Method of biological purification of industrial effluents from chromates and bichromates

Abstract

A method of biological purification of industrial effluents from chromates and bichromates, wherein industrial effluents are mixed with domestic sewage and then the chromates and bichromates contained therein are biochemically reduced under anaerobic conditions using a strain of Bacterium dechromaticans Romanenko B-1167 microorganism, selected by repeated seeding on liquid nutrient medium containing sources of carbon, nitrogen, phosphorus, under anaerobic conditions, in the presence of potassium chromate in the function of oxygen donor, followed by separation from the seeding on a meat-infusion agar under aerobic conditions without chromate, the strain having the following morphological features and physiological properties: small bacilli of about 1.2 micron long and 0.4 micron wide, forms rows when spread over a glass plate, sometimes at an angle to each other; forms no spores; Gramm negative; under anaerobic conditions with chromates they grow as single bacilli or in the form of short chains; immobile; under aerobic conditions they grow in a meat-infusion agar; the colonies are small in the beginning, in the form of dew droplets, watery, glittering, with even edges, they further become light pinkish and the colonies grow in size, the centre of the colony is elevated; in the bulk of agar they grow as small lenses; at the edge of the meat-infusion agar the colonies are small, then they join together to form a streak, the tint is slightly pinkish, then it is milky white with a slight pinkish tint, the streak is opalescent, flat, paste-like; grows on gelatine without diluting the latter in the form of a pale streak, the growth rate is very slow, the streak is slightly pinkish; grows on potato as a colliculus streak, the colour is pinkish or reddish, grows slowly, the streak is firm, colliculus; does not grow on glucose, lactase or cellular tissue; grows on sucrose, maltose, mannite, decomposes starch, grows well on ethyl alcohol forming acid; slightly peptonizes milk; does not reduce nitrates; assimilates small quantities of CO.sub.2 ; reduces chromates and bichromates to chromic hydroxide at a rate of 2.1 gram of potassium chromate during a period of three days per gram of dry biomass matter.

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