REPORT ON ‘FRAMEWORK FOR DIRECT POTABLE REUSE’
A CRITIQUE ON THE CHAPTERS ON SOURCE CONTROL AND WASTEWATER TREATMENT
Publication Date (Web): 8 March 2016
The report Framework for Direct Potable Reuse, released in mid-2015 by the WateReuse Research Foundation in conjunction with the American Water Works Association, the Water Environment Federation and the National Water Research Institute in the US, will be of great interest to those planning for, or considering, direct potable reuse in the future.
However, there are aspects of this report that should be viewed with caution, in particular the recommendations made in Chapters 5 and 6 that cover Source (or Trade Waste) Control and Wastewater Treatment respectively. The wording used in these chapters intimates that Direct Potable Reuse (DPR) drives the necessity for more rigorous Source Control Programs (SCPs) and Wastewater Treatment Plant (WWTP) design – over and above those required for all high-end reuse applications such as Indirect Potable Reuse (IPR), domestic non-potable reuse and, indeed, discharges to sensitive environmental locations.
It is contended that a rigorous SCP and well-designed (and operated) WWTP should be a pre-requisite for any high-end reuse application – the SCP to protect both the collection system and the performance of the WWTP, and the WWTP to produce an effluent of a quality that is beneficial to the operation and performance of downstream process units, no matter what the end use of the reclaimed water is.
The critique notes that there is good experience in Australia with the development of SCPs, with the Water Services Association of Australia’s (WSAA’s) June 2012 document, Australian Sewage Quality Management Guidelines, being a good example of work in this area. This document guides member utilities through a 12-element risk framework to ensure the protection of collection system assets and all treatment processes, ensure compliance with environmental legislation and reduce hazards and odours for workers and the community while also supporting utilities to better control recycled water and biosolids quality.
Adoption of the 12-element risk framework for Source Control aligns these Guidelines with both the Australian Drinking Water Guidelines (ADWG, 2011) and the Australian Guidelines for Water Recycling (AGWR, 2008).
WWTPs in Australia are generally designed and operated to achieve nitrogen removal, no matter whether the effluent produced is further treated for a reuse application or is discharged to the environment – a situation obviously not prevalent in the US and yet one that the Framework Report states as being a requirement for any DPR scheme.
The critique concludes by noting that a rigorous and functional SCP, together with an appropriately designed WWTP, are crucial elements in any high-end reuse scheme –not just for DPR applications. There is an opportunity to clarify the Source Control discussion in a current WateReuse Research Foundation project (WRRF-13-12).
The usefulness of the Framework for Direct Potable Reuse report would be enhanced considerably – both within and out of the US – by internationalising it and presenting a comparison of SCPs applied at reuse facilities around the world (DPR, IPR and other forms), including the principles involved and the legislation that covered their development.
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