SEWAGE WATER CLEANING METHODS

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Rivers and other water reservoirs have their own natural self-cleaning process. However it proceeds slowly. While industrial and domestic waste, were not severe, rivers can cope with it. In our industrial century due to sharp increase of waste, rivers cannot manage such significant pollution. The necessity of clearing sewage water and utilizing them has arisen.

Cleaning of sewage water is very difficult process. In this case, like as in other productions we have 2 products: raw material (sewage water) and product (clean water).

Methods of cleaning can be divided into mechanical, chemical, physicochemical and biological process. When all these methods apply together, the process is called combined. The way to choose the best method is determined by character and degree of harmful substances.

Essence of mechanical method consists of cleaning sewage water from solids by settling and filtration. Coarsely dispersed particles depend on their sizes are caught by grids, sieves, sand catchers and septic tank. Surface water is cleaned by oil traps, oil collector and clarifiers. Mechanical refinement allows allocate from domestic sewage water up to 65-70% of insoluble substances and from industrial up to 95%. Many of these substances are used in manufacture processes as valuable addition.

Chemical method consists of adding different chemicals reagents into polluted water, which enter into reaction with pollutants and precipitate them in the form of insoluble additions. By chemical method it is possible to achieve decreasing of insoluble substances up to 95% and soluble up to 25%.

By using physiochemical method, thinly dispersed and solute substances are removed and also organic and poorly oxidize substances are destroyed. From all physicochemical method the most applicable ones are coagulation, oxidation, sorption, extraction and etc.  Electrolysis also is widespread. This method, also consist of destroying organic substances in sewage water and extraction of metals, acids and other inorganic substances. 

Electrolytic cleaning is carried out in special constructions - electrolyzer. Sewage treatment by means of electrolysis is effective at the lead and copper enterprises, in paint and varnish and some other fields of the industry.

The polluted sewage clears also by means of ultrasound, ozone, ion-exchanging pitches and a high pressure, cleaning by a chlorination way well proved as well.

Precipitation of domestic and industrial sewage in some industries is good fertilizer and is used in agriculture.