Enhanced treatment of anionic and cationic dyes in wastewater through live bacteria encapsulation using graphene hydrogel

Organic dyes have been considered as persistent pollutants to the water environment and remain a challenge for industrial wastewater treatment. Here we integrated environmental biotechnology and adsorption technique into a highly porous, reactive hydrogel based material composed of live Shewanella xiamenensis BC01 encapsulated within reduced graphene oxide network (BC01-BGH). Because of the synergetic effects of adsorption and biodegradation, BC01-BGH showed exceptional decolorization performance of decomposing model anionic and cationic dyes, i.e., Congo red (CR) and methylene blue (MB), with efficiencies up to 99.8% and 97.3% in 55 h, respectively. Through a series of characterizations along the degradation process, we found the hydrogel network provided universal absorption to those dyes via joint electrostatic interaction, chemical interaction and π-π interaction with the assistance of the immobilized BC01, leading to the enhanced decolorization. The system did not require additional carbon sources an...