Desalination of shale gas wastewater: Thermal and membrane applications for zero-liquid discharge

Natural gas exploration from unconventional shale formations, known as "shale gas," has recently arisen as an appealing energy supply to meet the increasing worldwide demand. During the last decade, development of horizontal drilling and hydraulic fracturing ("fracking") technologies have allowed the cost-effective gas exploration from previously inaccessible shale deposits. In spite of optimistic expansion projections, natural gas production from tight shale formations has social and environmental implications mainly associated with the depletion of freshwater resources and polluting wastewater generation. In this context, the capability of desalination technologies to allow water recycling and/or water reuse is crucial for the shale gas industry. Advances in zero-liquid discharge (ZLD) desalination processes for treating hypersaline shale gas wastewater can play a key role in the mitigation of public health and environmental impacts, and in the improvement of overall process sustainability. This chapter outlines the most promising thermal- and membrane-based alternatives for ZLD desalination of shale gas wastewater.