Performance evaluation of different solar advanced oxidation processes applied to the treatment of a real textile dyeing wastewater.

The performance of different solar-driven advanced oxidation processes (AOPs), such as TiO2/UV, TiO2/H2O2/UV, and Fe2+/H2O2/UV–visible in the treatment of a real textile effluent using a pilot plant with compound parabolic collectors (CPCs), was investigated. The influence of the main photo-Fenton reaction variables such as iron concentration (20–100 mg Fe2+ L−1), pH (2.4–4.5), temperature (10–50 °C), and irradiance (22–68 WUV m−2) was evaluated in a lab-scale prototype using artificial solar radiation. The real textile wastewater presented a beige color, with a maximum absorbance peak at 641 nm, alkaline pH (8.1), moderate organic content (dissolved organic carbon (DOC) = 129 mg C L−1 and chemical oxygen demand (COD) = 496 mg O2 L−1), and high conductivity mainly associated to the high concentration of chloride (1.1 g Cl− L−1), sulfate (0.4 g SO 4 2 − L− 1), and sodium (1.2 g Na+ L−1) ions. Although all the processes tested contributed to complete decolorization and effective mineralization, the most efficient process was the solar photo-Fenton with an optimum catalyst concentration of 60 mg Fe2+ L−1, leading to 70 % mineralization (DOCfinal = 41 mg C L−1; CODfinal < 150 mg O2 L−1) at pH 3.6, requiring a UV energy dose of 3.5 kJUV L−1 (t 30 W = 22.4 min; \( \overline{T}=30\ {}^{\circ}\mathrm{C} \); \( {\overline{\mathrm{UV}}}_{G,n}=44\kern0.75em \mathrm{W}\ {\mathrm{m}}^{-2} \)) and consuming 18.5 mM of H2O2.