Techno-economic comparison between forward osmosis (FO) and temperature-enhanced osmotic membrane distillation (T-OMD) in agricultural fertigation

Abstract

Forward osmosis (FO), as one energy-efficient desalination technology, had been intensively studied in agricultural fertilization to meet the demand of the water resource and the fertilizer for plant growth, showing good techno-economic benefit. As such, the energy-efficient temperature-enhanced osmotic membrane distillation (T-OMD) heated by low-grade thermal sources (i.e. solar energy) was firstly investigated in agricultural fertilization via techno-economic comparison with FO. The experimental investigation revealed that T-OMD in the agricultural fertigation can be endowed with quadruple advantages of high water flux at a high-temperature difference (>40 °C), low fertilizer loss, good compatibility for different fertilizers, and good feasibility to utilize some unconventional waters (i.e. wastewater, seawater, and seawater RO brine). Furthermore, a preliminary economic analysis showed that the membrane area and the price of the FO membrane module are two significant indicators to evaluate the economic feasibility of T-OMD. In detail, T-OMD must be more cost-effective than FO if the total membrane area is larger than 10,000 m2 under the same operating temperature configuration or dilution factor lower than 0.25 and permeate flux higher than 10,000 m3/h are satisfied under different operating temperature configurations. Based on the experimental investigation and economic analysis, T-OMD can provide an alternative pathway to achieve high-efficient and cost-effective agricultural fertigation.