A Novel Cross-flow Wood Filter for Efficient Water Treatment

Water resource shortages have been regarded as an important problem across the world, and membrane filtration technology is one of the effective measures. As a sustainable and renewable biomass material, natural wood owns a fine hierarchical three-dimensional interconnected microstructure that is composed of perpendicularly aligned microchannels lined with micropores. Micropores on the channel walls exhibit suitable rejection ability, providing an advantage to filter water while the treatment speed is severely limited. In this study, we demonstrated a cross-flow wood filter in which muddy water can be transferred along the microchannels and out of the vertically stacked micropores. The cross-flow wood filter takes full advantage of the micropores without sacrificing the speed of hydraulic flow within the main transport channels, exhibiting excellent performance for mud removal. In this manner, the treatment efficiency of turbidity, decolorization, and water flux is highly dependent on the groove number, depth, and thickness of the filter. At vacuum filtration, the turbidity removal rate and decolorization rate of an 8 mm-thick cross-flow wood filter with 3 grooves and 2 mm depth reached around 99% and 92% at a water flux up to 6.75 L/(m$^{\mathrm{2}}\cdot$ h), featuring a compromise between the mutually exclusive properties. The design of the cross-flow wood filter provides an available platform that can be extended to various wastewater treatment processes with different impurities, displaying a good application prospect in the wastewater treatment field.