Patent ID: 6277285
Filing Date: 2001-08-21
Classification: B01D,C02F

Abstract:
A process for the clarification treatment of liquids comprising the steps of:injecting a granular material ballast and a polymer into an untreated liquid;flocculating the liquid thereby forming a ballasted floc;rapidly settling the ballasted floc to form clarified liquid;selectively recycling uncleaned ballasted floc into the liquid during the previous injecting step by a low energy transfer for so long as a ballast ratio in the ballasted floc is greater than a preselected level, wherein said ballast ratio is expressed as a percentage of clean ballast/(total ballast+sludge);selectively initiating a high energy cleaning and transfer of the ballasted floc wherein floc, in the form of sludge is removed from cleaned ballast; andthe resulting cleaned ballast is recycled into the liquid during the previous injecting step;wherein the low-energy transfer remains in service while the high energy cleaning and transfer becomes operational, but is shut down during operation of the high energy transfer;the low and high energy transfers being employed alternately so as to maintain the ballast ratio at the preselected level, wherein the low energy transfer consumes less energy per m.sup.3 of liquid treated than the high energy transfer.