WUYu-liang,HOUMing-xiu,CHENYu-liang,et al.Treatment Efficiency for Domestic Sewage with Low Carbon to Nitrogen Ratio Using Micro-expanded Activated Sludge Process[J].China Water & Wastewater,2025,41(9):73-80.
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Treatment Efficiency for Domestic Sewage with Low Carbon to Nitrogen Ratio Using Micro-expanded Activated Sludge Process

China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU] volume: 第41卷 Number: 第9期 Page: 73-80 Column: Date of publication: 2025-05-01
Author(s):
WU　Yu-liang1;  HOU　Ming-xiu2;  CHEN　Yu-liang1;  BA　Li-bo1;  LIU　Yi-jiang1;  ZHAO　Fang-bo3;  YI　Xue-song1
（1. School of Environmental Science and Engineering， Hainan University， Hainan 570228， China； 2. School of Environmental Science and Engineering， Shanghai Jiao Tong University， Shanghai 200240， China； 3. College of Materials Science and Chemical Engineering， Harbin Engineering University， Harbin 150001， China）
Keywords:
micro-expanded activated sludge;  sewage with low carbon to nitrogen ratio;  sequencing batch reactor;  filamentous bacteria
Abstract:
A sequencing batch reactor (SBR) was employed to implement the micro?expanded activated sludge process for the treatment of domestic sewage with low carbon to nitrogen ratio (C/N). The impact of reduced C/N ratios on the characteristics of micro-expanded activated sludge, pollutants removal efficiency, and microbial community composition was investigated. The C/N ratios of the sewage were established at 6, 3 and 1. The average SV and SVI values of the sludge reached their peak when the C/N ratio was 3, with respective values of 47% and 255 mL/g. Reducing the C/N ratio had a minimal impact on COD removal efficiency. The average COD removal efficiencies at the three different C/N ratios were 94.6%, 89.1%, and 86.5%, respectively. The reduction in C/N ratio did not influence NH4+-N removal efficiency, which consistently achieved a removal efficiency exceeding 99%. As the C/N ratio decreased, the TN removal efficiency dropped from 65% to 45%, and the TP removal efficiency declined from 50% to 34%. Significant variations were observed in the composition of microbial communities under different C/N ratios. Notably, the relative abundance of Thiothrix (Thiobacillus) peaked at 32% when the C/N ratio was 3. In a single operational cycle （8 hours）, the removal efficiencies of pollutants such as COD, NH4+-N, TN, and TP could achieve an optimal level within approximately 4 hours. Prolonging the cyclic time beyond this point had minimal impact on further improving the removal efficiency.
Last Update: 2025-05-01