AST/R-Based Water Reuse as a Part of the Total Water Solution for Water-Stressed Regions: An Overview of Engineering Practice and Regulatory Prospective

Water supply and demand are increasingly unbalanced in many parts of the world. To address the imbalance, the total water solution methodology simultaneously considers regulatory, engineering, environmental and economic factors to optimize risk management solutions for an entire water system. As one component of this methodology, aquifer storage, treatment and recovery (AST/R) has the potential for large-scale applications in the U.S. and Middle East. However, the AST/R process is not fully understood particularly in the fate and transport of nutrients and residual contaminants passing through treatment (e.g., pesticides, endocrine disrupting compounds). Residual pathogen growth and viability in subsurface is also poorly understood. In a reverse engineering approach, groundwater quality and end-use health risk management objectives are first established leading to effluent treatment requirements for specific site conditions. This approach can offer improved risk management among uncertainties and alleviate public perceptions surrounding the AST/R practice. Further research, however, is needed to advance the concept.