Aqueous phase of thermo-catalytic reforming of sewage sludge – quantity, quality, and its electrooxidative treatment by a boron-doped diamond electrode

•The aqueous phase separation in sewage sludge pyrolysis were compared for different technologies.•Thermo-catalytic reforming process was compared to fast pyrolysis process.•The amount of resulting aqueous phase strongly depends on the pyrolysis temperature.•Electrooxidation was investigated as purification technology for the resulting aqueous phase.•A COD removal of 95 % was achieved using a boron doped diamond electrode for oxidation.