Combined long-term aerated storage and photo-Fenton process for winery wastewater treatment: operational conditions...

Winery wastewater (WW) is an environmental problem in wine producing countries. In this work, a long-term aerated storage (LTAS) biological reactor was commissioned and optimal operational conditions were assessed. Regarding air supply, data shows that LTAS operational conditions (air flow = 110 dm³/h, aeration period 15 h/day, time = 15 days, V = 5 L) allowed to achieve a high microbial growth with a chemical oxygen demand (COD) reduction of 98.8 % and a dissolved organic carbon (DOC) removal of 88.7 % and low cost (0.124 €/g.DOC). The remaining non-biodegradable organic fraction was afterwards submitted to a UV-C photocatalytic reactor. Optimal photo-Fenton conditions obtained were pH = 3.0, [H₂O₂] = 97 mM, [Fe²⁺] = 2.5 mM and reaction time = 240 min. This allowed a DOC reduction of 98.2 % with an electric energy per mass (E_EM) = 0.410 kWh/g.DOC. Combined LTAS/photo-Fenton processes have a synergistic effect, achieving 99.0 and 98.2 % of removal of COD and DOC, respectively, and allowing the discharge of treated WW in conformity with the Portuguese Legislation (Decree-law n. 236/98) with a low cost (0.158 €/g.DOC). The LTAS/photo-Fenton system can be an interesting solution to manage WW treatment.