research project details
Project Title: Application of Bioreactor Systems to Low-Concentration
Perchlorate-Contaminated Water (Phase I)
Investigator(s): Bruce
Logan
Sponsor: Private Sponsor
Project Summary:
Perchlorate has recently been detected in several surface waters and ground water wells used to
supply drinking water at concentrations above the detection limit (0.4 ppb) to 0.37%. The California
Department of Health Services (CDHS), based on EPA work, has established a provisional action level
of 18 ppb for drinking water due to perchlorate's interference with iodine in the production of
hormones in the thyroid. The presence of perchlorate at these high concentrations in the environment,
coupled with a very low drinking water standard, has created a national water contamination crisis
in the US potentially affecting 12 million people. Perchlorate is readily biodegradable, and under
proper conditions, can be reduced to non-detectable levels by fixed and suspended cultures of microorganisms.
Since 1993, the PI has been conducting research on microbes that can respire chlorate or perchlorate:
that is, they can use either of these compounds as an electron acceptor in the oxidation of many
common substrates such as acetate, simple sugars and amino acids.
It is proposed here to conduct bench scale experiments on three different fixed-film biological treatment processes that should be capable of being scaled up to treat large quantities of drinking water. These treatment systems are: a packed bed (slow sand filter) amended with soluble substrates (acetate, methanol, and ethanol); a hydrogen gas fed four-phase (hydrogen gas, water, biofilm, and support media), unsaturated trickle-type packed column; a membrane-bound biofilm reactor. The hydrogen gas-based systems offer an additional potential advantage of achieving chlorinated aliphatic reduction by hydrogen-oxidizing bacteria under highly reducing conditions. With information gained in this proposal, we will estimate the costs of treating waters using the reactors and feed substrates that successfully remove perchlorate down to drinking water levels (<18 ug/L). Based on the engineering and economic analysis, one of these treatment systems will be selected for further testing in Phase II at the Crafton-Redlands site in Redlands, CA.
This project will involve researchers at Penn State University, the University of Nevada, Las Vegas, the City of Redlands, and Camp, Dresser and McKee (CDM) consulting Engineering. In order to assess the general nature of the findings, and to test the performance of the systems for Phase II work, water samples will be obtained from two sites: the Crafton-Redlands site, and a perchlorate contaminated areas in Nevada (the Nevada Wash area and Lake Mead).