AN ACTIVATED-SLUDGE PROCESS TO REDUCE THE POLLUTION LOAD OF A DYE-INDUSTRY WASTE

A laboratory-scale activated sludge process was developed to reduce the pollution load of a dye-industry waste, containing aniline, phenol, methyl violet and rhodamine B as its major components. The waste exerted an organic load of 5576 mg litre-1 as the chemical oxygen demand (COD), of 896 mg litre-1 as total organic carbon (TOC), and had a 31.5 mg litre-1 phenol content. A microbial sludge, capable of growing on the waste, was developed from cattle dung, adapted to the waste and used as a bioinoculum for the process. This resulted in reductions of 60% in COD, 37% in TOC, and 92% in phenol content, and a decrease in optical density of the colour of the waste from an initial 0.915 to 0.360 at 580 nm. Microorganisms isolated from sludge were identified as Pseudomonas alcaligenes and P. mendocina.