Biochar can be used as a sorbent to remove inorganic pollutants from water but the efficiency of sorption can be improved by activation or modification. This review evaluates various methods to increase the sorption efficiency of biochar including activation with steam, acids and bases and the production of biochar-based composites with metal oxides, carbonaceous materials, clays, organic compounds, and biofilms. We describe the approaches, and explain how each modification alters the sorption capacity. Physical and chemical activation enhances the surface area or functionality of biochar, whereas modification to produce biochar-based composites uses the biochar as a scaffold to embed new materials to create surfaces with novel surface properties upon which inorganic pollutants can sorb. Many of these approaches enhance the retention of a wide range of inorganic pollutants in waters, but here we provide a comparative assessment for Cd, Cu, Hg, Pb, Zn, NH, NO, PO, CrO and AsO.

Fabric shedding during laundering is detrimental to the longevity of clothing textiles, and in the case of non-biodegradable, synthetic fabrics, it is a source of diffuse microplastic fiber pollution. Textile recycling offers numerous economic and environmental benefits; however differences in fabric shedding due to their recycled fiber contents are relatively unknown. Accelerated laundering experiments were conducted to quantify the shedding propensity and characteristics of cotton knit, polyester knit, and twill weave fabrics, each at three differing recycled fiber contents. The 70% recycled polyester shed significantly fewer microfibers than the 40% recycled polyester. No other significant influences of recycled fiber content on shedding propensity were identified. The mean length of shed fibers from the 70% recycled polyester was significantly higher than that of the virgin polyester and the 40% recycled polyester.

The laundering of synthetic fabrics has been identified as an important and diffuse source of microplastic (< 5 mm) fibre contamination to wastewater systems. Home laundering can release up to...

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