Efficacy of Cellulose Degrading Microbial Strains on the Decomposition of Sewage Water Microalgae for the Production of Biogas

Abstract

Sewage water microalgae are potential sources of feed stock for the production of biofuel. In this study, six treatment combinations of microbial strains (C, N1 and N2) in single and combined treatments were used in a 5L plastic container as anaerobic digester. The use of sewage water microalgae alone was used as a negative control; and a separate application of effective microorganisms (EM) were used for comparison. A volume of 3L sewage water suspension containing 300g of microalgae biomass were used in all plastic containers as a feedstock. All treatment applications including the control showed some activity of pressure development in each bag per treatment per cycle except the combined treatment of strain (C, N1, N2). Significant volume of biogas production (4-5L/300g)) and pressure development (517.80 and 544.35 Nm-2 was observed in the first cycle when using cellulose degrading microorganism (C) alone and the combined treatment with nitrogen fixing strain (N1), respectively. High efficacy of shortening the retention time was observed while using strain C alone and combined treatment of C+N1 compared to other treatments including the control. Overall, strain C exhibited an increase of the final gas volume by 148.6% utilizing 60% of the microalgae biomass compared to the control. These results highlight the importance of the tested strains on efficiency of converting these algae to biofuel. However, further investigation of strain efficiency in a pilot scale application, outside the laboratory is recommended.