Abstract:In order to solve the problem of sludge bulking caused by the excess sludge alkaline fermentation liquid as the external carbon source of domestic sewage with low carbon nitrogen ratio, a sequencing batch reactor (SBR) was used to systematically study the correlation between the settling performance and the influencing factors of the viscous bulking sludge when the excess sludge alkaline fermentation liquid was taken as influent carbon source. The results show that when the influent COD was 300~350 mg·L?1, the SVI of sludge increased gradually with the running time, and finally reached 540 mL·g?1, and viscous bulking for the sludge occurred. The negative charge on the surface of viscous bulking sludge increased from 0.62 mV to 29.49 mV, the relative hydrophobicity(RH) decreased from 44% to 19%, and SVI was negatively correlated with Zeta potential or RH, and their R2 values were 0.837 71 and 0.678 54, respectively. SVI was not correlated with sludge size. The total amount of extracellular polymer increased from 31 mg·g?1 to 39 mg·g?1, but the ratio of LB-EPS to TB-EPS increased from 0.92 to 2.92. Compared with TB-EPS, LB-EPS was more strongly correlated with SVI, Zeta potential and RH with their own R2 values of 0.892 88, 0.885 29 and 0.776 68. The above results revealed the variation of viscous bulking sludge characteristics caused by taking fermentation liquid as external carbon source, which can provide reference for solving this problem in practical engineering. Key words:viscous bulking/ settlement performance/ surface properties/ extracellular polymeric substances.
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School of Environment and Energy Engineering, Beijing University of Technology, Beijing 100124, China Received Date: 2020-01-14 Accepted Date: 2020-03-19 Available Online: 2020-11-11 Keywords:viscous bulking/ settlement performance/ surface properties/ extracellular polymeric substances Abstract:In order to solve the problem of sludge bulking caused by the excess sludge alkaline fermentation liquid as the external carbon source of domestic sewage with low carbon nitrogen ratio, a sequencing batch reactor (SBR) was used to systematically study the correlation between the settling performance and the influencing factors of the viscous bulking sludge when the excess sludge alkaline fermentation liquid was taken as influent carbon source. The results show that when the influent COD was 300~350 mg·L?1, the SVI of sludge increased gradually with the running time, and finally reached 540 mL·g?1, and viscous bulking for the sludge occurred. The negative charge on the surface of viscous bulking sludge increased from 0.62 mV to 29.49 mV, the relative hydrophobicity(RH) decreased from 44% to 19%, and SVI was negatively correlated with Zeta potential or RH, and their R2 values were 0.837 71 and 0.678 54, respectively. SVI was not correlated with sludge size. The total amount of extracellular polymer increased from 31 mg·g?1 to 39 mg·g?1, but the ratio of LB-EPS to TB-EPS increased from 0.92 to 2.92. Compared with TB-EPS, LB-EPS was more strongly correlated with SVI, Zeta potential and RH with their own R2 values of 0.892 88, 0.885 29 and 0.776 68. The above results revealed the variation of viscous bulking sludge characteristics caused by taking fermentation liquid as external carbon source, which can provide reference for solving this problem in practical engineering.