Abstract:To study the energy utilization potential of wetland plants, a fully automated methane potential testing system was used to evaluate the anaerobic fermentation methane production characteristics of three wetland plants at different temperatures, and to simulate and analyze the methane production process and fermentation product stability. The results showed that during a 30 day fermentation period, the cumulative methane production of three wetland plants, namely Geotrichum macrophylla, Foxtail algae, and water hyacinth, reached 166.5, 159.4, and 236.9 mL · g -1 VS, respectively, at medium temperature (37 ℃), which were 29.6%, 18.3%, and 39.9% higher than at room temperature (25 ℃) (P<0.01). In addition, the gas production rate was faster, the fermentation period was shorter, and the volatile solid (VS) removal rate was higher during medium temperature fermentation; The stability of fermentation products was analyzed using thermogravimetric differential scanning calorimetry (TG-DSC). The TG curve showed three obvious weight loss processes (100 ℃, 250-350 ℃, and 400-600 ℃), and the total weight loss rate gradually decreased throughout the fermentation cycle. The DSC curve had two obvious exothermic peaks, with the exothermic intensity gradually decreasing in the low-temperature zone (300 ℃), the peak intensity of foxtail algae gradually decreasing in the high-temperature zone (400-550 ℃), and the peak intensity of giant mushroom grass and water hyacinth gradually increasing, with the peak shifting to the right, indicating that organic matter gradually degraded and the stability of fermentation products increased; The Cheynoweth equation was used to fit the gas production process of medium temperature fermentation of giant mushroom grass, foxtail algae, and water hyacinth. The model correlation coefficients were all greater than 0.95, and the difference ratios between predicted and measured gas production values were 1.98%, 0.82%, and 0.32%, respectively (P>0.05). Research shows that anaerobic fermentation for methane production is beneficial for wetland plant resource utilization
The effective ways of utilization are conducive to solving the problem of secondary pollution in artificial wetland technology.