RU2174961C2 - Waste water treatment method - Google Patents

Abstract

FIELD: waste water treatment. SUBSTANCE: method involves coagulation, flotation, and sorption. Flotation is performed in activated aqueous air dispersion, to which sorbent, in particular fired vermiculite is added. When waste water is treated to remove petroleum derivatives, weight ratio of vermiculite to the latter ranges between 1:1 and 1:15. Before firing, size of vermiculite should be at least 0.5 mm. Method allows creation of module installations and purification of water to oil levels below 0.05 mg/l. Method can be, in particular, applied at mining plants, in chemical industry, etc. EFFECT: enhanced oil removal efficiency. 3 cl, 1 tbl, 4 ex

Description

 The invention relates to wastewater treatment technology of various enterprises and can be used for wastewater treatment of oil depots, fleets, railway enterprises, as well as for the preparation of recycled water from mining and processing, metallurgical, chemical plants.

 A known method of wastewater treatment using sorbents based on vermiculite (AP Zosin. Technical sorbents based on vermiculite Kovdorsky deposits / Chemistry and technology of inorganic sorbents. - Perm, 1980, - pp. 86-91). The method is based on the sorption characteristics of calcined vermiculite. The considered method requires preliminary purification of water from the "suspended".

 There is also known a method of treating wastewater containing petroleum products, including flotation in the presence of a sorbent, where the sorbent, modified expanded perlite with a dispersion of 0.2 - 1.2 mm, is introduced into the flotation together with air. (A.S. USSR N 1263639, class C 02 F 1/24, Method for the treatment of oily wastewater, Yu.I. Tarasovich, L.D. Skrylev, L.K. Patyuk, A.N. Purich, A. A. Panasevich and O.V. Bezrudko, 1986, Bull. N 38). The proposed method allows to reduce the content of petroleum products in the treated water from 1000 mg / l to 2 mg / l, which significantly exceeds the MPC. The second disadvantage of this method is the use of modified calcined perlite, which is associated with the difficulties of obtaining such a sorbent, the organization of its production.

 The claimed invention is directed to the intensification of wastewater treatment and is associated with a combination of coagulation, flotation and sorption processes.

 The problem is solved in that coagulation, sorption and flotation are combined, and the intensification of wastewater treatment is achieved by the use of flotation using a sorbent, which eliminates the preliminary purification of treated water from “suspended” before using the sorbent. Coagulation is carried out using a coagulant, the resulting flocs float. For flotation and hydrophobization of the resulting flocs and sorbent, activated water dispersion of air (AVDV) is used, which is a mixture of water, air and surfactant, which significantly increases the flotation rate and the degree of purification of the treated water.

 The essence of the proposed method is as follows. Wastewater is sent to a tank where inorganic coagulant is fed. After the formation of flocs, they are flotated in a flotation attachment, which is a bath equipped with a device for introducing AVDV. Floccules containing "suspended", oil products, sorbent and other pollutants pass into the foam product. The resulting foam can be removed using a mechanical foam remover or go off spontaneously. Used sorbent, if necessary, is regenerated by simple firing.

 The essence of the proposed method is illustrated by the following examples.

 Example 1. In purified water containing 100 mg / l of petroleum products, g / l of "suspended", 3.7 mg / l of Fe (III), 100 mg / l of calcined vermiculite and 80 mg / l of iron sulfate are introduced. After mixing, a surfactant is added, for example, soap of crude tall oil, in an amount of 70 mg / l. The resulting mixture settles until flocculating and floats. Flotation time is 4.8 minutes 5 liters of purified water. In clarified water, the content of petroleum products is 1.6 mg / l, "suspended" - 84 mg / l, Fe (lll) - 0.1 mg / l.

 Example 2. In the purified water of the composition according to example 1, 100 mg / l of iron sulfate is introduced. After settling to the formation of flocculi, water is sent to a flotation unit where AVDV is supplied containing 100 mg / l of burnt vermiculite and 70 mg / l of surfactant. After flotation, which lasts 2.2 minutes, 5 liters of purified water. In the prepared water, the oil content is 0.04 mg / l, "suspended" - 52 mg / l, Fe- (lll) - 0.28 mg / l.

 Example 3. In purified water containing 1000 mg / l of petroleum products, 917 mg / l of “weighed”, 4.2 mg / l of Fe (lll) 120 mg / l of iron sulfate is introduced and, at optimal pH values, sedimentation is performed until floccules form. Then the water enters the flotation attachment, where it is flotated in a stream of AVDV containing 100 mg / l surfactant and 70 mg / l burnt vermiculite. Flotation time is 2.8 minutes. The content of oil products in purified water was 0.05 mg / l, "suspended" - 61 mg / l, Fe- (lll) - 0.30 mg / l.

 Example 4. In the purified water according to example 3, 120 mg / l of iron sulfate is introduced and sedimentation is carried out at optimal pH values. After that, water thus prepared is floated using AVDV containing 100 mg / L surfactant and 60 mg / L calcined vermiculite. Flotation time is 2.8 minutes. The content of oil products in purified water was 0.17 mg / l, "suspended" - 63 mg / l, Fe (lll) - 0.32 mg / l.

 To determine the effect of the dispersed composition of the introduced calcined vermiculite, experiments were carried out, the results of which are summarized in table.

 From the presented data it can be seen that the cleaning rates are almost identical when using burnt vermiculite with a particle size of 0.074 + 0.0 and 0.5 + 0.0 mm. Vermiculite fraction - 0.5 + 0.0 mm is produced by industry and, therefore, its use is most appropriate.

Claims (3)

 1. A method of wastewater treatment, including the use of coagulation, flotation and sorption, characterized in that the activated aqueous dispersion of air is prepared in the presence of surfactants and enriched vermiculite.  2. The method according to claim 1, characterized in that the mass ratio of calcined vermiculite to petroleum products is 1: 1-1: 15.  3. The method according to claim 1, characterized in that the fineness of vermiculite before firing is less than 0.5 mm

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