Effects Of Organics And Ferrors Ion On Nitrigen Removal And Microbial Communities In Anammox Reactor

Nitrogen cycle is a basic material cycle in the biosphere and an important part of the global biogeochemical cycle.However,human activities have seriously affected the balance of nitrogen cycle,and the eutrophication of water caused by it has seriously endangered our ecology.Therefore,various new nitrogen removal technologies have attracted people's attention in recent years.As a new biological reaction of nitrogen removal discovered in the late 1980s,anaerobic ammonia oxidation?ANAMMOX,Ananmmox?has attracted the attention of many researchers.This paper focuses on the problems existing in its practical application,such as long start-up time,low stability and interference of organic matter in practical wastewater.We adopted sequential batch reactor?SBR?to study the influence characteristics of inoculation sludge type and inoculation amount on the start-up of Ananmmox process,and the effects of organic matter,ferrous ion,organic matter and Fe²⁺on denitrification performance of Ananmmox reactor.At the same time,the composition and structure of microbial community in Ananmmox reactor under different conditions were analyzed.We get the following main conclusions:?1?Two different types?aerobic sludge and anaerobic sludge?of municipal sewage treatment plants were used as inoculation sludge to start the SBR process of anammox.The results showed that the start-up of aerobic sludge was faster.When the same load was reached,5g·L^-1 inoculation amount could shorten the start-up time by half compared with 3 g·L^-1inoculation amount.?2?When sodium acetate was added to the anaerobic ammonia oxidation reactor and COD/N reached 1:1,the removal rates of ammonia nitrogen,nitrous nitrogen and total nitrogen decreased to 3.64mg?m^-3?h^-1,8.88 mg?m^-3?h^-1 and 12.52 mg?m^-3?h^-1 respectively.When glucose was added to the anaerobic ammonia oxidation reactor and COD/N reached 1.33:1,the removal rate of ammonia nitrogen decreased from 8.79 mg?m^-3?h^-1 to 5.39 mg?m^-3?h^-1,and the removal rate of nitrous nitrogen increased from 12.59 mg?m^-3?h^-1 to 17.44 mg?m^-3?h^-1.The results showed that the tolerance of anammox to glucose was higher than that to sodium acetate.?3?The anaerobic ammonia oxidation denitrification performance reached the best when the Fe²⁺concentration was 0.12 mmol?L^-1.The average removal rate of total nitrogen was 40.81%higher than that of the control reactor(0.03 mmol?L^-1),and the total nitrogen removal rate reached 0.367 kg?m^-3?d^-1,1.75 times higher than that of the control reactor,heme c,average particle size of sludge,tight bond polysaccharide and tight bond protein were 1.26 times,1.71times,1.5 times and 1.33 times higher than those in the control group.When the concentration of Fe²⁺reaches 0.15 mmol?L^-1,the denitrification performance decreases.When Fe²⁺was combined with organic compounds,it was found that the optimal concentration of organic compounds combined with Fe²⁺was 100 mg?L^-1,and the removal rate of total nitrogen in the reactor was increased by 1.33 times.The heme c content in sludge was 1.75 times higher than that of Fe²⁺added purely.When the concentration of organic matter reaches 150 mg?L^-1,the denitrification efficiency begins to decline.?4?The anaerobic ammonia-oxidizing bacteria?AAOB?started with aerobic sludge were Candidatus Anammoxoglobus?24.71%?,Candidatus Kuenenia?1.41%?,and AAOB started with anaerobic sludge were Candidatus Kuenenia?1.69%?.The quantity and abundance of AAOB in microbial flora started with aerobic sludge were higher.The addition of organic matter reduced the abundance of AAOB in the reactor,but the structure of microbial community was more abundant and stable.Meanwhile,among sodium acetate,glucose and sodium propionate,sodium propionate had the least effect on the abundance of AAOB.