Regional analysis of technological alternatives for boron reduction in desalinated seawater for irrigation in south-eastern Spain

Desalinated seawater (DSW) is currently considered a reliable alternative supply of agricultural water in south-eastern Spain able to alleviate the looming water crisis as it buffers natural hydro-climatic volatility. However, irrigation with DSW may pose an agronomic risk because reverse osmosis permeates usually have high boron concentrations, representing a real toxicity damage risk for sensitive crops. Boron reductions to at least 0.5 mg/L, either on-farm or at the coastal seawater desalination plant, should be performed before irrigating with DSW, especially in areas with sensitive crops. The regional economic impact of reducing boron in diverse irrigation districts covered with different crops has never been evaluated. In this article, that impact is analyzed considering three scenarios replacing traditional irrigation water resources with DSW, and two boron reduction technologies: reverse osmosis membranes (RO) and ion exchange resins (IX).

The results reflected that: (i) boron reduction by IX is notably cheaper than by RO; (ii) at seawater desalination plant scale, the boron reduction cost remains constant regardless of the crop type, whereas at on-farm scale the higher the surface area covered by vegetables the lower the boron reduction cost; and (iii) the volume of by-product generated in resin regeneration is 40 times lower than that in the RO process, so consequently its handling and management would be far easier and less costly. Additionally, the study corroborates that the combined use of DSW with traditional resources is the most economically efficient option from the different perspectives of the study, compared to irrigating with DSW alone.