Spruce wood and Typha (wetland plant) derived biochars pyrolyzed at 350 °C and 600 °C were tested for their sorption affinity for organic pollutants (diclofenac, methylparaben, benzotriazole and sodium 1-decanesulfonate) and nutrients (nitrate, ammonium, phosphate and boron) commonly found in greywater. Batch and column studies combined with molecular dynamics modelling determined the sorption capacity, kinetics, and described the underlying mechanisms. The spruce biochar (600 °C) exhibited the highest sorption capacity mainly for the tested organics. The dynamic test performed for spruce biochar (600 °C) showed that the magnitude of desorption was low, and the desorbed amount ranged between 3 and 11 %. Molecular dynamics modelling (a computational tool for elucidating molecular-level interactions) indicated that the increased sorption of nitrate and boron on spruce biochar (600 °C) could be attributed to hydrophobic interactions. The molecular dynamics shows that predominant adsorption of organic pollutants was governed by π-π stacking, with a minor role of hydrogen-bonding on the biochar surface. In summary, higher pyrolysis temperature biochar yielded greater adsorption capacity greywater borne contaminants and the reaction temperature (10-34 °C) and presence of anionic surfactant had a limited effect on the adsorption of organic pollutants, suggesting efficacious application of biochar in general for greywater treatment in nature-based systems.

Civil and Environmental Engineering Department Faculty of Engineering The University of Auckland Private Bag 92019 Auckland 1142 New Zealand

Czech University of Life Sciences Prague Faculty of Environmental Sciences Department of Applied Ecology Kamýcká 129 165 21 Praha 6 Suchdol Czech Republic

Czech University of Life Sciences Prague Faculty of Environmental Sciences Department of Environmental Geosciences Kamýcká 129 165 21 Praha 6 Suchdol Czech Republic

Department of Power Engineering Faculty of Environmental Technology University of Chemistry and Technology Prague Technická 5 166 28 Prague 6 Czech Republic

Ecosphere Resilience Research Center Faculty of Applied Sciences University of Sri Jayewardenepura Nugegoda 10250 Sri Lanka

Faculty of Science University of South Bohemia in České Budějovice Branišovská 1645 31A 37005 České Budějovice Czech Republic

Institute of Chemical Process Fundamentals of the Czech Academy of Sciences 5 5 1 Rozvojová 135 165 02 Praha 6 Suchdol Czech Republic

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