Herbicide removal from water: Investigating the Potential of Electrochemistry and Hydrochar-based Activated Carbon

Terbuthylazine has been introduced to replace atrazine in most of the EU countries; nowadays, this herbicide is one of the most frequently detected in environmental waters. The persistence and the endocrine disruptor activity of this chemical of emerging concern have been established. Conventional treatments applied in drinking water plants do not lead to the complete removal of pesticides and among them, adsorption provides the greatest efficiency. Hydrochar obtained through the hydrothermal carbonization of sewage sludge has been activated and its adsorption capacity has been tested. Moreover, an innovative electrochemical reactor with a Solid Polymer Electrolyte (SPE) has been applied for removing terbuthylazine from an aqueous medium. The activated hydrochar demonstrated an adsorption capacity of 422 mg g-1, reached in 6 hours. Considering the reduction of the volume of sludge to be disposed of obtained if hydrothermal carbonization is carried out, and the thermovalorization of the exhausted hydrochar if used for pollutant removal, further analysis is encouraged to evaluate its effectiveness as adsorbent media in filtration vessels. Up to 88% of the herbicide has been completely removed by the electrolytic treatment in the first hour of treatment, while only 1% has been converted in minor metabolites. Both the sorbent and the advanced oxidation technique investigated here could be applied for the removal of other pesticides and drugs metabolites in water treatment facilities, while the fast removal attained by the SPE technology also offers a prospective for the in-situ remediation of pesticides-polluted groundwater.