CZ280037B6 - Method of treating water contaminated predominantly with oil component by the action of bentonite - Google Patents

Abstract

A method for treating water contaminated predominantly with an oil component by the action of bentonite in the form of an aqueous suspension which is treated at a temperature of 5 to 25 deg. C. The natural bentonite is first mixed with contaminated water, and then a stream of this mixture is formed, which is preferably fed to a milling and mixing pump. In it, the mixture is pressurized to 0.1 to 10 MPa in the range of 5 m / s to 500 m / s milled and mixed. The resulting suspension can be further activated by the addition of an organic flocculant. ŕ

Description

Method of treatment of water contaminated mainly by oil component by bentonite

Technical field

The present invention provides a process for treating water contaminated predominantly with an oil component by the action of bentonite in the form of an aqueous suspension.

BACKGROUND OF THE INVENTION

So far, the sorption and flocculation properties of bentonite and other clays from the montmorillonite group have been increased by their chemical treatment. The purpose of such treatments is to bind the chemical flocculants to the bentonite structure, thereby producing a stronger flocculation effect than the bentonite itself is capable of. It then advantageously, due to its specific ability, loads the sludge and thereby significantly accelerates its sedimentation.

For example, it is known to treat the aqueous suspension of bentonite in an iron, iron or aluminum cycle in an amount dependent on water contamination. Bentonite aqueous suspension treatments are also known in which bentonite is wet-ground in groups of chlorides, sulphates, nitrates, dosed in a quantity-dependent manner, and mineral-based bentonite treatments with the activating agent with the hydroxide and phosphates of the bentonite used. They are acids, for example hydrochloric and / or sulfuric acid. These acids are mixed with bentonite at elevated temperatures and vigorous stirring. As a result, the metal part of the base material is extracted from the bentonite and at the same time the remaining material increases its volume and its microporous size. Thereafter, the extracted metal salts and excess acid are separated, the resulting product is washed, dried, followed by extraction, for example by adsorption and grinding. Sometimes still with hydrochloric acid, activated bentonite.

but at the expense

A more modern way is the continuous countercurrent activation of bentonite, which takes place at the boiling point in two to four stages. A fine-grained bentonite suspension enters the first stage and the extracted metal salts and residual acid exit. An acid solution enters the last step and a suspension of extracted bentonite exits. It is then washed, dried, ground and sorted.

The disadvantages of the prior art bentonite activation processes are high chemical consumption, wastewater salinisation, energy consumption and additional costs for water purification from the activation process and washing of activated bentonite.

SUMMARY OF THE INVENTION

The aforementioned drawbacks are largely eliminated by the method of treating water contaminated predominantly with the oil component by the action of bentonite in the form of an aqueous suspension, which is treated at a temperature of 5 to 25 ^° C.

The principle of the invention is that the natural bentonite is mixed with contaminated water, then a stream is formed from this mixture which is pressurized to 0.1 to 10 MPa and then the mixture stream is alternately

Accelerating and retarding in the speed range of 5 to 500 m / s while the mixture is ground and vigorously stirred. Preferably, an organic flocculant may be added to the suspension prior to mixing.

The method according to the invention has been verified in an industrial waste water treatment plant. It has the advantage of eliminating the need to use chemical additives, significantly increasing the sorption properties of activated bentonite and reducing the environmental burden of waste chemicals.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

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Per 1m of 5 ° C carwash wastewater containing 0.52 mg / l of non-polar petroleum substances (NEL), 2 kg of ground, unactivated bentonite from the Obrnice bearing was dosed through the hopper of the grinding and mixing pump. The mixture was sucked through a grinding and mixing pump and pressurized to 0.3 MPa. It was then milled while being mixed at local alternating acceleration and retardation in the range of 5 to 500 m / s. This procedure activated bentonite and adsorbed petroleum substances onto its surface. The cationic polymeric flocculant based on polyacrylate was then added to the suspension in an amount of 1 g of cationic polymeric flocculant per kg of bentonite. Floccules were formed with subsequent rapid sedimentation.

Purified waste water was subjected to laboratory analysis and was found to contain 0.257 mg / l NEL.

Example 2

Per 1 m ^{3 of the} same waste water, 5 kg of the same bentonite was dosed through the hopper of the grinding and mixing pump at the same temperature. Water was cleaned to 0.032 mg / l NEL using the same procedure.

Example 3

For 1 in ³ polluted motor vehicle washer waste water containing 0.52 mg / l NEL, the spent oil was added and the NEL content was increased to 4000 mg / l NEL. 4.44 kg of ground bentonite from the Obrnice bearing was dosed through the hopper of the grinding and mixing pump. The mixture was sucked through a grinding and mixing pump and pressurized to 0.5 MPa. Following the procedure described in the previous examples, bentonite was activated, oil emulsified, and oil products sorbed in various forms to bentonite grains. Addition of 2 g of polyacrylate-based cationic polymeric flocculant per kg of bentonite resulted in flocculation followed by rapid sedimentation. Purified water contained 0.24 mg / l NEL.

-2GB 280037 B6

Industrial applicability

The process according to the invention can also be used in analogous processes in which the fine grinding and mixing of, for example, powdered powders in liquids is important to form suspensions or emulsions of liquids and various substances, not only bentonite.

PATENTOVÉ

Claims

Claims (1)

A process for treating water contaminated mainly by an oil component with bentonite in the form of an aqueous suspension which is treated at a temperature of 5 to 25 ° C, characterized in that the natural bentonite is mixed with the contaminated water, then forming a stream which is pressurized to 0.1 to 10 MPa, and then the mixture stream is alternately accelerated and retarded at a speed range of 5 to 500 m / s, the mixture being milled and vigorously stirred.