SU1527180A1 - )method of treating waste water containing non-ionogenic surfactants - Google Patents

Abstract

This invention relates to methods for electrochemical treatment of wastewater containing petroleum, petroleum products and non-ionic surfactants. The purpose of the invention is to increase the degree of purification of waste water containing petroleum products, as well as simplify the process. For the implementation of the method, industrial anionic surfactants (alkyl sulfates), alkyl sulfonates, linear alkyl benzene sulfonates) are introduced or, if present, industrial waters containing anionic surfactants are present, and electrochemical coagulation is carried out at PH 4.5-5 and a current density of 0.010-0.012 A / cm ² . The method can be used to clean wastewaters containing a cooling lubricant, grinding fluid from metal processing plants, as well as household and industrial wastewaters. The method allows to increase the degree of wastewater treatment, as well as to obtain a flotation condensate less than twice as compared with the known method. 3 tab.

Description

The invention relates to methods for electrochemical treatment of wastewater containing petroleum, petroleum products and non-ionic surfactants, and can be used to clean the waste water of metal-working and rolling mills, chemical plants and various industries.

The aim of the invention is to increase the degree of wastewater treatment, which also contain petroleum products and simplify the process.

For the implementation of the process, anionic surfactants (alkyl sulfates, alkyl sulfonates, linear alkyl benzene sulfonates, for example dodecyl sulfate, decanolsulfonate, dodecsh1-benzenesulfonate), i.e., are introduced into wastewater as flocculating. Industrial surfactants, and the process of separation of petroleum products and surfactants are carried out simultaneously at pH 4.5-5 on iron or aluminum electrodes at a current density of 0.010-0.012 A / cm.

By creating an acidic medium, the surface positive charge of iron or aluminum hydroxide sols and the ability to anion exchange, i.e. adsorption capacity is increased. At pH 4.5-5, sorption of non-ionic surfactants increases dramatically, since they appear in an acidic medium as oxonium compounds.

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The scientific research institute, which leads to the enhancement of the bond with hydroxides through the oxyethylene chain with the help of water molecules, this makes it easier to adsorb solubilized oil products from the micelle surfactant solutions, since they, together with the surfactant molecules, transfer to the surface of hydroxides,

Due to the introduction of anionic surfactants, the rate of precipitation of metal hydroxides sols increases, since surfactant anions replace counterions in the electric double layer of hydroxides and reduce their positive charge, which promotes coagulation. The presence of anionic surfactants gives greater hydrophobicity of the surface of hydroxides. The formation of mixed aggregates is also possible due to the electrostatic and hydrophobic interaction of anionic and noniogenic surfactants (appearing in an acidic medium as oxonium compounds), which condenses the adsorbed surfactant associates. Hydrophobization of the surface of hydroxides promotes sorption of oil products and flotation separation of contaminants. Thus, the creation of an acidic environment and the addition of aiaoactive surfactants ensures a high cleaning efficiency.

The object of purification can be such nonionic surfactants: the products of the interaction of alkylphenols with ethylene oxide (OP-7, OP-10), polyethylene glycol ethers of higher fatty alcohols (OC-20) steroks-6, synth) 1op DS-10, butyl stearate, glycerol monooleate,

If the production water contains anionic surfactants (for example, alkyl sulfates, castor oil, sulfated castor oil, oleic acid, ricinoleic acid sulfo esters), then the cleaning process can be carried out without first adding anionic surfactants.

Example: In wastewater containing petroleum products 130 mg / l (the norm for SNiP is not more than 25 mg / l) and non-ionic surfactants 32 mg / l (the norm is for SNiP not more than 20 mg / l), 40 mg / l anionic surfactants, acidified with a solution of HC1 to pH A, 5-5, and electrochemical coagulation is carried out using iron or aluminum electrodes. 0.1% NaCl, Obra

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The resulting flotation condensate is separated. A sample of purified water is analyzed for the content of petroleum products and surfactants,

The results are presented in Table 1,

As follows from Table 1, after electrochemical treatment of (1) waste water at pH 7, the decrease in oil products to the SNiP norm is achieved at a cost of electricity of 5.8 kW X h / m, the content of surfactant does not change.

When conducting electrochemical purification (2 and 3) in an acidic medium (pH 4.5-5) under conditions when the joint adsorption of petroleum products and surfactants occurs, the required degree of purification for petroleum products is achieved at a cost of electricity 3-4.5 times smaller than in the first case. At the same time, the sum of nonionic and anionic surfactants and purified water is 5-7 mg / l, which is significantly lower than the SNiP norm. With simultaneous separation of petroleum products and surfactants, the required degree of purification is achieved on iron anodes, while aluminum anodes are usually used for preparation of drinking water.

The results of wastewater treatment at various values of current density are given in Table 2,

At a current density of 0.010 A / cm, there is a minimum of energy consumption when the required degree of purification is achieved. With a current density of 0.008 and 0.012 A / cm, the power consumption increases by 12%,

In the range of 0.010-0.012 A / cm, the electric treatment time (14 min), corresponding to a current density of 0.012 A / cm, is closer to the optimal time (16 min) than the electric treatment time (24 min), corresponding to a current density of 0.008 A / cm, therefore 0.010-0.012 is optimal, 1

Data on the electrochemical purification of the original wastewater composition with the addition of 40 mg / l of industrial sodium alkyl sulfonate

(1) and sodium alkyl benzene sulfonate

(2) are listed in Table 3.

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Thus, the presence of anionic surfactants and carrying out electrochemical purification under the specified conditions provide hydrophobicity of the surface of hydroxides, significantly increase the sorption of petroleum products and nonionic surfactants under conditions of joint separation, increase the rate of coagulation of hydroxides and promote flotation separation of contaminants. In addition, according to the proposed method, the amount of flotation condensate per Img of non-ionic surfactants is 2 times less than that known.

80 Formula

the invention

The method of purification of wastewater containing non-ionic surfactants, including the introduction of flocculation with subsequent electrochemical coagulation, characterized in that, in order to increase the degree of purification of wastewater containing petroleum products and simplify the process, as a flocculant input T anion-active surfactants, and electrochemical coagulation is carried out at pH 4.5-5 and current density of 0.010-0.012 A / cm.

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Table 2

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Claims (1)

Claim A method for treating wastewater containing nonionic surfactants, comprising introducing a flocculant followed by electrochemical coagulation, characterized in that, in order to increase the degree of purification of wastewater containing oil products and simplifying the method, anionic surfactants are introduced as a flocculant, and electrochemical coagulation 15 is carried out at a pH of 4.5-5 and a current density of 0.010-0.012 A / cm ⁴ . Table! 1 A1 - Al 7 20 0.015 6.2 ' 5.80 25 32 40 2 A1 - Al 4,5-5 16 0.010 3,1 1.78 25 3.2 . 4.0 3 Fe - Al 4,5-5 16 0.010 3,5 1.30 25 ι, ο 4.0 1 Table and 2 Density Time Residual content, mg / l Consumption A / cm ¹ chemical Oil and gas Nonionogen Anion energy. what about ducts nye surfactants active kW "h / m ^? work Surfactant min 0.008 24 25 3.4 3.8 2.1 0.010 16 25 3.2 4.0 1.8 0.012 * 14 25 3,1 3.8 2.2 0.014 12 25 3.0 3.6 2.6 Material pH Time Raft- Directly electro environment back nost zhenie Dov boots current IN anode - min A / cm ⁴ cathode Tables a 3 Electricity consumption ^ kW-h / m ³ The residual content, mg / l Petroleum products Nonionic surfactants Anionic surfactants Fe - Al 4,5-5 19 0.010 3,1 2.1 25 3,5 6.2 Fe - Al 4,5-5 21 0.010 3,1 2,3 25 3.4 7.1