Fit-for-purpose urban wastewater reuse: Analysis of issues and available technologies for sustainable multiple barrier approaches

A selective approach for multiple wastewater recovery is nowadays desirable and technologically feasible, to provide water at specific quality standards for each reuse objective. This "fit-for-purpose" approach to water reuse could both save water and would reduce production cost and energy demand by eliminating unnecessary treatment and long-range conveyance, as it typically aims at local reuses. The appropriate choice of technologies for such approaches is perhaps the most critical planning and design decision when evaluating systems for implementation or refurbishing. This article examines wastewater reuse goals (direct potable use, indirect potable use, non-potable uses and industrial uses) and related requirements as relevant case studies, and issues that may arise during implementation. It then proposes an overview of current conventional and advanced technologies and their possible combination to meet foreseen uses under a multiple barrier treatment (MBT) approach, which implies a sequence of complementary processes at an increasing level of protection for both conventional and emerging pollutants according to reuse goals.