Bioremediation of Recalcitrant Nitroaromatic and Azo Dye Compounds from Contaminated Environmental Media

Dear Colleagues,

Nitrogen-containing organic compounds, such as nitrobenzenes and azo compounds are applied to produce pesticides, herbicides, dyes, pharmaceuticals, rubber chemicals, and other chemical intermediates. However, the improper disposal and widespread use of these chemicals have caused significant environmental pollution. The presence of the nitro group in these compounds, combined with the stability of the benzene ring, makes nitroaromatic compounds recalcitrant to biodegradation. Moreover, their toxicity, mutagenicity, and potential to be converted into carcinogenic aromatic amines pose severe environmental concerns.

In recent years, there has been increasing focus on biological remediation of nitroaromatic-contaminated sources. Although nitroaromatic compounds and azo dyes are highly resistant to oxidative degradation due to the electron-withdrawing nature of the nitro group and the stability of the benzene ring, there have been reports of the effective reductive biotransformation of nitroaromatic compounds into aromatic amines using anaerobic bacteria.

Sequential anaerobic–aerobic biological treatment is considered as an efficient and sustainable method for the complete mineralization of nitroaromatics and azo dyes. Additionally, the use of redox mediators has been reported as an effective method to accelerate the biotransformation of electron-accepting pollutants in contaminated water. Various redox mediators have been employed in wastewater treatment systems to facilitate the reductive biotransformation of electron-accepting pollutants, such as nitrobenzenes and azo dyes. Carbon-based materials, including activated carbon, reduced graphene oxide, and black carbon, have been utilized as redox mediators to enhance the reductive transformation of the pollutants.

Hence, the focus of this Special Issue is on the application of redox-mediator-based bioremediation technology for the remediation of nitrobenzenes and azo dyes in contaminated soil and water media. Thus, it is my pleasure to invite you to contribute research articles, communications, or reviews dedicated to bioremediation, encompassing a wide range of pollutants, including pesticides, herbicides, pharmaceuticals, dyes, etc.

Dr. Fisseha Andualem Bezza
Prof. Dr. Evans Martin Nkhalambayausi Chirwa
Guest Editors

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