Design Of Solar-Driven Multistage Wastewater Treatment Device And Investigate Of Water Collection Rate

Solar-driven interfacial light-vapor conversion technology is an effective pathway and is widely used to alleviate the shortage of freshwater resources.However,the multistage devices for freshwater collection still face the problems of complicated preparation methods,high prices,and low water collection rates.In this work,we prepared a solar-driven multistage wastewater treatment device based on three components with inexpensive and easy-to-get materials,such as copper sheets,carbon fibers,and viscose-based non-woven fabrics to efficiently collect fresh water.In detail,the carbon fiber array structure can greatly increase light absorption rate as the photothermal layer,the viscose-based non-woven fabric for rapid water supply as a water channel and evaporation layer,and the hydrophobic water collection layer for rapid condensation water collection.Based on the above-mentioned material optimization,we designed a water supply mode from the middle to both sides to achieve fast and efficient water collection.The hydrophobic water collection layer presents a certain inclination angle to facilitate spontaneous water collection.The air gap distance between the evaporation layer and the condensation layer greatly affects energy utilization and water collection.Therefore,in this work,we optimized the air gap distance of the single-stage device to 3 mm and achieved the highest water collection rate of 0.39 kg m^-2h^-1under a simulated solar illumination.In addition,to explore the rationality of the device design,we used COMSOL Multiphysics software to perform mathematical modeling and heat transfer simulation analysis and simulate the temperature distribution in the steady state of device operation.To realize the full utilization of energy,we built a multistage device based on the above single-stage device to facilitate the recovery of latent heat.Ultimately our ten-stage device achieved a water collection rate of up to 2.05 kg m^-2h^-1under one solar illumination,with an actual energy utilization efficiency of 148.85%（>100%）,indicating that the device made full use of latent heat and realized efficient water collection.Finally,we selected printing and dyeing wastewater as the water to be treated for outdoor water collection experiments to test the practical application performance of the ten-stage device.The device can achieve 10.43 kg m^-2of freshwater collection in one day.The chemical oxygen demand and major ion concentration of the collected freshwater are substantially reduced,indicating that the device possesses broad development value and application prospects.It also provides a new idea for the design of subsequent multistage interface evaporation devices.