Ultra-Efficient Saline Soil Remediation with Passive Multistage Solar Distiller via Water Recycling

The remediation of saline land is of great strategic significance for ensuring food security and promoting ecological restoration. Interfacial solar evaporator shows considerable potential in soil remediation but still faces challenges, such as low solar-steam efficiency and high freshwater consumption. Herein, we report for the first time a passive multistage solar distiller for ultra-efficient saline soil desalination that integrates the latent heat recovery, water recycling and edge salt rejection. Under one-sun irradiation (1 kW m^-2), the 7-stage solar distiller achieves a water yield of 3.0 kg m^-2 h^-1 with a solar-steam efficiency of 200% in saline soil. After 12 days of treatment, the salinity in 30 cm-thick saline soil had decreased from 22.5 to 2.33 g kg^-1, with a water consumption (water-to-soil ratio) of 40.1 kg m^-2. Furthermore, the large-scale saline soil desalination using the multistage solar distiller works efficiently outdoors, indicating that such technology can promote the green remediation of global saline land and the sustainable development of agriculture.