Researcher says bacteria might help remove perchlorate from water

Saturday, Oct. 11, 1997 | 2:03 a.m.

Bruce Logan, a Penn State environmental engineering professor, said a certain bacteria that thrives on the contaminant, perchlorate, and a related compound, chlorate, can be used to extract both compounds from water supplies. Perchlorate is a component of ammonium perchlorate, an ingredient in rocket fuel.

The bacteria, he said, breaks down the compounds, using their oxygen for respiration, leaving behind nontoxic chloride.

The bioremediation technique, he said, has been demonstrated in the laboratory and was the focus of research he conducted under a National Science Foundation grant while at the University of Arizona in 1994 and 1995 before he became an environmental engineering professor at Penn State in University Park, Pa.

The technique can be refined to remove perchlorate in the trace amounts - parts per billion levels - that have turned up in Lake Mead and Southern Nevada's drinking water supplies, Logan said Friday.

At a morning news conference, the state Environmental Protection Division announced it had completed the first step in a three-step process aimed at a cleanup attempt next year.

Doug Zimmerman, the division's chief of corrective actions, said it's a top priority to extract the contaminant from ground water near the sites of two chemical plants in the Henderson area where ammonium perchlorate has been produced.

Zimmerman said it will be up to the companies that caused the contamination to choose a cleanup technology, but bioremediation, he said, appears to be a front runner.

Zimmerman released a map of 40 sampling locations for ground water layers and Las Vegas Wash that scientists believe are carrying the contamination downstream of Kerr-McGee Chemical Corp. and the former site of Pacific Engineering & Production Co. of Nevada, or PEPCON, American Pacific Corp.'s predecessor.

Kerr-McGee, located on an island of Clark County land surrounded by Henderson, is the only company still producing ammonium perchlorate in Southern Nevada. Company officials announced Friday they want to sell the ammonium perchlorate business to American Pacific Corp., and that production of the rocket fuel oxidizer at the Kerr-McGee plant would cease by the end of the year.

Another plant, PEPCON, was destroyed by a series of explosions in 1988, and American Pacific has since relocated its ammonium perchlorate operations to a plant near Cedar City, Utah, Western Electrochemical Co., which will become the sole U.S. producer of ammonium perchlorate.

The next step in resolving the contamination problem, Zimmerman said, is for the companies to submit a work plan to the division by Nov. 1 that will detail where perchlorate migrates from ground water into Las Vegas Wash and, eventually, Lake Mead.

The plan will explain how the chemical can be intercepted before it reaches the wash, which flows into the lake, six miles upstream of the intakes for Southern Nevada's drinking water supply.

The map shows perchlorate levels are highest in some of the 47 wells at the Kerr-McGee plant.

The highest level, based on the state's analysis of 10 of those wells, was 3.7 million parts per billion. But Zimmerman said one sample that was analyzed by the company but not by the state's contractor laboratories, showed one concentration of 18 million parts per billion for perchlorate.

The primary health concern from consuming perchlorate is that, at high enough levels, it could affect the thyroid gland's ability to produce growth hormones.

The chemical is not regulated federally, or in any state except California, where health officials have set 18 parts per bi temporary guideline that triggers remedial action.

Zimmerman said once the Environmental Protection Division has accepted the companies' work plan, it would take about six months until investigators reach the third and final step: cleanup.