Combined Photo-Fenton–SBR Processes for the Treatment of Wastewater from the Citrus Processing Industry

Abstract

In this study, the photo-Fenton process was combined with a sequencing batch reactor (SBR) for the treatment of synthetic samples of citrus wastewater (CWW). An experimental design based on the surface response methodology was applied to assess the individual and combined effects of several operating parameters (CODinitial, Fe3(+) concentration and H2O2 concentration) on the photo-Fenton treatment efficiency (DOC removal) with the aim of optimizing the process. The experimental results obtained under optimal conditions for CWW with high CODinitial (10000 mgO2/L) showed a partial degradation of organic matter of around of 61% (measured as DOC). Thereafter, the photo-Fenton effluent was neutralized and clarified before being subjected to the SBR reactor. The results show degradation yields up to 93% of the initial DOC removal without producing undesired side effects, using a hydraulic retention time (HRT) of 1.59 d. The final effluent contained a concentration of organic matter (measured as COD) of 120 mg O2/L.

Thiamethoxam removal by Fenton and biological oxidation

“…Biotreatments provide an environmentally friendly choice for pollutant management, yet they are largely inefficient as the likely result of the limited resistance of microorganisms to toxic substances . This has led to the use of AOPs as pretreatments to increase biodegradability and reduce toxicity before biological degradation arousing increasing interest recently . A combination of Fenton and biological oxidation allows the shortcomings of Fenton's reagent (e.g.…”

“…23 This has led to the use of AOPs as pretreatments to increase biodegradability and reduce toxicity before biological degradation arousing increasing interest recently. [24][25][26] A combination of Fenton and biological oxidation allows the shortcomings of Fenton's reagent (e.g. high reactant consumption) and the restrictions of biotreatments (e.g.…”

Bimolecular versus Trimolecular Reaction Pathways for H2O2 with Hypochlorous Species and Implications for Wastewater Reclamation

“…For example, palm oil mill effluent has been reported to be highly contaminated with a COD exceeding 8.0 × 10 4 mg L −1 . Manickam et al used the combination of ultrasound and H 2 O 2 technologies to lower the COD in the effluent, and the dose of H 2 O 2 in their study was 8.8 M. 60 Further, Guzman et al applied a photo-Fenton process to treat wastewater from the citrus processing industry with a COD of 2.6 × 10 4 mg L −1 , and the H 2 O 2 dose was also high, up to 0.5 M. 61 H 2 O 2 -based AOTs have been widely used in municipal and industrial wastewater treatment, while hypochlorous species are extensively used as a disinfectant in potable water and other waters (e.g., swimming pool water and landscape water) that directly contact skin. The present study demonstrates that using the cheap and readily available hypochlorous species as the final treatment unit of the tertiary stage not only provides disinfection benefits but also neutralizes the residual H 2 O 2 .…”

Combination of solar advanced oxidation processes and biological treatment strategy for the decolourization and degradation of pulp and paper mill wastewater

“…The coupled system completed the dye degradation in 34 h, reaching a mineralization level of 70%, measured as COD. Guzmán et al [28] studied the degradation of citrus wastewater by the combined solar photo-Fenton and sequential batch reactor. The results showed degradation yields up to 93% of the initial DOC removal without producing undesired side effects, using an HRT of 1.59 d.…”