Integrated Electrocoagulation/Ultrafiltration-Membrane Distillation-Crystallization for Treating Hydraulic Fracturing Produced Water

Abstract

In this work, produced water (PW) generated from hydraulic fracturing was treated using an integrated electrocoagulation/ultrafiltration, membrane distillation and crystallization processes (EC/UF-MDC). The focus of this work was to determine the feasibility of this integrated process for increasing water recovery. The results of this work suggest that optimizing the various unit operations in this integrated process could be used to recover PW. All membrane based separation processes suffer from membrane fouling. Pretreatment of the feed is essential to suppress fouling of the membrane. Here electrocoagulation (EC) followed by ultrafiltration (UF) was used to achieve high removal efficiency of both total suspended solids (TSS) and total organic carbon (TOC). Dissolved organic compounds are known to foul the hydrophobic membrane used in MD. In this study, a significant reduction in membrane fouling was obtained, which can lead to a long-term durability of MD system. In addition, the use of membrane distillation crystallization (MDC) can help mitigate the scale formation. Crystallization in the feed tank was used to suppress scale formation on the MD membrane. The integrated EC/UF-MDC process can have a potential impact on Water Resources/Oil Gas Companies. By treating and reusing PW, preservation of surface and groundwater forming 80% of the water utilized in hydraulic fracturing could be achieved. In addition, treating PW will reduce the amount of PW directly disposed in Class II disposal wells, which further address the main cause of earthquakes.