The main purpose of secondary treatment is to provide BOD removal beyond what is achievable by simple sedimentation. It also removes appreciable amounts of oil and phenol. In secondary treatment, the dissolved and colloidal organic compounds and colour present in waste water is removed or reduced and to stabilize the organic matter. This is achieved biologically using bacteria and other microorganisms. Textile processing effluents are amenable for biological treatments [3]. These processes may be aerobic or anaerobic. In aerobic processes, bacteria and other microorganisms consume organic matter as food. They bring about the following sequential changes