BOTELHO RUAS, Diego; RODRIGUEZ CHAPARRO, Tatiana    CLETO PIRES, Eduardo. Advanced oxidation process H₂O₂/UV combined with anaerobic digestion to remove chlorinated organics from bleached kraft pulp mill wastewater. []. , 63, pp.43-54. ISSN 0120-6230.

This study investigated the application of an advanced oxidation process combining hydrogen peroxide with ultraviolet radiation (H₂O₂/UV) to remove recalcitrant compounds from Kraft bleaching effluent. Anaerobic pre-treatment was performed to remove easily degraded organics using a horizontal-flow anaerobic immobilized biomass (HAIB) reactor. Bleaching plant effluent was treated in the HAIB reactor processed over 19 h of hydraulic retention time (HRT), reaching the expected removal efficiencies for COD (61 ± 3%), TOC (69 ± 9%), BOD₅ (90 ± 5%) and AOX (55 ± 14%). However, the anaerobic treatment did not achieve acceptable removal of UV₂₅₄ compounds. Furthermore, there was an increase of lignin, measured as total phenols. The H₂O₂/UV post-treatment provided a wide range of removal efficiencies depending on the dosage of hydrogen peroxide and UV irradiation: COD ranged from 0 to 11%, UV₂₅₄ from16 to 35%, lignin from 0 to 29% and AOX from 23 to 54%.  All peroxide dosages applied in this work promoted an increase in the BOD₅/COD ratio of the wastewater. The experiments demonstrate the technical feasibility of using H₂O₂/UV for post-treatment of bleaching effluents submitted to anaerobic pre-treatment.

: Advanced oxidation process; bleaching effluents; recalcitrant organic matter; AOX; biodegradability ratio.

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