Rapid Start-up Method And Strategy Of Sulfur Autotrophic Denitrification For Effluent Advanced Nitrogen Removal Filter

Sulfur autotrophic denitrification bacteria grow slowly and accumulate enough biomass slowly,which leads to a longer time for biofilm formation and development and a slow start-up rate of sulfur autotrophic denitrification system.In engineering applications,it is not only required to be able to start quickly but also to meet the high emission standards of the country.In this study,a rising-flow fixed-bed sulphur autotrophic denitrification reactor was constructed using a monolithic sulphur-rhodochrosite composite filler to carry out a study on the rapid start-up method and strategy of a sulphur autotrophic denitrification deep denitrification filter.With the overall objective of the sulphur autotrophic denitrification biological denitrification system to achieve rapid denitrification,the actual operation process was simulated to explore the rapid start-up method of the deep denitrification filter,which has practical reference significance for the engineering application of the sulphur autotrophic denitrification process.(1)The laboratory water was used as feed water to run the sulphur autotrophic pilot reactor,and the existing monolithic sulphur-rhodochrosite composite filler was used to meet the domestication of microorganisms in the pilot sulphur autotrophic denitrification reactor,and the number of days required to achieve stable nitrate removal was the same(7-8 days)for a 1 h residence time start-up and a 20 min residence time start-up without inoculation of activated sludge.The residence time also had no effect on the ability to remove nitrate and total nitrogen after start-up was complete.Compared to the reactor without activated sludge inoculation,the reactor was able to increase the start-up rate of sulphur autotrophic denitrification after inoculation,but a certain amount of nitrite accumulation(1.5-2mg/L)occurred during the stable operation phase after start-up,which reduced the total nitrogen removal rate and removal load and affected the effluent quality.The nitrite concentration in the effluent after inoculation of activated sludge was still high(2-3mg/L),which made it difficult to ensure the effluent quality.Although the biomass after inoculation of sludge is large,the proportion of dead cells is high and the biological activity is poor,resulting in nitrite being unable to fully convert into nitrogen and remaining in water which affects the denitrification effect.(2)Operating with a retention time of 1h and daily backwashing accelerated the start-up rate of sulphur autotrophic denitrification,and the denitrification load after the reactor start-up was completed was higher(0.8kg N/m3/d);while operating with a retention time of 0.33 h and daily backwashing had no accelerating effect on the start-up rate.This suggests that at longer residence times,daily backwashing helped to accelerate the start-up rate of the sulphur autotrophic denitrification reactor;whereas at shorter residence times,backwashing prior to start-up may have damaged the colony structure of the filler and affected the start-up rate.(3)The main phylum in the system is Proteobacteria.Proteobacteria is the most common denitrification bacteria in denitrification bioreactor,which contains a large number of bacteria related to denitrification and can promote the process of denitrification.Among them,Thiobacillus is a key functional bacteria in sulfur autotrophic denitrification,which can use sulfur as electron donor to achieve denitrification effect in anaerobic environment.Among them,Thiobacillus thiooxidans,Thiobacillus thiooxidans and Thiobacillus denitrifiers all have excellent denitrification performance.