Wind-enhanced interfacial evaporation from simulated and real slurry wastes

Reducing the volume of slurry waste is urgently needed for shortening the timeline for reclamation of the occupied land for waste slurry storage. In this work, an eco-friendly, clean and efficient wind-driven interfa- cial evaporation technology was developed to accelerate drying of particle-laden wastewater. A self-floating mini-boat was constructed to transfer water from the slurry source to an evaporation surface of a porous sail for fast evaporation. The evaporator could speed up the drying process of the slurry beyond 75 wt% solid concentration at an evaporation rate (ER) of 8 kg/(m²h¹), 18 times faster than natural evaporation. Before reaching a transition point of the solid content, the ER was found to scale with the Peclet number of the wind with a power 0.5, due to the enhanced mass transfer on the sail surface. Even for real tailing wastewater, effective volumetric reduction with over 80 wt% fines concentration can be reached in the dried slurry. The scalability of this clean approach was demonstrated by using a large evaporator surface up to 4750 cm² in the outdoor experiments. The wind-driven interfacial evaporation developed in this work may be applied to speed up the drying process of particle-laden wastewater entirely powered by renewable energy.