Aerated Electrolysis for Reducing Impacts of Shale Gas Production Wastewater on Water Sources regarding Disinfection Byproduct Formation

Advances in treatment technologies of shale gas production wastewater are needed to minimize its toxic potency in polluted water sources. An aerated electrolysis (AE) process was employed for treatment of both synthetic and field production wastewaters. Results showed AE led to a 64% reduction in the formation of total disinfection byproducts (DBPs) analyzed in this study and 79% reduction in the formation of more toxic brominated DBPs (Br-DBPs) in polluted natural water in an 8-h treatment, suggesting a potential of scaling up as an in situ pretreatment strategy to reduce negative impacts caused by accidental spills or surface discharges during transportation. The mechanisms for reduced formation of DBPs were associated with bromide oxidation followed by bromine stripping from production wastewater, as evidenced by first-order kinetics on bromide removal. Along with bromide removal that led to the reduction of Br-DBP formation and decreased bromine substitution factors (BSFs), the results also revealed alteration of organic DBP precursors during the AE process by exploring the profile of formed DBP species. Formation of bromate in production wastewater was minimal, as bromate was consistently found below a reporting limit of 500 μg/L during the 8-h AE treatment. The lowest energy consumption at 5.9 kWh/m³ warrants further investigations on process optimization. Application of this technology on site of shale gas exploration is beneficial for water utilities that are facing challenges due to contamination of water sources by production wastewater and inability of conventional water treatment processes in attenuation of DBP precursors.