Abstract:By changing the traditional continuous biogas production to demand-oriented flexible biogas production, the fluctuation of intermittent renewable power can be balanced, thus maintaining the stability of the distributed energy system. However, whether livestock manure and wheat straw, which are typical agricultural wastes, can be used as fermentation substrates to produce biogas on demand through feeding scheme management has not been studied. For this purpose, experiments were carried out to simulate the feeding scheme of demand oriented biogas production, and the corresponding response characteristics of biogas production, as well as the anaerobic reaction stability under different feeding control parameters were investigated. On this basis, a prediction model for biogas production response under demand oriented operation was constructed. The feeding organic loading rate, frequency and feeding interval feeding control parameters were selected as the typical feeding control parameters. Results show that no obvious biogas delay periods arise under the low feeding OLR scenario (1.5 kg VS m-3 d-1) with the feeding frequency twice per day and 10 h interval, and the biogas production response rates are relatively high with the fluctuations of stability parameters (e.g., pH、FOS/TAC、VS/TS、NH3-N) fluctuate within the reasonable range. The biogas production delay period increases when the feeding OLR increases to 3 kg VS m-3 d-1, while the fermentation stability parameters fluctuate slightly in 10 h interval scenario, which states that the operation is still feasible. When the feeding OLR further increases to 6 kg VS m-3 d-1, the methane content in biogas drops to about 30%, and the biogas production response slows down obviously. In this scenario, the speed limiting step is the hydrolysis of wheat straw and lignocellulose in manure substrates, which indicates that produced biogas is not beneficial for following utilization under high OLR. Based on the experimental results, the modified Gompertz-BP neural network hybrid model was further constructed to realize the model prediction of the biogas production’s response under the demand oriented operations. The results of the study show that on-demand biogas production can be achieved by co-digestion of poultry manure with wheat straw as the substrates, which supplemented by appropriate controls at low feed loads.