Phase 1: Laboratory and Bench Scale Experiments

Project funded by: American Water Works Research Foundation (Grant dates: Nov 1998-Oct 2001).

Principal Investigator: Bruce Logan, Kappe Professor of Environmental Engineering, Penn State University, Phone: 814-863-7908, Fax: 814-863-7304, Email: blogan@psu.edu
Co-Investigator: Jacimaria Batista, Assistant Professor, Department of Civil and Environmental Engineering, University of Nevada, Las Vegas.

Project Abstract

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).

Participating Graduate Students

Ms. Kijung Kim (kxk215@psu.edu) has demonstrated that it is possible to obtain perchlorate and chlorate reduction in sand columns inoculated with mixed cultures from wastewater treatment plants. Her work will lead to design information and models to apply to larger scale water treatment processes. Kijung will continue to work on Phase 2 of this project.
Ms. Dina Lapoint (dinal33@hotmail.com) is continuing Joel Miller's resaerch on perchlorate removal in reactors fed hydrogen gas.
Mr. Joel Miller (jpm157@psu.edu) (M.S. 1999) developed a prototype reactor capable of supporting biofilms of hydrogen-oxidizing perchlorate-reducing cultures. He obtained fundamental data that is being used to design a hydrogen-gas based reactor for drinking water treatment.