| The denitrification of wastewater is one of the key factors in meeting the constantly improving wastewater discharge standards.The main reason for the low nitrogen removal efficiency of sewage treatment plants in China today is the insufficient carbon source of influent water.Adding exogenous carbon has become a main strategy to achieve the standard discharge of total nitrogen emissions.Traditional carbon sources such as sodium acetate and acetic acid have high costs and transportation costs,exacerbating the operating costs of sewage treatment plants.Polyol rectification residue has good water solubility and low nitrogen and phosphorus content.The key is that it contains a high content of carbon element.If it can be added as an external carbon source to the process of nitrogen and phosphorus removal of sewage,the cost of external denitrification carbon source in the sewage treatment system can be greatly reduced,and the method of efficient utilization of organic solid waste generated by heavy pollution industry has been found,which has realized the efficient treatment and resource utilization of waste.Based on the theory of comprehensive utilization of organic waste and biochemical treatment of wastewater,this experimental study aims to explore the feasibility of using polyol distillation residue as an external carbon source based on the analysis of the physicochemical characteristics of polyol distillation residue.After batch test,determine the denitrification rate and the optimal C/N ratio of the polyol rectification residue as an external carbon source.On this basis,the continuous test of SBR reactor was carried out,and the anaerobic aerobic process was used to operate.With sodium acetate as the control test,the denitrification denitrification performance of polyol distillation residue as the external carbon source was investigated;Carry out carbon balance analysis and Nitrogen balance analysis to investigate the impact of distillation residue as denitrification carbon source on nitrogen removal process of sewage treatment system;Comparing the effects of two carbon sources on activated sludge concentration(MLSS and MLVSS),extracellular polymer(EPS),microbial activity,and microbial population in biochemical systems,this study aims to investigate the effect of distillation residue as an additional carbon source on the characteristics and microbial population structure of activated sludge.The research results are as follows:(1)Sodium acetate was used as the carbon source in the control experiment,and the denitrification rate of polyol distillation residue at different C/N was investigated.The optimal C/N of distillation residue as the carbon source of denitrification is 4.4,the denitrification rate is 17.96mg/(g VSS·h),and the denitrification capacity is 0.21gN/g COD;The denitrification rate is 17.1 lmg/(g VSS·h)and the denitrification capacity is 0.29gN/g COD when sodium acetate under the same C/N condition is used as the external carbon source.It shows that the denitrification performance of polyol distillation residue is close to that of sodium acetate,and it can be used as an external carbon source for biological nitrogen removal.(2)The SBR reactor was used for 60 days of continuous denitrification denitrification test.When the dosage of rectification residue was 240 mg/L,the effluent TN decreased from 59.70 mg/L to 26.68 mg/L,with a removal rate of 55.31%.Under the same conditions,when sodium acetate was used as carbon source,the effluent TN could be reduced from 58.23 mg/L to 21.74 mg/L.When the distillation residue is used as the carbon source,the TN removal rate is 88.24%higher than when sodium acetate is used as the carbon source.The use of polyol distillation residue as a carbon source can improve the denitrification efficiency of wastewater.(3)The analysis of the carbon Nitrogen balance of the reactor system when the polyol distillation residue is used as the carbon source shows that when the distillation residue is used as the carbon source,the TN removal rate of the reactor system is increased by 55.42%,and the nitrogen load of the sewage treatment system is not increased.Therefore,the polyol distillation residue can be used as an external carbon source for sewage treatment.(4)The addition of polyol distillation residue and sodium acetate can both increase the MLSS and MLVSS of activated sludge,stimulating its growth.Like sodium acetate,the carbon source of polyol distillation residue can increase the extracellular polymer(EPS)of microorganisms to varying degrees,thereby reducing the settling performance of activated sludge.Compared to sodium acetate,the effect of distillation residue as an external carbon source on sludge yield and sludge settling performance is relatively small.Therefore,polyol distillation residue can be used as an external carbon source for sewage treatment systems.(5)Through the analysis of microbial community in the reaction system,the types of denitrification bacteria changed with the addition of two different carbon sources;Compared with sodium acetate,the reduction of denitrification bacteria abundance caused by distillation residue was small,and the activity of denitrification bacteria was not affected.By comparing and analyzing the levels of bacterial phylum and genus,it was found that compared with sodium acetate as the carbon source,the difference in microbial community in the reaction system was relatively small.Polyol distillation residue can be used as a carbon source in sewage treatment biochemical systems. |
