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Nitrate water study in SCV

Posted: August 15, 2012 2:00 a.m.
Updated: August 15, 2012 2:00 a.m.
 

A controversial plan to use bacteria to remove harmful nitrates from groundwater in Acton was approved Tuesday by the Los Angeles County Board of Supervisors.

The decision authorizes the director of Public Works to sign a contract with Denver-based Water Research Foundation to remove the salty compound from Acton wells “biologically” using special nitrate-eating bacteria.

Under the agreement, the county will split the $300,000 cost of the project with the foundation, with no funds drawn from its general fund.

In the 90-page proposal given to county supervisors explaining “biological denitrification,” Denver scientists admit technology “for nitrate removal from groundwater has been met with resistance by regulators and the public.”

In promoting the technology, however, they remind county officials: “A number of recent projects funded by federal, state and local agencies have clearly demonstrated the reliability of this technology for nitrate removal from groundwater.”

In a nutshell, the bacteria used in the process convert nitrates found in water into nitrogen gas.

Nitrogen makes up almost 80 percent of the air we breathe, so the process is viewed as completely organic.

What makes it controversial is that “biological denitrification” technology is associated with wastewater treatment.

“You can find this bacteria in our water naturally,” said Hsiao-Wen Chen, research manager for the Water Research Foundation. “This process is used in wastewater treatment and that’s what makes some people uncomfortable.”

On the plus side, the technology does not produce a salty-brine byproduct, which — foundation promoters note in their report to the county — contribute to the salt content of local waterways.

Foundation report writers note that popular nitrate-removing technologies such as ion-exchange and reverse osmosis “are encumbered by the fact that they generate a high-salinity waste stream with several limited disposal options.”

Salinity, and particularly salinity caused by chloride contamination of the Santa Clara River, prompted public outrage in the Santa Clarita Valley two years ago at the prospect of ratepayers footing the bill for a proposed $250-million chloride-ridding reverse osmosis plant.

Eliminating nitrate contamination in county wells remains a priority for the Los Angeles County Department of Public Works.

Several groundwater systems in the county’s unincorporated areas have nitrate levels above the limit set at 45 milligrams of nitrate per liter of water, according to the report submitted to supervisors.

County officials want to remove nitrate from the water for health reasons.

When nitrate is absorbed into the bloodstream, it hinders the blood’s ability to transport oxygen to the cells.

Nitrate levels are highest in agricultural areas since it is used in fertilizers, according to a national survey on nitrates carried out by the U.S. Geological Survey.

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