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Hygienic characteristic underground waters.
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Hygienic characteristic underground waters.
Subsoil waters. Open reservoirs are better polluted, but all the same subsoil waters in wells frequently become polluted.
Inter-layer waters - are practically sterile, lacks: small stocks, it is expensive to extract, frequently has high mineralization and temperature.
Atmospheric waters. A changeable source, atmosphere it is considerably polluted - pollution these waters. Besides it has low mineralization.
Distillation sea waters.
Very dearly - it is a lot of electric power for distillation, seawaters are polluted - at boiling toxic substances can be formed.
Hygienic characteristic systems of water supply.
There are 2 systems of water supply:
1. Centralized system - a city waterpipe. Structure: 1) Head constructions (place of water-fence, pump stations, clearing constructions), 2) Distributive network (main, inhouse water supply systems).
2. Decentralized system - small rural waterpipes, wells - there are no complex clearing constructions.
Zones of sanitary protection water sources.
1) Zone of the strict mode. It is include place of water-fence, head constructions of waterpipe.
2) Zone of restrictions – it is all or a part of the area of water reservoir. Restriction accommodation objects of pollution water sources.
3) Zone of supervision. Supervision for epidemic conditions (cases of infectious diseases) in the big territory and strengthening clearing and disinfecting water at adverse epidemic conditions.
METHODS OF IMPROVEMENT QUALITY OF WATER.
There are 3 basic groups of methods:
1) Methods of water cleaning - removal from mechanical impurity and improvement оrganoleptic parameters of water (turbidy, colouring)
2) Methods disinfecting of water - destruction microflora in water
3) Special methods improvement quality of water – distillation, dechlorination, fluorization, defluorization, deodorization, decontamination, deactivation water.
Methods water cleaning.
Water cleaning will be carried out by:
1) upholding water
2) filtration water through filters (slow and fast filters).
For acceleration cleaning used coagulation water - adding salts Al or Fe - are formed flakes with salts Са or magnesium in water. Now use flocculants – polyacrylamid, etc. for more quickly water cleaning.
Control efficiency of water cleaning:
а) By оrganoleptic parameters - turbidy, colouring, smell, taste
b) By oxide ability water.
Methods disinfecting of water.
There are 2 groups of methods of disinfecting:
1) Physical, 2) Chemical.
Physical methods of disinfecting:
а) boiling - good bactericidal effect, but expensive method - the big power consumption - is applicable in domestic conditions.
b) UVR - 100 % effect, but needs the big power consumption and small volumes of water - in clean water UV pass through only 50 sm, in muddy - is even less.
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c) Gamma irradiation - is used seldom - the complex equipment, threat of an irradiation of the personnel and the induced water radioactivity.
d) A ultrasonic irradiation - complex method, influence on the personnel.
Chemical methods disinfecting of water:
а) Ozonization - action of atomic oxygen - good bactericidal effect. The big power consumption. It is improved water organoleptics. Full destruction of toxic substances in water.
b) Action ions of silver. " Sacred water" in churches. Ions of silver has bactericidal effect. Dearly method.
c) Chlorination water - most wide used method in view of cheapness.
Chlorination water.
At entering chlorine in water there is a hydrolysis of chlorine and formation hydrochloric and chlorinewatic (HOCl) acids, dissociates to ions Н + and ions OCl - bactericidal effect.
Scheme of chlorination:
90 % of chlorine contacts with various substances in water and inactivated (chlorine absorbing), there is residual or free chlorine - for sufficient bactericidal effect it should be 0, 3-0, 5 mg / l (below - there is no bactericidal effect, is higher - change a smell of water more than 2 points).
Chlorine absorbing + residual chlorine = chlorine necessity water. It is determined at skilled chlorination - on practical lessons.
Kinds of chlorination water.
1) By chlorine necessity or chlorination by normal dozes of chlorine - under the control contents of residual chlorine 0, 3-0, 5 mg / l.
For improvement bactericidal effect there are other kinds of chlorination:
2) Superchlorination - application big dozes of the chlorine exceeding chlorine necessity waters. It is used for very much polluted waters, unknown waters on bacteria indications (field conditions), on epidemic indications. Water then demands dechlorization - through the activated coal, hyposulfit.
3) Double chlorination - entering chlorine before and after water cleaning - is increased exposition action of chlorine, but formation toxic chlorine-organic substances raises.
4) Chlorination with ammonization - entering into water chlorine and ammonia - are formed chloramines - the greater bactericidal effect, there is no " chemist's" smell, as at usual chlorination when in water can be formed chlorphenols.
Lacks water chlorination:
а) Deterioration organoleptics (smell) of water
b) Not always reliable disinfecting (viruses of a hepatites etc. )
c) At pollution water at chlorination are formed toxic chlorine-organic substances such as chloroform, tetrachloretylen, etc. having mutagen and cancerogen activity.
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