| Membrane bioreactor (MBR) is a wastewater treatment system, which combines membrane separation technology and biological treatment technology. However, the system has several disadvantages, such as membrane fouling, and poor nitrogen removal. A study on nitrogen removal for membrane bioreactor using the Short-Cut Nitrification and Denitrification is presented in this dissertation. The results obtained show a desirable quality effluent with effective removal of nitrogen. A study of combining aerobic granular sludge with MBR is also carried out in this dissertation with the aim to remove nitrogen and reduce member fouling.The dissertation is divided into two sections.In the first section, nitrogen removal was studied with a membrane reactor in the treatment of simulated domestic wastewater at moderate temperatures (25-30℃). The short-cut nitrification and denitrification technique was used to effectively remove nitrogen. The results showed that the COD of effluent was steadily below 100 mg/L (49 mg/L on the average), and the NH4+ - N of effluent was less than 5.0mg/L (3.1 mg/L on the average), when the aeration flow rate was 0.15 m3/h and pH was 7-8. With the stabilization of the system, the accumulation of NO2- was achieved, and NO3- wasn't detected in the effluent. The average removal efficiency of total nitrogen could reach 86.2% (94.0% as the maximum). It was also revealed that the process was capable of overcoming shock loadings of the influents. In addition, the aeration flow rate and pH were the significant influencing factors on the short-cut nitrification.In the second section, the aerobic granular sludge with high activity was cultivated from the anaerobic granular sludge, and used for nitrogen removal in Sequencing Batch Reactor (SBR) fed with simulated domestic wastewater. It was shown that the removal efficiency of COD was 91.8%, and total nitrogen could reach 81.0% at the condition of aeration flow rate of 0.20 m3/h. In other words, through controlling the operation conditions, the aim of enhancing nitrogen removal could be achieved by using the aerobic granular sludge.On the other hand, it was found that extracellular polymeric substances (EPS) were developed with the activation of sludge and deteriorated the qualities of the effluent. Therefore, the effect of operation conditions on composition and content of EPS was studied. Results showed that NS, C/N, DO, pH and temperature were the factors, which affected the formation of EPS. When the reaction conditions were NS of 2.0 kg COD/(kg MLSS·d), C/N of 60, DO of 2-3 mg/L, pH of 7-8, temperature of 20-25℃, less EPS was formed, and it was in favor of keeping the activation of aerobic granular sludge.
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