Purificn. of highly polluted industrial effluent esp. from dye-works - by heat evapn. followed by physico:chemical treatment

摘要

A process and an installation for the purificn. of polluted industrial effluent with high COD and contg. fine solids in suspension. Effluent is evaporated by heating and the condensate is subjected to further phyisico-chemical treatment as required, partic. coagulation/flocculation, decantation and filtration. Pref. the process includes using the vapour produced by evapn. of the effluent to preheat effluent on its way to the evaporator. Water obtd. by purifying the effluent is pref. recycled directly for use in the industrial process which gave rise to the polluted effluent. This applies partic. to effluent from the dyeing industry. The installation pref. comprises a multi-stage evaporator which receives the effluent, each stage being equipped with a separator which eliminates sludge from heating vapour. Effluent for treatment does not require the usual pre-screening and decanting. Degree of purificn. is such, e.g. 80-95% redn. of COD, that the purified water can be re-used in the process producing the effluent. All colour is removed from dye works effluent.