Treatment of waste water containing azo- and sulphur-based dyes from textiles and leather industry

摘要

Treatment of waste water containing azo- and sulphur-based dyes from the textiles and/or leather processing industries, comprises treating the water in a first aerobic stage with negative redox potential, the time allocated for primary waste water treatment depending upon the nature of the dye, then treating the waste water in a second aerobic or anaerobic process with a space-load of no less than 1.0 kg BOD/(m<3> x d) (biological oxygen demand per cubic metre waste water per day) and a positive redox potential of 0-180 mV, generating activated sludge, sedimenting, returning the activated sludge partly to the activated sludge stage and partly to the anaerobic pre-stage, partly thickening and removing, adding nutrients to the waste water in the first and second stages and maintaining the redox potential in the first stage, discharging waste water from the activated stage to a third, aerobic treatment stage and discharging the treated waste water to a tank or basin.