Environmental pollution caused by dyestuff industry wastewater is two-fold since it contains toxic chemicals like phenol, aniline etc. and also imparts the colour of the dye manufactured. For management of dyestuff wastewater, microbial technology becomes a novel approach since microorganisms have the characteristic ability to break down aromatic compounds and decolourize the dyes.
Microbial treatment of a dyestuff wastewater containing phenol and methyl violet was studied at the site of a dye factory near Pune in a fixed film bioreactor. The bioreactor consisted of a rectangular cement concrete tank of dimensions 9.5 m length × 7.3 m breadth × 1.5 m height and brick pieces of size 10 cm × 8 cm × 6.5 cm used as supporting media for formation of microbial film. A mixed culture of Pseudomonas alcaligenes (phenol degrader) and Pseudomonas mendocina (decolourizing methyl violet) grown in the dyestuff wastewater was spread on brick media. After formation of a microbial film on brick media, the dyestuff wastewater was recycled in form of a shower through the brick bed for 24, 48 and 72h. The influent loading rate was 1.44 m3/m2 brick bed area per day. The phenol and Chemical Oxygen Demand (COD) loading rates were on average 0.9 kg phenol/m2/day and 5.67 kg COD/m2/day respectively.
The performance of the microbial degradation evaluated for a period of 68 days showed 97.5%, 63%, 54.4% and 51% removal in phenol, methyl violet (MV) content, COD and Total Organic Carbon (TOC) respectively in 24 hours of recycling and marginally enhanced in 48 and 72 hours.
The microbial technology was thus effective in removal of phenol and the dye from dyestuff wastewater.