The Effect Of Phosphorus Nutrition Lack On The Treatment Efficiency Of Activated Sludge Process

Phosphorus plays a very important role in sewage treatment system.The appropriate phosphorus content ensures the stable operation and treatment effect of the system.When the phosphorus content in sewage is too low,it will affect the metabolism of microorganisms,easily cause sludge bulking,and even cause the collapse of the whole system.However,the lack of nitrogen and phosphorus nutrient sources often manifests in the special industrial wastewater.Therefore,the research in this direction is of great significance to the biological treatment of wastewater.The effects of phosphorus deficiency on treatment efficiency and the changes of activated sludge system in aerobic and anoxic-aerobic operation were investigated.The differences of species diversity between the two operation modes were analyzed by high-throughput sequencing.The following results were obtained:The treatment efficiency of COD and NH4+-N is greatly affected by different C/P ratios in aerobic operation mode.The C/P ratio increased from 950:1 to 3100:1,the average removal rate of COD decreased from 89.88%to 78.56%,and the average removal rate of NH4+-N decreased from 87.64%to 71.49%.Different levels of phosphorus deficiency had little effect on the sedimentation of activated sludge,and EPS had higher polysaccharide content and lower protein content.Under the condition of lack of phosphorus source,the treatment effect of activated sludge under two operation modes is still better,and the treatment effect of COD and NH4+-N under anoxic-aerobic operation is better than that under aerobic operation.Under the condition of C/P ratio of 3100:1,the NH4+-N concentration of the two operation modes decreased in one operation cycle,and the degradation rate of NH4+-N was faster in the first three hours.The concentration of NO2--N in aerobic operation remained at a low level and decreased slowly during a period of operation.The concentration of NO2--N in anoxic-aerobic operation increased in the anoxic stage and decreased in the aerobic stage.For the change of NO3--N,the concentration of NO3--N in aerobic operation is increasing continuously,while the concentration of NO3--N in anoxic-aerobic operation decreases in anoxic stage and increases in aerobic stage.The dominant strains of activated sludge with different operation modes and different C/P ratios are different.Proteobacteria is the dominant strain under different C/P ratios of anoxic-aerobic operation and aerobic operation,and its abundance is about 50%.The dominant bacteria in anoxic-aerobic operation were Aridibacter and Aquicella at C/P ratios of 950:1 and 3100:1,respectively.The dominant strains of Parcubacteria_genera_incertae_sedis and Aquabacterium in aerobic operation were 950:1 and 3100:1 respectively,and the dominant strains changed greatly.