Dissolved methane-supported denitrification to enable mainstream bioenergy recovery from wastewaster

Overview

Wastewater management is undergoing a strong paradigm shift from pollutant removal to resource recovery. One of the most promising configurations for bioenergy recovery from wastewater is the upfront conversion of organic carbon in wastewater to biogas, using anaerobic processes, followed by autotrophic nitrogen removal.
This configuration boasts a high energy yield, and is therefore of considerable interest to the water industry including our partners. However, it has two well-known technology barriers, which prevent widespread adoption:

1. Up to 50% of methane produced remains dissolved in the effluent discharged from the anaerobic treatment reactor. Stripping of methane to the atmosphere in the subsequent aerobic treatment process causes not only a substantial loss of bioenergy but also a sharp increase of the carbon footprint of the treatment process.
2. The autotrophic nitrogen removal process has limited efficiency, often below 70% removal, as will be further discussed, and the effluent generally does not meet stringent nitrogen discharge standards in areas with sensitive receiving waters.

In this project, we aim to develop an innovative solution to simultaneously remove both of these technology barriers. The solution involves the use of dissolved methane to support denitrification, thus simultaneously enhancing nitrogen removal, avoiding methane emission and achieving beneficial use of dissolved methane.
(LP180100772)

Project Outcomes

1. Develop a novel membrane biofilm reactor, which achieves simultaneous aerobic ammonium oxidation, Anammox and methane-supported denitrification in a single biofilm, thus achieving high-level nitrogen removal from anaerobic treatment effluent without methane stripping;
2. Gain a fundamental understanding of the in-biofilm processes, the microbial community involved and their interactions, and to develop effective strategies to manipulate this community and achieve the appropriate stratification in the biofilm;
3. Demonstrate and optimise the technology at pilot-scale, to enable the technology uptake by the partners and the wider water industry following the completion of the project.

Publications

• Liu, T., Lu, Y., Zheng, M., Hu, S., Yuan, Z. and Guo, J. (2021) Efficient nitrogen removal from mainstream wastewater through coupling Partial Nitritation, Anammox and Methane-dependent nitrite/nitrate reduction (PNAM). Water Research 206, 117723.
• Lim, Z.K., Liu, T., Zheng, M., Yuan, Z., Guo, J. and Hu, S. (2021) Versatility of nitrite/nitrate-dependent anaerobic methane oxidation (n-DAMO): First demonstration with real wastewater. Water Research 194, 116912.
• Liu, C., Liu, T., Zheng, X., Meng, J., Chen, H., Yuan, Z., Hu, S. and Guo, J. (2021) Rapid formation of granules coupling n-DAMO and anammox microorganisms to remove nitrogen. Water Research, 116963.
• Liu, T., Li, J., Khai Lim, Z., Chen, H., Hu, S., Yuan, Z. and Guo, J. (2020) Simultaneous Removal of Dissolved Methane and Nitrogen from Synthetic Mainstream Anaerobic Effluent. Environmental Science & Technology 54(12), 7629-7638.
• Liu, T., Khai Lim, Z., Chen, H., Hu, S., Yuan, Z. and Guo, J. (2020) Temperature-Tolerated Mainstream Nitrogen Removal by Anammox and Nitrite/Nitrate-Dependent Anaerobic Methane Oxidation in a Membrane Biofilm Reactor. Environmental Science & Technology 54(5), 3012-3021.
• Liu, T., Lim, Z.K., Chen, H., Wang, Z., Hu, S., Yuan, Z. and Guo, J. (2020) Biogas-driven complete nitrogen removal from wastewater generated in side-stream partial nitritation. Science Of The Total Environment, 141153.