Study On Dynamic Simulation Of Anaerobic Digestion System Model(ADSM) And Processstability Evaluation Index

Anaerobic digestion system is unstable due to the changes in external environmental conditions and the inhibition of mid-products in the system,which seriously restricts the application of anaerobic digestion technology.The development of anaerobic digestion mathematical model and stability evaluation index system will help to shorten the start-up period of the anaerobic digestion system,improve the stability of the system,and overcome the bottleneck of the application of anaerobic digestion technology.Based on the anaerobic digestion system dynamic model for glucose developed earlier,and the anaerobic digestion system model?Anaerobic Digestion System Model,ADSM?is developed,which embodied the disintegration and hydrolysis of particulate organic matter,amino acid and long chain fatty acid acidification,sulfate reduction process and hydrogen sulfide inhibition.ADSM model can simulate the real operation state of the reactor better with higher accuracy.The main research tasks and research results are as follows:Based on the dynamic model of anaerobic digestion system for glucose developed earlier,the disintegration and hydrolysis of particulate organic matter,amino acid and long chain fatty acid acidification,sulfate reduction process and hydrogen sulfide inhibition were improved into the ADSM.The biochemical rate matrix of the ADSM model was constructed,which covers 27 composites and 20biochemical subprocesses.The stoichiometric coefficients in the rate matrix are calculated by the balance of CODCr,C and N.ffa,li=0.95,fvfas,su=0.40190,fvfas,aa=0.54,fac,su=0.40755,fac,aa=0.40,fh2,su=0.19055,fh2,aa=0.06,fac,vfas=0.78,fh2,vfas=0.22,fac,fa=0.7,fh2,fa=0.3,and the precision of the balance calculation is up to 10^-17.Based on the rate matrix,the ADSM model is constructed by using Stella software.Based on the sensitive dynamic parameters self-adjusting program developed earlier,the adjustment mode is optimized on the basis of parameter sensitivity index and deviation percentage,which makes the self adjusting program more quickly and stable.The ADSM model was used to simulate the laboratory EGSB reactor in the medium temperature and compared with the simulation results of ADM1.The results show that both ADSM and ADM1 can predict the effluent CODCr,VFA,pH,AlK,biogas production and CH₄%.The R²?rAE?value of the ADSM simulation results are88.6%?32.3%?,94.14%?25.19%?,99.98%?0.73%?,98.8%?8.2%?,97.32%?12.7%?and 99.51%?5.4%?respectively,and The R²?r AE?value of the ADM1 simulation results were 84.9%?25%?,80.3%?31.2%?,97.96%?14.8%?,95.90%?17.6%?and98.8%?10.1%?respectively.Obviously,ADSM can not only simulate the operation state of the reactor,but also has better correlation and goodness of fit than the ADM1.Based on literature analysis,ADSM dynamic simulations and the inhibition mechanism,the stability evaluation index system of anaerobic digestion system is developed,which includes qualitative evaluation method and quantitative evaluation method.By evaluating the state of the reactor that affects the dynamic simulation experiment of stability factors,the results show that the evaluation index system is feasibility,and the results are consistent with the real performance of the reactor and can be used as the basis for judging the stability of anaerobic digestion.The ADSM and stability evaluation for the performance of the full scale IC anaerobic reactor show the ADSM model can simulate and predict the effluent COD,VFA,alkalinity,pH value and biogas of the full scale project.The correlation coefficient R² of the effluent COD was 89.3%,rAE was 13.2%;the R² value of effluent VFA was 83.3%,rAE was 15.7%;the R² value of effluent alkalinity was95.1%,rAE was about 14.3%;the R² value of effluent pH was 97.8%,rAE was 1.5%.Using the stability evaluation system of anaerobic digestion system developed in the5.3 section,the stability of engineering reactor under the conditions of COD load of42.59kg/m³.d,38.55kg/m³.d and 46.46kg/m³.d were evaluated.The results show that the reactor operation under three high loads is still stable,and the degree of the stability under 38.55kg/m³.d is higher than 42.59kg/m³.d and 46.46kg/m³.d.The ADSM model and the stability evaluation index system of anaerobic digestion system are conducive to optimize the process design,process control mode and operation management of anaerobic digestion system.It can shortens the start-up period of anaerobic digestion system,improves the stability of anaerobic digestion system,overcomes the bottleneck of the application of anaerobic digestion system,and promotes the application of anaerobic digestion technology in the field of organic waste pollution control and resource recovery.