Effects Of Fulvic Acid And Humic Acid On Denitrification Performance And Sludge Microbial Community Structure Of Canon Process

At present,the common landfill leachate treatment process in China is a combination process of biological denitrification,reverse osmosis membrane and advanced oxidation advanced treatment.There are many problems in landfill leachate biological denitrification,such as high energy consumption,high aerobic,high load and so on.However,the traditional nitrification and denitrification process needs to face the problem of adding carbon source.If we can use CANON(complete autotrophic nitrogen removal over nitrite)process to treat landfill leachate,we can solve the problem that a large number of carbon sources need to be added,and CANON process can adapt to high ammonia nitrogen compound water body,and the combination of aerobic and anaerobic can reduce the consumption of oxygen.There are a lot of organics in leachate,including degradable organics and refractory organics.Among them,the main component of refractory organic matter is humus,which accounts for a very high proportion of the total organic matter of leachate,making the treatment of leachate more difficult.The influence of humus on CANON process has not been studied.This paper focuses on the effects of fulvic acid and humic acid on denitrification performance,sludge properties and microbial community of CANON process,and studies how to start CANON reaction in a short time.It also provides experimental preparation and theoretical support for the future application of CANON process to the treatment of landfill leachate.Therefore,in the form of aeration tank sludge inoculated with mature anaerobic ammonia oxidation sludge in the laboratory,CANON process was started in a short period of time.The removal rate of ammonia nitrogen and total nitrogen in the stable operation stage of CANON can reach 98% and 80% respectively.After reaching the stable operation stage,first add fulvic acid into the reactor as 50 mg/L,100 mg/L,150 mg/L and 200 mg/L respectively.After the concentration of fulvic acid and humic acid reached 200 mg/L,the addition of fulvic acid and humic acid was stopped and the recovery was observed for a period of time.Furthermore,the effects of fulvic acid and humic acid on denitrification performance,sludge activity,microbial community and stability of CANON process were evaluated.Therefore,this paper draws the following conclusions:(1)Under the optimum condition,after 45 days of culture,CANON reaction was successfully started.The removal rate of ammonia nitrogen and total nitrogen could reach98% and 80%,respectively.In the process of CANON reaction,part of the nitrification and anaerobic ammoxidation were carried out simultaneously,and reached the maximum rate in the aerobic aeration stage at the beginning of the reaction.(2)Fulvic acid has a significant effect on CANON process.FA with concentration more than 50 mg/L inhibited the denitrification performance,sludge activity,microbial community and stability of CANON process.With the increase of FA concentration from 50 mg/L to 200mg/L,the removal rate of ammonia nitrogen and total nitrogen decreased from 98.00% and80.00% to 71.32% and 48.18% respectively,and the concentration of sludge decreased from3.291 g/L to 2.245 g/L.The abundance of AOB and an AOB in the reactor decreased gradually with the increase of fulvic acid concentration,while the variation trend of nob was just the opposite.(3)Humic acid also has some influence on CANON process.Humic acid with concentration more than 50 mg/Lhas some negative effects on denitrification performance,microbial community structure and sludge morp Hology of CANON process.With the increase of humic acid concentration from 50 mg/L to 200 mg/L,the removal rate of ammonia nitrogen and total nitrogen decreased from 98.00% and 82.00% to 81.01% and 56.14%,respectively.With the increase of humic acid concentration,the abundances of AOB and an AOB decreased gradually,while the abundances of nob increased instead of decreasing.When the concentration of humic acid is more than 50 mg / L,the cell spacing of sludge in the translator will be larger,the aggregation effect will be worse,and then the sedimentation and activity will be reduced.(4)After stopping adding fulvic acid or humic acid,the denitrification performance and granular sludge activity of CANON process were restored,but it could not return to the operation state before adding.Compared with the impact of fulvic acid on CANON process,the impact of humic acid on CANON process is smaller.After the impact of humic acid concentration,the denitrification performance,sludge activity,microbial community and stability of CANON process can recover faster than that after the impact of fulvic acid.