United States Environmental Protection Ml M % Agency EcoMat Inc.'s Biological Denitrification Process Innovative Technology Evaluation Report EPA/540/R-01/501 May 2002 EcoMat Inc.’s Biological Denitrification Process Innovative Technology Evaluation Report National Risk Management Research Laboratory Office of Research and Development U.S. Environmental Protection Agency Cincinnati, Ohio 45268 Recycled Recyclable Printed with vegetable-based ink or paper that contains a minimum ot 50a? post-consumer fiber content processed chlorine free Notice The information in this document has been funded by the U.S. Environmental Protection Agency (EPA) under Contract Nos. 68-C5-0036 and 68-C00-179 to Science Applications International Corporation (SAIC). It has been subjected to the Agency’s peer and administrative reviews and has been approved for publication asan EPA document. Mention oftrade names or commercial products does not constitute an endorsement or recommendation for use. Foreword The U.S. Environmental Protection Agency is charged by Congress with protecting the Nation’s land, air, and water resources. Under a mandate of national environmental laws, the Agency strives to formulate and implement actions leading to a compatible balance between human activities and the ability of natural systems to support and nurture life. To meet this mandate, EPA’s research program is providing data and technical support for solving environmental problems today and building a science knowledge base necessary to manage our ecological resources wisely, understand how pollutants affect our health, and prevent or reduce environmental risks in the future. The National Risk Management Research Laboratory (NRMRL) is the Agency’s center for investigation of technological and management approaches for preventing and reducing risks from pollution that threatens human health and the environment. The focus ofthe Laboratory’s research program is on methods and their cost-effectiveness forprevention and control of pollution to air, land, water, and subsurface resources; protection of water quality in public water systems; remediation of contaminated sites, sediments and ground water; prevention and control of indoor air pollution; and restoration of ecosystems. NRMRL collaborates with both public and private sector partners to foster technologies that reduce the cost of compliance and to anticipate emerging problems. NRMRL’s research provides solutions to environmental problems by; developing and promoting technologies that protect and improve the environment; advancing scientific and engineering information to support regulatory and policy decisions; and providing the technical support and information transfer to ensure implementation of environmental regulations and strategies at the national, state, and community levels. This publication has been produced as part of the Laboratory’s strategic long-term research plan. It is published and made available by EPA’s Office of Research and Development to assist the user community and to link researchers with their clients. Hugh W. McKinnon, Director National Risk Management Research Laboratory Abstract This report summarizes the findings of an evaluation of a biodenitrification (BDN) system developed by EcoMat Inc. of Hayward, California (EcoMat). This evaluation was conducted between May and December of 1999 under the U.S. Environmental Protection Agency Superfund Innovative Technology Evaluation (SITE) Program; it was conducted in cooperation with the Kansas Department of Health and Environment (KDHE). The demonstration site was the location of a former public water supply well in Bendena, Kansas. The well water is contaminated with high levels of nitrate. Based on historical data, nitrate concentrations in the water have ranged from approximately 20 to 130 ppm, well above the regulatory limit of 10 mg/I. Low concentrations of volatile organic compounds (VOCs), particularly carbon tetrachloride (CCI4), have been a secondary problem. The overall goal of EcoMat was to demonstrate the ability of its process to reduce the levels of nitrate in the groundwater to an acceptable concentration, thus restoring the water supply well as a drinking water source. EcoMat's process is a two component process consisting of 1) an ex situ anoxic biofilter BDN system, and 2) a post-treatment system. The BDN system utilizes specific biocarriers and bacteria to treat nitrate-contaminated water, and employs a patented reactorfor mixing the suspended biocarriers and retaining biocarrier within the reactors to minimize solids carryover. Methanol is added to the system as a carbon source for cell growth and for inducing metabolic processes that remove free oxygen and encourages the bacteria to consume nitrate. EcoMat’s post-treatment system can be subdivided into two primary treatment parts: one part for oxidation and a second part forfiltration. The oxidation treatment is intended to oxidize residual nitrite back to nitrate, oxidize any residual methanol, and destroy bacterial matter exiting the BDN system. The oxidation treatment may consist of ozonation or ultraviolet (UV) treatment, or a combination of both. Filtration usually consists of a clarifying tank and one or more filters designed to remove suspended solids generated from the BDN process. The demonstration consisted of four separate sampling events interspersed over a 7!4 month period of time. During these events EcoMat operated its system to flow between three and eight gallons per minute. During this same time period nitrate levels in the well water varied from greaterthan 70 mg/I to approximately 30 mg/I. ForEvent 1, chlorination was the only post-treatment used. Post-treatment for Event 2 consisted of clarification; sand filtration; cartridge filtration using 20pm rough filters; and UV oxidation. Post-treatment for Event 3 consisted of ozone; UV oxidation; clarification; cartridge filtration using 20pm rough filters, 5pm high efficiency filters, carbon adsorption, and 1 pm polishing filters. Post-treatmentforEvent4 consisted of chlorination, clarification, 5pm high efficiency filtration, airstripping, and 1pm polishing filtration. The primary objective of the study focused on three performance estimates. The first performance estimate was to determine if the BDN portion of the process was capable of reducing combined nitrate-N/nitrite-N (total-N) to less than 10.5 mg/I. The second performance estimate included evaluation of the post-treatment for its ability to produce treated groundwater that would meet applicable drinking water standards with respect to nitrate-N, nitrite-N, and total-N, using a level of significance of 0.10. This required reducing high levels ofnitrate-N to less than 10.5 mg/I, maintaining nitrite-N levels to less than 1.5 mg/I, and achieving a total-N level of less than 10.5 mg/I. When rounded to whole numbers, these performance estimates would meet the regulatory maximum contaminant limits (MCLs) of 10, 1, and 10 mg/I for nitrate-N, nitrite-N, and total-N respectively. The IV