Efficient integrated module of gravity driven membrane filtration, solar aeration and GAC adsorption for pretreatment of shale gas wastewater

Low-cost and efficient treatment processes are urgently needed to manage highly decentralized shale gas wastewater, which seriously threatens the environment if not properly treated. We propose a simple integrated pretreatment process for on-site treatment, whereby gravity driven membrane filtration is combined with granular activated carbon (GAC) adsorption and solar aeration. The rationale of exploitment of sustainable solar energy is that most shale gas production areas are decentralized and located in desert/rural areas characterized by relatively scarce transportation and power facilities but also by abundant sunshine. In this study, GAC and aeration significantly increased the stable flux (170%) and improved effluent quality. Specifically, the dissolved organic carbon removal rate of the integrated system was 44.9%. The high stable flux was attributed to a reduction of extracellular polymeric substances accumulated on the membrane, as well as to the more porous and heterogeneous biofilm formed by eukaryotes with stronger active predation behavior. The prevailing strains, Gammaproteobacteria (35.5%) and Alphaproteobacteria (56.5%), played an important active role in organic carbon removal. The integrated system has great potential as pretreatment for shale gas wastewater due to its low energy consumption, low operational costs, high productivity, and effluent quality.