Research On Anaerobic Fermentation Of Aquatic Plants For Biogas Production And Biogas Generation Model Construction

The aquatic plants have good ability for the water purification, so they are widely used in the bioremediation of entropic water. However, the rapid growth and decomposition of aquatic plants could easily cause the secondary pollution of water bodies, if the aquatic plants were used as a high yielding energy plant to convert to biogas through anaerobic fermentation, which will not only stop the secondary pollution, but also produce economic value. In order to explore the feasibility of using aquatic plants for biogas through anaerobic fermentation, several aquatic plants were explored as fermentation materials for biogas production in this paper. The composition of the selected aquatic plants was determined and their effects on anaerobic fermentation were analysised, and the fermentation concentration and inoculums rate were also optimized in the fermentation process of Typha. The main conclusions are as follows:(1)The exploratory anaerobic fermentation experiments of Canna indica and Typha orientalis were carried out first. The results indicated that the measures like increasing the inoculation amount and raw materials, grinding and selecting suitable inoculums all had notable influence on the biogas production, enhancing the stability of the gas production, prolonging the gas production cycles and increasing the gas volume.(2)The major organic components of the aquatic plants are lignocellulose, carbohydrates and protein, which showed a good biodegradability. The biogas production rates of the seven aquatic plants were:Typha orientalis513.23mL·g-1VS, Hydrocotyle vulgaris539.09mL·g-1VS, Thalia dealbata577.96mL·g-1VS, Acorus calamus508.95mL·g-1VS, Canna indica555.05mL·g-1VS, Colocasia tonoimo629.41mL·g-1VS and Pontederia cordata473.09mL·g-1VS respectively, which suggested that the aquatic plants can be utilized to be resources for biogas production.(3)The C/N of Typha orientalis and Colocasia tonoimo was18.59and16.97respectively, and their theoretical biogas potential was969.21mL·g-1VS and897.69mL·g-1VS respectively, so their anaerobic degradation rate was52.95%and70.11%respectively.(4) The correlation between lignocellulose content and anaerobic biogas potential(ABP) was studied in this paper. The results showed that the correlation between lignin and ABP (R2=0.067) is very weak, while there is a certain correlation between hemicelluloses and ABP (R2=0.610, p<0.05). The conclusion believed that the hemicelluloses content directly affected the ABP. While the previous research results suggested a different opinion that the ABP was affected by lignin. We established a model equation for predicting ABP by using hemicellulose as an independent variable. The inclination, intercept and relative deviation of the linear regression line was3.592,587.104and6.81%respectively.(5) In the experiment of optimizing parameters of anaerobic fermentation for Typha, the results showed that:the pH value for the fermentation concentration of6%with inoculums rate of50%was most stable, and the biogas production rate of which was the highest, total biogas yield and biogas production rate were6482mL and581.39mL·g-1VS respectively. While the total biogas yield for the fermentation concentration of8%with inoculums rate of40%was the highest, and the total biogas yield and biogas production rate were9297mL and521.17mL·g-1VS respectively, and the above process conditions was the most suitable for the anaerobic fermentation of Typha.