Production of microalgae on source-separated human urine

Approximately 80% of nitrogen, 50% of phosphorous, and 90% of potassium in domestic wastewater originate from human urine, depending on diet and lifestyle, use of detergents, etc. However, the production volume of urine is only 1–1.5L per person per day, while the total wastewater discharge may be up to 150–250L/d. In addition to large amount of N, P, and K, human urine also contains trace elements like B, Cu, Zn, Mo, Fe, Co, and Mn. Nitrogen and phosphorus are only partially captured in a reusable form in conventional centralized wastewater treatment systems. The development of urine-sorting toilets has made it possible to separate urine for nutrient recovery instead of directing the urine to centralized wastewater treatment plants. Microalgae, if grown on urine, may provide an economically and environmentally sustainable way to capture nutrients from urine as nutrients are utilized by the growing microalgal cells. This chapter reviews literature on the use of microalgae for nutrient recovery from source-separated urine. Scale of production, start-up, maintenance of the system, and all other aspects of a pilot reactor are discussed critically in this review. © 2022 Elsevier Inc. All rights reserved