Abstract: Phosphorus, nitrogen and BOD are removed from organic waste liquid containing the same by mixing the organic waste liquid with activated sludge which is substantially free of oxygen, nitric acid and nitrous acid and subjecting the mixture to the action of the activated sludge under anaerobic conditions which forms a mixture of a liquid rich in soluble phosphorus and an activated sludge low in phosphorus. The sludge and liquid are separated. A portion of the liquid is subjected to solid-liquid separation to form a liquid high in phosphorus and a sludge low in phosphorus. This latter sludge is, along with the other portion of the liquid and the sludge from which the liquid has been initially separated are mixed with oxygen, in the presence of nitric acid or nitrous acid and subjected to aerobic biological oxidation. This results in the formation of a liquid low in phosphorus and an activated sludge.

Abstract: Water or waste water is purified by passing same through a packed layer of active carbon utilizing the absorbing activity of active carbon. An apparatus for practicing this method is disclosed.

Abstract: A solid-liquid separation process is provided for clarifying water containing colloidally-suspended solids such as clay, metal minerals and hydroxides, organic and inorganic materials and like substances wherein the solids concentration in the mother liquor is less than 10 g/l. The colloidally-suspended solids are converted to a coagulum of substantially spherical particles characterized by a high density and large particle size and generally exhibit different properties than the flocs thereof. The coagulum separates from a supernatant at about 5 to about 10 times the precipitation rate of a floc treated according to a conventional flocculation-precipitation method. The resulting sludge exhibits superior condensability and is extremely suitable for treatment by a hydroextraction technique. The water obtained from the treatment is unusually clear and free of suspended matter.

Abstract: An effective and efficient process and apparatus for treating a mother liquor including therein both suspended and dissolved impurities, and in particular, metal hydroxides, metal oxides and phosphate ions, at a concentration of less than 10 g/l, are provided. The process comprises admixing at least 0.5 ppm of an organic high molecular weight flocculating agent and after an interval at least 10 ppm of an inorganic metal salt flocculating agent therewith, subjecting the admixture to rotational flow to form a particulate layer of solids and simultaneously therewith, agitating the admixture, while maintaining the suspension liquor at a solids concentration of at least 10 g/l, and concurrently upwardly directing the suspension so that it flows through the agitated particulate layer and thereby intimately contacting flowing particles thereof for separating the particles from the treated mother liquor. A preliminary treatment removes dissolved matter including phosphate ions, and a clarified effluent results.