Electrolytic Reactor for N Removal from Existing Septic Tanks
Environmental Protection Agency
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Small Business Information
Enviro Utilities, Inc.
621 Mobrey Dr., Richmond, VA, 23236-
Socially and Economically Disadvantaged:
AbstractAccording to the US EPA 2002 Onsite Wastewater Treatment Systems Manual, approximately 26 million homes, businesses, and recreational facilities in the United States use onsite wastewater treatment and disposal systems (OWTD) (also called septic systems). Numerous studies have found correlations between OWTDs and elevated NO3 levels in drinking water. The U.S. EPA has reported that nitrates (NO3) were the contaminant that most frequently exceed federal drinking water standards among organic and inorganic contaminants in public water systems (USEPA, 2005).§Conventional septic tanks remove only 1-3% of total nitrogen (N) before effluent is released into the environment. Almost all current N removal technologies on the market rely on organic compound digestion as a precursor to N removal. The current technologies rely on long hydraulic retention times, hydraulic circulation, and the high amounts of aeration for any N removal through nitrification and denitrification. These pre-packaged systems generally entail a treatment train of multiple tanks coupled with recirculation pumps, aerators or large amounts of treatment media. There is a largepotential market for cost effective N removal system that the typical household could afford. Current technologies have been limited by high costs due to the required installation of new and multiple tanks. Several states are currently mandating the N removal technologies be utilized in new septicsystems in certain areas. §Enviro Utilities, Inc. (EU) a wastewater treatment system design company has collaborated with Ion Power, Inc., which specializes in ion selective membranes and electro-chemical technologies to design a unique device to remove N from within existing septic tanks. The device uses a combination of electrolytic chemistry, chemical species separation and biological transformations. §The Innovation: An Insertable Electrolytic Nitrogen Removal Device The innovation of the EU device is that it is small enough to be inserted into existing septic tanks and remove Nfrom wastewater without the need for organic compound digestion. Almost all current treatment technologies on the market rely on organic compound digestion as a precursor of N removal. Nitrogen removal in the EU system is conducted by isolating ammonium (NH4+) from the waste stream into a compactnitrifying through a cation selective membrane and electrode system. The N is ultimately converted to dinitrogen gas (N2) and released to the atmosphere. All of these processes will occur within the existing septic tank. §Project Objective 1: Test Device Configuration One key to the success of the device is that it is small enough to fit into an existing septic tank. For that purpose several configurations of the anode, membrane and cathode placement and size of the device will be evaluated. Several unknown design questions will be addressed in bench scale reactors. §ProjectObjective 2: Measure the N Removal Efficiency and the Microbial Environment Several configurations will be tested for its ability to isolate NH4+ and remove N from a synthetic domestic wastewater the N removal efficiency will be determined by direct measurements of the reactor influent and effluent NH4+ and NO3 concentrations. Denitrification efficiency will also be directly measured. The water chemistry within the device and its effects on the nitrosomonas nitrifying microbial population will be evaluated. Water chemistry parameters within the reactors to be evaluated include: alkalinity, carbon dioxide (CO2) content, and oxygen (O2) content. §Research Team Gregory T. Monnett, Ph.D. of Enviro Utilities, Inc. is the Principal Investigator (PI). Dr. Monnett has been involved with onsite wastewater treatment designs for over 20 years. He has extensive knowledge of nitrogen dynamics and the current technologies and their applications in the marketplace. Stephen Grot, Ph.D. of Ion Power, Inc. is a subcontractor on the project. Ion Power, Inc. is a major subcontractor on the project due to their expertise with membrane technology. Stephen Grot will contribute his 15years experience working with electro-chemistry and membrane technology. Charles Hagedorn, Ph.D., Professor at Virginia Tech University, is a microbiologist and will consult with the research team and assist in the analysis of conditions that affect nitrification and denitrification. Walther Grot, Ph.D., who is a retired Technology Fellow with DuPont, in which the majority of his career with in the development of ion-selective membranes. Dr. Walther Grot will assist in the development and testing of the device configuration also a consultant. §Commercial Application This technology would create a new class on onsite wastewater pretreatment units that benefit rural development. Current technology focuses on organic compound digestion prior to N removal through extended aeration or fixed film digestion. These existing technologies usually require the installation of new multiple tanks and pumps at major costs and disruptions for the typical homeowner. The EU system can upgrade existing conventional septic tanks with an N removal component. An affordable insert the may remove 70-80% or more of the N in conventional septic systems should gain the interest of environmentalhealth officials and environmentalists worldwide. Some states are now mandating N removal in certain septic systems creating a market demand. The high cost of existing technologies has limited the use of N removal systems in rural developments. This consequently has degraded drinking and surfacewater quality. The cost saving created by eliminating organic digestion would create affordability for the typical owner of a standard septic tank. Successful configurations of the EU system evaluated in Phase I can be developed into full scale prototypes for Phase II testing.
* information listed above is at the time of submission.