2016 Fiscal Year Annual Research Report
膜通気バイオフィルムリアクターによる高濃度窒素排水の効率除去とＮ２Ｏ削減
| Project/Area Number |
16J08490
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| Research Institution | Tokyo University of Agriculture and Technology |
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Principal Investigator |
CO THIKINH 東京農工大学, 大学院工学府, 特別研究員(DC2)
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| Project Period (FY) |
2016-04-22 – 2018-03-31
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| Keywords | Nitric oxide / Microelectrode / Nitrous oxide / Membrane-aerated biofilm |
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| Outline of Annual Research Achievements |
We operated 2 laboratory-scale reactors representative for flat-sheet type MABR and conventional biofilm (or co-diffusion biofilm, CBR) in order to clarify the possibility of MABR in term of treating nitrogen concentrated wastewater and low N2O production. Specifically, we focus on 3 objectives: (i) whether a counter-diffusion biofilm geometry in an MABR allows lower N2O concentrations than a co-diffusion biofilm geometry, (ii) whether microbial community structure in the counter-diffusion biofilm is distinct or comparable within biofilm depth, and (iii) which spatial distribution of N2O reducers contributes to N2O reduction. Two laboratory-scale reactors with the same dimensions but distinct biofilm geometries namely membrane-aerated biofilm reactor (MABR) with counter-diffusion biofilm geometry and conventional biofilm reactor (CBR) with co-diffusion biofilm geometry, were operated to determine depth profiles of DO, N2O, microbial community structure and functional gene abundance. The results show that total nitrogen removal efficiency was higher in the MABR (71.9 ± 4.8%) than in the CBR (63.3 ± 5.6%) (p < 0.05). In stark contrast, the dissolved N2O concentration in the MABR was two orders of magnitude lower (0.011 ± 0.001 mg N2O-N/L) than that in the CBR (1.38 ± 0.25 mg N2O-N/L). The zones for N2O production and consumption were adjacent in the MABR biofilm. Analyses of the microbial community composition showed the presence of Thauera, Rhizobium, Stenotrophomonas, and Brevundimonas as potential N2O-reducing bacteria with higher abundances in the MABR.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
I have published 2 papers in high ranked journals
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| Strategy for Future Research Activity |
1. Development of 1-d mathematical model to compare MABR versus conventional biofilm system in terms of N removal performance and mitigation of N2O production
1-d mathematical model for MABR and conventional biofilm system will be developed in cooperation with an N2O production model. The model, incorporating several parameters including oxygen mass transfer coefficient, bacteria types, biofilm thickness, carbon per nitrogen ratio, etc. will be constructed with the simulation software AQUASIM to corroborate the process concept of the MABR and to reveal an operational range for high nitrogenous wastewater treatment with N2O emission minimized.
2. Elucidation of N2O production or consumption mechanisms in an MABR
15N tracer study will be conducted by spiking 15N nitrite to be able to infer N2O production pathway in an MABR. Our laboratory has a quadruple GC-MS retrofitted to be able to distinguish different molecular weights of N2O; hence, the predominant N2O pathway in biofilm of the MABR will be, for the first time, elucidated. Biofilm thickness, stratification of microbial community, chemical profiles, and effect of surface loadings of O2 and NH4+ on the reactor performances will be investigated to confirm validity of mathematical model to be described in next session.
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Research Products
(4 results)
