锰离子对硫自养反硝化去除地下水硝态氮的影响机制OA

Nitrate nitrogen pollution in water bodies is becoming increasingly severe,posing a threat to human health.Sulphur-autotrophic denitrification(SADN)technology,with its high efficiency and low carbon footprint,has been widely applied for the removal of nitrate nitrogen from groundwater.Groundwater often contains high concentrations of divalent manganese(Mn2+),and the impact of Mn2+on SADN remains unclear.This study conducted batch experiments using sulfur(S0)as an electron donor to analyse the effects of different Mn2+concentrations on SADN performance and to investigate the response patterns of microbial community structure,nitrogen cycling,and sulfur oxidation functional genes to Mn2+in the system.The results showed that low concentrations of Mn2+(≤1 mmol/L)significantly promoted the SADN process,with the highest nitrate nitrogen removal rate reaching 0.735 mmol/(L·d).The proportion of Thiobacillus,the dominant microorganism in the SADN process,increased from 9.41%to 14.92%,and the relative expression levels of denitrification genes nirS and nosZ,as well as sulfur oxidation genes dsrA and soxB,also significantly increased.However,high concentrations of Mn2+(>4 mmol/L)inhibited the SADN process,reducing the nitrate nitrogen removal rate to 0.674 mmol/(L·d).The proportion of SADN microorganisms Thiobacillus and Longilinea in the system decreased from 23.11%to 15.60%,and the expression of denitrification genes narG,nirS,nirK,norB,and sulfur oxidation genes dsrA were also inhibited.In summary,Mn2+affects the denitrification performance of the SADN system by regulating functional genes and microbial community structure in the SADN system,in which nitrite nitrogen reduction as well as S0 and thiosulfate oxidation were important rate-limiting processes in SADN at different Mn2+concentrations.In this paper,the response mechanism of Mn2+to the SADN process was revealed at the level of community structure and functional genes,which can provide a theoretical basis for the application of SADN technology in the removal of nitrate nitrogen from Mn2+-containing groundwater.