LAUSR

Shortages in nutrients and freshwater for a growing population are critical global issues. Source separation of waste streams combined with decentralized resource recovery is a promising approach to address this problem. Urine contains within 1% of household wastewater up to 80% of nitrogen (N) and 50% of phosphorus (P). Since microalgae are efficient at nutrient uptake, growing them in urine is a promising technology to clean urine and produce biomass as fertilizer. The aim of this study was to develop a process for nutrient recovery from minimally diluted human urine using immobilized cultivation of microalgae on porous substrate photobioreactors (PSBRs). Treatment of urine, unamended except for a 1:1 dilution with tap water, was performed with the green alga Desmodesmus abundans, chosen among 96 algal strains derived from urine-specific enrichments and culture collections. A growth rate of 7.2 g dry weight m−2 day−1 and removal efficiencies for N and P of 13.1 and 94.1% were determined. Pre-treatment of urine with activated carbon was found to eliminate potentially detrimental effects of pharmaceuticals. In combination with other technologies, PSBRs could be applied in decentralized resource recovery systems, helping to close the link between sanitation and food production.