Comparative adsorption evaluation of biochars from paper mill sludge with commercial activated carbon for the removal of fish anaesthetics from water in Recirculating Aquaculture Systems

Tricaine methanesulfonate (MS-222), benzocaine and 2-phenoxyethanol (2-PE) are widely used in intensive aquaculture systems to control stress during handling and confinement operations. This work aimed to study the adsorptive removal of these anaesthetics from water, comparing two waste-based adsorbents produced by pyrolysis of paper mill sludge with a commercial activated carbon. The use of commercial activated carbon resulted in maximum adsorption capacities of 631, 435 and 289 mg g⿿1 for MS-222, benzocaine and 2-PE, respectively (obtained by the fitting of Langmuir-Freundlich model), which are between 4 and 8 times higher than those determined for the alternative adsorbents. Even so, the obtained results point to the promissory utilization of these waste-based adsorbents in Recirculating Aquaculture Systems, as an integrated way of managing such residues and treatment of aquaculture waters contaminated with anaesthetics.