reed has been prepared for perchlorate removal, and the laden perchlorate was bioreduced on the surface of the biosorbent by mixed perchlorate-reducing bacteria. Results of kinetics, isotherms, and computations revealed strong competitive impact of coexisting NO3- on the uptake of perchlorate. Perchlorate capacity loss dropped significantly (37-50%) at relatively lower molar ratio of nitrate to perchlorate (<5), but 33-46% of the capacity was still retained at a molar ratio of 20. Nitrate laden on the surface of the biosorbent would inevitably inhibit the bioreduction of laden perchlorate. The highest bioreduction rate for laden perchlorate (0.046 mg(p).mg(ss)(-1).day(-1)) was obtained in the first 24 h of bioreduction. Biofouling on the surface of the biosorbent indicated that small amounts polymeric substances were possibly still attached on the surface of the biosorbent even after sterilization, which may potential cause of the decline in the recovery capacity. The nano-Fe3O4 embedded in the biosorbent showed a negligible effect on perchlorate capture but some laden perchlorate (6.5 mg/g) was bioreduced by using the attached nano-Fe3O4 as the sole electron donor.