CS237038B1 - Method of treatment of waste water containing crude oil - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the purification of petroleum-containing waste water from metal cutting, metal stamping, automotive repair, agricultural machinery, electric motors, etc. Non-ionic, anionic and cationic emulsifiers are present in wastewater stable emulsions.

So far, known methods of treating water containing oil in the form of a water / oil nobo oil / water emulsion can be divided into four categories:

- chemical processes: addition of acids, salts, demulsifiers, foculants;

- physical processes: adsorption, electrophoresis;

- thermal processes: simple heating, evaporation, burning;

- mechanical processes: centrifugation, filtration.

Said principles of wastewater treatment are insufficiently effective, in particular highly concentrated and stabilized emulsions, for example used degreasing baths from the engineering and repair industries. In order to achieve the quality values of the discharged waste water permitted for discharge into the recipient or for re-use in the production process, the waste water must be further diluted. This only reduces the concentration of petroleum substances, but not their removal, and thus the environment is burdened with high residual mass contamination.

Another disadvantage of the known purification processes, especially chemical processes, is the formation of large amounts of sludge which cannot be stored in public landfills. These sludges can only be disposed of thermally, which brings further disadvantages such as sealing of combustion equipment, conveyors, fuel tanks and other heating technology.

The above drawbacks are overcome by treating the oil-containing wastewater of the invention by treating the wastewater with a combination of a two-stage thermal and chemical treatment process. The first phase is treated with sulfuric acid in the pH range of 2.5 to 3.9 at a temperature of 70 to 90 ° C, which phase is completed by the contraction of the upper oil layer. In the second phase, the waste water is boiled and treated with potassium permanganate 0.01 to 0.05 kg m ^-3 , heating is terminated and the oil fraction is withdrawn again during cooling of the waste water.

The first purification stage is by adding sulfuric acid to a pH of between 2.5 and 3.9 to the waste water and heating the mixture to a temperature of 70 to 90 ° C. The oil that is deposited in the form of an oil layer on the surface is suitably withdrawn from the surface. In the second phase, the waste water is heated to the boiling point, followed by the addition of potassium permanganate in the range of 0.01 to 0.05 kg m ^-3 . This is followed by termination of heating and further withdrawal of the oil. The necessary optimum pH, potassium permanganate weight and temperature are determined by a series of tests preferably in a sample volume of 1 dm ³ .

The advantages of this purification process are that, when the optimum dosages of the reagents are correctly determined, the purified water remains clear with a very low oil content, the second advantage being that there is no formation of sludge loaded with oil substances. Example 1

In the molding of car body parts, moldings of oil-containing lubricants and non-ionic emulsifiers are used for the lubrication of highly exposed areas. After dripping and machine degreasing of these moldings, a highly stable aqueous emulsion is formed which contains 95 g / ^{l of} petroleum substances. A series of 1 din ³ samples is run to determine optimal dosages of reagents needed for the cleaning process. The optimum amount of cleaning agents was determined to be 1 l / m ³ H ² SO 4 - 96%, temperature 80 ° C and for the second phase of the purification process 0.03 kg / m ³ KMnO ³ .

In the first stage of the purification process, the mixture is heated to 80 ° C after adding sulfuric acid to the reaction vessel. Upon reaching this temperature, heating is terminated and the oil fraction is separated by flooding over the overflow edge of the reaction vessel. By completely separating the oil fraction, the first phase of the cleaning process is completed.

In the second phase, the mixture is again heated to the boiling point and potassium permanganate is added. The heating is then stopped and the oil fraction is separated again. The mixture is then neutralized with lime hydrate to pH 8.5. The treated water content was 2.3 mg l ^-1 · extractables.

Example 2

In the machining of metals, cutting oils are used which drip off when handling waste metal chips, and together with other impurities resulting from floor cleaning, form an emulsion containing anionic and non-ionic emulsifiers. Emulsions before entering the purification process contains 56 g 1 ^_1 extractables. The optimum amount of reagents was determined by a series of tests in a sample of 1 dm ^{3 of the} crude emulsion at 0.9 lm ^-3 H ² SO 4 96%, for the second stage of the purification process 0.04 kg / m ³ potassium permanganate. Another procedure is identical to Example 1. The content of extractables amounted to 2.1 mg, 1 ^_1.

Claims (1)

PftEDMET Process for the purification of oil-containing waste water by means of sulfuric acid and potassium permanganate, characterized in that the waste water is treated by a combination of a thermal and chemical treatment process in two phases, in the first phase it is treated with sulfuric acid in a pH range of 2.5 to 3 In the second phase, the waste water is boiled and treated with potassium permanganate in an amount of 0.01 to 0.05 kg m- ³ , terminated. heating and the oil portion is withdrawn again during cooling of the waste water.