Advanced oxidation processes for the treatment of winery wastewater: a review and future perspectives

Abstract

AbstractWinemaking is a water‐intensive operation; it is estimated that 70% of the water input is downgraded, mainly via cleaning processes, to wastewater. The quality and the quantity of the waste effluents vary considerably due to the seasonal operation of wineries and the diversity of winemaking technologies applied. High organic load, acidic pH, significant polyphenolic content, and residual concentration of phytosanitary products are included among the main characteristics of winery wastewater (WiWW). Discharge of untreated or partially treated WiWW into watercourses or land poses high environmental risks. To this end, biological oxidation has been thoroughly studied for the treatment of WiWW yielding up to 95% reduction of chemical oxygen demand (COD) at a low cost and in an environmentally benign manner. Biological treatment, however, cannot provide a barrier to the slip of bio‐recalcitrant compounds present in WiWW, such as phenols and pesticides, into the environment. The release of these compounds raises serious concerns over ecological well‐being due to their toxicity and endocrine‐disrupting effects. Sustainable post‐treatment technologies are sought, able of breaking down the bio‐recalcitrant fraction of WiWW to harmless products without stressing the environmental resources. Advanced oxidation processes (AOPs) can offer a sound technological solution towards the integrated WiWW treatment. This paper presents an up‐to‐date overview of the AOPs (TiO2‐, sulfate radical‐, Fe‐, ozone‐based AOPs, and wet oxidation processes) that have been studied for the treatment of WiWW, remarks the most efficient ones, and identifies research areas and concepts aiming towards process sustainability and, ultimately, actual application. © 2021 Society of Chemical Industry (SCI).