Effect Of NaCl On Denitrifying Sulfide Removal Process And Its Mechanism

Chinese petroleum,chemical,pharmaceutical industries,etc,emit a large number of wastewater containing emissions such as: sulfur 、 nitrogen and organic.This kind of wastewater have multiple harms of sulfur、nitrogen and carbon,also has high salinity,it will do great harm to the environment if not handled.In recent years,the emerging denitrifying sulfide removal process can remove carbon,sulfur and nitrogen pollutants in a reactor at the same time,and has the advantages of simple process,low operation cost,no secondary pollution and sulfur recyclable etc.It will have good prospects for application in the treatment of wastewater containing nitrogen and sulfur pollutants.However,the effect of treating high salinity wastewater containing nitrogen and sulfur pollutants using denitrifying sulfide removal process is seldom reported.Based on above,this study choose to use UASB reactor,to investigating the effect of salinity(NaCl)on the denitrifying sulfide removal process,and analyzing the changes of sludge index in the experimental process,then using sequencing technology analyzes microbial composition and community characteristics of different conditions of salt,to revealing the mechanism of NaCl’s effect on denitrifying sulfide removal process.The results will provide a theoretical and technical reference for treatment of wastewater containing salt、organic、nitrogen pollutants.When the time of hydraulic retention(HRT)was 5 hour,the operating temperature of the reactor was 30 oC,and the concentration of NaCl range from 2g/L to 35g/L,NaCl had almost no influence on denitrifying sulfide removal process.Throughout the experiment,sulfide removal efficiency remained 100%,little of them are transformed to sulfate and thiosulfate,most of them(60%)are transformed to elemental sulfur;nitrate removal efficiency remained 100%;acetate removal efficiency remained 70%.The results showed that denitrifying sulfide removal process can adapt to the treatment of wastewater containing high concentration of NaCl.There were granular appeared in the reactor during the process,which showed that NaCl was able to promote the formation of denitrifying sulfide removal process granular.After the whole process,the size of granular was range from 0.2mm to 4mm,SEM photos of granular showed its microbes mainly were bacillus.This research results provide technical reference for denitrifying sulfide removal process sludge’s fast granulation.By using sequencing technology analyzes microbial composition and community characteristics under different concentrations of NaCl,its autotrophic microorganism mainly include: Piscinibacter,Arenimonas,Azoarcus,etc,heterotrophic microorganism mainly include: Thauera,Xanthomonadales,Chitinophagaceae,Thermomonas,Anaerobacillus,Solibacillus,etc.With the concentration of NaCl changed from 2g/L to 35g/L,heterotrophic microorganism’s percentage changes from 86.88% to 25.30%,autotrophic microorganism’s percentage changes from 13.12% to 74.70%.