Algal systems have emerged as a promising strategy for simultaneous treatment and valorization of wastewater. While organics and nutrients in the wastewater can be metabolically assimilated into algae, the harvested biomass can be converted to various energy and nutrient products in biorefineries. However, no previous studies have been conducted to quantify and evaluate the full energetic and nutrient product potentials that can be generated from such systems. The lack of a comprehensive study on the conversion of wastewater algae (WW-algae) hinders both techno-economic and life cycle analyses that are critical to the further development and real-world implementation of WW-algae systems. To address such key challenges, this work designed and demonstrated a thermo- and electrochemical system for the conversion of WW-algae and upgrading of crude products. Multiple bio-oil, fuel gas, and fertilizer products were generated from a single batch of WW-algae harvested from a municipal wastewater treatment facility. Thorough analyses conducted along the process chain conclude that for 1,000 kg of WW-algae (with a heating value of 156 gasoline gallon equivalent (GGE), 85 kg N, and 9.3 kg P), 79 GGE of energy can be recovered in bio-oil, 42 GGE in fuel gas, and a total of 37 kg N and 8.5 kg P can be recovered as fertilizers. For the first time, experiment-derived energy and nutrient recovery potentials of WW-algae are presented in an integrated manner, and possible approaches to improve recovery efficiency as well as future research needs are identified.

Complete valorization of wastewater algae via an integrated thermo- and electrochemical processing strategy

256th National Meeting (2018)

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