Advanced Water Management Centre

AWMC Seminar Program: Tao Liu

Developing denitrifying anaerobic methane oxidation (DAMO)-based technologies for nitrogen and dissolved methane removal from wastewater.

Abstract: Nitrogen removal is one of the most concerned issues for wastewater treatment plants (WWTPs). Conventional biological nitrogen removal processes based on nitrification and denitrification (N/DN) are suffering several major drawbacks, including substantial aeration consumption, unwanted greenhouse gas emissions, requirement for external carbon sources, excessive sludge production and low energy recovering efficiency, thus unable to satisfy the escalating public needs. Recently, the discovery of anaerobic ammonium oxidation (anammox) bacteria has promoted the updating nitrogen removal processes from conventional N/DN-based technologies to anammox-based technologies. There are over 110 full-scale WWTPs succeeding in treating sidestream wastewater through employing anammox process worldwide, whereas the application of mainstream anammox has been hindered mainly due to the relatively low temperature and nitrogen concentrations. In addition, the emission of dissolved methane from anaerobic treatment (accounting for ~45% of total methane production) and unsatisfactory effluent quality (> 200 and 15 mg TN L-1 for sidestream and mainstream respectively) are two major problems remaining to be clarified, for both mainstream and sidestream anammox.

Denitrifying anaerobic methane oxidation (DAMO) processes, in which methane is oxidized anaerobically to provide electrons for denitrification, were discovered in the last decade. Interestingly, the in-depth understanding about the unique properties (e.g., mechanisms, diversity, distribution and influencing factors) of these novel microorganisms has not only promoted our comprehension about the global nitrogen and methane cycles, but also provided promising opportunities to enhance the nitrogen removal and mitigate dissolved methane emission from wastewater concurrently.

In this study, we aim to develop and demonstrate three novel DAMO-based technologies to achieve high-level nitrogen and dissolved methane removals from wastewater. The first technology is to achieve complete nitrogen removal from sidestream with high nitrogen loading and from mainstream at low temperature in two-stage membrane biofilm reactors (MBfRs), in which biogas and purified methane will be fed through gas permeable hollow fibre membranes as the sole organic carbon respectively. The second technology is to develop one-stage methane-based MBfRs, where aerobic ammonium oxidizing bacteria (AOB), anammox bacteria and DAMO microorganisms will be simultaneously enriched on the surface of hollow fibre membrane. The third technology is to achieve simultaneously nitrogen and dissolved methane removals from sidestream and mainstream in one-stage oxygen-based MBfR, where oxygen will be effectively delivered through gas permeable hollow fibre membranes to avoid dissolved methane stripping. Six MBfR reactors will be set-up for achieving the above aims. Both long-term performance monitoring and a series of batch tests will be carried out to confirm the interactions among various microorganisms.  Fluorescence in situ hybridization (FISH) and high-throughput 16S rRNA gene sequencing will also be carried out to characterize the microbial evolution and the functional microbial communities. Meanwhile, simulations and optimizations of the established DAMO-based systems will be conducted through applying mathematical modelling, which could provide guidelines for practical applications. This study will provide strong support to the on-going paradigm shift in wastewater management from energy negative to energy positive services, potentially leading to a revolutionary change in the water industry.

Event Details
Date & Time: 
Friday, 05 May 2017
9am - 10am
Venue: AIBN Building 75, Level 1 Seminar Room

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