Purifying residual industrial waters contg. organic contaminants by initial incomplete purificn. with catalytic redox system followed by complete biological purificn. with active sludge

Residual industrial waters polluted with organic cpds., e.g. HCHO, butanol, isobutanol, MeOH, propylene glycol and pentaerythritol, are purified by first treating with a catalytic redox system, consisting of FeCl3 and CuSO4 or of FeSO4 and CuSO4, with stirring or bubbling air through the water, at the temp. and pressure of the ambient medium. After reaching a degree of purity of 74-81%, the waters are passed to a biological purificn. plant with active sludge. A final degree of purificn. of 97-99% is achieved, expressed in the CCOCr
system. The catalysts can be reused for a new purificn. process.