SU789410A1 - Method of waste water purification - Google Patents

Description

(54) METHOD FOR CLEANING WASTE WATER

one

The invention relates to a technology for the treatment of wastewater containing organic and mineral impurities (proteins, carbohydrates, fats, dyes, detergents, phosphorus compounds, petroleum products, etc.).

There are known methods for treating such wastewaters, which consist in coagulating them with various reagents, upholding the coagulated polluted with 10 Pip and the biological oxidation of residual contaminants.

For example, a sewage treatment method is known, in which coagulation of waste is carried out by non-organic coagulum (ferric or ferrous iron salt), after which the waste water is subjected to settling and biological oxidation 1.20

The closest to the proposed technical specification is cnocoS, according to which coagulation of contaminants is carried out by adding one 25 to the wastewater. . Of inorganic coagulants Ali (S04) 3, Fe, j (S04) j, FeCl, Ca (OH) 2, NaAlOj, FeSOj. In order to consolidate the flakes and improve clarification, cationic flocculant is dispensed into the wastewater in 30

amount up to two mg / l. The coagulated impurities are separated from the water during settling and the residual contaminants are separated during biological oxidation 2.

The disadvantage of this method is insufficient purification and deterioration of the operation of settling tanks and biological treatment facilities when used as a coagulant of ferrous iron salts, which are the most accessible reagent, namely, the removal of contaminants due to incomplete oxidation of ferrous iron increases. water dissolved oxygen. Incomplete oxidation of ferrous iron will also be in all cases when the pH of the wastewater is less than 7.5. At the same time, dissolved bivalent iron in the form of a cation remains in the settled water, which has a toxic effect on the microorganisms of the activated sludge, which makes biological treatment of waste water difficult.

Another disadvantage of this method is the complexity of the technological scheme, due to the use of two reagents, one of Koxopjjjt, cationic flocculant, is also very expensive. Bivalent iron salts effectively coagulate contamination only when there is an excess of oxygen dissolved in water and pH values of water are greater than 7.5. Under these conditions, bivalent iron is oxidized to trivalent iron to form Fe (OH) -j ,. which destabilizes the negatively charged colloidal contaminants to form a flake from water during the process of settling. With a lack of dissolved oxygen, and also at a pH of less than 7.5, Fe (OH), 2. Is formed, the solubility in water of which is higher and the flocculation ability is lower, as a result of which the coagulation process partially or completely stops. As a rule, dissolved oxygen is not sufficient to oxidize all the ferrous iron in the water being treated. The purpose of the invention is to increase the degree of purification due to aeration of waste water and the use of activated sludge instead of cationic flocculant and simplification of the technological scheme. The goal is achieved by the fact that the mixture of coagulant-bivalent iron salts, with wastewater, is subjected to aeration before settling, preferably for L520 minutes with an air flow rate of 2-4, and introduced into it as flocculant active sludge. The pH of the mixture should be more than 7.5, for which, if necessary, it is alkalinized. The method is carried out after the uuushm pattern. D wastewater entering the primary sedimentation tanks. Mineral coagulum, a salt of ferrous iron, is introduced; The mixture of reagent with waste water is aerated for 15–20 min with air flow rate of 24 m / m and activated sludge in the amount of 30–50 mg / l is added to it on a dry basis. When the pH of the wastewater is less than 7.5, alkalinization is made to p greater than 7.5. The waste water treated in this way is sent to sedimentation tanks and further to biological treatment facilities. EXAMPLE 1. Highly concentrated wastewater treatment is carried out. Municipal wastewater with a BOD of 556 mg / l, COD 1360 mg / l, pH 7.5, containing 10. mg / l X-ray, 600 mg / l suspended solids, 5 mg / l surfactant and 10 mg / l petroleum the treatment with an optimal dose of ferrous iron salt (75 mg / l in heZOD). The mixture of reagent with waste water is aerated for 20 minutes with an intensity of 4 m VM, the pH of the mixture is adjusted to 7.6 by the addition of 15 mg / l of marketable lime. Excess activated sludge in an amount of 50 mg / l is introduced into the reagent mixture with waste water to improve flocculation. Then the waste water is settled, the precipitate is separated and subjected to biological oxidation in aeration tanks. Purified water has mg / l, COD 75 mg / l, suspended matter content 13 mg / l, pacTBopHVbix phosphates 0.2 mg / l, surfactant 0.4 mg / l, oil products 0.5 mg / l. PRI mme R 2. Purification of less concentrated wastewater is carried out, municipal wastewater has 1pH 7.8, VPK 5-250 mg / l, COD 660 mg / l, suspended solids concentration 240 mg / l and soluble phosphates 8 mg / l, surfactant 4 mg / l, subjected to treatment with an optimal dose of ferrous iron (50 mg / l according to FeSO). The mixture of coagulant with waste water is aerated for 15 min with a flow rate of air of 2MVw and excess active sludge is introduced into it in an amount of 30 mg / l. Then the wastewater is settled and biologically oxidized in aeration tanks. Purified waste water has a BOD of 3 mg / l, COD 30 mg / l, suspended matter concentration 4 mg / l, soluble phosphate 0, 1 mg / l, surfactant 0.2 mg / l. Comparative data obtained by Sch5I of purification water by the known and proposed methods are given in the table.

700

960 270

350

93,8

60 6

420

150 29 98.3 150

The use of this cleaning method allows to increase the efficiency of wastewater treatment while reducing the capital costs of the facilities by 25-30%.

Claims (2)

Invention Formula 1, Wastewater treatment method, including the introduction of coagulant salts of ferrous iron, the introduction of flocculating, settling and separation of the sediment, followed by biological oxidation, characterized in that the whole table Neither the degree of purification and simplification of the technological scheme, after the introduction of the coagulant, the mixture is aerated, active sludge is used as flocculant, 2. A pop method, 1, characterized in that the mixture is aerated for 15-20 minutes with an air flow rate of 2-4. Sources of information taken into account in the examination 1. Japanese Patent No. 51-1948, cl. 91 C 91, 21.06,76. 2.Patent UK W 1443192, cl. C 1 C, 07.21.76 (prototype) -.