Grantee Research Project Results
Final Report: Electrolytic Reactor for N Removal from Existing Septic Tanks
EPA Contract Number: EPD13037Title: Electrolytic Reactor for N Removal from Existing Septic Tanks
Investigators: Monnett, Gregory T.
Small Business: Enviro Utilities Inc.
EPA Contact: Richards, April
Phase: I
Project Period: May 15, 2013 through November 14, 2013
Project Amount: $79,749
RFA: Small Business Innovation Research (SBIR) - Phase I (2013) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Water
Description:
Enviro Utilities (EU) has developed an innovative device that is small enough to be inserted into existing septic tanks and remove nitrogen (N) from wastewater without the need for organic compound digestion. Almost all current treatment technologies on the market rely on organic compound digestion as a precursor to N removal. N removal in the EU system is conducted by isolating ammonium (NH4+) from the waste stream into an electrolysis reactor through a cation selective membrane and electrode assembly (MEA). The N is ultimately converted to dinitrogen gas (N2) and released into the atmosphere.
Summary/Accomplishments (Outputs/Outcomes):
Configuration evaluations found that the anode material was critical to the device. Several anode materials were tested, including nickel wire, gold plated metal, stainless steel, graphite powder, graphite rods and graphite felt. The graphite felt was found to be the most durable in the high oxidation conditions of an electro-chemical cell. The felt material also demonstrated the best N removal rates. The cation selective membrane used in the MEA was proven to be durable and have a good chemical resistance. The most promising MEA configuration was used in subsequent tests to measure N removal rates. The electrical requirements of the system was low with sufficient ion transfer occurring at less than 1 watt.
Conclusions:
The Phase 1 results demonstrated proof of concept for the device. The membrane electrode assembly effectively removed and isolated NH4 from a synthetic wastewater in less than a few hours. The electrical requirements to transfer the ions was small and would equate to less than 1.7 cents per day for a typical household. The final materials used for the MEA were found to be durable in the harsh chemical environment. A design change in the device was demonstrated to remove N using ammonia electrolysis instead of relying on microbial population to transform the ammonium to N2 gas. Currently, the National Sanitation Federation (NSF) 245 testing deems 50 percent removal of N as a suitable N removal technology. Our preliminary results indicate that the innovative device could exceed that standard. The device could be an alternative to current technologies that rely on organic compound digestion and microbial populations for effective N treatment.
Supplemental Keywords:
nitrogen, water quality, wastewater, septic tank, electrodeThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.