Abstract Hydraulic fracturing flowback and produced water is a highly impaired wastewater containing dissolved salts polar and non-polar organic compounds, oil and surfactants. Here a combined electrocoagulation - microfiltration – membrane distillation process has been used to treat this wastewater. Electrocoagulation followed by microfiltration was used to pretreat the wastewater prior membrane distillation. The initial total dissolved solids (TDS) concentration was extremely high being 245,300 mg L−1. After electrocoagulation, the total organic carbon (TOC) was reduced from 120 mg L−1 to 64 mg L−1. Tangential flow microfiltration using a 0.1 μm pore size polyethersulfone membrane was used to separate the particulate matter after electrocoagulation and to further reduce the TOC to 44 mg L−1. Membrane distillation was used to desalinate the pretreated produced water resulting in a high quality treated water (TDS of 56 mg L−1 and TOC 1 mg L−1). Three membranes with very different surface morphology were used: commercially available polyvinylidene fluoride, electrospun poly(vinylidene fluoride-co-hexafluoropropylene) nanofibers and multiwalled carbon nanotube coated polytetrafluoroethylene. The TDS in the retentate increased to over 350,000 mg L−1. During membrane distillation, the temperature of the feed tank was maintained at 36 °C while the feed entered the module at 60 °C in order to minimize scaling on the membrane. The surface properties of an ideal membrane that is resistant to wetting and provides high flux is likely to depend on the TDS and properties of the wastewater.

中文翻译：

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电凝-微滤-膜蒸馏联合处理水力压裂采出水

摘要 水力压裂返排和采出水是一种含有溶解盐、极性和非极性有机化合物、油和表面活性剂的严重受损废水。在这里，联合电凝-微滤-膜蒸馏工艺已被用于处理这种废水。在膜蒸馏之前使用电凝聚和微滤对废水进行预处理。初始总溶解固体 (TDS) 浓度极高，为 245,300 mg L-1。电凝后，总有机碳 (TOC) 从 120 mg L-1 减少到 64 mg L-1。使用 0.1 μm 孔径聚醚砜膜的切向流微滤用于在电凝后分离颗粒物质，并将 TOC 进一步降低至 44 mg L-1。膜蒸馏用于对预处理后的采出水进行脱盐，得到高质量的处理水（TDS 为 56 mg L-1，TOC 为 1 mg L-1）。使用了三种表面形态非常不同的膜：市售聚偏二氟乙烯、电纺聚（偏二氟乙烯-共六氟丙烯）纳米纤维和多壁碳纳米管涂覆的聚四氟乙烯。渗余物中的 TDS 增加到超过 350,000 mg L-1。在膜蒸馏过程中，进料罐的温度保持在 36 °C，而进料在 60 °C 下进入模块，以最大限度地减少膜上的结垢。抗润湿并提供高通量的理想膜的表面特性可能取决于 TDS 和废水的特性。