Production of an engineered fertilizing solution from treated waste water using forward osmosis

Abstract

Treated sewage effluent (TSE) contains high concentrations of total dissolved solids and nutrients, which makes TSE unsuitable for direct use for irrigation. In this study, forward osmosis (FO) is utilized to produce a fertilizing solution from TSE that can be directly used for irrigation. An engineered fertilizing solution was used as a draw solution while the feed solution was TSE in the forward osmosis process. The engineered fertilizing solution is made of 0.5 M NaCl and 0.01 M of Diammonium phosphate [(NH4)2HPO4]. The effect of feed solution and draw solution flow rate on the permeate flux is studied. Furthermore, the impact of the membrane orientation on the permeate flux is also studied. Results showed that the highest membrane flux was 13.2 LMH, achieved at a flow rate of 2 LPM for the feed solution and the draw solution. Moreover, at 2 LPM flowrate, when the feed solution is facing the active layer of the membrane (FO mode) showed 114% higher permeate flux than when the draw solution is facing the active layer (PRO mode).