FPUD's citric acid treatment test deemed successful

Fallbrook Public Utility District staff conducted a pilot project whether the use of citric acid would improve the efficiency of ultraviolet treatment reactors, and the pilot project found the addition of citric acid to be worthwhile.

A non-voting presentation item at FPUD’s Dec. 10 board meeting presented the findings, and FPUD’s board did not object to the continuation of the treatment process.

“We’re just going to move forward and implement the citric acid addition,” FPUD general manager Jack Bebee said.

The purpose of the study was to determine whether a less labor-intensive and more cost-effective approach would reduce sleeve fouling and improve efficiency.

“It was a study and project we did to determine how to operate the facility more cost-effectively,” Bebee said. “It was just a project we developed here to adjust the pH.”

The test analyzed the performance of a test ultraviolet reactor with no citric acid being injected for the first week, a low dose of citric acid being injected during the second week and a gradual increase in the citric acid concentration for the third and fourth weeks. The rate of fouling of the sleeve was examined by evaluating reactor performance and making visual observations, and water sampling was also part of the review.

A dose of 1.07 milligrams per liter of citric acid adjusted the pH by 0.1.

“It was just enough to prevent fouling of the reactor,” Bebee said.

FPUD estimates a savings of $15,900 annually through the injection of that dose level.