Mechanism And Engineering Regulation Of Sulfide Generation In The Treatment Of Rural Sewage By Sulfur-autotrophic Denitrifying Packed Bed

Rural revitalization of the goal and the construction of ecological civilization of rural living environment improvement,the current due to rural sewage containing nitrogen pollution problems are increasingly serious in China,our country of nitrogen pollution in waste water processing standards also continued to deepen,baiyang lake region,this study required standard to total nitrogen in water below 5 mg/L,traditional heterotrophic denitrifying denitrification technology to meet the requirements,And the traditional process is easy to cause secondary pollution,high cost and other shortcomings,sulfur autotrophic denitrification process emerged at the historic moment.In recent years,the sulfur autotrophic denitrification process has gradually become a research hotspot in the field of in-depth nitrogen removal of wastewater.However,there are few studies on the pilot scale treatment of rural sewage,and there are few studies on the engineering regulation related to the fluctuation of the quality and quantity of rural sewage,which will affect the treatment efficiency of the filter and the overflow risk of sulfur-containing by-products.The research content of this topic includes the following three aspects:（1）A sulfur-autotrophic denitrification packed bed deep denitrification reactor was constructed and operated stablyIn some area,practical domestic sewage was introduced to start the reactor and run the sulfur-autotrophic denitrification filled bed depth denitrification pilot reactor,the efficiency index of the sulfur-autotrophic denitrification filled bed depth denitrification reactor was measured,and the COD of the sulfur-autotrophic denitrification filled bed depth denitrification pilot reactor was monitored.It was found that influent nitrite load was linearly correlated in the range of 0-0.6（kg NO₃^--N/m~3/d）,and influent NO₃^--N load was above 0.6（kg NO₃^--N/m~3/d）.The denitrification load is approximately 0.27（?） 0.0096（kg NO₃^--N/m~3/d）,and the maximum size of the sulfur autotrophic denitrification packed bed bioreactor is0.27（?） 0.0096（kg NO₃^--N/m~3/d）.（2）Explore the causes of sulfide overflowSulfur autotrophic denitrification packed bed bioreactor has the risk of sulfide overflow.Through the analysis of the generation of sulfide and sulfate radical in the extended process,and the consumption of DO,nitrite,nitrite and alkalinity,it is determined that the reason of sulfide overflow is the sulfur disproportionation in the low nitrate and low DO area,resulting in the formation of sulfide.In the process,p H decreases and basicity decreases,indicating that both sulfur autotrophic denitrification and sulfur disproportionation are hydrogen ion generating reactions.The influence of filter material compaction caused by non-backwashing on the formation of sulfur-containing by-products was investigated.The experimental results show that the compaction area of the filler will form a dead zone,which will lead to a significant increase of sulfide concentration in the effluent（3）Engineering regulation to inhibit sulfide generationThe formation mechanism and engineering regulation of sulfide in rural sewage treatment were studied in a packed bed pilot reactor with sulfur-autotrophic denitrification.In the packed bed reactor of sulfur autotrophic denitrification,due to the existence of dead volume and low NO₃^--N concentration of wastewater,when low NO₃^--N concentration exists,sulfide disproportionation will occur in the effluent.In order to suppress sulfide disproportionation,the engineering method of this study was to optimize the distance of water distribution,the distance of aeration pipe and the frequency of backwash.This study provides theoretical guidance for the advanced treatment of rural sewage by sulfur-autotrophic denitrification packed bed.