A biological reactor for controlled nitrate-to-nitrite conversion and efficiently processing wastewater

This technology is a method for selective conversion of nitrate to nitrite during denitrification of wastewater.

Unmet Need: Efficient process for denitrification of wastewater

Current methods for biological nutrient removal during wastewater treatment consist of nitrification followed by denitrification involving an aerated process that is costly and inefficient. A potentially more cost-effective approach involves converting nitrate to nitrite prior nitrite conversion to nitrogen gas by combining denitrifying and anaerobic ammonium oxidation (anammox) bacteria in one bioreactor. However, this approach relies on toxic sulphides, is difficult to control, and is inefficient in continuously operated systems where anammox bacteria is outcompeted. Therefore, currently no methods exist to adequately control denitratation as a method to remove nitrogen from sewage.

The Technology: Cost-effective, controlled approach for denitrification using a biological reactor

This technology provides a method for incomplete denitrification using an individual bioreactor with bacteria. The denitrification reaction is controlled in a biological reactor that includes denitrifying bacteria with conditions that favor denitratation of nitrate to nitrite. The nitrite effluent from the incomplete denitrification process can then be fed to an anammox reactor to efficiently and cost-effectively reduce nitrite to harmless nitrogen gas. As a result, this process is more environmentally friendly and allows for better control of individual steps in the overall process. Furthermore, the sequential use of the bioreactors adds operational flexibility and allows detailed optimization to maximize nitrogen removal and to reduce aeration requirements, making this an improved method for treating wastewater.

This technology has been validated with denitrifying bacteria and glycerol as the carbon and electron source.

Applications:

• Treatment of industrial wastewater
• Treatment of contaminated groundwater
• Surface water denitrification
• Organic solid waste treatment

Advantages:

• Reduces aeration requirements
• Reduces costs
• Maximizes nitrogen removal
• Increases health and environmental safety
• Provides operational flexibility
• Increases efficiency
• Adds selectivity and new layers of control
• Enables anammox bacteria activity without competition with denitrifying bacteria

Lead Inventor:

Kartik Chandran, Ph.D.

Patent Information:

Patent Issued

Related Publications:

• Brotto AC, Li H, Dumit M, Gabarró J, Colprim J, Murthy S, Chandran K.“Characterization and mitigation of nitrous oxide (N2O) emissions from partial and full-nitrification BNR processes based on post-anoxic aeration control” Biotechnol Bioeng. 2015 Nov;112(11):2241-7.

• Regmi P, Miller MW, Holgate B, Bunce R, Park H, Chandran K, Wett B, Murthy S, Bott CB. “Control of aeration, aerobic SRT and COD input for mainstream nitritation/denitritation.” Water research 2014 Jun 15;57:162-171.

• Ahn JH, Kwan T, Chandran K. “Comparison of partial and full nitrification processes applied for treating high-strength nitrogen wastewaters: microbial ecology through nitrous oxide production.” Environ Sci Technol 2011 Apr 1;45(7):2734-40.

• Ahn JH, Yu R, Chandran K. “Distinctive Microbial Ecology and Biokinetics of Autotrophic Ammonia and Nitrite Oxidation in a Partial Nitrification Bioreactor” Biotechnol Bioeng. 2008 Aug 15;100(6):1078-87.

Tech Ventures Reference:

• IR CU16314

• Licensing Contact: Satish Rao