P.J. Lammers, E. Fini, K. Lauersen
Arizona State University,
United States
Keywords: wastewater treatment, sustainability, biomanufacturing
Summary:
Sludge management at wastewater treatment plants can account for 25-50% of operational costs, while wastewater from anaerobic digestors (centrate) is recirculated to activated sludge treatment, creating significant parasitic efficiency losses. While AD centrate comprises only ~1% of the total water flow it carries up to 25% of the total nitrogen. We will present an alternative approach in which centrate is redirected to a nutrient removal treatment system using polyextremophilic algae and bioreactors. Members of the Cyanidiophyceae are the only photosynthetic eukaryotes that thrive at extremely low pH (0.5−5) with optimal temperatures between 42-50ºC. Such growth conditions greatly restrict the complexity of the microbiome that develops during treatment of acidified centrate. Previous published results have shown that Galdieria sulphuraria and Cyanidioschyzon merolae: • are the dominant microbes when grown in acidified municipal wastewaters • neutral pH microorganisms and their viruses, pathogens and competitors do not survive these treatment conditions • efficiently remove carbon, nitrogen and phosphorous via mixotrophic metabolism to discharge standards from primary wastewater as well as undiluted anaerobic digestor wastewater • are efficiently transformable via homologous recombination for metabolic engineering These advances underpin our goal to design biorefineries using outputs from anaerobic digestors. The presentation will describe the metabolic engineering of two strains of the Cyanidiophyceae; Cyanidioschyzon merolae 10D an obligate photoautotroph, and Galdieria sulphuraria CCMEE 55587.1 which has photoautotrophic, mixotrophic and heterotrophic capabilities. The presentation will cover process models for production of discharge-ready clean water, bio-asphalt production from algal biomass using hydrothermal liquefaction, engineering of strains producing bio-hydrogen and astaxanthin as by-products of algal centrate treatment, and opportunities for recovery of high value metals.