Combined effect of ozone and PTFE membrane on treating shale gas produced wastewater in Fuling Shale Gas Field

Abstract

Shale gas produced wastewater (SGPW) is difficult to be treated by conventional treatment processes due to its high total dissolved solids, chemical oxygen demand (COD), salinity (SAL), bacteria, and complex physicochemical composition. In this study, a new combined process of ozonation and polytetrafluoroethylene (PTFE) membrane was developed to treat SGPW in Fuling Shale Gas Field, China, for the first time. Polyaluminum chloride (PAC) was selected as flocculant for the pretreatment, and the ozonation was used to control sulfate-reducing bacteria (SRB), iron bacteria (FEB), total growth bactericide (TGB), and degrade macromolecule organic matter. The PTFE microfiltrate membrane was applied to treat COD and SAL. The results demonstrated that the removal of SRB, FEB, TGB, and COD was 55.6%, 78.6%, 77.3%, and 67.0%, respectively, with the conditions of PAC dosing quantity 400 mg/L, Ozone dosing quantity 3 g/h, and residence time 20 min. The combined process exhibited effective removal performance and is potential to be applied for treating SGPW in China.