The influence of inorganic components and carbon-oxygen surface functionalities in activated hydrothermally carbonized waste materials for water treatment

In this study, we have examined how the activation of hydrothermally carbonized sewage sludge and horse manure influences the inorganic component of these materials and surface chemistry. This was examined through statistical correlations between kinetic tests using trimethoprim, fluconazole, perfluorooctanoic acid, and copper, zinc, and arsenic and physicochemical properties. Yield and inorganic content varied considerably, with potassium hydroxide–activated materials producing lower yields with higher inorganic content. Phosphoric acid activation incorporated inorganically bound phosphorus into the material, although this showed no statistically relevant benefit. A maximum surface area of 1363 m(2)g(−1) and 343 m(2)g(−1) was achieved for the horse manure and sewage sludge. Statistical analysis found positive correlations between carbon-oxygen functionalities and trimethoprim, fluconazole, perfluorooctanoic acid, and copper removal, while inorganic content was negatively correlated. Conversely, arsenic removal was positively correlated with inorganic content. This research provides insight into the interactions with the organic/inorganic fraction of activated waste materials for water treatment. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s11356-020-09839-1) contains supplementary material, which is available to authorized users.