Research On Clean And Carbon-reduction Technology For Biomass Anaerobic Digestion Systems

As a renewable and clean energy source,biomass has the advantages of wide distribution,low environmental impact and sustainable use.However,the low utilisation of biomass resources has limited the development of biomass-related industries.In response to this situation,anaerobic digestion of biomass has received widespread attention as a clean and efficient technology.In this paper,anaerobic digestion experiments were conducted using phosphoric acid pretreated maize straw mixed with cow dung under high temperature conditions to investigate the feedstock characteristics and gas production characteristics of the system.Based on the experiments,the anaerobic digestion process of the system was simulated using a modified Anaerobic Digestion 1(ADM1)model,and methane production was predicted after calibration and validation.The main conclusions are as follows.(1)Mixed anaerobic digestion is conducive to improving the overall stability of the system;phosphoric acid pretreatment accelerates the start-up of the anaerobic digestion system,shortens the overall reaction cycle and improves the reaction efficiency;the cumulative methane production of the anaerobic digestion system under 4%and 6%concentration of phosphoric acid pretreatment is 25.3 mL/g TS and 26 mL/g TS,respectively,showing a better gas production effect.(2)The original ADM1 model could not effectively characterize the mixed anaerobic digestion system of cattle manure and maize straw,so the model structure was modified according to the characteristics of the feedstock,mainly including the modification of the single input substrate in the anaerobic digestion model and the splitting of the decomposition process products,and the addition of the corresponding biochemical reaction rate equation.(3)The results of the model sensitivity analysis and parameter estimation were:the first-order kinetic constants k(dis,cd)and k(dis,cs)were calibrated to 0.47 and 0.36 d-1,respectively;the Monod maximum specific absorption rate constants k(m,su),k(m,ac)and k(m,h2)were calibrated to 30.20,16.30 and 42.97 d-1 and the half-saturation constants k(s,su),k(s,pro)and k(s,ac)were calibrated to 6.25,1.24 and 0.39 gCOD/L,respectively.The modified model was used to simulate the cumulative methane production from the anaerobic digestion experiment,and the Pearson correlation coefficient was 0.994 and the root mean square error RMSE was 0.28,indicating that the simulated values of the modified model correlated well with the experimental values.The calibration value can be used as the setting value for the model to simulate the anaerobic digestion process.(4)Using the experimental data to further evaluate the simulation performance of the modified ADM1 model,the results showed that the modified model had good simulation results for the cumulative methane production,with Pearson correlation coefficients above 0.95 and root mean square error RMSE below 0.3,indicating that the model could complete the simulation of the anaerobic digestion process of mixed cow manure and maize straw.This study investigated the gas production performance of the mixed anaerobic digestion system of phosphoric acid pretreated maize straw and cattle manure,and modified,calibrated,validated and evaluated the ADM1 model to establish an anaerobic digestion model to simulate this system,which provides theoretical support for the engineering application of clean carbon reduction technology of biomass anaerobic digestion system.