Advanced treatment of coal gasification wastewater using a multistage aerated biofilm reactor with hydrophilic polyurethane carriers
Hongwei Chen, Chao Song, Qingbin Wang, Zimin Chai, Maosheng Zheng
Abstract
To address the challenges posed by the complexity and recalcitrance of coal gasification wastewater (CGW), this study developed a multistage aerated biofilm reactor incorporating hydrophilic polyurethane as the biofilm carrier for advanced treatment of CGW. The results demonstrated that the reactor exhibited excellent resistance to shock loads and effectively treated high concentrations of ammonia nitrogen (NH 4 + -N) and refractory organic compounds. At hydraulic retention times (HRTs) of 24 h, 12 h, and 8 h, the NH 4 + -N removal efficiency consistently exceeded 97 %, with complete conversion to nitrate. Notably, at an HRT of 12 h, the chemical oxygen demand (COD) removal efficiency reached a maximum of 42.68 ± 9.27 %. Further analyses using three-dimensional fluorescence spectroscopy and gas chromatography-mass spectrometry revealed high removal efficiencies of 75.66 %, 76.58 %, and 63.89 % for alkanes, phenolic compounds, and phthalate esters, respectively. The reactor's robust biofilm stability was confirmed by the high protein-to-polysaccharide ratio in extracellular polymeric substances (EPS) ranging from 3.35 to 5.85, with tightly bound EPS correlating significantly with biofilm stability. Microbial community analysis identified Nitrosomonas as the dominant ammonia-oxidizing bacteria (AOB), alongside Nitrospira and Candidatus_Nitrotoga as the key nitrite-oxidizing bacteria (NOB). Simultaneously, dominant genera including PLTA13 , Fimbriimonadaceae , Blastocatellia 11–24 , and Ahniella played key roles in degrading refractory organic compounds. These findings highlight the promising potential of the multistage aerated biofilm reactor for the efficient advanced treatment of CGW.