Patent ID: 6210587
Filing Date: 2001-04-03
Classification: B01D,C02F

Abstract:
A physico-chemical process for treating effluent comprising the steps:subjecting the effluent to coagulation for forming microflocs;subjecting the coagulated effluent to flocculation for agglomerating the microflocs into flocs;subjecting the resulting flocculated effluent to settling for separating flocs and interstitial water components thereby forming sludge and clarified water;recycling a portion of the sludge to the flocculated effluent during the step of flocculation, the recycled sludge serving as a contact mass for the floc; andadding a ballast to the coagulated effluent during the step of flocculation thereby densifying the sludge, wherein a portion of the densified sludge is recycled, after settling, to the flocculated effluent during the flocculation step without cleaning the ballast, wherein said ballast consists of a material having a particle size of at least about 200 .mu.m, and wherein the volume of densified sludge constituting the contacting mass, which is recirculated, after settling, to said flocculation step, is between 0.5 and 4% of the effluent volume treated.