Risk Management - Selection of Critical Control Points for Potable Reuse


  • Ben Stanford PhD and Troy Walker MIE(Aust) - Hazen and Sawyer
  • Stuart Khan PhD - University of New South Wales
  • Shane Snyder PhD - University of Arizona
  • Cedric Robillot PhD - Head Start Development

The final report for Water Environment and Reuse Foundation project #13-03 (Critical Control Point Assessment to Quantify Robustness and Reliability of Multiple Treatment Barriers of a DPR Scheme) was recently made available.

With opportunities for potable reuse increasing around the US, including North Carolina with the passage of Senate Bill 163 in 2014, many utilities and regulators are considering how a path forward for potable reuse would look from a regulatory and operational construct. Of particular concern is ensuring that there is a framework for identifying and managing water quality risks and operational risks that could impact public health. Hazen and Sawyer recently completed a project funded by the WateReuse Research Foundation’s direct potable reuse (DPR) initiative whereby we adapted the hazard analysis and critical control point (HACCP) methodology into a framework that could be used for potable reuse.

Critical control points (CCPs) are locations in a treatment plant, including specific processes and chemical addition steps, that have a direct impact on the quality of finished water as it relates to public health. CCPs must have both a monitoring component, which allows the operator to verify that the process is operating as intended, and a control component, which allows the operator to adjust the functioning of the unit process to improve its performance. While there are many “critical” aspects to the proper and efficient operation of a water, wastewater, or water reuse facility, there are only a handful that have direct bearing on the public health implications of water from that facility. This is a key concept as it allows operations staff to better manage various alarms and issues that will inevitably arise in any treatment process, focusing on those that are critical to public health protection.

Through the WRRF-funded project we have identified and evaluated critical control points (CCPs) for both a membrane based process (MF/RO/UV H2O2/Cl2) and a non-membrane treatment system (Floc/Sed/O3/BAC/GAC/UV/Cl2) by adapting the HACCP methodology to DPR. The data from this project in addition to the application of the HACCP framework for DPR provides a transparent, logical process by which potable reuse projects can be evaluated and permitted by various state and federal agencies.

This presentation will provide an overview of the HACCP methodology and will present a summary of the full scale data collected and analyzed by our team to demonstrate how well process barriers perform in potable reuse. We’ll address questions such as “how does the disinfection system actually perform” and “what happens when we limit the amount of disinfection credit applicable to any one unit process”.

For more information, please contact the author at bstanford@hazenandsawyer.com.

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Horizons Fall 2017 (pdf)

Horizons showcases significant water, wastewater, reuse, and stormwater projects and innovations that help our clients to achieve their goals, and can help you achieve yours. Articles are written by top engineers and process group leaders, demonstrating and explaining the beneficial application of a variety of technologies and tools.

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