GB694458A - Waste disposal process - Google Patents

Abstract

694,458. Treating waste effluents. DU PONT DE NEMOURS & CO., E. I. Jan. 31, 1951 [March 23, 1950], No. 2466/51. Class 111 Pollution of fluids, into which effluents containing factory wastes containing organic contaminants are discharged, is inhibited by destroying the polluting power of the organic constituents by passing the waste in the liquid phase with oxygen over a metallic oxide oxidation catalyst under a pressure between 200 and 2,500 lbs./sq. in. at a temperature between 50 and 350‹C and with a space velocity between 10 and 2,000 cu. ft. liquid waste per hour per cubic foot of catalyst. The amount of oxygen is. preferably at least sufficient to bring about the complete oxidation of the organic constituents of the effluent. The preferred catalyst is a mixture of manganese oxide,. zinc oxide and chromium oxide in the proportions 80:20:47 parts by weight. A contaminated waste effluent is passed through a preheater 1 and air through a preheater 1a, and the mixed air and waste are passed into a catalyst disposed in a pressure resisting vessel 2 preferably provided with electrical heating means. The catalyst may be arranged as a number of beds in parallel or in series. A baffle 2b to ensure intimate contact is preferably provided. The oxidation products are passed through a let-down valve 3 into an exhauster for removal of air or volatile pro-- ducts of oxidation. The liquid part is passed through a heat-exchanger 5 to a sewer or the like. To prevent overheating and to avoid lowering the activity of the catalyst the reaction temperature is controlled e.g. by passing steam or water or both into the catalyst bed, or by passing the waste effluent directly into the bed without preheating. The exothermic heat of reaction may be used to improve the efficiency of the process. Instead of air or the like a compound that will give upoxygen under the conditions of the reaction may be mixed with the waste effluent. In one example 25 parts by weight of an aqueous effluent containing 1.21 parts formic acid by weight together with 188 parts of oxygen are heated to 135 ‹C and' passed through 50 parts of a manganese oxide, chromium oxide, zinc oxide catalyst (80:47:20) at the same temperature and' at a space velocity of about 60. The chemical oxygen demand as measured by reduction of potassium dichromate is reduced' from 4640 to 94 p.p.m. In a second example 75 parts by weight of an aqueous solution containing 1 per cent formic acid by weight, 4.3 parts of oxygen and 0.3 parts of air are reacted in the presence of vanadium oxide catalyst at a temperature between 197 and 205‹C and under a pressure between 200 and 600 1bs./sq. in. The percentage weight of carbon is reduced from 0.27 to 0.047 and 84 per cent to 95 per cent of the formic acid oxidized. In another example the aqueous solution contains 1 per cent methanol instead of formic acid. The process may be applied to wastes containing such compounds as aromatic carboxylic acids, alcohols, aldehydes, lower alkyl esters, liquid hydrocarbons, ketones, cyanogen compounds, amines, amides and carbohydrates. A particular example is the effluent compris-- ing a mixture of methanol and formaldehyde obtained in the manufacture of formaldehyde by catalytic oxidation of methanol with air. Also, in the rectification of industrial alcohol, by-products of high volatility such as aldehydes and ethers may be drawn off as a liquid and treated; and the fusel oils which are steam distilled in a subsequent column may be conveniently removed as a mixture of water, and organic liquid.