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

Industrial wastewater such as oil refining,food processing and mining contains high concentrations of inorganic nitrogen in addition to sulfide pollutants.It is urgent to explore a method to simultaneous removal of nitrogen and sulfide in wastewater.The anaerobic ammonia oxidation(anammox)process has emerged in recent years.The feasibility and stability of anammox process depend largely on the sustainable supply of nitrite in practical applications.Partial nitrification and partial denitrification are two common processes that provide nitrite for the anammox process,and are usually coupled with the anammox process in the actual wastewater nitrogen removal.The coupling process of sulfide-depended partial denitrification and anammox(S-DEAMOX)start to get attention due to the simultaneous demand for nitrogen and sulfur removal.This process is a complete autotrophic reaction,without the carbon source,no need of aeration,and can realize the recovery of elemental sulfur.It is an economical and energy-saving wastewater treatment process.This paper explored the effects of N/S ratios and HRT on the nitrogen and sulfide removal performances,elemental sulfur accumulation and microbial community of the S-DEAMOX coupling process.The PNA process has been widely used in mainstream wastewater treatment,but its high nitrate concentration in effluent seriously affects the total nitrogen removal efficiency How to selectively inhibit NOB activity is the key to the stable operation of the PNA process.Studies on PN process found that NOB bacteria are more sensitive to sulfide than AOB.In this paper,the effects of different concentrations of sulfide on the performance of the PNA-Sulfide autotrophic denitrification coupling process and the microbial community changes were exploredThe main conclusions of the paper are as follows:(1)In the short-term experiment of S-DEAMOX,it was found that the N/S ratio has a significant effect on the removal effect of nitrogen and the accumulation of elemental sulfur in the coupled system.The NO3--N removal rate gradually decreased as the N/S ratio increased.When the N/S ratio 1.08,the N03--N removal rate was above 97%;when the N/S was 1.08,the reactor had the best nitrogen and sulfide removal performance,with the total nitrogen and sulfide removal rates at 85.9%and 100%,respectively.The accumulation of elemental sulfur was up to 44.9%.15N isotope analysis results showed that when the N/S ratio was 1.08,the contribution rate of the anammox process was up to 68.3%;qPCR results showed that when the N/S ratio was 1.08,the content of anammox and denitrifying bacteria was the highest in the reactor.(2)In the long-term experiment of S-DEAMOX,it was found that the decrease of HRT has a significant promotion effect on the partial denitrification reaction.When the HRT is 6 h,the contribution rate of Anammox process was 98.5%,and the NRR increased to 86.4%.TNR increased to 89.7%.The formation of elemental sulfur was obviously affected by HRT.A shorter HRT is beneficial to the conversion of sulfide to S0.When the HRT was 24 h and the nitrogen and sulfur loads were 0.10 kg N/m3·d and 0.12 kg S/m3·d,most of the sulfide is converted to SO42-,and the S0 conversion rate was only 25.1%.When the HRT was 6 h,the S0 conversion rate increased to 60.6%.During the operation of the reactor,Thiobacillus was one of the main bearers of the sulfur autotrophic denitrification function in the coupled system.Under shorter HRT,the relative abundance of Thiobacillus genus was significantly improved,and the relative abundance of Anammox genus Candidatus Kuenenia and Candidatus Brocadia were also increased.(3)The PNA process was successfully started in SBBGR,but the TNR was only 68.6%due to the accumulation of nitrate in the effluent.After the addition of sulfide,it was found that the denitrification performance of the reactor was significantly improved.When the addition of sulfide was 150 mg/L,the TNR reached to 93.3%.At this time,the contribution rates of denitrification and anammox processes were 89.4%and 10.6%,respectively.However,when the added sulfide was 350 mg/L,the microbial activity was inhibited and the reactor operation became unstable.The desulfurization efficiency has been stable above 90%,and almost all of sulfide was oxidized to SO42-.Thiobacillus was the main sulfur autotrophic denitrifying bacteria.(4)The high-throughput results showed that the addition of sulfide significantly reduced the relative abundance of NOB genus Nitrospira in the reactor(0.65%to 0.06%).While the relative abundance of AOB genus Nitrosomonas and anammox genus Candidatus Kuenenia increased significantly.When the concentration of sulfide continued to increase,the growth of AOB and anammox was significantly inhibited,and the reactor operation was destabilized.