Urine collection in a multi-story building and opportunities for onsite recovery of nutrients and non-potable water

Abstract

Abstract The purpose of this research was to demonstrate urine collection in a multi-story building and evaluate the quantity of phosphorus (P), nitrogen (N), potassium (K), and water recovered by struvite precipitation, ammonia stripping–acid absorption, and distillation, respectively, and the quality of fertilizers (struvite, ammonium sulfate, potash) and non-potable water generated. Urine was collected from a 5-story building in which floors 2–5 had one flush urinal, and the urinals were piped separately from building wastewater to a storage tank on the 1st floor. The extent of urea hydrolysis, defined as total ammonia nitrogen (TAN) divided by total nitrogen (TN), was measured in urine entering the storage tank (in the pipe) and after urine had been collected for 8 h (in the storage tank). In the pipe, complete hydrolysis of urea, i.e., greater than 90 %, occurred at TN concentrations below 600 mg N/L. In the storage tank, complete hydrolysis of urea was realized after each 8 h urine collection. The pH, conductivity, inorganic anions and cations of urine collected for 8 h on 17 different days is also reported. Three batches of urine were put through a multi-process approach of struvite precipitation, ammonia stripping–acid absorption, and distillation. The mass of N, P, K, and water recovered was over 90 % and the synthesis of value-added products compared well with non-potable water and fertilizers on the market such as struvite, ammonium sulfate, and potash.