Algal blooms resulting from eutrophication pose a significant global challenge, contributing to the degradation of freshwater ecosystems. In this study, algal biomass from eutrophic water bodies was utilized for bioenergy production, offering a dual benefit of addressing energy demands while contributing to water body restoration. Alum, a widely used coagulant (40 mg/L), was employed to harvest algal biomass from eutrophic water. Anaerobic digestion (AD) was used to convert the harvested biomass into bioenergy, with the process efficiency strongly dependent on substrate hydrolysis. To enhance hydrolysis, a combined pretreatment involving sonication and alkyl polyglucoside was investigated. Under optimal sonication conditions (160 W for 30 min), chemical oxygen demand (COD) solubilization reached 21.2%. The addition of alkyl polyglucoside (10 µL) during sonication increased COD solubilization to 30.9%. Biomethane yield following the combined pretreatment reached 240.1 mL/gVS, which is significantly higher than that obtained with sonication alone (189.5 mL/g VS). Energy analysis indicated an energy ratio of 0.976 and a net energy of −2.4 kWh for the combined pretreatment. Despite improved solubilization and biomethane yield, the current energy ratio does not support the viability of scaling up the process.
Preethi et al. (2026) studied this question.