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Water availability is an important issue all over the world, and membrane filtration technology is one of the most effective measures for remediation. As a sustainable and renewable biomass material, natural wood has a hierarchical and three-dimensional interconnected microstructure, which provides an alternative for water filter design. Longitudinal filtration could take advantage of the micropores, while the treatment speed is severely limited. This study examined a wood filter in which muddy wastewater can be transported into the microchannels and out of the vertically stacked micropores. The filter takes full advantage of the pores present in the wood without sacrificing the speed of hydraulic flow within the main transport channels, exhibiting excellent performance for mud removal. In this manner, water flux, decolorization, and turbidity are highly dependent on the groove number, groove depth, and thickness of the filter. Due to the reorientation of the water transport pathways, the clogging of micropores could be easily alleviated, thus promoting the filter lifecycle. The design of the cross-flow wood filter can provide an available platform for various wastewater treatment cases with different impurities, displaying an application prospect in the wastewater treatment field.

Hierarchical porous carbons were prepared from several common lignins, including sodium lignosulfonate (SLS), alkali lignin (AL), and calcium lignosulfonate (CLS) via one-step carbonization at 800 °C for 10 h without oxygen or any additional templating/activation agent for the decolorization of dyes from wastewater. The obtained carbons showed high porosity and microporous-mesoporous-macroporous hierarchical porous structures. The specific surface areas of SLS-C, AL-C, and CLS-C were 346 m²/g, 405 m²/g, and 512 m²/g, respectively. The total pore volumes of SLS-C, AL-C, and CLS-C were 0.12 cm³/g, 0.21 cm³/g, and 0.28 cm³/g, respectively. The obtained carbon materials displayed excellent adsorption-decolorization abilities for 5 dyes, including ethyl violet, malachite green, cationic brilliant red, acid blue 92, and direct red 23. The concentrations of these 5 dyes in wastewater were reduced by SLS-C from 20 mg/L to 0.12 mg/L, 0.20 mg/L, 0.32 mg/L, 0.78 mg/L, and 3.77 mg/L, respectively, over a 60 min treatment. AL-C reduced these concentrations from 20 mg/L to 0.02 mg/L, 0.01 mg/L, 0.04 mg/L, 0.71 mg/L, and 1.72 mg/L over the same time period. In addition, the concentrations of these respective dyes were reduced by CLS-C from 20 mg/L to 0.01 mg/L, 0.01 mg/L, 0.02 mg/L, 0.30 mg/L, and 0.20 mg/L. [ABSTRACT FROM AUTHOR]