The Study Of The Simultaneous Removal Of Nitrogen And Sulfide Based On Anammox And Autotrophic Denitrification Processes

The wastewater produced by many industrial enterprises contains both nitrogen and sulfur pollutants.Therefore,it is urgent to explore how to simultaneously remove nitrogen and sulfur pollutants in wastewater.Anammox,as a new type of wastewater denitrification process,has been widely used in actual production and life.In addition,the denitrification process using sulfide,nitrate or nitrite as the electron donor and electron acceptor is a completely autotrophic process and does not require the addition of external energy substances.It is a green,environmentally friendly,economical and energy-saving water treatment process.The technical coupling of the above two processes can not only improve the total nitrogen removal rate in wastewater treatment,but also remove sulfur pollutants at the same time.In this study,the new sulfide SCN-successfully started the sulfur autotrophic denitrification process.Establish a two-stage coupled system of anammox and sulfur autotrophic denitrification,and use the residual NO3-in the anaerobic ammonia oxidation stage to participate in the denitrification process,which greatly improves the total nitrogen removal of the entire two-stage coupled system Through periodic experiments,the conversion path of N and S elements in SCN-ion and the influence of SCN-on system microorganisms are clarified.By adding different concentrations of sulfide,the one-stage coupling system was successfully started,and the sludge surface morphology and element composition of the one-stage coupling system were explored;the 15N isotope experiment confirmed that denitrification and anaerobic ammonia in the same reactor.The contribution rate of each oxidation denitrification.The main conclusions of this study are as follows:(1)The anammox and SCN-driven autotrophic denitrification processes were started in the UASB reactor,and the start-up time was 22 d and 20 d,respectively.The total nitrogen removal rate of each reactor is maintained at about 80%.Based on mature sulfur autotrophic denitrification sludge cycle experiments,it is shown that N in SCN-is converted into NH4-,and a larger part of S element is converted into SO42-in one cycle,with a conversion rate of 69.4%.(2)The two-stage coupling system greatly improves the denitrification performance of a single reactor.The total nitrogen removal rate is 92.42±1.98%,and the NLR of the coupling system is 0.269±0.04 kg/m3/d.The functional genes related to denitrifying bacteria in the reactor basically showed an increasing trend.High-throughput data showed that the microbial diversity in the sludge samples in the sulfur autotrophic denitrification reactor increased,and PHOS-HE36,Methanosaeta and Thiobacillus were abundant in the reactor.The relative abundance of genes related to amino acid metabolism and synthesis,polysaccharide synthesis,nitrogen metabolism,organic matter degradation and cytochrome P450 metabolism is higher in bacteria with higher degrees than inoculated sludge samples.(3)A one-stage coupling process of anammox-sulfur autotrophic denitrification was constructed in the same reactor,and the process was successfully started in 10 days.The total nitrogen removal rate during the start-up stage was 87.11±0.38%,the sulfide removal rate was 98.91±0.12%,and the long-term operation stage(11-90 d)total nitrogen removal rate was 89.68±3.33%.In the short-term cycle experiment,the NH4+-N and part of NO2--N in the water are consumed by the anaerobic ammonia oxidation reaction,the remaining NO2--N and the NO3--N produced by anammox are consumed by the denitrification process,and the SCN-The N element in is converted into NH4+-N.(4)SEM analysis confirmed the stability of the granular sludge in the reactor and its adaptability to sulfide.The isotope tracer experiment found that the anammox and denitrification rates were 106.38μmol/L/h and 69.06 μmol/L/h,respectively,and the corresponding denitrification contribution rates were 60.63%and 39.36%.Microbial community structure analysis showed that Proteobacteria is the dominant bacteria phyla in the phylum classification level,and Bacteroidetes_vadinHA17 and Thiobacillus are the genus with the highest relative abundance in the genus classification level.(5)In order to optimize the coupling process,this paper studies two coupling modes:one-stage and two-stage coupling processes.The results show that the total nitrogen removal rate of the two-stage coupling process is higher than that of the one-stage coupling process,and the most abundant microorganisms in the two modes are Thiobacillus.