Study On Application Of Nitrogen And Phosphorus Removal Process Combined With Membrane Bioreactor In Municipal Wastewater Treatment

Membrane bioreactor (MBR) is becoming a more and more promisingtechnology in the field of wastewater treatment in lights of its stable and high qualityeffluent in China. With more strict regulations on nitrogen and phosphorus removalfor wastewater treatment, the development of MBR technology for nitrogen andphosphorus removal attracted more attention. The current research focused on3MBRprojects for nitrogen and phosphorus removal (NAPR-MBR) located at3municipalwastewater treatment plants in Wuxi, Jiangsu province. The objective of this study isto monitor and optimize the NAPR-MBR plants in terms of the pollutant removalefficiency, the kinetic parameters as well as the stability of the system. The mainconclusions are obtained as followed:3NAPR-MBR plants all achieved high removal efficiencies of pollutants; theconcentrations of COD, TN, NH4+-N and TP in the effluent were far lower than thegrade A standards regulated in GB18918-2002of China. The removal rates of COD,NH4+-N and TP basically over90%and, TN around75%-85%, respectively.The kinetic parameters of the activated sludge in aerobic tank were obtained for3NAPR-MBR plants. KdH(Heterotrophic decay rate) ranged from0.14to0.25d-1,while KdA(Autotrophic decay rate) were0.20-0.48d-1. YH(Yield coefficient forheterotrophic biomass) was0.52-0.55gVSS/gCOD, and YA(Yield coefficient forautotrophic biomass) was0.22-0.29gVSS/gCOD. vmS(Maximum removal rate forCOD) was1.27-1.78gCOD/(gVSS·d), and Ks(Half saturation coefficient for COD)was24.27-41.27mgCOD/L. vmN(Maximum removal rate for ammonia) was0.11-0.15gN/(gVSS·d), while KN(Half saturation coefficient for ammonia) was2.35-2.63mgN/L.The kinetic parameters would provide basic information and scientificfoundation for MBR’s engineering design and theoretical investigation in the future.Meanwhile, the stability of the3NAPR-MBR systems was also investigated.The energy consumptions were0.51-0.68kWh per cubic wastewater treated. Theblowers in the aerobic and membrane tanks were the major high-energy-consumingequipments. It is a key issue to reduce the energy consumption in the practicalapplication of the MBR in the future.It was found that, compared with the CAS process, the MBR process whichoptimized and designed under the current level of technology got higher removal efficiencies of pollutants. The economic performance of MBR is expected to improveon the further study of energy saving in the future.