Cyanophycin from Urine
Human urine has high nutrient content, containing up to 80% of the nitrogen (N) and 40% of the phosphorus (P) that end up in household wastewater, while accounting for only 1% of its volume. Microalgae have previously been shown to grow in undiluted urine when employing high light supply rates and short light path photobioreactors, making it possible to recover most of these nutrients in form of biomass. However, the N:P ratio of urine (30-47:1) limited microalgae growth along with the recovery of N. This limitation could be overcome by cyanobacteria, which accumulate a storage material called Cyanophycin Granule Polypeptide (CGP) when facing P limitation. CGP has potential applications as dispersant and as a raw material for bioplastics production. In this context, the production of cyanobacterial biomass on source-separated urine could make it possible to fully recover these nutrients, and even transform a significant fraction of them into useful products for industry, contributing to a circular economy.
The aim of this project is to grow cyanobacteria on urine and in this manner combine urine treatment with CGP production and biorecovery of nutrients. Additionally, phycobiliproteins and other compounds can be recovered as by-products.
In this project, it will be assessed if also cyanobacteria can be grown on minimally diluted urine while accumulating CGP. Furthermore, process control will be adjusted in order to maximize biomass production, CGP accumulation, and to improve nutrient removal. Additionally, the process will be described by means of a mathematical model as basis for a bioreactor design.