METHOD OF TREATMENT OF WATER POLLUTED PREDOMINANTLY BY AN OILY COMPONENT USING BENTONITE

Abstract: Firstly, the natural bentonite is mixed e.g. with polluted water, and then a stream of this mixture is made, being put advantageously into the milling/mixing pump. In this pump the mixture is pressurized in the range 0.1 - 1000 MPa and milled and stirred under local alternative acceleration and retardation in the range 5 - 500 m/s. The originated suspension can be further activated by an organic flocculant.

Description: Method of treatment of water polluted predominan ly by an oily component using benton te The invention solves a method of bentonite activation by means of a mechanical and physical treatment of this substance i Until now, sorption properties of bentonite and other clays from the montmo i 1 lonite group can be enhanced by their chemical treatment. The reason for such treatment is cracking of tiny bentonite grains aiming at enhancing their volume. For example, the mechanical and chemical treatment of bentonite water suspension in the ferrous (Fe 2+ ), ferric (Fe 3+ ), or aluminium (Al 3+ ) cycle is well known, in amount dependent on water pollution. Other known bentonite benefiσiation in the water suspension is based on the wet milling of the clay with activation chemicals such as with chlorides, sulphates, nitrates, hydroxides, and phosphates depending on the amount of bentonite used. Up-grading of bentonite by means of mineral acids are also known, e.g. using hydrochloric and/or sulphuric acid. These acids are mixed with bentonite at elevated temperatures under vigorous stirring. By this procedure, the metallic part of the basic material is extracted and the rest material increases its volume simultaneously, as well as micropores increase their size. After that, extracted-out metallic salts and the exσessing acid are separated and the resulting product is washed through, dried, and mil led. Sometimes the subsequent extraction, e.g. by hydrochloric acid is performed but the absorption ability of the activated bentonite may be reduced. The continuous counter-current activation of bentonite is a more modern method being performed up to the boiling point in two up 4 to four steps. The fine-grain suspension of bentonite enters the first step, and salts of extracted-out metals and rest acid are ■ * outgoing into the last step, the solution of an acid goes in, and the suspension of extracted bentonite goes out. In the further processing, this is washed- hrough, dried, milled, and classi fied. The disadvantage of hitherto given activation methods is a high consumption of chemicals, salting of wastewater, high energy demand, and supplementary costs for treatment of water outgoing from activation process and from washing-through of activated bentonite. The absences given above are minimal ized by the method of treatment of water polluted predominantly by an oily component using bentonite at the temperature of the environment. The subject of this method is mixing the loose natural bentonite with polluted water followed by sucking and pressurizing this mixture at O.l - 1000 MPa, and after that is is alternatively accelerated and retarded in the speed range of 5 - 500 m/s under milling and intensive mixing. Before mixing the component, it is possible to add organic flocculant into the suspension. The method according to the invention has been proved in a plant treating industrial wastewaters. Its advantage is no necessity to utilize chemical admixtures, markable increasing of sorption properties of activated bentonite, and lowering the impact of waste chemicals on the environment. EXAMPLE Example No.1 For 1 cubic meter of wastewater originating from car washing station, having its temperature 5°C, and containing 0.52 mg/ 1 of non-polar extraσtable compounds (NEC), 2 kilograms of milled natural non-activated bentonite (Obrnice deposit, Czech Republic) were added through the hopper of the milling/mixing pump. The mixture was sucked by the mi 11 ing/mixing pump and pressurized on 0.3 MPa. Then it was milled and at the same time stirred at the local alternating acceleration and retardation in the range 5-500 m/s. By this procedure, bentonite became activated and oily substances got adsorbed on its grains. Then, lg of the cation-acti e polymeric flocculant on 1kg of bentonite was added. The flocks had been created followed by their rapid sedimentation. The water after treatment was subjected to chemical analysis and it was proved that the content of oily substances (NEC) dropped down to 0.257 mg/ 1. Example No.2 For 1 cubic meter of the same wastewater, 5 kg of the same bentonite as in the example 1 was dosed through the hopper of the mixing/milling pump. By the same procedure, the water after treatment contained 0.032 mg/ 1 NEC. Example No.3 To 1 cubic meter of the polluted wastewater from the carwash station, containing 0.52 mg/ 1 NEC, the used motoroil was added resulting i n the increasing NEC value amounting 4 000 mg/ 1. Through the hopper of the milling/mixing pump, 4.44 kg of the natural milled bentonite (Obrnice deposit, Czech Republic) was added. The mixture was sucked by the mi 11 ing/mixing pump and pressurized on 0.5 MPa. By the previous procedures given in examples No.l and 2, respectively bentonite became activated, oils became emulsified, and different oily substances were sorbed onto bentonite grains. After adding 2g cation-active polymeric flocculant (based on 1kg of bentonite), flocks originated followed by their rapid sedimentation. The water after treatment contained 0.24mg/ 1 NEC. The method according to the invention can be also applied in analogical processes where fine milling and mixing is important, e.g. for loose powder materials in liquids in order to prepare suspensions or emulsions from liquids and di ferent substances, not only from bentonites.

Claims: CLAIMS Method of treatment of water polluted predominantly by an oily component using bentonite in the form of water suspension which is processed at the temperature of the environment, c h a c¬ t e r i z e d t h e r e i n, that natural bentonite is mixed with water, followed by making a stream from this mixture which is pressurized on 0.1 - 1000 MPa, and then the stream is alternatively accelerated and retarded in the range of speeds 5 - 500 m/s, under milling and vigorous stirring the mixture.

Inventors: HRUSA EMIL, PODUSKA JAROSLAV, SIEGEL LUDVIK, HRUSA, EMIL, PODUSKA, JAROSLAV, SIEGEL, LUDVIK
Applicants: VODNI STAVBY PRAHA
Application year: 1995
Main classification: B01J20
IPC codes: B01D17, B01J20, B03B5, C01B33, C02F1