A critical review of risks, characteristics, and treatment strategies for potentially toxic elements in wastewater from shale gas extraction. (April 2019)

• Record Type: Journal Article
• Authors: Sun, Yuqing; Wang, Di; Tsang, Daniel C.W.; Wang, Linling; Ok, Yong Sik; Feng, Yujie
• Is Part Of: Environment international. Volume 125(2019)
• Page Start: 452
• Page End: 469
• Publication Date: 2019-04
• Subjects: Unconventional energy -- Hydraulic fracturing -- Environmental pollution -- Metals/metalloids -- Wastewater treatment -- Sustainable remediation; Environmental protection -- Periodicals; Environmental health -- Periodicals; Environmental monitoring -- Periodicals; Environmental Monitoring -- Periodicals; Environnement -- Protection -- Périodiques; Hygiène du milieu -- Périodiques; Environnement -- Surveillance -- Périodiques; Environmental health; Environmental monitoring; Environmental protection; Periodicals; 333.705
• DOI: 10.1016/j.envint.2019.02.019
• Languages: English
• ISSNs: 0160-4120

Abstract

Abstract: Shale gas extraction via horizontal drilling and hydraulic fracturing (HF) has enhanced gas production worldwide, which has altered global energy markets and reduced the prices of natural gas and oil. Water management has become the most challenging issue of HF, as it demands vast amounts of freshwater and generates high volumes of complex liquid wastes contaminated by diverse potentially toxic elements at variable rates. This critical review focuses on characterizing HF wastewater and establishing strategies to mitigate environmental impacts. High prioritization was given to the constituents with mean concentrations over 10 times greater than the maximum contamination level (MCL) guidelines for drinking water. A number of potentially harmful organic compounds in HF wastewaters were identified via the risk quotient approach to predict the associated toxicity for freshwater organisms in recipient surface waters. Currently, two options for HF wastewater treatment are preferred, i.e., disposal by deep well injection or on-site re-use as a fracturing fluid. Supplementary treatment will be enforced by increasingly rigorous regulations. Partial treatment and reuse remain the preferred method for managing HF wastewater where feasible. Otherwise, advanced technologies such as membrane separation/distillation, forward osmosis, mechanical vapor compression, electrocoagulation, advanced oxidation, and adsorption-biological treatment will be required to satisfy the sustainable requirements for reuse or surface discharge. Graphical abstract: Unlabelled Image Highlights: Shale oil and gas production via hydraulic fracturing poses risks to water quality and quantity. High risk level is related with the management of hydraulic fracturing wastewater. Wastewater quality data limitation is an obstacle for developing sustainable treatment strategies. Integration of multiple technologies is required for wastewater reuse or discharge.