Patent ID: 6872312

Claim:
An activated sludge process for the clarification of wastewater comprising (i) introducing the wastewater into a reactor where microorganisms consume organic material in the wastewater to form a mixed liquor comprising water, the microorganisms and an activated sludge; (ii) separating clarified water from the mixed liquor by filtration through a microfiltration or ultrafiltration membrane; (iii) separating excess activated sludge from the mixed liquor; (iv) adding to the excess activated sludge at least one high molecular weight water soluble polymer to form a mixture of water and coagulated and flocculated solids; (v) dewatering the coagulated and flocculated solids to form a mixture of dewatered solids and filtrate water; and (vi) recycling the filtrate water into the mixed liquor, wherein the high molecular weight water soluble polymer is added to the excess activated sludge in an amount sufficient to obtain a level of less than about 5 ppm of polymer in the mixed liquor.