(302a) Integration of Algal Wastewater Treatment with Hydrothermal Liquefaction to Increase Process Net Energy Recovery

Current wastewater treatment processes are energy intensive and expensive. Places with limited financial resources sometimes cannot follow all the guidelines for safe wastewater treatment and discharge contaminated water into rivers or oceans. This affects people who depend on surface water. The water from rivers also leeches underground and can contaminate groundwater aquifers. By integrating low-cost biological wastewater treatment with biofuel production, the net energy intensity of wastewater treatment can be reduced and provide a more cost-effective solution to water contamination problems. In this research, algae was used to treat wastewater through uptake of carbon, nitrogen and phosphorus in the municipal wastewater for growth. Hydrothermal liquefaction of the algae grown on wastewater yields bio-crude oil, char, and nutrient-rich aqueous phase. Here, HTL was performed under different operating conditions (temperature, solids loading, reaction time) to understand the effects of these parameters on product yield. The energy content and CHNS elemental composition of the products were measured to construct mass and energy balances. The energy recovered in the HTL products, along with the lower-cost algal treatment method, increased the net energy recovery (NER) ratio, making the overall process more feasible.