Narrow Results

Studied was the effect of the natural (riboflavin, RF) and synthetic (9,10-antraquinone-2, 6-disulphonic acid disodium salt, AQDS and 2-hydroxy-1, 4-naphthochinon, LQ) redox-mediators on the microbial decolorization of the azo dye Acid Orange 7 (AO7) by resting cells of the Gram negative Alcaligenes faecalis 6132 and the Gram positive Rhodococcus erythropolis 24. Experiments were performed in conditions of limited oxygen supply. Results obtained in the experiments on AO7 decolorization with two different bacterial strains, Rh. erythropolis and A. faecalis, underlined the fact that the influence of redox-mediators on the decolorization reaction depended not only on the kind of the redox-mediator used but to a higher extent on the type of the microorganism performing the process. Results about the influence of redox-mediators on AO7 decolorization in conditions of limited oxygen supply showed a similarity with those reported in the literature about experiments in strictly anaerobic conditions.

In the present work, the degradation of acid orange 7 was studied by the electrocatalytic anodic oxidation through the use of boron-doped diamond (BDD) electrode. A factorial design analysis was adopted to evaluate the effects of operating parameters on the treatment performance. Five operating parameters including treatment time, flow rate, applied current, initial concetration and electrolyte concentration were chosen as test factors. Of the five test factors involved, treatment time, applied current and initial concentration had considerable contributions on the treatment performance. Additionally, the remaining two factors possessed less influences on the treatment efficiecy. The result obtaied, suggested that the factorial design analysis was of great use to the parameter optimization of BDD electrocatalytic treatment.