The Performance Of Denitrifying Sulfide Removal Process And Functional Microbial Community For Treating High Salinity Wastewater

When both autotrophic and heterotrophic denitrifiers were presented in the reactor,simultaneous removal of nitrogen,sulfide and carbon can be achieved,referring to denitrifying sulfide removal?DSR?process.However,there was no research about the effect of high salinity on the DSR process proformance.The DSR process was carried out in UASB reactor with phenolic compounds as carbon source?P-DSR?,and the removal efficiencies of carbon,nitrate and sulfide were investigated when NaCl concentrations were in the range of 0 to 100g/L.Meanwhile batch cultivation experiment was taken to study the degradation and conversion of carbon,nitrate and sulfide.The microbial composition and community characteristics in the reactor were investigated using high-throughput amplicon sequencing method.The results showed that:?1?When the phenol acted as carbon source,the removal efficiency of phenol,NO₃^--N and S^2-reached about 99%,75%and 95%respectively at the0g/L NaCl concentration and there was no S⁰ accumulation;the average removal efficiency of phenol,NO₃^--N and S^2-kept about 80%,85%and 95%respectively with the NaCl concentration in the range of 4 to 50g/L;Under the range of 75 to 100g/L NaCl concentration,the average removal rates of phenol and S^2-kept about 69%and 95%respectively,however the removal efficiency of NO₃^--N decreased significantly and elemental sulfur accumulation increased gradually,the removal efficiency of NO₃^--N decreased to 22%and the S⁰accumulation rate reached about 95%when NaCl concentration was 100g/L.?2?The range of50 to 100g/L NaCl concentration was beneficial for the increasing accumulation of S⁰ with the phenol as carbon source.The oxidation of S^2-,phenol and S⁰ displayed in such order:q_S^2->q_S⁰>q_Phenol without NaCl;however the oxidation orders of S^2-,phenol and S⁰ revealed that:q_S^2->q_Phenol>q_S⁰ when the NaCl concentration was 75g/L.?3?When the p-cresol acted as carbon source,the removal efficiency of p-cresol,NO₃^--N and S^2-reached about 55%,99%and 95%respectively and the S⁰ accumulation rate reached about 10%at the 0g/L NaCl concentration;the average removal efficiency of p-cresol,NO₃^--N and S^2-kept about 60%,99%and 95%respectively with the NaCl concentration in the range of 10 to 40g/L and there was no S⁰ accumulation;Under the range of 60 to 100g/L NaCl concentration,the average removal rates of p-cresol and S^2-kept about 60%and 95%respectively,however the removal efficiency of NO₃^--N decreased significantly and S⁰ accumulation increased gradually,the removal efficiency of NO₃^--N decreased to 40%and the S⁰ accumulation rate reached about95%when NaCl concentration was 100g/L.?4?Under high NaCl concentration,the Marinobacter and Thauera were the main heterotrophic denitrifiers,and the Thiobacillus and Azoarcus were the main autotrophic denitrifiers identified in the DSR process with the phenol as carbon source;the Marinobacter was the main heterotrophic denitrifier,and the Azoarcus was the main autotrophic denitrifier identified in the DSR process with the p-cresol as carbon source.