Optimal decolorization and kinetic modeling of synthetic dyes by Pseudomonas strains

Pseudomonas spp were isolated from an anaerobic-aerobic dyeing house wastew ater treatment facility as the most active azo-dye degraders. Decolorizatio n of azo dyes and non-azo dyes including anthraquinone, metal complex and i ndigo was compared with individual strains and a bacterial consortium consi sting of the individual strain and municipal sludge (50:50 wt). The consort ium showed a significant improvement on decolorization of two recalcitrant non-azo dyes, but little effect on the dyes that the individual strains cou ld degrade to a great or moderate extent. Decolorization of Acid violet 7 ( monoazo) by a Pseudomonas strain GM3 was studied in detail under various co nditions. The optimum decolorization activity was observed in a narrow pH r ange (7-8), a narrow temperature range (35-40 degreesC), and at the presenc e of organic and ammonium nitrogen. Nitrate had a severe inhibitory effect on azo dye decolorization: 10 mg/L led to 50% drop in decolorization activi ty and 1000 mg/L to complete activity depression. A kinetic model is establ ished giving the dependence of decolorization rate on cell mass concentrati on (first-order) and dye concentration (half order). The rate increased wit h temperature from 10 to 35 degreesC, which can be predicted by Arrhenius e quation with the activation energy of 16.87 kcal/mol and the frequency fact or of 1.49x10(11) (mgL)(1/2)/g DCM min. (C)2001 Elsevier Science Ltd. All r ights reserved.