Ozonation of Dyes and Textile Wastewater in a Rotating Packed Bed

Abstract

This study investigates the ozonation of Reactive Red 120 and Acid Red 299 dyes in the synthesized solution and textile wastewater by using a rotating packed bed. The decomposition rate of Reactive Red 120 and Acid Red 299 dyes via ozonation can be described by the pseudo-first-order kinetics. Ozonation of Reactive Red 120 exhibited the higher mineralization rate compared with that of Acid Red 299. The biodegradability of the two dyes could be significantly promoted during the ozonation. The BOD₅/TOC (5-day biological oxygen demand/total organic carbons) ratios of the ozonated Reactive Red 120 and Acid Red 299 solutions would increase and have the maximum values. Moreover, the oxidized textile wastewater revealed the fast decolorization and moderate COD (chemical oxidation demand) removal rates. The optimal ADMI (American Dye Manufactures Institute) and COD removal of the textile wastewater were 93% and 37% in 30 minutes ozonation time, respectively. The performance evaluation of ozonation in the rotating packed bed indicated that the higher water flow rate, gas ozone concentration and rotational rotating speed would increase the efficiency of mineralization.

Key Words :

• Ozonation
• Rotating Packed Bed
• Reactive Red 120
• Acid Red 299

ACKNOWLEDGMENTS

The authors would like to thank the National Science Council of the Republic of China, Taiwan for financially supporting this research under Contract No. NSC 90‐2211-E-002‐107.

Notes

^aSynthesized solution was dyes with pure water (Milli-Q).

^bThe wastewater was from location processes and the concentrations of RR-120 and AR-299 are determined by the absorbances of the characteristic wavelengths of 513 and 512 nm, respectively.

^cBOD₅ value.

^dCOD value.

^eND: not detected, less than 0.01 mg/L.