Treatment of winery wastewater by a Fe²⁺-EDDS-photo-Fenton process. Assessment of UV-C, UV-A and solar radiation

The winery wastewater (WW) generally presents a high organic load and phytotoxicity, constituting an environmental problem if disposed directly to natural water courses or soils. Therefore, suitable treatment processes must be applied to reduce their pollutant load. In this work, it was performed the treatment of WW by employing a modified photo-Fenton process. The aim of this work was (1) application of Ethylenediamine-N,N’-disuccinic acid (EDDS) to reduce the precipitation of iron, (2) evaluate the application of different radiation types (UV-C, UV-A and solar). The results showed that under the best operational conditions, as follows: [Fe²⁺] = 5 mM, [H₂O₂] = 175 mM, [EDDS] = 1 mM, [HA] = 1mM, pH 3.0, agitation 350 rpm, temperature 298 K, UV-C (254 nm), reaction time 240 min, it was achieved a chemical oxygen demand (COD) removal of 99.5%. The pH of the WW was varied from 3.0 to 6.0, and results showed that at pH 6.0 it was achieved a COD removal of 93.2 % (UV-C) > 81.6% (solar radiation) > 60.6% (UV-A) > 8.5% (dark). Therefore, it is concluded that using a pH higher (pH = 6.0) than that usually used for the photo-Fenton process (pH = 3.0) because of EDDS, which reveals the potential application of this process.