Abstract—Advanced oxidation of ECF (elemental chlorine free) bleaching wastewater (D1 and E stage of DED and ODED sequences) using TiO₂ photocatalysis has been investigated for environmental load reduction. The wastewaters were generated in the laboratory by chlorine dioxide (D) bleaching and alkaline extraction (E) of the mixed hardwood kraft pulp under controlled conditions. The bleaching wastewaters were subjected to photocatalytic oxidation under UV radiation with 0.5 g/L of TiO2 at a pH 7.0 for 4 h in a slurry-type reactor. Higher removal efficiencies have been observed for ODED sequence wastewaters as compared with DED sequence. UV/TiO2 oxidation removed 46.3% BOD (biochemical oxygen demand), 64.2% COD (chemical oxygen demand), 88.3% color, and 59.3% AOX (adsorbable organic halides) for D1 and 55% BOD, 66.5% COD, 86.7% color, and 64.2% AOX for E stage wastewaters of ODED sequence. Higher improvement in BOD/COD ratio has been observed for ODED sequence wastewaters as compared with DED. This shows that wastewaters from ODED sequence are more amenable to photocatalytic degradation.

Index Terms—Advanced oxidation, AOX, biodegradability, TiO₂ photocatalysis.

Parveen Kumar was with DPT, Indian Institute of Technology Roorkee, Saharanpur Campus, Saharanpur - 247001, U.P., India. He is now with the ASET, Amity University Haryana, Gurgaon (Manesar) – 122413, Haryana, India (e-mail: parveenenv@gmail.com).
Satish Kumar is with DPT, Indian Institute of Technology Roorkee, Saharanpur Campus, Saharanpur - 247001, U.P., India (e-mail: kumarfpt@iitr.ernet.in).
Nishi Kant Bhardwaj was with DPT, Indian Institute of Technology Roorkee, Saharanpur Campus, Saharanpur - 247001, U.P., India. He is now with TCIRD, Paper Mill Campus, Yamuna Nagar - 135001, Haryana, India (e-mail: nishi.bhardwaj@gmail.com).

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Cite: P. Kumar, S. Kumar, and N. K. Bhardwaj, "Advanced Oxidation of ECF Bleaching Wastewater Using TiO₂ Photocatalysis," International Journal of Environmental Science and Development vol. 3, no. 5, pp. 501-506, 2012.