Janus 3D solar crystallizer enabling an eco-friendly zero liquid discharge of high-salinity concentrated seawater with antiscalant

Abstract

Zero liquid discharge (ZLD) of high-salinity brine has attracted increasing attention recently. Interfacial solar crystallizers, which employ solar-driven water evaporation for salts crystallization from the near-saturation brine to achieve ZLD, are promising in ZLD due to low energy consumption and cost. However, many interfacial solar crystallizers were only used to treat high-salinity NaCl solution in the past while probably failing when treating high-salinity concentrated seawater. Here we explored the failure mechanism of the solar crystallizers in the high-salinity concentrated seawater and proposed a novel strategy to stably treat high-salinity concentrated seawater by combining a solar crystallizer with antiscalant (Nitrilotriacetic acid, NTA), taking Janus 3D solar crystallizer (Janus-3DSC) as an example. Janus-3DSC exhibited a stable average evaporation rate of 2.29 ± 0.36 kg m−2 h−1 under 1.5 sun in the 20.0 wt% concentrated simulated seawater containing NTA. The large-size Janus-3DSC could treat 20.0 wt% concentrated natural seawater containing NTA outdoors with a salt recovery rate of 11.27 kg m−2 day−1 and an evaporation rate of 18.63 kg m−2 day−1. We believe that this work would provide a novel and effective way to achieve effective and eco-friendly ZLD of high-salinity concentrated seawater, even other high-salinity brine.