Congo Red Decolorizing Bacteria from Paper Factory Effluent - Microbial Degradation of Synthetic Dyes in Wastewaters - page 131

Congo Red Decolorizing Bacteria
from Paper Factory Efuent

Aileen C. Jalandoni-Buan, Anna Lynn A. Decena-Soliven,
Ernelea P. Cao, Virginia L. Barraquio and Wilfredo L. Barraquio

1 Introduction

Synthetic dyes usually consist of aromatic rings, methyl, methoxy, sulfo or nitro
group. They are not readily degradable and can not be removed from water by
conventional wastewater treatment systems (Anliker 1979 ).
Synthetic dyes are frequently found in ef

uents from the textile and paper
industries. These dyes are generally very toxic. One example of these synthetic dyes
is the azo dyes (e.g. monoazo, diazo, triazo and polyazo). Azo dyes represent
the largest class of organic colorants listed in the Color Index (i.e. 60 70 % of the

total). They constitute a vast majority of the dyes which are discharged in
the wastewaters (van der Zee 2002 ).
Azo dyes are synthetic dyes that have a azo group of two nitrogen atoms (N = N)
connecting aromatic ring compounds. Azo dyes may be direct, acid or basic. Direct
dyes are relatively large molecules with high af

-

bers. Acid dyes
are anionic compounds that are mainly used for dyeing nitrogen-containing fabrics

nity especially for