Start-up And Microbial Properties Of Anammox Coupled Autotrophic Desulfurization-denitrification Process

Anaerobic ammonium oxidation?anammox?is widely applied for the biological nitrogen removal,due to its features of high nitrogen removal efficiency with less energy input,no need of organic carbon,and independency on oxygen.Sulfide is a kind of substance with odor nuisance,toxicity and corrosion properties,which can inhibit microbial activity and even cause proteins denaturation.Sulfide and nitrogen pollutants are often coexisted in the wastewater of paper manufacturing,landfills and pharmaceutical discharge.It is challenged for application of anammox to treat the above nitrogen and sulfide containing wastewater.Hence,it is of great significance to investigate the effect of sulfide stress on anammox system and construct the treatment process for simultaneous removal of nitrogen and sulfide.This work explored the long-term effect of sulfide on anammox system,and deciphered the microbial community and functional genes response of anammox sludge to sulfide stress.Afterwards,merely inoculating anammox sludge to achieve the start-up of anammox and autotrophic desulfurization-denitrification process was proposed,to achieve ammonium,nitrite and sulfide removal simultaneously.The main results and findings are:?1?The long-term effect of sulfide on anammox nitrogen removal performance,extracellular polymeric substances?EPS?secretion and fluorescence intensity were studied.The results showed that 10 mg L^-1 sulfide caused inhibition on the specific anammox activity?SAA?from 541 to 231 mg TN g^-1 VSS^-1 d^-1.However,the value only declined to 388 mg TN g^-1 VSS^-1 d^-1 during its second exposure after 20 days recovery,which is higher than the SAA value at the initial exposure of 10 mg L^-1 sulfide.These phenomena implied that the anammox bacteria were resistant to sulfide after long-term acclimation.In addition,20 mg L^-1 sulfide could inhibit the SAA by 61.7%and the nitrogen removal efficiency and nitrogen removal rate was 30.7%and 5.2 kg N m^-3 d^-3,respectively.Excitation-emission matrix?EEM?coupled with parallel factor analysis?PARAFAC?revealed that protein-like substances were the main components in effluent dissolved organic matter.The fluorescence at excitation/emission wavelength=274/305 nm was quenched under high sulfide concentration(20 mg L^-1)stress.?2?The microbial community and functional genes response of anammox sludge to sulfide stress were deciphered.The relative abundance of Candidatus Kuenenia significantly decreased from 28.7%to 6.4%while Thiobacillus increased from 0 to 7.2%due to sulfide stress.Moreover,network analysis showed that Candidatus Kuenenia has a strong interaction with Denitratisoma,implying that the interaction between functional bacteria related to nitrogen removal might be strengthened in response to sulfide inhibition.Furthermore,the abundances of functional genes?hzs A,hdh,nir K and nir S?significantly decreased when the sulfide concentration reached 20 mg L^-1.?3?The possibility of using single anammox sludge to initiate the anammox and autotrophic desulfurization-denitrification process was explored in this study,and the nitrogen removal performance,EPS secretion amount,and microbial community shift were also investigated.Results demonstrated that the 90%nitrogen removal efficiency,2.55 kg m^-3d^-1 nitrogen removal rate,and 95%sulfide removal efficiency were obtained at the influent total nitrogen of 280 mg L^-1 and sulfide of 221.5 mg L^-1.The final effluent nitrate concentration was as low as 8 mg L^-1.EEM and PARAFAC identified that tryptophan-like and protein-like substances were characterized as the main components in bound EPS.High-throughput sequencing showed that Pseudoxanthomonas?11.61%?and Thiobacillus?35.68%?were the predominant genera.The enrichment of autotrophic denitrifying and sulfide-oxidizing bacteria indicated that the anammox and autotrophic desulfurization-denitrification process was started up successfully.