Application Of A/O+MBR Process In Domestic Sewage Treatment Station Of Alumina Refinery

ShanXi HuaXing Aluminum Refinery is a large-scale alumina production enterprises,including alumina plant,power plant,gas station,and supporting the dormitory,canteens,bathrooms and other living facilities.The Refinery is located in XingXian of ShanXi Province,North by Lan Yi River.The direct discharge of domestic sewage of the factory would seriously polluted the living environment of the town,and affect the water quality of Lan Yi River.Therefore,Huaxing Aluminum Refinery plans to build a domestic sewage treatment station,the reuse of the domestic sewage water would avoid the pollution of the environment,and reduce the amount of new water to improve water use rate.In order to make the sewage treatment station to meet the requirements of water reuse,the selection of sewage treatment process,the analysis of treatment facilities design and calculation is essential.Aim at the domestic sewage treatment station of SHANXI HUAXING aluminum refinery,this study analyze the water quality and quantity of the sewage treatment plant,the process plan selection and the operating parameters.According to the plant size and the number of employees,through the study of highest daily water consumption and hourly variation coefficient,the design capacity is determined for 300m3/d.Through analyzing the influent water quality of the sewage treatment plant from city and alumina plant,the influent water quality of SHANXI HUAXING sewage treatment station was determined as:SS<250mg/L,BOD5≤200mg/L,CODcr≤350mg/L,NH3-N≤40mg/L,TP<4mg/L。According to the requirements of the reused water,the effluent quality of the project shall be determined as:Turbidity≤1NTU,CODcr≤25mg/L,NH3-N≤5mg/L,TP<0.5mg/L。Based on the situation of SHANXI HUAXING domestic sewage treatment plant and the requirements of water quality,through the process analysis and comparison,this study selected the combination of Anoxic/Oxic and MBR(A/O+MBR)as the key process.The design parameters,equipment selection and structure dimensions of each processing unit were determined,and the design of construction drawing was completed.After the system is running,the removal efficiency of CODcr,NH3-N,TP,Turbidity is analyzed.Through the analysis of the project investment and operation cost,the main factors which influencd the investment and operation cost of MBR process was found.Membrane bioreactor has been widely used in the field of sewage treatment and reuse system because of its excellent water quality,small capacity and reliable operation.However,there are some disadvantages of the MBR,such as the low removal rate.of NH3-N and TP.The combination of A/O and MBR can combine the advantages of both process,which resulted in the high removal rate of CODcr,NH3-N and TP,and the water quality could be meet the design requirements.The A/O+MBR process is used in the domestic sewage treatment station of the alumina refinery,and the effluent quality is excellent,which provides a reference for the application of the advanced wastewater treatment technology in the alumina refinery.