title: Phosphorus recovery from microbial biofuel residual using microwave peroxide digestion and anion exchange.
abstract: Sustainable production of microalgae for biofuel requires efficient phosphorus (P) utilization, which is a limited resource and vital for global food security. This research tracks the fate of P through biofuel production and investigates P recovery from the biomass using the cyanobacterium Synechocystis sp. PCC 6803. Our results show that Synechocystis contained 1.4% P dry weight. After crude lipids were extracted (e.g., for biofuel processing), 92% of the intracellular P remained in the residual biomass, indicating phospholipids comprised only a small percentage of cellular P. We estimate a majority of the P is primarily associated with nucleic acids. Advanced oxidation using hydrogen peroxide and microwave heating released 92% of the cellular P into orthophosphate. We then recovered the orthophosphate from the digestion matrix using two different types of anion exchange resins. One resin impregnated with iron nanoparticles adsorbed 98% of the influent P through 20 bed volumes, but only released 23% during regeneration. A strong-base anion exchange resin adsorbed 87% of the influent P through 20 bed volumes and released 50% of it upon regeneration. This recovered P subsequently supported growth of Synechocystis. This proof-of-concept recovery process reduced P demand of biofuel microalgae by 54%.
authors.affiliation: Arizona State University, School of Sustainable Engineering and the Built Environment, Tempe, AZ 85287-5306, USA. Electronic address: mac.gifford@asu.edu.
authors.forename: McKay
authors.initials: M
authors.lastname: Gifford
authors.affiliation: School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai 200444, PR China.
authors.forename: Jianyong
authors.initials: J
authors.lastname: Liu
authors.affiliation: Arizona State University, Swette Center for Environmental Biotechnology, Biodesign Institute, Tempe, AZ 85287-5701, USA.
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Rittmann
authors.affiliation: Arizona State University, Swette Center for Environmental Biotechnology, Biodesign Institute, Tempe, AZ 85287-5701, USA.
authors.forename: Raveender
authors.initials: R
authors.lastname: Vannela
authors.affiliation: Arizona State University, School of Sustainable Engineering and the Built Environment, Tempe, AZ 85287-5306, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Westerhoff
mesh_terms: D000838:Anions; D001674:Bioelectric Energy Sources; D018533:Biomass; D008872:Microwaves; D010084:Oxidation-Reduction; D010545:Peroxides / Q000737:chemistry*; D010758:Phosphorus / Q000302:isolation & purification*
chemical_list: D000838:Anions; D010545:Peroxides; D010758:Phosphorus
keywords: Anion exchange; Iron nanoparticles; Microbial biofuel; Oxidation; Phosphorus recovery