Life cycle assessment of advanced oxidation processes for olive mill wastewater treatment

The efficient management of biorecalcitrant agro-industrial effluents, such as olive mill wastewater (OMW), is a matter of concern along all Mediterranean countries. However, the applicability of any treatment technique is strongly related, apart from its mineralization and detoxification efficiency, to its joint environmental impacts. In this work, the life cycle assessment methodology was utilized to estimate the environmental footprint of three advanced oxidation processes (AOPs), namely UV heterogenous photocatalysis (UV/TiO₂), wet air oxidation (WAO) and electrochemical oxidation (EO) over boron-doped diamond electrodes, for OMW treatment. It was observed that both EO and WAO can be competitive processes in terms of COD, TPh and color removal. EO was found to be a more environmentally friendly technique as it yields lower total environmental impacts, including CO₂ emissions to atmosphere. The environmental impacts of all three AOPs show that human health is primarily affected followed by impacts onto resources depletion. All in all, it was found that the environmental sustainability of AOPs is strongly related to their energy requirements and that their total environmental impacts decline according to the following order: UV/TiO2 > WAO > EO.