Analysis On The Operation Of An Anaerobic Digester In A Wastewater Treatment Plant With The Anaerobic Digestion Simulation

Anaerobic digestion is not in general use in sewage sludge treatment ofwastewater treatment plants in our country. Sewage sludge from most wastewatertreatment plants hasn’t been treated and disposed in order to achieve the goal ofreduction, stabilization, harmlessness and resource utilization. A few of anaerobicdigesters in operation in wastewater treatment plants is in low efficiency of organicmatters degradation, low rate of biogas production and poor operation management.Anaerobic Digestion Model No.1is used to simulate the effect of sludge influent flowand quality on the operation result of an anaerobic digester, and then select theoptimal operation condition to meet the requirement of organic matters degradationand biogas production in order to achieve the operation optimization and guide theengineering application.According to the sludge anaerobic digestion in WangXinzhuang WastewaterTreatment Plant in Zhengzhou, Henan Province, the anaerobic digester is simulatedby the Anaerobic Digestion Model No.1put forward by IWA based on the sludgeinfluent flow and quality from April2012to March2013. The Model Parameters aredetermined corresponding to different months. And the dosing ratio, moisture contentand VS/TS ratio of the influent sludge is changed respectively to investigate theireffects on the operation result of the anaerobic digester. The operation condition isproposed to meet the requirement of the40%removal efficiency of the volatile solidsand0.8m3/per kg volatile solid destroyed of the biogas production.The anaerobic digester in WangXinzhuang Wastewater Treatment Plant is instable operation. The biogas production was less than6.0m3/m3sludge influent flow（96%moisture content）in summer and was between8.0-13.0m3/m3sludge influentflow（96%moisture content）in the other months. The removal efficiency of thevolatile solids was commonly less than40%.In order to determine the parameters with high sensitivity, the sensitivity analysisto the stoichiometry and kinetic parameters is made and it’s proved that thedisintegration rate coefficient kdisis in highest sensitivity. The hydrolysis ratecoefficients of the carbohydrate, protein and lipid, uptake rate coefficients of the totalpropionate and acetate, hydrogen inhibition coefficients of the long chain fatty acidsuptake, total valerate and butyrate uptake and total propionate uptake processes arealso in high sensitivity. According to the simulation to the anaerobic digester from April2012to March2013, it is found that the disintegration rate coefficients varyfrom month to month. While the the hydrolysis rate coefficients of the carbohydrate,protein and lipid are basically the same.According to the analysis to the effect of changes of the sludge influent flow,moisture content and VS/TS ratio on the volatile solids removal efficiency and biogasproduction rate, it is found that when the dosing ratio is5.0-5.8%, sludge influentVS/TS is more than0.60and influent moisture content is94.5%, the anaerobicdigestion will meet the requirement of40%removal efficiency of volatile solids and0.8m3/per kg volatile solid destroyed of the biogas production.