Phototrophic Recovery of Nutrients and Biobased Products from Urine

Summary

Nitrogen and phosphorus are not always removed from wastewater and often reach natural water bodies. Excess of these nutrients in natural water bodies causes the overgrowth of cyanobacteria and microalgae; and results in eutrophication, the destabilization of ecosystems, and the release of potent greenhouse gases such as methane and nitrous oxide.
Most of the nutrients in domestic wastewater come from human urine, which contributes 70% of the nitrogen and 40% of the phosphorus but only 1% in volume. This project aimed to develop a process to recover these nutrients from source-separated human urine in the form of cyanobacteria biomass, preventing the arrival of nutrients to water bodies and the need for expensive nutrient removal in wastewater treatment plants. After separation from the water, the cyanobacteria biomass can be used as a soil amendment and for producing biobased chemicals such as the biopolymer cyanophycin. Cyanophycin can be used as a biobased chemical platform to produce polyaspartic acid, acrylonitrile, and other compounds that can replace various fossil-fuel-based chemicals.