Simultaneous phosphorous and nitrogen recovery from source-separated urine: A novel application for fertiliser drawn forward osmosis

Abstract

Re-thinking our approach to dealing with waste is one of the major challenges in achieving a more sustainable society. However, it could also generate numerous opportunities. Specifically, in the context of wastewater, nutrients, energy and water could be mined from it. Because of its exceptionally high nitrogen (N) and phosphorous (P) concentration, human urine is particularly suitable to be processed for fertiliser production. In the present study, forward osmosis (FO) was employed to mine the P and N from human urine. Two Mg-fertilisers, i.e. MgSO and Mg(NO) were selected as draw solution (DS) to dewater synthetic non-hydrolysed urine. In this process, the Mg reverse salt flux (RSF) were used to recover P as struvite. Simultaneously, the urea was recovered in the DS as it is poorly rejected by the FO membrane. The results showed that, after concentrating the urine by 60%, about 40% of the P and 50% of the N were recovered. XRD and SEM - EDX analysis confirmed that P was precipitated as mineral struvite. If successfully tested on real urine, this process could be applied to treat the urine collected in urban areas e.g., high-rise building. After the filtration, the solid struvite could be sold for inland applications whereas the diluted fertiliser used for direct fertigation of green walls, parks or for urban farming. Finally, reduction in the load of N, P to the downstream wastewater treatment plant would also ensure a more sustainable urban water cycle.

Research on Forward Osmosis Membrane Technology Still Needs Improvement in Water Recovery and Wastewater Treatment

“…Federico [90,123] exploited a FO process to recover phosphorus, nitrogen, and other substances from human urine with Mg(NO 3 ) 2 ·6H 2 O as DS. The urine was concentrated and reclaimed as N (2.24 AUD/kg) with the recovery rate of 50%, meanwhile the concentrated PO 4 3and the RSD Mg 2+ could be recovered as struvite.…”

Bacteria-supported iron scraps for the removal of nitrate from low carbon-to-nitrogen ratio wastewater

“…Traditional nitrate removal methods include biological denitrication, [5][6][7] ion exchange, 8,9 osmosis, 10,11 electrodialysis, 12,13 etc. The chemical and physical methods of ion exchange, osmosis and electrodialysis have their drawbacks such as high cost and energy consumption, which limit the larger scale application.…”

Effect of Brine Water on Discharge of Cations in Membrane Capacitive Deionization and Its Implications on Nitrogen Recovery from Wastewater

“…The technologies recovering nitrogen and phosphorus from wastewaters, however, are still in progress of development as they are yet economically challenging [4,5].…”