Studies On The Performance Of Membrane Bioreactor For Wastewater Treatment

Membrane bioreactor (MBR) technology is a promising method for water and wastewater treatment because of its ability to produce high-quality effluent that meets water quality regulations. A surmerged membrane bioreactor system(SMBR) was established to deal with synthetic wastewater. The purpose of this study was to investigate the operation efficiency and membrane fouling factors. Meantime, kinetics models of microorganism multiplication and organic pollutants removal were established based on mass balance in a membrane bioreactor.The purpose of this study is to offer theory basis and design basis of SMBR engineer application.The main contents of the dissertation are as follows:1. The experimental results show that the optimal HRT is 3.5 h, the optimal volume loading is 3.4-4.0 kgCOD/m3·day, COD average removal rate is 95.1%; During the continuous operation, the turbidity removal rate is 98.6%, the average sludge loading is 0.54 kgCOD/kgMLSS·day.2. Based on the operation, the membrane fouling is studied. the solid content of sludge, temperature and viscosity is the main factor influencing the membrane fouling. The optimal the solid content of sludge region is obtained via analyzing the relationship between TMP, the solid content of sludge and sludge loading; Higher temperature can release the membrane fouling through quantitative analysis of k; The Newtonian model, Ostwald model and Bingham model are studied separately. It is indicated that Ostwald de Vaele was the most suitable model to measure the flow properties of sludge in the SMBR. The apparent viscosity decreased logarithmically with an increase in the rotary velocity and increased exponentially with an increase in the the solid content of sludge.3. Based on the mass balance in the SMBR, kinetics models of microorganism multiplication and organic pollutants removal were established. The relationship between Y and kd is obtained according to the experimental results; Kinetic constants ofνmax and Ks were solved in this study; The the solid content of sludge in SMBR can be predicted and the synthetic wastewater was chosen and examined to verify the model and the results showed that the experimental data were coincident with the calculating data. Based on the continuous running of the experiment for a long time, the paper analyses the operating parameters and influencing factors of membrane fouling, determines the optimal scheme and simulates the process of substrate degradation. The dissertation establishes the basis for theoretical analysis and practical application of SMBR.