Removal of COD and color from hydrolyzed textile azo dye by combined ozonation and biological treatment.
The application of ozonation has been increasing in recent years, the main disadvantage of this type of treatment being related to the by-products, which can have toxic and carcinogenic properties, and therefore should be studied further. In this study, the combined treatment of ozonation and subsequent biological degradation with a biofilm, to reduce the color and chemical oxygen demand (COD), was investigated. The experimental part of the study consisted of two phases. The first phase was the ozonation process, the results obtained demonstrated that the ozonation of Remazol Black B dye at pH values of 3-11, was effective, partially oxidizing and completely decolorizing the effluent, even at relatively high concentrations of the dye (500 mg/L). Color removal efficiencies greater than 96% were obtained in all cases. The degradation kinetics of ozone is a pseudo-first-order reaction with respect to the dye concentration. It was possible to verify that the ozonation process as a pre-treatment increases the dye degradation efficiency. For the biological treatment, an increase in ozonization time increased the dye concentration reduction in hydrolyzed dye synthetic effluent. The toxicological results of the tests with Daphnia Magna showed that there is an increase in toxicity after ozonization and a decrease after submitting the ozonized synthetic wastewater to biological treatment with a biofilm.
Federal University of Santa Catarina, Chemical Engineering Department, Mass Transfer Laboratory, PO Box 476, CEP 88.040-900 Florianópolis, SC, Brazil. selene@enq.ufsc.br
Selene Maria de Arruda Guelli Ulson
SM
de Souza
Karin Angela Santos
KA
Bonilla
Antônio Augusto Ulson
AA
de Souza
D000818:Animals; D001391:Azo Compounds / Q000302:isolation & purification*; D001419:Bacteria / Q000737:chemistry / Q000378:metabolism; D001673:Biodegradation, Environmental; D018441:Biofilms; D002138:Calibration; D003116:Color; D004396:Coloring Agents / Q000302:isolation & purification*; D003621:Daphnia; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D009282:Naphthalenesulfonates; D010083:Oxidants, Photochemical / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D010126:Ozone / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013783:Textile Industry
D001391:Azo Compounds; D004396:Coloring Agents; D009282:Naphthalenesulfonates; D010083:Oxidants, Photochemical; D010126:Ozone; C063421:Remazol black B; D010100:Oxygen