HILMAR — Hilmar Cheese Co., which has worked for several years to solve problems with its waste water, is proposing a change in the treatment process.
The company is asking state regulators to allow the change in a part of the process that removes salts from the water.
The current system uses reverse osmosis — forcing water through a membrane to trap the salts — for up to 1.4 million gallons a day.
Up to 500,000 additional gallons do not go through this step because of a lack of capacity, but it is still "highly treated" in the other steps, said Michael Boccadoro, a public relations consultant to Hilmar Cheese.
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The company proposes to replace the reverse osmosis with electrodialysis, which removes salts by applying an electrical current. Boccadoro said the alternative is being sought because reverse osmosis uses a lot of energy and the membranes often have to be cleared of trapped material.
The Central Valley Regional Water Quality Control Board will consider the proposal at its Jan. 27-29 meeting in Rancho Cordova. The board's staff has recommended approval of the change.
Hilmar Cheese, whose Lander Avenue complex is the world's largest cheese plant, paid $3 million in 2006 to settle a pollution case brought by the board. Since then, the company has operated under a permit aimed at preventing future problems.
Boccadoro said the plant has spent more than $150 million on the treatment process. It includes trucking away some of the solids for energy production, reducing other material via digestion by microbes, putting waste water through filters and reverse osmosis, injecting concentrated material into deep wells, and using the treated waste water to irrigate nearby farmland.
The permit allows irrigating with the water that is less than fully treated while Hilmar Cheese works toward a long-term solution. Monitoring so far has not found contamination of nearby water supplies, Boccadoro said.
The proposed change would be in a new permit that already has drawn fire from at least one environmental group.
"It's an absolutely horrible permit," said Bill Jennings, president of the California Sportfishing Protection Alliance. "This is a poster child for the failure of the regional board to seriously address water pollution problems in the Central Valley."
Under the proposal, Hilmar Cheese would test electrodialysis in early 2010 and install it by July 2011 if it proves worthwhile. If not, the plant would continue using reverse osmosis.
The proposal includes an increase in the maximum discharge from 1.9 million to 2.5 million gallons of water a day, once the treatment improvements are done.
"We look forward to working with the regional board on development of updated water reclamation requirements for our facility," Burt Fleischer, the company's environmental director, said in a written statement.
The Merced Sun-Star contributed to this report.
Bee staff writer John Holland can be reached at firstname.lastname@example.org or 578-2385.