Debugging the Plant - Managing Reverse Osmosis Biofouling at a Groundwater Treatment Plant

Learn more about this project with the full JAWWA article.

At the Arcadia plant, the RO treated water (or permeate) then runs through a decarbonation tower to remove dissolved carbon dioxide before the permeate is reblended with the 25% of water that bypassed the RO. The resulting blend is then dosed with chlorine and ammonia to provide chloramine disinfection before delivery in the drinking water network.

Improvement was also noted in the normalized differential pressure and normalized flow data (above) with a more subtle effect that can be seen particularly in the first stage, which showed steady improvement followed by stabilized performance.

(TEMPE, AZ – March 1, 2016) – Troy Walker is among authors of a recent Journal AWWA article titled “Debugging the Plant – Managing Reverse Osmosis Biofouling at a Groundwater Treatment Plant”.

The article details our experience with the Arcadia Water Treatment Plant in Santa Monica, CA. Commissioned in 2010, the Arcadia Water Treatment Plant treats local groundwater to provide approximately 10 mgd of treated water as part of the Santa Monica’s drinking water supply. The plant removes iron and manganese and then treats a portion of the water with reverse osmosis (RO) as a softening process to achieve desired levels of hardness.

Shortly following the plant’s commissioning, biological fouling occurred, first at the pretreatment cartridge filters and then spreading to the RO units. Chloramine dosing, long established as an effective strategy for RO biological fouling control in wastewater reuse, is not as widespread in groundwater treatment. Previous studies of chloramine use in surface water and groundwater RO systems reported an undesirable increase in salt transport, which can adversely affect treated water quality and decrease usable membrane life. Despite this, successful implementation of chloramine dosing was achieved at the Santa Monica facility, which has overcome fouling.

A PDF of the full article is available.

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