Purification treatment

Claim 1

A PROCESS EMPLOYING TRICKLING FILTER MEANS FOR TREATING SEWAGE AND OTHER AQUEOUS WASTES CONSISTING IN SUPPLYING AN INFLUENT OF SAID MATERIAL TO A PRIMARY CLARIFICATION BY SEDIMENTATION IN ADVANCE OF THE TRICKLING FILTER AND INTERMIXING WITH SAID INFLUENT AT THE BEGINNING OF SAID PRIMARY CLARIFYING DETENTION PERIOD OF SAID MATERIAL AN AERATING SUPPLY OF OXYGEN CONTAINING GAS AND SUBSTANTIALLY SIMULTANEOUSLY THEREWITH A SUPPLY OF TREATED MATERIAL RECIRCULATED FROM A LATER STAGE OF THE PROCESS FOLLOWING CONTINUOUS TREATMENT OF THE MATERIAL BY BIOLOGICAL OXIDATION MAINTAINED AT A DISSOLVED OXYGEN CONTENT OF AT LEAST TWO PARTS PER MILLION, SAID AERATING GAS SUPPLY BEING INTRODUCED INTO THE MIXTURE AT THE BEGINNING OF SAID DETENTION AND SEDIMENTATION PERIOD IN AMOUNT SUFFICIENT TO MAINTAIN IN AND THROUGH THE SAID PERIOD SAID DISSOLVED OXYGEN CONTENT OF AT LEAST TWO PARTS PER MILLION, CONTINUING THE DETENTION AND SEDIMENTATION OF SAID MATERIAL AND INTRODUCED AERATING GAS AND RECIRCULATED MATERIAL FOR A PREDETERMINED CONTACT AND CULTURE PERIOD AND DRAINING OFF AND SEPARATING OUT ALL OF THE SETTLED SOLIDS WITH RESULTANT CLARIFYING ACTION ON THE MIXTURE IN THE PRESENCE OF SAID INTRODUCED AERATING GAS TO CONTINUOUSLY CULTURE AND MAINTAIN THE NITRIFYING BACTERIA AND OXIDIZING ORGANISMS AND BIOLOGICALLY OXIDIZE SAID MATERIAL AT SAID DISSOLVED OXYGEN CONTENT OF AT LEAST TWO PARTS PER MILLION AND CORRESPONDINGLY REDUCE THE BIOCHEMICAL OXYGEN DEMAND OF THE INFLUENT WHILE SETTLING OUT SOLIDS FROM THE MIXTURE BY SEDIMENTATION, SUBSEQUENTLY SUBJECTING THE CLARIFIED MATERIAL WITH GREATLY INCREASED SURFACE EXPOSURE TO A FURTHER SUPPLY OF AERATING OXYGEN-CONTAINING GAS IN A TRICKLING FILTER RAISING THE DISSOLVED OXYGEN CONTENT FURTHER ABOVE SAID TWO PARTS PER MILLION WITH CORRESPONDINGLY INCREASED BIOLOGICAL OXIDATION AND PRODUCING EFFLUENT FROM SAID TRICKLING FILTER HAVING A HIGH STABILITY AND A LOW BIOCHEMICAL OXYGEN DEMAND, DRAWING OFF A PORTION OF SAID EFFLUENT FROM SAID TRICKLING FILTER AND PASSING SAID PORTION BACK FOR RECIRCULATION AS SAID SUPPLY OF TREATED MATERIAL FOR MIXTURE WITH SAID INFLUENT AND AERATING GAS IN SAID PRIMARY CLARIFICATION BY SEDIMENTATION, AND CONTINUING SAID TREATMENT OF THE MATERIAL CONSTANTLY UNDER BIOLOGICAL OXIDATION IN THE PRESENCE OF A DISSOLVED OXYGEN CONTENT OF AT LEAST TWO PARTS PER MILLION.