Valorization of wastewater-derived biomass via integrated aqueous systems

Abstract

Ever-increasing population and urbanization are placing greater pressure on wastewater treatment plants (WWTPs), yet these facilities exercise energy-intensive strategies that focus on meeting discharge requirements through simple removal or downcycling. These strategies disregard the great valorization potential held by the organic matter and nutrients in wastewater, which can be converted to biofuels, chemicals, and nutrient products through appropriate technologies. This thesis research leverages microorganisms that can metabolically assimilate waste organics and nutrients as storage compounds, and focus on developing integrated aqueous systems for conversion of wastewater-derived biomass into valuable products. The elimination of drying steps and reduction in solvent use make these processes ideal for processing wastewater-derived biomass, thereby enabling the simultaneous treatment and valorization of wastewater via more economically efficient and environmentally sustainable routes. Emphases of this thesis research are placed upon: (a) wastewater-derived algae (WW-algae) systems, which have shown promise in wastewater treatment, but are challenged by lack of systems focused on recovering both energy and nutrient potentials of wastewater as well as quantitative evaluation approaches of such systems; and (b) wastewater-derived polyhydroxybutyrate-accumulating bacteria (WW-PHB) systems, where pilot-scale production of the biopolymer PHB has been demonstrated with no impact to effluent discharge quality, yet critical barriers remain in identifying competent technologies for converting WW-PHB biomass into valuable products. Conclusions drawn from this thesis research are instrumental to the transformation of wastewater into a resource by demonstrating new techniques and processes with improved conversion efficiencies, as well as analyzing the economic feasibility of both existing and proposed systems.