BIODEGRADATION OF DIAZO DYE DIRECT RED 81 BY FUNGI ISOLATED FROM DYES INDUSTRIAL EFFLUENTS

Document Type : Original Article

Authors

1 Botany and Microbiology Department, Faculty of Science, Al-Azhar University (Girls Branch), Cairo, Egypt.

2 Botany and Microbiology Department, Faculty of Science, Al-Azhar University (Girls Branch), Nasr city, Cairo, Egypt

3 Microbial Biotechnology Department, National Research Centre, Dokki, Giza, Egypt

4 The Regional Center for Mycology and Biotechnology (RCMB), Al-Azhar University, Cairo, Egypt

Abstract

Azo dyes industrial effluents are toxic and can cause many hazard effects on the environment. Therefore they have to be treated before their releasing into the environment. The Direct Red 81 (DR81) is one of these azo dyes which can be toxic to human, animals and aquatic environment. The treatment of the synthetic dyes by fungi is an effective and appropriate method. The aim of this study is to isolate fungi capable of decolorizing and degrading the DR81 dye. The ability of thirteen fungi belonging to Aspergillus Spp., Penicillium Spp., and Trichoderma Sp. to degrade DR81 was tested. The optimal conditions for dye decolorization by the most potent isolate were found to be pH 5.0, temperature 25ºC, in shaking and dark conditions after 6 days of incubation and 99.8 mg/L dye concentration. The decolorization percentage, COD and BOD removal percentages were found to be 95.48%, 79.94%, and 77.76%, respectively. The UV-VIS analysis confirmed that the maximum peak of DR81 disappear after the decolorization in the optimum conditions. The phytotoxicity tests on Trigonella foenum-graecum, Vicia faba and Lens culinaris indicated that the toxicity of the dye was reduced after decolorization by the most potent fungi. The results have revealed the potential of the selected fungal isolate in the treatment of DR81 dye.

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