Classification of sewage
In technological processes the following basic kinds of sewage are formed.
Reactionary waters are the characteristic for the reactions proceeding with formation of water. Reactionary waters are polluted both initial substances, and products of reaction. Clearing of these waters usually is a serious problem.
The waters, contained in raw material and initial products - the free or connected water, contained in many kinds of raw material (coal, oil, slate) and initial products, during technological processing are polluted different organic substances. So, combustible slates contain 2-2,5 % of water which as a result of thermal processing of slate becomes soiled phenols, aldehydes, etc.
Washing water - is widely used for washing of raw material and the products used and received in technological processes. The quality of received substances frequently is defined by carefulness of washing.
Mother liqueurs- are formed as a result of carrying out of production processes or processing of products in water environments. During crystallization of solutions are formed the sewage, polluted with mineral substances, etc.
Water extracts and absorbing liquids - are formed at use of water in quality of an extragent or an absorbent. It contains significant amounts of chemical substances. A plenty of absorbing liquids is formed at wet clearing of departing gases.
Cooling waters - are used at the chemical enterprises for cooling of products and devices. The water, which is not adjoining with technological products, is used in systems of turnaround water supply.
Other kinds of sewage are formed from vacuum pumps, direct-contact condensers, at condensation of water steam, from washing of equipment, container and premises, etc. The atmospheric precipitation from territories of chemical enterprises also can be polluted with chemical substances.
There are other kinds of classification of sewage in which basis are put the principle of opportunity of their use in system of turnaround water supply, a degree of impurity, etc. There isKulskii L.A. classification.The essence of it: all impurities of water under their attitude to the dispersive environment are divided into four basic groups:
Group 1 - sewage contains water-insoluble impurities with size of particles 10-5- 10-4 m and more;
Group 2 - sewage represents colloid solutions;
Group 3 - sewage contains dissolved gases and molecular-soluble organic substances;
Group 4 - sewage contains the substances, dissociated on ions.
The phase-disperse characteristic of sewage impurities allows to offer the certain set of methods of sewage treatment for each group.
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