Biological purification of waste water of the textile industry

Effluents in the textile industry differ by the quantity and the composition, and it depends on the type of textile raw materials and treatment. The effluents are frequently heavily dyed, alkaline, contain organic substances (high values of biological and chemical oxygen demand) and considerable amounts of fats and detergents. The decision on a method of efficient, enviornment-friendly and cost effective effluent purification is made after an analysis of effluents and after purifying water in a pilot-plant or semi-industrial plant. By mechanical purifying a smaller part of contamination is removed, whereas a greater part remains in efluents and is removed by biological or physico-chemical purifying. Biological purification of effluents is based on activities of microorganisms decomposing organic matter. In this decomposition organic matter serves as nourishment for building new cells, whereby gases and undecomposable residue develop. Among biological methods for purifying effluents in the textile industry, purification in aired lagoons, by means of biological filters - filtering units is considered, and in most cses the process with active carbon is applied. Anaerobic decomposition of textile effluents increasingly replaces the use of aerobic decomposition.