Study On Nitrogen Removal Performance And Mechanism Of Landfill Leachate Treated By Anaerobic Ferriammoxidation Process

The landfill leachate is highly complex in compositions and contains high concentration of heavy metals.Thus,it is difficult to remove nitrogen from landfill leachate economically and effectively.The traditional biological and chemical treatment processes still suffer a lot of problems,such as high investment cost,unstable operation performance,etc.Although the anammox process has the characteristics of low energy consumption,no carbon source consumption and low sludge production,it has a slow growth rate,a long domestication period,and easily affected by environmental factors.Organic matters and heavy metals will cause irreversible damage to it.Therefore,its stable operation and engineering application require high quality conditions.Anaerobic iron ammoxidation has high metal resistance,fixed effect on heavy metals,and reduces the toxicity of heavy metals in sewage.At the same time,it can oxidize ammonia nitrogen to nitrite nitrogen to provide electronic donors for subsequent processes.In order to explore the feasibility of the application of anaerobic iron oxidation for landfill leachate treatment,this study investigated the effects of differentMoreover,based on the effect of Fe³⁺on the anammox system,the enrichment of anaerobic iron ammonia oxidation and treatment of simulated landfill leachate were conducted.The main results obtained in this work are as follows:?1?In the short-term impact test,the NRR of the influent system with Fe³⁺concentration of 5mg/L was the highest,which was 17.36 mg-N/g VSS/h.When the influent concentration of Fe³⁺is 50 and 100mg/L,the nitrogen removal performance of anammox was seriously inhibited.After 24 hours recovery,the nitrogen removal performance performance of the reactor with 100mg/L Fe³⁺addition was restored,suggesting that the short-term inhibition of high Fe³⁺concentration was reversible.?2?In the long-term impact test,the average total nitrogen removal load of the control group?S1?,the low concentration group?S2?and the high concentration group?S3?reactors was maintained at 2192.9,2242.8 and 1220.9 mg-N/?L·d?.The average total nitrogen removal load of S2 was higher than that of the S1 and S3.Low concentration of Fe³⁺can promoted the secretion of extracellular polymer,while high concentration of Fe³⁺can dissociated EPS and make sludge particles more dense.The contents of Heme c and HDH activity in the S2 were higher than those in the S1 and the S3.Low Fe³⁺concentration can promoted the nitrogen removal performance of anammox system,while high Fe³⁺concentration can inhibit microbial metabolic activity and destroy the stable environment of the system.?3?In ASBR reactor,after 88 days'enrichment of anaerobic culture,the maximum conversion rate of NH₄⁺-N reached 52.73%,and the maximum conversion amount was28.37mg/L.The Fe²⁺concentration in effluent increased gradually with the increase of operation time,with maximum concentration of 2.87 mg/L.High throughput analysis showed that Acidimicrobiaceae were enriched in ASBR reactor,from 0.73%on the 0 th day to 2.07%on the 88 th day,and the relative abundance of acid microbiology increased from 0%to 4%,that Feammox was driven by acid micro bacteria.?4?Under the condition of high influent substrate concentration,feammox still has oxidation of NH₄⁺-N in this reactor was not only contributed by Feammox bacteria,but also by other processes.Through the above experimental research results,it was verified that the Feammox system still has Fe and N metabolic activity in simulated landfill leachate after enrichment cultivation,which provides a theoretical basis for the practical application of landfill leachate,and developed New ideas.