Biodegrading evaluation of azo dye group – Congo Red, Methyl Blue and Methyl Orange using bacteria isolated from textile wastewater sediment

Abstract

Textile wastewater is one of the most water polluted sources affecting the environment, ecosystems, and causing human malignancy because it contains azo dye pigment group. The treatment requires various types of physical and chemical methods which are time-consuming and hazardous environmental effects. The biodegradable method using microorganisms for textile effluent has been applied due to its environmental friendliness and affordability. Our study aims to identify the microorganisms that are capable of simultaneous degradation of three monochromatic colors belonging to the azo dying group, including Congo Red, Methyl Blue, Methyl Orange via qualitative experiments using Potato Dextrose Agar (PDA) media plus the three monochromatic colors and quantitative experiments using Pt-Co calibration curve to identify the biodegradable efficiency of each and combined bacterial isolated strains. The results showed that six bacterial strains isolated from textile waste sludge were capable of decolorizing the three azo - monochromatic pigments. Moreover, we found that strain Bacillus Subtilis E1 owning Quorum Sensing mode had the highest decoloration efficiency with color removal performance for Methyl Orange, Methyl Blue, and Congo Red was 83.7%, 30.6%, and 94.4%. In particular, the combinations of two Bacillus Subtilis strains yielded a multi-color decolorizing performance with an efficiency of over 80% for each pair.