SU952768A1 - Method for biologically purifying effluents from organic substances and sulfides - Google Patents

Description

The invention relates to environmental protection and can be used in oil refineries and the petrochemical industry for wastewater treatment.

A known method of purification of industrial effluents, including the petrochemical and chemical industries, by active oil. Pa3p5mieHHe organic matter in the effluent is carried out by the bacteria from the genera Pseudomonas, Bacillus, Plavobacterium, Achromobacter, etc. that form part of the sludge. Tl.

However, all these microorganisms are not capable of oxidizing sulfides.

The known method of biologic purification of sulfurous wastewater by treating them with microflora, obtained as a result of a long-term (about 3 months) adaptation of urban waste bacteria to increasing concentrations of sulfur-containing compounds 2.

The disadvantage of this method is that this microflora functions in an acidic environment, which is unfavorable for the operation of bacteria of active sludge.

The closest to the invention in its technical essence is the method of oxidation of reducing sulfur compounds in wastewater by thiobacteria Thiobacillus. Wastewater after alkalinization and introduction of nutrients (superphosphate, ammonium sulfate) into the aeration tank, where water is purified using known microflora of activated sludge together with thiomas bacteria. The aeration period of sewage is 16 hours, the air consumption is 30 drains. Wastewater

10 waters are purified from sulphide-α; the efficiency of organic contaminants removal by COD is 70-80%; on BOD. 86-95%. COD of purified water is 8095 mg / l; VPK5 35-40 mg / l 3.

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The disadvantage of this method is that the oxidation of sulfur-containing compounds by bacteria of the genus Thiobacillus lowers the pH of the medium to 4.4, which inhibits the development of other microorganisms that carry out the purification process. Biological treatment of wastewater from organic matter in these conditions is difficult and

25 requires a long stay in the aero tank. The main indicators of purified water COD and MIC are high and cannot be reduced.

The purpose of the invention is to reduce the cost of the process and improve the degree of purification from

organic substances with simultaneous oxidation of sulfides.

This goal is achieved by the fact that wastewater treatment is carried out with active sludge containing bacteria of the genus Leptothrix in the presence of two to five active iron salts.

The number of bacteria of the genus Leptothrix in relation to bacteria of the activated sludge is 0.005-0.1%.

In addition, 10 ferrous iron is introduced into the wastewater to the ratio of the latter to the amount of sulphides ranging from 1: 2 to 1: 8.

Moreover, the quality of the bivalent iron source uses spent activated sludge under anaerobic conditions for 1-3 days.

Such sludge, in addition, contains various biogenic elements - vitamins, growth agents, which promote the metabolic activity of the entire complex of microorganisms that purify wastewater. The use of bacteria of the genus Leptothrix eliminates the need for alkalization of wastewater; these bacteria oxidize sulfides in a neutral or slightly alkaline medium, i.e. under conditions favorable for the development of other microorganisms of activated sludge, which facilitates purification, reduces the residence time of effluents in the aeration structure and does not require such intensive aeration of wastewater that contributes to .

Example. Real industrial wastewater: the refinery's water is fed at a rate of 20 l / day to a laboratory aeration tank (with a capacity of V l) with active sludge containing bacteria of the genus Leptothrix. 2 times a day, 20 ml of 2-nd aged for 2 days under anaerobic conditions of activated sludge containing 400 mg / l of ferrous iron are added to the aeration tank. I The main indicators of the work of the aerotank and the results of the biological treatment of wastewater are given in Table. 1 and 2.

Claims (3)

Table To determine the limiting values of the amount of input double-stent iron and the ratio of the concentration of bacteria of the genus Leptpthrix to the concentration of bacteria of activated sludge, water purification experiments were carried out as in Example 1. The concentration of bacteria of the genus Leptothrix, at which it provides reliable cleaning of the effluent from organic substances and sulphides, is from 5-10 to 1-10 cells / ml, which is from 0.005 to 0.1% of the bacterium concentration of activated sludge. The dependence of the efficiency of wastewater treatment on the amount of ferrous iron introduced is given in Table. 3. Table The results of experiments show that wastewater treatment according to the proposed method goes more deeply. Withdrawal of contaminants is 86–93% for COD (instead of 70–80% for known), and for MIC 99–99.6% (instead of 86–95% for known). Due to the fact that there is no need to introduce alkalis and biogenic additives into wastewater, as well as due to a 1.5-fold reduction in electricity consumption for aeration, the approximate economic effect from the introduction of the proposed method only at the Afipsky refinery is 5,000 rubles a year. The maintenance of the treatment facilities is given, their capacity increases by 60%. 1. Method of biochemical treatment of wastewater from organic substances and sulphides with activated sludge, which is also due to the fact that, with the aim of v / Cheaper the process and increasing the degree of purification from organic substances while oxidizing sulphides, cleaning is carried out with active sludge containing bacteria of the genus Leptothrix in the presence of ferrous salts. 2. The method according to claim 1 is different from the fact that the concentration of bacteria of the genus Leptothrix relative to the concentration of bacteria of the activated sludge is 0.005-0.1%. 3. A method according to claim 1, characterized in that bivalent iron is introduced into the wastewater to a ratio of the latter to the amount of sulphides from 1: 2 to 1: 8. 4. Method according to paragraphs. 1 and 3, characterized in that used activated sludge, previously aged under anaerobic conditions for 1-3 days, is used as a source of ferrous iron. . Sources of information taken into account in the examination 1. Proskurkov VA, Schmidt L.I. Wastewater treatment in chemical industry. M., Himi, 1977, p. 273-306. 2. For France 2375144, cl. From 02 to 5/10, published on 21/07/1978. 3. Porutsky G.V. Biochemical sewage treatment of organic production. M., Hilsch, 1975, p. 60