Evaluation of Fenton oxidation process coupled with biological treatment for the removal of reactive black 5 from aqueous solution

Biodegradation of azo dyes is difficult due to their complex structures and low bod to cod ratios. in the presentstudy, the efficiency of using fenton’s reagent (h2o2 + fe2+) as a pretreatment process to enhance microbialtransformation of reactive black 5 (rb5) in an aqueous system was evaluated. the rb5 with an initial concentrationof 250 mg/l was decolorized up to 90% in 60 h by using a bacterial consortium. fenton’s reagent at a fe2+concentration of 0.5 mm and h2o2 concentration of 2.9 mm (molar ratio, 1:5.8) was most effective fordecolorization at ph = 3.0. the extent of rb5 removal by the combined fenton–biotreatment was about 2 timeshigher than that of biotreatment alone. the production of some aromatic amines intermediates implied partialmineralization of the rb5 in fenton treatment alone; in addition, decreasing of gc-ms peaks suggested thatdearomatization occurred in fenton-biological process. fenton pretreatment seems to be a cost–effective optionfor the biotreatment of azo dyes, due mainly to the lower doses of chemicals, lower sludge generation, and savingof time. our results demonstrated positive effects of inoculating bacterial consortium which was capable of dyebiodegradation with a fenton’s pretreatment step as well as the benefits of low time required for the biologicalprocess. in addition, the potential of field performance of fenton-biological process because of using bacterialconsortium is an other positive effect of it.