Water cleaning by way of flotation as a method of protection of reservoirs from pollution
Now the need for fresh water is high in the world, and discrepancy of preservation аква sources, their protection against industrial drains is very sharp. One of often meeting methods of water purification is water cleaning by way of flotation.
The word "flotation" was formed from the French verb of "Flotter" that practically means «to float on a water surface. Flotation is a method of cleaning of water by means of air vials. It use for removal from water of oils, oil products, surface-active substances, wool, asbestos and other substances, insoluble in water
Cleaning of water takes place in flotator and in general looks the next way: rapprochement of an air vial and a part of substance which pollutes water, and their connection together. Degree of durability of their connection is in dependence from the sizes of a vial, physical and chemical parameters of a part, hydrodynamic criterion and other requirements. For example, vials of air emerge very promptly and mix water, without managing to be fixed on a surface of particles. Properly, cleaning of water occurs inefficiently.
When vials at flotation emerge on a water surface, they grasp also parts of impurity, forming there foamy sing. Foam acts in film penosborny mechanisms.
Methods of flotatsionny cleaning differ between themselves is dependent on how vials were received:
• method of mechanical crushing;
• from peresyshchenny mixes in water (pressure head, vacuum);
It use for cleaning of sewage from fats and oil products.
Process consists in an air dispergirovaniye by means of a mechanical mixer. Impeller turns and forms a zone of the lowered pressure. Its blades mix air and water and throw out vials in the flotatsionny chamber where they clean impurity from water.
Defects of cleaning of water in the way of impellerny flotation contain in its small efficiency. In turning out to a fine very large volume of water that asks creations of additional installations for its processing contains.
Flotation by means of porous plates
Porous materials for this purpose are obliged to have quite huge distance between openings that vials of air did not grow together over a material surface. Here plays a role and speed of the expiration from an opening. The speed of the expiration less, the it is less than vials and that efficiency of cleaning of water in this way of flotation is higher.
Pressure head flotation
It is made in 2 stages:
– water is sated with air in pressure head tanks under the highest pressure;
– in the flotatsionny chamber pressure decreases to atmospheric and vials of air of a demanded diameter emerge together with the weighed and emulgirovanny parts of impurity.
Pressure head flotation can be carried out without reagents and with reagents in case of need effect strengthenings. Flotation without addition of reagents belongs to physical methods of cleaning of sewage.
Pressure head flotatsionny installation consists of modular tanks for sewage, the compressor or an ezhektor, the pressure head tank and the flotatsionny (settling) chamber where the emerging mass of pollution is removed. Also there is a reagentny installation and a warehouse of reagents.
In the flotator chamber pressure decreases below atmospheric and the air dissolved in water is allocated. Vials are formed in the measured environment and integrity of the particle vial complex is not broken till that time while they will not come up on a water surface.
At electroflotation waste liquid under the influence of a current is sated with hydrogen vials.