Techno-economic feasibility of recovering phosphorus, nitrogen and water from dilute human urine via forward osmosis

Abstract

Due to high phosphorus (P) and nitrogen (N) content, human urine has often proven to suitable raw material for fertiliser production. However, most of the urine diverting toilets or male urinals dilute the urine 2 to 10 times. This decreases the efficiency in the precipitation of P and stripping of N. In this work, a commercial fertiliser blend was used as forward osmosis (FO) draw solution (DS) to concentrate real diluted urine. During the concentration, the urea in the urine is recovered as it diffuses to the fertiliser. Additionally, the combination of concentrate PO4 3-, reverse Mg 2+ flux from the DS and the Mg 2+ presents in the flushing water, was able to recover the PO4 3as struvite. With 50% concentrated urine, 93% P recovery was achieved without the addition of an external Mg 2+ . Concurrently, 50% of the N was recovered in the diluted fertiliser DS. An economic analysis was performed to understand the feasibility of this process. It was found that the revenue from the produced fertilisers could potentially offset the operational and capital costs of the system.Additionally, if the reduction in the downstream nutrients load is accounted for, the total revenue of the process would be over 5.3 times of the associated costs.

Role of Operating Conditions in a Pilot Scale Investigation of Hollow Fiber Forward Osmosis Membrane Modules

“…DS selection has been abundantly studied [20,31,57,58,59] in order to tune the FO process for a specific application, to reduce the costs of the process, or to obtain a more environmentally friendly technology. Here, three common inorganic salts (NaCl, MgCl 2 , MgSO 4 ) at various concentrations were tested as a draw solute.…”

Human urine as a forward osmosis draw solution for the application of microalgae dewatering

“…severe flux decline and irreversible fouling. Recent papers have shown that when urine is facing the active layer of the membrane, the fouling is reversible [35,44]; however, no investigations into support layer fouling when urine is used as a draw solution have yet been published.…”

New frontiers from removal to recycling of nitrogen and phosphorus from wastewater in the Circular Economy

“…By way of example, Singh et al (2019) achieved recoveries of phosphate (PO4 3− ) and ammonia (NH3, FAN) of 75% and 66%, respectively, using divalent magnesium chloride as the draw solution. Volpin et al (2019) recovered 93% of the P and 50% of the N from dilute human urine. The economic analysis revealed that the revenue from the fertilizers produced could potentially offset the overall costs of the system.…”