Potential environmental impact and zero-valent iron treatment of wastewater from hydraulic fracturing

Abstract

Shale gas, as a form of clean, efficient and high-quality energy, has become an important product for establishing an energy-efficient and environmentally-friendly society, and promoting low-carbon economic development. According to China's "Thirteenth Five-year Plan of Shale Gas Development" and "Action Plan for Prevention and Control of Water Pollution", China will strongly support shale gas extraction by hydraulic fracturing and aim to minimize the potential environmental impact of shale gas development. This project has (i) identified the mobility of key risk-drivers in fracturing wastewater (FWW) (e.g., As and Se) correlated with wastewater chemistry and geochemical soil formation; (ii) elucidated the potential chemical toxicity of FWW on soil organisms, functionalities of soil microbial communities and human health; (iii) provided risk mitigation by innovative design of zero-valent iron (ZVI) composite as in-situ pollution control measures; (iv) established sustainable FWW pretreatment with cost-effective nano-scale ZVI-based technologies. The obtained outcomes of this project include: (a) a theoretical foundation to establish a system of environmental risk assessment for FWW; (b) technical support to improve the concept of pollution control in FWW; (c) practical direction to design treatment processes for FWW in China.