Integrated aerobic biological–chemical treatment of winery wastewater diluted with urban wastewater. LED-based photocatalysis in the presence of monoperoxysulfate

ABSTRACT

The oxidation of Winery Wastewater (WW) by conventional aerobic biological treatment usually leads to inefficient results due to the presence of organic substances, which are recalcitrant or toxic in conventional procedures. This study explores the combination of biological and chemical processes in order to complete the oxidation of biodegradable and non-biodegradable compounds in two sequential steps. Thus, a biological oxidation of a diluted WW is carried out by using the activated sludge process. Activated sludge was gradually acclimated to the Diluted Winery Wastewater (DWW). Some aspects concerning the biological process were evaluated (kinetics of the oxidation and sedimentation of the sludge produced). The biological treatment of the DWW led to a 40–50% of Chemical Oxygen Demand (COD) removal in 8 h, being necessary the application of an additional process. Different chemical processes combining UVA-LEDs radiation, monoperoxysulfate (MPS) and photocatalysts were applied in order to complete the COD depletion and efficient removal of polyphenols content, poorly oxidized in the previous biological step. From the options tested, the combination of UVA, MPS and a novel LaCoO₃–TiO₂ composite, with double route of MPS decomposition through heterogeneous catalysis and photocatalysis, led to the best results (95% of polyphenol degradation, and additional 60% of COD removal). Initial MPS concentration and pH effect in this process were assessed.

KEYWORDS:

• Winery wastewater
• monoperoxysulfate
• LEDs
• photocatalysis
• perovskites

Acknowledgments

The authors would like to express their gratitude to Águas de Trás-os-Montes e Alto Douro (AdTMAD) for providing activated sludge sample from the urban wastewater treatment plant of Vila Real (Portugal).

Funding

Authors thank the economic support received from Gobierno de Extremadura (GRU15033) and MINECO of Spain (CTQ2015/64944-R and red FOTOCAT CTM2015-71054-REDT), co-financed with FEDER founds.

Mr. Rafael Rodríguez Solís acknowledges Gobierno de Extremadura, Consejería de Empleo Empresa e Innovación, and FSE Funds for his Ph.D. grant (PD12058).

Authors also acknowledge the funding provided by the Project INTERACT- Integrative Research in Environment, Agro-Chains and Technology – NORTE-01-0145-FEDER-000017 and Project INNOVINE & WINE – Innovation Platform of Vine and Wine – NORTE-01-0145-FEDER-000038 (Portugal).