Enhanced removal of TN in shale gas wastewater by a novel porous polymer monolith immobilized microorganisms

Shale gas flowback and produced water (SGFPW) pose significant challenges to biotechnology due to their high salinity. In this study, we explored a novel method utilizing an amphiphilic copolymer of methyl methacrylate and acrylamide (p(MMA-AAM)) and powdered activated carbon (PAC) to modify poly(ether sulfone) (PES). We prepared a series of monoliths for microorganism immobilization using both thermal-induced phase separation and non-solvent-induced phase separation. Characterization of the monoliths via fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), nitrogen adsorption-desorption analysis revealed improved hydrophilicity in the p(MMA-AAM)-modified monoliths and increased specific surface area (SSA) in monoliths with PAC addition. Particularly, the highest SSA was observed for the 0.5 g PAC (0.5-PAC/PES) monolith at 235.19 m2/g. Wastewater treatment experiments demonstrated that the 0.5-PAC/PES system exhibited superior pollutant removal performance, and it achieved nearly 100 % removal of NO3 - and total nitrogen (TN) in simulated SGFPW. Besides, the removal rates of TN and total organic carbon (TOC) in actual SGFPW by the 0.5-PAC/PES system were 1.5 times and 1.3 times higher, respectively, than those achieved with suspended microorganisms. After 96 h biological treatment, the extracellular polymeric substances (EPS) content of 0.5-PAC/PES was highest, showing its positive role in enhancing microbial activity. This work introduces a new approach to immobilize microorganisms, enhancing biological activity for SGFPW treatment under high salinity conditions.