A zero-wastewater-discharge noncontact solar desalter for saline–alkali soil remediation and grain yield increase using brackish water

Abstract

Over one billion hectares of land worldwide are at risk of salinization, posing a significant threat to global agriculture. Soil washing is the major remediation method, but freshwater dependence and high-salinity wastewater discharge remain formidable challenges, making this technology unsustainable. We regulate soil salinity directly using brackish water by constructing zero-wastewater-discharge noncontact solar soil desalters, minimizing freshwater dependence and negative environmental impacts, thus promoting agricultural production. The non-contact structure can convert sunlight into infrared radiation to drive the desalters to extract salt from the soil, avoiding the performance degradation caused by salt accumulation in the desalters. Meanwhile, this design also suppresses the residue of high-salinity wastewater in the soil, ensuring that all high-salinity wastewater is harmlessly treated. Ultimately, soil salinity sharply decreases from 11.04 to 0.95 mg g⁻¹ without wastewater discharge, sufficient to support 100% germination of wheat. Global wheat production is expected to increase by 1.09% based on the geographic information of wheat and soil. Our desalters provide guarantees for global food security with its environmental concepts of “zero wastewater discharge” and “soil remediation using brackish water”.