Improving sustainability of electrolytic wastewater treatment processes by green powering.

This work focuses on the evaluation of the impact of powering electrolytic wastewater treatment processes with grid or renewable energy on the sustainability of this electrochemical remediation technology. To face this goal, it was performed an inventory of three bench-scale plants made up by the same treatment technology but powered from different supplies: connected to grid and directly coupled with solar photovoltaic panels or a wind turbine. Results show that the powering mode can significantly affect the environmental risks of the treatment, not only in terms of electricity demand but also on the formation of intermediates, which are more important in the cases in which the intensity profile varied. A life cycle assessment (LCA) is carried out in order to quantify the environmental impacts of green powering electrolytic wastewater treatment processes. Ecoinvent 3.3 data base, AWARE, USEtox, IPPC and ReCiPe methodologies are used to quantify the environmental burden into 5 midpoint (water footprint, global warming 100a, ozone layer depletion, human toxicity, freshwater ecotoxicity) and 17 endpoint impact categories. All impact categories are higher in the case in which the supplied power cames from a electricity grid mix. For the removal of 0.1 g 2,4-dichlorophenoxyacetic acid (2,4D) per liter (functional unit) of treated wastewater releases 0.14 kg CO eq. If the energy is provided by a wind turbine or a solar panel the processes emit 0.020 kg CO eq and 0.019 kg CO eq, respectively. A comparison of the impact based on the grid mix used in different countries is also made, which has pointed out the relevance of this input on the sustainability of the environmental electrochemical technologies.