Nitrogen containing compounds, like ammonia (NH3), are serious water pollutants - but removing them from wastewater is very a costly process. Each step of traditional removal methods, nitrification/oxidation and denitrification/reduction, requires many resources in the form of energy, aerated oxygen, and an electron source (typically methanol), increasing the cost of operation. The present invention achieves partial denitrification by simply controlling the level of dissolved oxygen. By keeping a low level of dissolved oxygen in the bio-reactor it is found that the rate of ammonia oxidation (nitrite production) is much higher than that of nitrite oxidation (nitrate production).
Avoid producing nitrates and proceed directly from nitrite to nitrogen gas.
Nitrite production and nitrate production are performed by two different kinds of microbes: ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB). Using this technology in a waste removal system, the population of AOB far exceeds than that of NOB in the system. This results in the nitrification process essentially stopping at nitrite without proceeding to nitrate. By avoiding the production of nitrates the reaction can proceed directly from nitrite to nitrogen gas, saving a significant amount of resources and energy. This partial nitrification method can dramatically improve the efficiency of nitrogen removal from waste and result in significant savings.
Lead Inventor:
Kartik Chandran, Ph.D.
Applications:
- Efficient nitrogen removal from municipal wastewater and sewage.
- Removal of nitrogen from animal wastes, land fill leachate, and farm fertilizer waste.
- Optimizing performances of conventional bioreactors
- Since it is an oxidation/reduction process, one potential application can be power generation, similar to a microbial fuel cell. This can potentially make the process self-sustaining.
Advantages:
- Optimized reactor parameters could result in 25% savings in aeration costs by achieving partial nitrification solely to nitrite.
- Subsequently, a 40% savings in electron donor costs can be achieved by direct denitrification of nitrite rather than nitrate to nitrogen.
- Allows industry to comply with stringent total N-effluent concentration limits in a cost effective and sustainable fashion.
Patent information:
Patent Issued
Licensing Status:
Available for licensing and sponsored research support
Tech Ventures Reference: IR M08-022
Related Publications:
- Ahn JH, Yu R, Chandran K. Distinctive microbial ecology and biokinetics of autotrophic ammonia and nitrite oxidation in a partial nitrification bioreactor. Biotechnol Bioeng, Vol. 100, Issue 6, Aug. 2008, pp. 1078-87.
- 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. Vol. 45, Issue 7 Apr 2011, pp. 2734-40.
Patent No. 8,586,337