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Abstract. Disperse dyes constitute the largest group of dyes used in local textile industry. This work evaluates the potential of the Cucurbita peroxidase(C-peroxidase) extracted from courgette in the decolourization of disperse dye in free and immobilized form. The optimal conditions for immobilization of C-peroxidase in Ca-alginate were identified. The immobilization was optimized at 2%(w/v) of sodium alginate and 0.2 M of calcium chloride. After optimization of treatment parameters, the results indicate that at pH 2, dye concentration: 80 mg/L(for FCP) and 180 mg/L(for ICP), H 2 O 2 dose: 0,02M (for FCP) and 0,12M(for ICP), the decolourization by free and immobilized Cperoxidase were 72.02% and 69.71 % respectively. The degradation pathway and the metabolic products formed after the degradation were also predicted using UV-vis spectroscopy analysis.

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The removal of direct yellow 106 (DY106, C.I.40300) by a combined process of Fenton oxidation and enzymatic degradation in a sequential or mixed batch reactor is discussed. Experiments were first conducted with the enzymatic and chemical oxidation processes separately in order to determine the effects of various parameters such as pH, ferrous ion, hydrogen peroxide, dye and enzyme concentrations on the overall yield and kinetics of both processes. Decolourization was followed by UV-visible spectroscopy and high performance liquid chromatography (HPLC). Results showed that 89.5 % of DY106 were removed by enzymatic treatment after only 2 min, while 10 min of contact time were necessary to eliminate more than 98 % of 50 mg/L by Fenton’s process. A high performance was achieved under optimized conditions by the mixed combined process with time reduction down to 5 min. The study was also conducted to evaluate the efficiency of combined Fenton’s reaction as a pre-treatment and post treatment process combined with C-peroxidase at different ferrous ions concentrations. The optimal doses of Fe2+ were 2.5 mM, 1m M and 0.8 mM for Fenton, Fenton-enzymatic sequential and mixed processes. Intermediate products absorbing in UV range were detected for single Fenton or enzymatic treatment but were eliminated in all combined enzymatic-Fenton processes. Phytotoxicity tests showed that no toxicity was detected after treatment by combined process.