PROCESS AND PLANT FOR AEROBIC BIOLOGICAL PURIFICATION OF WASTE WATER Russian patent published in 1997 - IPC

FIELD: waste water purification. SUBSTANCE: excessive activated sludge is subjected to physico-mechanical treatment to stimulate microorganisms to release extracellular biopolymers. A portion of treated activated sludge is mixed with initial waste water before its transferring into the primary settler, and another portion is mixed with a waste water-activated sludge mixture withdrawn out of air tank before its transferring into the secondary settler. Agitation of the above suspensions is conducted under conditions of most full use of bioflocculating capability of treated sludge mixture by way of choosing optimum regime for agitation, intensity and interaction mode of coagulating particles with disperse solid and colloidal particles. Mode and conditions for physico-mechanical treatment of activated sludge are chosen on condition of complete exhaustion of cell protein reserve to provide maximum concentration of extracellular biopolymers in medium under treatment. Plant for this process is additionally provided with arrangement for physico-mechanical treatment of excessive activated sludge to intensify bioflocculation process. In parallel connection to this arrangement are means for mixing a portion of partially treated sludge with initial waste water before its transferring into the primary settler and for mixing another portion of treated sludge with a waste water-activated sludge mixture withdrawn out of air tank before its transferring into the secondary settler. EFFECT: intensified biological processes in activated sludge and increased waste water purification degree. 4 cl, 2 dwg