Fouling behaviors of membrane distillation (MD) in shale gas wastewater treatment

摘要

One of the major environmental risks of shale gas development is water contamination caused by hydraulic fracturing, resulting in the generation of high salinity wastewaters. During the shale gas wastewater treatment, there are typically multi-step treatment processes, including candidates such as air flotation, biological treatment, and chemical coagulants. In this paper, membrane distillation (MD) technique with simple and economical pre-treatment was applied to treat the shale gas wastewaters containing more than 300,000 mg/L total dissolved solids with porous hollow fiber membranes. In addition, fouling mechanisms in the MD treatment of the wastewaters were explored using a theoretical model based on the crystallization theory. From the laboratory results, it was found that the flux decline due to scale formation was the serious problem in the treatment of the real wastewaters. The analysis of the MD membrane surfaces using scanning electron microscopy and X-ray photoelectron spectroscopy revealed the morphologies and compositions of the foulant layers after the MD treatment.