Can pre-ozonation be combined with gravity-driven membrane filtration to treat shale gas wastewater?
2021
Tang, Peng | Shi, Mengchao | Li, Xin | Zhang, Yongli | Lin, Dong | Li, Tong | Zhang, Weiming | Tiraferri, Alberto | Liu, Baicang
Low-cost gravity-driven membrane (GDM) filtration has the potential to efficiently manage highly decentralized shale gas wastewater (SGW). In this work, the feasibility of combining low dosage pre-ozonation with the GDM process was evaluated in the treatment of SGW. The results showed that pre-ozonation significantly increased the stable flux (372%) of GDM filtration, while slightly deteriorating the quality of the effluent water in terms of organic content (−14%). These results were mainly attributed to the conversion of macromolecular organics to low-molecular weight fractions by pre-ozonation. Interestingly, pre-ozonation markedly increased the flux (198%) in the first month of operation also for a GDM process added with granular activated carbon (GGDM). Nevertheless, the flux of O₃-GGDM systems dropped sharply around the 25th day of operation, which might be due to the rapid accumulation of pollutants in the high flux stage and the formation of a dense fouling layer. Pre-ozonation remarkably influenced the microbial community structure. And O₃-GDM systems were characterized by distinct core microorganisms, which might degrade specific organics in SGW. Furthermore, O₃-GDM outperformed simple GDM as a pretreatment for RO. These findings can provide valuable references for combining oxidation technologies with the GDM process in treating refractory wastewater.
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