Study On Enhanced Biological Purification Of Tail Water And In-situ Ecological Restoration Of Black Odorous Water

At present,in addition to rainwater supply for many rivers in China,the tail water of urban sewage treatment plants is mainly used as the water source.However,its pollutant concentration limit is far higher than the surface water class IV standard,and it is prone to black odor after being discharged into the surface water,which causes different degrees of pollution to the environment.Therefore,it is necessary to strengthen the research on tail water ecological restoration technology in order to achieve deep denitrification of tail water under lower operating cost and higher treatment effect.In this study,bacteria with high ability to remove inorganic nitrogen were selected.Based on the study of the characteristics and mechanism of nitrogen removal in tail water and black odorous water by biofilm technology,a bacterial-algae symbiosis system was established to simulate the microenvironment of urban river channels.The urban tail water test system aims to build a river ecological floating bed tail water purification system,which uses high-efficiency denitrifying microorganisms and algae to deeply purify the tail water in the river to strengthen the removal of nitrogen in the tail water.Provide technical reference for landscaping river water environment restoration.The thesis research includes the following:?1?Screening and identification of denitrifying bacteria:The concentration of“trinitrogen”in the liquid-enriched culture medium at 24h and 48h of the strain was measured,and the results showed that the strains A3,A6,and A8 of the ammoniated bacteria were at NH₄⁺-N at 48h.High synthesis rate;the synthesis rates of strains X2,X3,X5 and NO₂^--N in nitrifying bacteria were 300.71%,221.59%,and 702.4%,respectively;the removal rates of NO₃^--N in the culture broth of strains F5 and F9 in denitrifying bacteria were respectively 90.01%and 90.02%.?2?Deep purification of tail water by aeration-enhanced biofilm and in-situ ecological restoration of black and odorous water bodies:With the increase of time,the degradation effect of nitrogen in the channel of the aeration group and biofilm group is not obvious,After aeration in the membrane group,the concentration of NH₄⁺-N and NO₃^--N in the river channel decreased significantly,and the removal rate of NO₃^--N reached 93.96%.Aeration can enhance the purification of nitrogen-containing tail water by biofilm ecological floating bed.?3?Analysis of purification characteristics of nitrogen-containing tail water and black odorous water under different biofilm length,HRT and coverage area conditions.Among them,the removal rate of NO₃^--N reached 62.7%,and the removal rate of TN reached81.96%in the suspended 1/2-depth biofilm river channel.The removal rate of the blank channel and the overall water depth hanging film channel was lower;When HRT is 6d,the removal effect of NH₄⁺-N and TN is better than that is 12d.When the floating bed coverage area is 20%,the removal rate of ammonia nitrogen,nitrate nitrogen and total nitrogen by the system reaches 87.62%,71.09%and 97.3%,respectively.The removal effect is significant.?4?Analysis of purification characteristics of nitrogen-containing tail water by the bacteria-algae symbiosis system.Under the operating conditions of air temperature of 25²6?,the removal rates of NH₄⁺-N in biofilm group and algae group were 57.5%and74.87%respectively,and the ammonia nitrogen removal rate in the symbiotic group was98.62%.The TN removal rates were 21.6%,13.8%,17.1%,and 31.2%,respectively.The bacteria-algae symbiosis system has a better removal effect on target pollutants in the tail water of urban sewage treatment plants.