Study On Three-stage Treatment Of Campus Wastewater By Up-flow Anoxic-aerobic Series Activated Carbon Biofilter

With the rapid development of society,people are paying more and more attention to the treatment of sewage,and the discharge standards of sewage are becoming stricter,it is necessary to find a sewage treatment process with a small footprint,low operating cost,easy management and good treatment effect.At present,the upflow anoxic-aerobic tandem biological filter process is applied to the advanced treatment of sewage with its unique advantages.The process integrates filtration,adsorption,and biodegradation,and has the advantages of small footprint,high impact load,and good treatment effect.In this study,an up-flow hypoxic-aerobic tandem activated carbon biological filter was used for three-stage treatment of campus sewage.The effects of reflux ratio and carbon-nitrogen ratio on the removal efficiency of the system were mainly investigated.The changes of DO,p H and other indicators along the height of the filter material layer were discussed to provide theoretical guidance for the practical application of the process.The test results show that under the condition of hydraulic load of 0.75m~3/(m~2·h)(excluding reflux),the optimal reflux ratio suitable for the system is 100%,and the optimal carbon-nitrogen ratio is 3:1.Under these operating conditions,the removal rates of COD,ammonia nitrogen,total nitrogen,and total phosphorus by the system were 96.32%,98.38%,87.46%,and 36.17%,respectively.Studying the changes in the DO,p H and other indicators along the filter layer height found that the DO concentration in the hypoxic reaction column was below0.5mg/L,and it gradually decreased.In the aerobic reaction column,the DO concentration was Above 2mg/L,it shows a gradual increase trend;while the change rule of p H is just the opposite of DO.In addition,the system removes COD and total nitrogen mainly in the hypoxic reaction column,and the removal of ammonia nitrogen is mainly in the aerobic reaction column.Simultaneous nitrification and denitrification may occur in the aerobic reaction column.This test uses air-water combined backwashing.The washing strength is3-4L/(m~2·s),the gas washing strength is 8-10L/(m~2·s),and the backwashing time is10-15min.Efficiency,determine the backwash cycle of the hypoxic reaction column is 5d,and the backwash cycle of the aerobic reaction column is 7d;After backwashing,the system's removal effect of COD and ammonia nitrogen was significantly reduced,and normal levels were restored after 6-7 hours,and the effect of backwashing on nitrification performance was small.