Hydrothermal liquefaction of swine wastewater-cultivated Chlorella sorokiniana SU-1 biomass for sustainable biofuel production

The environmental impact of fossil fuel consumption has shifted the focus of research toward biomass and bioenergy. Renewable biomass, such as microalgae, has several benefits, including growth in wastewater, sequestration of carbon dioxide, economic feasibility, and environmental friendliness. This study investigated the feasibility of using Chlorella sorokiniana SU-1 biomass cultivated on a swine-amended medium as a renewable feedstock to produce biocrude oil. Microalgal cultivation under optimal conditions of 50% swine wastewater (SW), inoculum sizes of 1g/L, CO2 concentration of 2%, and light intensity of 300 μmol m−2 s−1 obtained a high biomass concentration (6.53g/L), biochemical production (56.65% carbohydrate content, 33.5% protein content, and 4.35% lipid content) and wastewater treatment performance [92.29% chemical oxygen demand (COD) removal, 93.7% total phosphorus (TP) removal, and 95.64% ammonia removal]. Subsequently, hydrothermal liquefaction (HTL) of the obtained microalgal biomass achieved a 29.45% biocrude oil yield with a composition of 34.3% esters, 23.5% hydrocarbons, 5.14% aldehydes, 7.54% furans, and 11.1% phenolic derivatives, making it a promising choice for biofuel production. Thus, the findings confirmed that C. sorokiniana SU-1 could be effectively utilized for the phycoremediation of SW with simultaneous biomass production as a renewable feedstock for biocrude oil production.