Advantages And Disadvantages Of Dyes

INTRODUCTION:

Environmental pollution has been recognized as one of the major hazard of the modern world. Due to rapid industrialization, lot of chemicals including dyes were manufactured and used in day to day life (Moorthi et al., 2007).

Dyes usually have a synthetic origin and complex aromatic molecular structures which make them more stable and more difficult to biodegrade (Aksu, 2005). Approximately 10,000 different dyes and pigments are used industrially and over 0.7 million tons of synthetic dyes are produced annually worldwide. Due to modern life style, increasing urbanization and development the use of dyes and dye based products grows. Once they enter an ecosystem, dye-based pollutants initiate a series of processes, affecting both

It is usually treated by physical or chemical treatment process. These include physical or chemical flocculation, flotation, electro-flotation, membrane-filtration, electro kinetic–coagulation, electro chemical-destruction, and precipitation. These conventional chemical and physical methods are versatile and useful, but they only transfer the pollutant from one form to another, and produced secondary waste products. But these types of technologies are inefficient, expensive and have low adaptability to diverse type of dye effluent. Traditional methods for the cleanup of dyes in the textile waste water usually involve the removal of unwanted materials through sedimentation, filtration and chemical treatments such as flocculation, neutralization and electro-dialysis before disposal. These processes may not guarantee the treatment of toxic dye in the effluent. Moreover, considering the volume of wastes released during the industrial production process these are often laborious and expensive (Gopi et al., 2012). Over the past decades, biological decolorization has been investigated as a method to transform, degrade or mineralize dyes (Banat et al., 1996). Moreover, such decolorization and degradation is an environmental friendly and cost-competitive alternative to chemical decomposition processes (Verma et al., 2003) .Bioremediation a economic viable safe

Decolorization of Direct yellow and Erio red dyes by bacterial and actinomycetes were studied by Waffa and Moawad (Moawad et al., 2003). Decolourization of C.I Reactive Red 11 (mono azo) and C.I Reactive Yellow 84 (di azo) dyes was studied by developing bacterial consortia isolated from dye contaminated soil. Maximum decolourization of 85% was achieved at 100 mg /L of C.I Reactive Red 11 and 83% at 100 mg /L of C.I Reactive Yellow 84 after 72 h under shaking condition using 40% inoculum size of the respective consortia (Tandon et al., 2014). Maximum dye decolorization of 89% was shown by Pseudomonas sp. and Bacillus sp. at the end of 144h under optimum condition. But the Bacillus sp. was found to be more efficient in dye decolorization (Ponraj et al., 2011). Efficient decolorization of Remazol Brilliant Blue R (RBBR) was screened by using strains of terrestrial white rot (WRF) and marine fungi (MF). Irpex lacteus and Pleurotus ostreatus (WRF) were efficient dye degraders whereas were less efficient and selective degradations were observed with Dactylospora haliotrepha and Aspergillus ustus (MF). Seawater salinity often reduced decolorization efficiency of WRF but increased decolorization ability of MF. I. lacteus was found to remove 77% of RBBR in soil used at 150 μg/g within 6 weeks (Novotný et al., 2003).