Optimal design and engineering verification of microbial filters based on multi-model coupling simulation

ZHU Huajun; ZHU Jie; XIE Gang; ZHANG Qiqi; HE Zhendong; LI Donghao; LI Long; MIN Xingyue

doi:10.3969/j.issn.1004-7948.2025.12.024

Abstract：Aiming at the problems of aging and reduced activity of the returned sludge in the secondary sedimentation tank,a filter for enhancing the activity of the returned sludge is designed based on the optimization method of coupling computational fluid dynamics(CFD)and population equilibrium model(PBM).By simulating the sludge settling process under different structural parameters(the number of inlets,the angle of the cone bucket)and operating conditions(sludge concentration,retention time),determine the optimal structure and operating conditions,and then conduct a pilot test at the sewage treatment plant under the optimal working conditions in summer to systematically analyze and screen the basic parameters,biological activity,pollutant removal capacity and microbial community structure of the sludge.The results show that the 8 DN80 water inlets and the 45° cone bucket angle are the optimal structure,and the operation effect is the best in winter(4 500 mg/L,5 min)and summer(2 000 mg/L,120 min).Compared with imported sludge,the sludge volume index(SVI)of the underflow sludge separated by it decreased by 4.37%,the volatile suspended solids concentration/suspended solids concentration(MLVSS/MLSS)increased by 4.00%,and the aerobic rate(SOUR)is 10.09%higher.The removal rates of chemical oxygen demand(COD)and NH₄+-N increased by 3.99%and 13.62%,respectively.Microbial community analysis further revealed that during the screening process,key functional bacterial communities such as Nitrospirota,Nitrospira and Ellin6067 are significantly enriched,enhancing the nitrification capacity of the system.The effectiveness of the filter in enhancing the activity and treatment capacity of sludge is verified.