Sewage. The hygienic characteristic
Sewage are the polluted waters formed as a result of use of water water for household and industrial needs. An atmospheric precipitation which form storm waters concern sewage also.
Household sewage include waters of kitchens, toilet rooms, per capita, baths, laundries, table, hospitals, the economic waters formed at washing of premises, etc. They arrive from inhabited and public buildings, from household premises of the industrial enterprises. Structure and properties of household sewage are characterised by the same indicators as sources of their pollution are homogeneous. In sewage the considerable quantity of organic substances (about 60%) contains. This pollution is characterised by such sanitary indicator, as biochemical consumption of oxygen (BPK) - the quantity of oxygen necessary for full biochemical oxidation of organic substances, containing in 1 l of water at temperature 20 В°s within 20 days. In sanitary practice are often limited to definition BPKl, i.e. Biochemical consumption of oxygen in 1 l of water within 5 days. BPKb for household sewage equally 185-600 mg/l. Oxidability of household sewage makes from 35 to 220 mg of S/L. To other indicators characterising sewage, the weighed substances, nitrogen ammonijnyh connections, chlorides, hydrogen sulphide, the dry rest, phosphates, acidity, reaction concern.
Household sewage have a low transparency, alkalescent reaction, a considerable quantity of the weighed substances.
Household waste yoody are dangerous in ejjdemjcheskom otnoshe-nii as contain pathogenic microorganisms and ente-rovirusy, and also a considerable quantity of viable eggs gelmintov.
Industrial sewage differ from economic-household themes, that their formation is connected with use of water water in technological process at the industrial enterprises. Water can be applied as the heat-carrier, solvent, transportation means, to waste disposal. It also defines structure of industrial sewage which cannot be to constants. As a part of them many toxic substances, various specific components, reaction also is various - from sour to alkaline. Often waters have the specific smell, the expressed colouring and the raised temperature. In them there are no activators of infectious diseases.
The Water used for cooling of industrial raw materials, production or the equipment, after clearing can be reused for technological needs. The sanitary characteristic of household and industrial sewage.
Storm waters share on rain and thawed. Rain sewage are characterised by the expressed non-uniformity.
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