Study On The Performance Of Denitrifying Sulfide Removal Process With P-cresol As The Carbon Source

The wastewater from petrochemical,pharmaceutical and other industries contains sulfur,nitrogen and phenol.in high concentration.It will cause serious environment problems without treatment.The denitrifying sulfide removal process can remove sulfide,nitrate and organic matter in a reactor,and has the advantages of high treatment effect,simple process and convenient operation.It has wide application prospect in sulfur and nitrogen treatment field.However at present,there is few reports of phenol as the the carbon source.Therefore,in this study,UASB reactor was used to study the effect of simultaneous removal of carbon,nitrogen and sulfide and the accumulation of elemental sulfur in the denitrifying sulfide removal process.The change of microbial community structure was analyzed by high-throughput sequencing.The effects of the types and concentrations of quinone on the removal of carbon,nitrogen and sulfide and the accumulation of elemental sulfur in the denitrifying sulfide removal process were studied under the optimum experimental conditions.The BP neural network model was used to simulate the denitrifying sulfide removal process of p-cresol as carbon source and discover the main influencing factors to provide theoretical and technical reference for the industrialization and intelligent application of the process.The results of the simultaneous removal of carbon,nitrogen and sulfur of denitrifying sulfide removal process of p-cresol as the carbon source showed that when the concentration of S^2-is 100mgS/L and the influent ratio is C:S=7:4,the removal rate of p-cresol,sulfur and nitrogen was 95.39%,99.32%and 96.31%respectively,the accumulation rate of elemental sulfur increases with the increase of carbon and sulfur ratio,which was up to 53.58%.The results of high-throughput sequencing showed that the diversity of microbial decreased but the evenness increased.The main kind of heterotrophic microorganisms were Proteinilasticum,Pseudomonas,Rhizoblum,Simplicispira and Petrimonas.The main kind of autotrophic microorganisms were Arcobacter,Acetoanaerobium and Sulfurimonas.When the hydraulic retention time was shortened from 12 h to 7 h and 3 h,the removal rate of p-cresol was 95.39%,62.11%and 51.44%respectively,the removal rate of sulfur was 99.32%,78.76%and 99.21%respectively,the removal rate of nitrogen was 96.31%,95.09%and79.92%respectively.The accumulation rate of elemental sulfur decreased from53.58%to42.53%and 20.44%.When the substrate concentration was increased from p-cresol 87.5mg/L,nitrate?NO₃^-N?51.25 mg/L and sulfide 50 mg/L to p-cresol 175 mg/L,nitrate?NO₃^-N?102.5 mg/L and sulfide 100 mg/L,the accumulation rate of elemental sulfur increased markedly from 20.02%to 53.58%.The removal rate of carbon,nitrogen and sulfur remained above 95%.When the substrate concentration was p-cresol 350 mg/L,nitrate?NO₃^-N?205mg/L and sulfide 200 mg/L,the removal rate of p-cresol and nitrogen declined to 5.78%and87.30%sharply,and the system collapsed.This paper studied the enhancement of AQDS and NQS on denitrifying sulfide removal process of p-cresol as the carbon source.The result showed that the accumulation rate of sulfur was increased by 24.46%,the removal rate of p-cresol and nitrogen was grew up by10.79%and 0.64%.The enhancement of NQS on denitrifying sulfide removal is more obvious.BP neural network model is used to simulate the denitrifying sulfide removal process.After 15731 steps of iteration,the average deviation was 4.92%which proved that the predicted value of the model was in good agreement with the actual value.The relative importance of the input parameters was influent C/S ratio>HRT>S^2->pH.Therefore,during the actual operation of the denitrifying sulfide removal process,the substrate concentration was adjusted to improve the effect of the process under appropriate influent substrate ratio and hydraulic retention time.