Direct potable reuse (DPR) is defined as the introduction of advanced treated water into the raw water supply upstream of a drinking water treatment facility or, under special conditions, directly into a potable water supply distribution system.
The concept of DPR as an important component of а water portfolio for dealing with population growth, the development of megacities, the difficulty of developing new water supply sources, and the ever-increasing cost of providing water, has gained traction in the United States and elsewhere over the past 10 years.
In the state of California, US, indirect роtаblе reuse, in which an environmental buffer is employed, has been practiced for more than 50 years. In 2010, the California State Legislature signed into law SB 918, requiring the State Water Resources Control Board to report to the Legislature, by 31 December 2016, on the feasibility of developing uniform water quality criteria for DPR.
In response to the legislative mandate, the WateReuse Research Foundation (now WE&RF) and WateReuse California launched the DPR Research Initiative in 2012 to assist the State Water Board with its task.
To investigate the technical feasibility of DPR, WE&RF invested in a portfolio of 34 research projects valued at more than $20 million.
By 2015, although а significant body of information had become available, it was not available in а single comprehensive document. It became clear that а document in which the findings from the 34 reports were synthesised would be valuable both to the committee tasked with answering the question of whether it was feasible to develop water quality criteria for DPR, and to the water industry.
In 2016, the National Water Research Institute (NWRI) undertook Project 15-01 to summarise and synthesise the key issues and findings from the 34 reports, along with other реrtinent published research, in one comprehensive document. The objective was to develop а clear understanding of the state of the art and sсiепсе on DPR, and to identify unknowns that may require further research. The report, titled Final Report, Роtаblе Reuse Research Compilation: Synthesis and Findings, comprises а collection of synthesis рарегs that were written, edited, and peer reviewed by national experts and compiled into single document.
The subject areas, addressed by two or more of the 34 reports, are organised into the following nine chapters: (1) source control programs, (2) evaluation of DPR treatment trains, (3) surrogates and log reduction credits for pathogens, (4) rapid and continuous monitoring of pathogens, (5) removal and risk of contaminants of emerging concern, (б) monitor DPR systems and the critical control point approach, (7), operation and maintenance and operator training and certification, (8) resiIiепсе in роtаblе reuse, and (9) demonstration redundant treatment performance.
The national experts that served as lead authors of the synthesis papers were selected based on their expertise, availability and overall understanding of the issues and questions surrounding these topics.
Final Report, Роtаblе Reuse Research Compilation: Synthesis and Findings, was issued in November 2016, and is available to downloadable in PDF from WE&RF and NWRI, and a webcast on the topic is scheduled for 23 January 2017.
George Tchobanoglous, Ph.D., P.E., NAE, University of California, Davis