Biogas yield by co-fermentation of Scenedesmus and solid waste collected from sturgeon culturing system

Co-fermentation of Scenedesmus cultured in waste water and the solid waste collected from sturgeon culturing system was studied for biogas yield. The biogas yield efficiency could be increased obviously by adding a certain amount of aquaculture solid waste. With mass ratio of Scenedesmus to aquatic solid waste of 1:2, total biogas yield and the methane content in biogas were 6329.5mL and 48.2% during 30 days' fermentation, while the highest biogas yield per unit mass of VS of 499.7mL/g was obtained with mass ratio of Scenedesmus to solid waste of 1:1. However, the biogas yield was not influenced significantly by treatment method of algae cells. Total biogas yield of Scenedesmus of untreated, heat treated and ultrasonic treated were 3451.2mL, 3854.5mL and 3854.5mL, respectively, during the fermentation process, and the corresponding methane content and per unit VS biogas yield in the biogas of 49.6% and 440.8mL/g, 49.4% and 492.2mL/g, and 48.4% and 467.6mL/g, respectively. It was also shown that higher biogas yield could be obtained by increasing the ratio of inoculum. With mass ratio of Scenedesmus to the inoculum of 2:3, the highest total biogas yield and biogas yield per unit VS of 3654.5mL and 478.3mL/g were achieved, and methane content in the biogas reached 57.2%. The co-fermentation process of Scenedesmus and aquaculture solid waste for biogas yield generally lasted for 25∼30 days.