A Novel Membrane Process For Autotrophic Denitrification

摘要

Nitrate is one of the most frequently occurring pollutants in groundwater. Heterotrophic denitrification processing is used to remove nitrogen in the wastewater industry in the U.S. and in both wastewater and drinking water processing in Europe. To facilitate heterotrophic denitrification, organic compounds such as methanol, ethanol and acetic acid are added to provide a carbon source for the bacteria. The addition of these carbon compounds is expensive and results in added sludge production. The resulting organic residual may react with chlorine to produce disinfection byproducts. This study focuses on the use of autotrophic hydrogen oxidizing bacteria for denitrification of nitrate-contaminated water. Autotrophic denitrification was investigated using bubble diffusers to deliver hydrogen and carbon dioxide to suspended growth batch reactors. Hydrogen oxidizing bacteria were maintained under anoxic conditions. The pH of the reactors was maintained between 6.8 and 9. The nitrate depletion data were fitted using the Monod equation. The results compare well with the data reported by previous investigators. Studies are currently in progress using hollow fiber micro porous membranes to supply hydrogen and CO2 to denitrification reactors. Results of these studies will be used for the preliminary design of flow through systems. The performance of the flow through system will be evaluated by measuring the nitrate and dissolved hydrogen concentrations in the effluent and the nitrate loading to the reactors.