For the purification of industrial polluted wastewater, there are various ways that depend on the level of pollution and their compositions. The composition of these methods of water purification includes: mechanical, as well as physico-chemical and biological methods.
In order to separate all organic and insoluble mineral impurities from polluted wastewaters, mechanical wastewater treatment can be applied. This includes settling, filtering, filtering. To complete the process of full clarification of wastewater, it is necessary to skip it (that is, filter) through layers of granular material (it may be clay, sand) with particles of different sizes. As a rule, this purification is used as a preliminary method of wastewater treatment. Although in rare cases, this method is final.
Chemical treatment of industrial waters. It is used when there is a need to remove contamination using chemical reactions. During the purification of water this method occurs:
- oxidation and reduction of impurities that are already dissolved in water, so get non-toxic or low-toxic products;
- the elimination of alkalis, acids;
- conversion to compounds not soluble in liquids.
Chemical purification has different types. One of them is electrochemical purification of industrial waters. It consists in the destruction of harmful impurities contained in wastewater, using electrochemical oxidation at the anode or in the regeneration of substances that have any value (and this is iron, copper) and they can be returned back to production.
Physico-chemical methods of purification of wastewater from production include the use of such processes: coagulation, sorption, decontamination, extraction, ion exchange, flotation, crystallization, evaporation, dialysis, deodorization, and desalting.
So, the first process is coagulation of water. This is the process of converting colloidal and dispersed particles into larger ones. Coagulation occurs by gluing them under the influence of the forces of attraction of molecules. When the process is completed, there are flakes that can be seen by the human eye. There are two variations of coagulation:
– that which occurs in a free volume (it is carried out in specially designed reaction chambers or in chambers in which flakes are formed);
– contact coagulation (it is carried out in the thickness of the granular load of contact illuminators and filters, or in the mass of sediment clarifiers).
The sorption process consists in separating organic substances and gases from wastewater by concentrating them on the surface of a solid (this is called adsorption), or by absorbing compounds from solution, a combination of gases or solids (called absorption). You can also apply the chemical effects of dissolved substances with a solid (this is chemisorption).
The method of separation of substances into parts using a solvent is called extraction. During this process, substances dissolve in different ways. Extractor – special equipment in which the extraction takes place.
Evaporation consists in the purification of wastewater from the production using water vapor. Steam passes through the heated wastewater. Coming, he collects volatile substances.
Flotation – removal of impurities from industrial water. The essence of this process: a special substance is added to the water, enveloping particles of impurities. These particles are given buoyancy.
Desalination of wastewater from production is carried out using ion exchange, evaporation and freezing, as well as reverse osmosis.
Another very interesting method of water demineralization is crystal hydrate. For its use do not need huge energy and financial costs. Also, its advantage is that due to the low temperatures (they are the same as the ambient temperature), oxide is not formed. In the crystalline hydrate process, corrosion is manifested to a lesser extent.
There are also destructive ways to purify water. Thanks to them, pollutants are destroyed by oxidation or reduction. Destructive methods are used in situations where the industrial wastewater contains organic impurities and does not represent any technical value. They can also be used as an after-treatment after regeneration methods of water purification. The key method related to destructive is biological oxidation under aerobic or anaerobic conditions. If you clean the water by this method, then it will meet all sanitary and hygienic standards, so it can be lowered into the reservoir. The price of biological wastewater treatment depends on the substances that are in it.