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| DOI：10.13522/j.cnki.ggps.2025208 |
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| Performance of membrane aerated biofilm reactor (MABR) for treating rural domestic wastewater with low C/N ratio |
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LI Xiaolin, LI Xiaoliang, RU Qiujin, LUO Yanyu, QI Mingxing, WANG Yifan
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1. College of Water Resources Engineering, Shaanxi A&F Technology University, Yangling 710048, China;
2. School of Water Resources Hydro-electric Engineering, State Key Laboratory of Water Engineering Ecology and
Environment in Arid Area, Xi’an University of Technology, Xi’an 710048, China;
3. Power China Northwest Engineering Corporation Limited, Xi’an 710065, China
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| Abstract: |
| 【Objective】Rural domestic wastewater is typically characterized by low carbon-nitrogen (C/N) ratio, which limits denitrification efficiency in conventional biological treatment processes. This paper evaluates the performance of a membrane-aerated biofilm reactor (MABR) for treating rural domestic wastewater with low C/N ratio.【Method】An integrated MABR system was constructed by combining flexible flat-sheet oxygen-permeable membranes with activated sludge to treat artificial rural domestic wastewater with varying C/N ratios (expressed as ratios of chemical oxygen demand, COD, to total nitrogen, TN) to investigate their influence on treatment efficiency and nitrification and denitrification (SND). During the experiment, we measured the changes in dissolved oxygen concentration (DOC) and pH variations across the biofilm. The effect of C/N ratios was evaluated using indicators COD, total nitrogen (TN), ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3--N), nitrite nitrogen (NO2--N), total phosphorus (TP), mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS), and SND.【Result】Increasing the COD/TN ratio in the influent led to gradual improvements in the removal efficiencies of COD, TN and TP. When the COD/TN ratio in the influent was 3, the removal efficiencies of TN and TP were 72.01% ± 0.33% and 50.29% ± 0.17%, respectively, with an SND occurrence rate of 83.16% ± 0.25%. Under this COD/TN ratio, the biofilm reached its maximum thickness of 425 μm. In contrast, when the COD/TN ratio was 2, the removal efficiency of COD was 92.77% ± 0.17%. We found distinct differences in DO and pH gradients across the biofilm under different COD/TN ratios, which facilitated functional stratification and enhanced SND performance in the MABR system.【Conclusion】The MABR system is effective for treating rural domestic wastewater with low C/N ratios. The COD, TN and TP concentrations in the effluent meet the requirements of the DB61 standards. Its high nitrogen removal efficiency and suitability for low C/N ratio influent underscore its potential for scale-up and practical application in rural wastewater treatment systems. |
| Key words: low carbon-to-nitrogen ratio; rural domestic wastewater; membrane aerated biofilm reactor (mabr); simultaneous nitrification and denitrification (SND) |
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