Combination of adsorption and heterogeneous photo-Fenton processes for the treatment of winery wastewater.

Abstract

The performance of both adsorption and heterogeneous photo-Fenton processes, combined for the first time for the treatment of a real winery wastewater (WW), was evaluated under different operational conditions. A Portuguese natural Ca-smectite (Ca-Sm) was applied in both processes, however, with different purposes: (1) as an adsorbent, which reveals great capacity to retain organic acids, and (2) as catalyst support for the production of an iron-based catalyst (Fe-Sm). Both Ca-Sm and Fe-Sm materials were characterized by XRD, FTIR, low temperature N2 adsorption isotherms, and SEM-EDX. The adsorption process was investigated under different experimental conditions, namely, different pH, adsorbent dosages, and different concentrations of the organic contaminant. The adsorption isotherm was successfully described by Jovanovich isothermal model (R2 = 0.990), which predicted a maximum adsorption capacity of 161 mg C/g. Regarding to the heterogeneous photo-Fenton process, the higher TOC removal percentage obtained (78.7% - 240 min) was achieved at pH 4.0, with a H2O2 concentration of 98 mM and a catalyst dosage (S:L, solid:liquid ratio) corresponding to 6.00 g/L (UV-C). As a result, the combination of both treatment processes, using the optimized conditions, allowed a total TOC removal of 90%, where the initial TOC0 (825 mg C/L) was reduced by 54%, through the adsorption process, and by 36% by means of heterogeneous photo-Fenton process [TOC0 = 825 mg C/L (1) - TOCf-ads = 380 mg C/L (2) - TOCf-pF = 81 mg C/L (3)].