Study On The Performance Of Short-cut Sulfur Autotrophic Denitrifying Process

Anaerobic ammonia oxidation?ANAMMOX?process is considered as one of the most economical wastewater denitrification technologies to date,when the process is applied,nitrite is required as an electron acceptor.The sulfur autotrophic denitrification process can react with nitrates in wastewater as electron acceptor and sulfides as electron donor under the action of autotrophic bacteria.If the sulfur autotrophic denitrification production is controlled in the nitrite and elemental sulfur phase through reasonable process regulation,it can not only provide an electron acceptor source for anaerobic ammonia oxidation,but also can recycle the elemental sulfur,to achieve the purpose of simultaneous nitrogen and sulfides removal.Based on this,this study aims at the simultaneous accumulation of nitrate and elemental sulfur in the process of short-cut sulfur autotrophic denitrification,constructing UASB reactor to setup short-cut sulfur autotrophic denitrification process,and analyzing the accumulative effect of nitrite and elemental sulfur,meanwhile investigate the effect of pH,organic matter,temperature and hydraulic retention time?HRT?in the process,and analyze the microbial community structure and composition of short-cut sulfur autotrophic denitrification under different conditions from the perspective of microbe through high-throughput sequencing.In the feasibility study of short-cut sulfur autotrophic denitrification process,the experimental results show that in the process of S^2-/NO₃^--N?m/m?increases from 1:3.42,1:2.28 to 1:1.71,1:1.14 in sequence,the sulfides and nitrate removal rate,elemental sulfur accumulation rate all showed an increasing trend,but the nitrite accumulation rate gradually decreased to nearly 0,and the sulfur-nitrogen ratio continued to increase to 1:0.76.The removal rates of sulfide and nitrate were stable at 98%and 75%,the average accumulation rate of elemental sulfur increased to 86.41%,and the nitrite accumulation rate reached over70%,indicating that the short-cut sulfur autotrophic denitrification process was gradually achieved with the increase of the ratio of sulfur to nitrogen.The most suitable sulfur-nitrogen ratio is 1:0.76,and the short-cut sulfur autotrophic denitrification process is feasible.The microbial community structure analysis showed that Arcobacter,Azoarcus and Thiacacilus are functional genus of short-cut autotrophic denitrification process,their existence ensures the successful realization of short-cut sulfur autotrophic denitrification process.In the study of influencing factors of short-cut sulfur autotrophic denitrification process,including the effects of pH,organic matter concentration,temperature,and HRT.The experimental results show that when the influent pH is 7.5 and 8.5,the system has better results.After the pH is lowered to 6.5,the nitrate removal rate increases,but the nitrite accumulation rate is only 3%;When the organic concentration increased from 0 to 0.25mmol/L,the short-cut sulfur autotrophic denitrification process changed little,but when the organic concentration reached 0.5 mmol/L,the system collapsed.High-throughput sequencing results showed that Pseudomonas,Thauera are typical facultative autotrophic denitrifiers,Arcobacter,Thiobacillus,and Azoarcus are the main autotrophic denitrifying microorganisms.The addition of organic substances will promote the growth of the autotrophic denitrifying genus and inhibit the growth of autotrophic genus;when the temperature was increased from20°C to 30°C,the sulfide removal rate and the average accumulation rate of elemental sulfur varied little,but the nitrate removal rate and nitrite accumulation rate showed an upward trend,which could reach more than 85%;when the HRT decreased from 8h to 6h,the impact of HRT on the system was small.After continuing to reduce the HRT to 4 hours,the nitrate removal rate,the sulfur accumulation rate,and the nitrite accumulation rate decreased significantly.The system collapsed.The results of high-throughput sequencing showed that:Arcobacter,Azoarcus and Thiobacillus are typical autotrophic denitrifiers.Pseudomonas is the main facultative autotrophic denitrifying genus.The decrease of HRT will affect the growth of autotrophic genus,but it also has small promotion effect to Pseudomonas.