Direct Potable Reuse: Are We Ready? A Review of Technological, Economic, and Environmental Considerations

Meeting
future water demand will require serious consideration
of direct potable reuse (DPR) for many water agencies. There has been
tremendous progress in the technologies needed to address the concerns
that conventional and novel water contaminants pose. Yet, to date,
only a few relatively small DPR operations have been installed. As
we get closer to the point where regulations are finalized and serious
investments are planned, there is a need to ask: Are we ready? In
this Review, we explore the technological, economic, and environmental
considerations associated with DPR. In particular, we focus on the
status of technologies for addressing the most challenging water pollutants,
the cost estimates for DPR, and the energy demand and associated implications
of DPR. We find that, although the technologies are nearly ready for
DPR, the most critical issue will be real-time monitoring of a number
of molecules that pose distinct challenges to advanced treatment trains.
In addition, there is a need to consider emergency planning, both
in terms of emergency buffer reservoir(s) and planning for situations
in which the treated water does not meet specifications. Since any
advanced treatment train will result in a significant increase in
embedded energy, it will be particularly important to plan for renewable
energy to minimize environmental impacts.