(612a) Membrane Distillation and Crystallization for Treating Hydraulic Fracturing Produced Water

Water is a very valuable natural resource. Maximizing reuse of wastewater is essential to meet increasing demands for fresh water. Hydraulic fracturing oil and gas flow back and produced water is frequently highly impaired. Currently it is often deep well injected into geologically isolated formations. Maximizing recovery of this water for beneficial uses is essential to promote a circular economy. However multiple unit operations are needed if these wastewaters are to be recovered for beneficial uses. Electrocoagulation is considered a promising pretreatment technology. Herein, we have investigated the use of aluminium electrodes for electrocoagulation as a pretreatment operation. The effects of electrode arrangement, applied current, reaction time, pH, and inter electrode distance on the quality of the treated water have been investigated.

The results obtained here indicate that electrocoagulation can obtain good removal of turbidity (95%), total suspended solids, TSS (90%), and total organic carbon, TOC (69%) by carefully choosing the reaction conditions. The performance of the electrocoagulation process depends strongly on the quality of the feed water. The viability of a practical continuous electrocoagulation process will depend on the volume (footprint) of the reactor which in turn will depend on operating conditions and the quality of the feed water.

Microfiltration using submerged membranes was used to rapidly separate the sludge from the supernatant. Next membrane distillation was used to remove nonvolatile inorganic salts. We show that combining membrane distillation with crystallizer can maximize wastewater recovery. Crystallization in the feed tank was used to suppress scale formation on the membrane distillation membrane. 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.