Use of Fungal Laccases and Peroxidases for Enzymatic Treatment of Wastewater Containing Synthetic Dyes - Green Chemistry for Dyes Removal from Wastewater - page 203

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Use of Fungal Laccases and Peroxidases
for Enzymatic Treatment of Wastewater
Containing Synthetic Dyes
Keisuke Ikehata
Pacific Advanced Civil Engineering, Inc., Fountain Valley, California, USA
Abstract
Synthetic organic dyes such as azo dyes in wastewater discharged by dye man-
ufacturing and textile industries constitute a major environmental concern due
to their poor biodegradability and toxicity; as well as affecting aesthetics and
inhibiting photosynthesis and other biological activities in receiving water. Most
synthetic dyes contain characteristic multiple aromatic rings that are fused and/or
linked by various C-C, C-O, and C-N linkages and substituted by multiple func-
tional groups such as amino, nitro, hydroxyl, sulfonate, carbonyl, and carboxylate
groups. Because of the similarity of dye molecules and lignin, a natural polymer
of aromatic alcohols, many of the synthetic dyes can be degraded and decolor-
ized by lignin-degrading white rot fungi such as Phanerochaete chrysosporium
and Trametes versicolor and their oxidoreductase systems including peroxidases
and laccases. This chapter discusses the sources and application of these lignino-
lytic enzymes for the treatment of synthetic dyes, reaction mechanisms, and other
developments and challenges associated with this enzymatic process.
Keywords: Anthraquinone dye, azo dye, dye-decolorizing peroxidase, enzymes,
white rot fungus, indigoid dye, laccase, lignin peroxidase, manganese-dependent
peroxidase, triarylmethane dye, versatile peroxidase, wastewater treatment
6.1 Introduction
Synthetic dyes are widely used in fabrics, including textiles, paper making,
and inks and other coloring agents in many industries [1]. Most of the