by Sheryl Hamlin
The California DDW (Department Drinking Water) responded to the first publicly available comments from its Expert Panel which has been assembled to review and critique the new Direct Potable Reuse (DPR) ordinance. The most current draft may be read here.
The short duration of the meeting did not mask serious questions raised by the Expert Panel. Below are a few of the issues raised.
Over-notification will saturate the public to the point notifications will be ignored, as they are in Prop 65, according to the Panel. The DPR notifications should be consistent with other public notifications involving water, although existing water notifications could be strengthened. One suggestion would be a table comparing existing notifications to proposed notifications. Close communication with major hospitals was noted by the Panel, but there was no elaboration.
There was a significant discussion about the placement of Ozone and BAC processes. The panel emphatically felt these should occur prior to Reverse Osmosis (RO) for effectiveness. Any deviation must be requested and proven on a case by case basis by the applicant. The panel recommended acetone and formaldehyde as BAC performance indicators. The concept is described here. The panel recommended carbamazepine and sulfamethoxazole as ozone performance indicators. Ozone wastewater treatment is discussed here.
These recommendations relate to the real-time operation and monitoring of the plant. Specifically, the panel itemized these concerns: 1) Changing wastewater characteristics, 2) Climate change, 3) Influent flow and load equalization, 4) WWTP optimization to reduce energy and chemical use at AWPF, and 5) Equalization and treatment of return flows. There was strong language about unintended consequences:
While the focus of this review is to determine if the proposed code provides “adequate public health protection” relative to the risk posed by the water being produced, there is a significant concern about unintended consequences — particularly related to energy consumption, excessive energy use, and carbon footprint.
Pathogen Controls and blending are two of the topic to be considered for the February 2022 meeting.
Communicate to DDW
History of Water Reuse in California
This fascinating history of California’s wastewater reuse shows the progress since the early 20th century. It was not discussed at the webinar but intended as background material as to how we arrived at this point.
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