ТаТаshkent Medical Academyshkent Medical Academy

Department of Communal Hygiene and Department of Communal Hygiene and Labour Hygiene Labour Hygiene

from Communal hygienefrom Communal hygienelecture for 4-year studentslecture for 4-year students

Subject: Hygienic characteristic Subject: Hygienic characteristic techniques and methods to improve techniques and methods to improve

the quality of drinking water.the quality of drinking water.

•The main task of purifying The main task of purifying water from open water water from open water reservoirs is to fully release it reservoirs is to fully release it from the slurry and thereby from the slurry and thereby make the transparent color make the transparent color and reduce to a level where it and reduce to a level where it becomes invisible and becomes invisible and decontaminated waterdecontaminated water

•..

•Under water purification in Under water purification in preparation for its drinking preparation for its drinking water supply understand water supply understand decrease impurity decrease impurity concentration to a level that concentration to a level that ensures the safety and ensures the safety and harmlessness of human harmlessness of human demand for water, ie, to the demand for water, ie, to the level of hygienic standards.level of hygienic standards.

The main methods of cleaning The main methods of cleaning the surface source arethe surface source are

::

• Rainwater or water intake, structures Rainwater or water intake, structures are divided into 3 typesare divided into 3 types

• ::

•The task of receiving waters - to The task of receiving waters - to create a reservoir from which create a reservoir from which water can climb pumps in terms water can climb pumps in terms of protection from damage and of protection from damage and the oscillation mode of the the oscillation mode of the reservoir, as well as delay the reservoir, as well as delay the coarse suspended dirt on lattices coarse suspended dirt on lattices at the inlet and grids to suction at the inlet and grids to suction pipes pumps.pipes pumps.

• The usual scheme of water treatment The usual scheme of water treatment at waterworks using water from open at waterworks using water from open reservoirs, Presley - blowing the reservoirs, Presley - blowing the following tasksfollowing tasks

• :: 1) Relief of suspended solids

and colloidal impurities to improve its organoleptic properties, especially transparency and color;2) Ensuring the safety of water in epidemiological terms.

coagulation watercoagulation water   Coagulation is the process of    Coagulation is the process of enlargement, the aggregation enlargement, the aggregation of colloidal and fine impurities of colloidal and fine impurities of water due to their mutual of water due to their mutual adhesion by the forces of adhesion by the forces of molecular attraction.molecular attraction.

Coagulation impurities water Coagulation impurities water accelerates clarification and accelerates clarification and discoloration. As the coagulants useddiscoloration. As the coagulants used    chemical reagents which are    chemical reagents which are    a charge opposite of colloidal     a charge opposite of colloidal particles in water. Coagulants form a particles in water. Coagulants form a colloid rapidly coagulated flocs form colloid rapidly coagulated flocs form precipitates.precipitates.

The three most commonThe three most common              coagulants are              coagulants are

- aluminum sulfate (alumina sulfate)              Al2 (SO4) 3 * 18H2O;- Iron sulfate (iron oxide)              FeSO4 * 7H2O;  -сhlornoe iron              FeCl3 * 6H2O.

•The most widely used in many The most widely used in many water pipes aluminum sulfate. In water pipes aluminum sulfate. In water, it is hydrolyzed and reacts water, it is hydrolyzed and reacts with the bicarbonate of calcium with the bicarbonate of calcium and magnesium salts and magnesium salts (bicarbonate), which define the (bicarbonate), which define the so-called disposable rigidity and so-called disposable rigidity and alkalinity.alkalinity.

•The amount of lime The amount of lime calculated so that in the calculated so that in the water after the reaction water after the reaction with a slight excess with a slight excess coagulant remained coagulant remained alkalinity.alkalinity.

• The optimal dose of coagulantThe optimal dose of coagulant

its called the fewestits called the fewest

  (in mg) required to  (in mg) required to

lightening and bleaching 1l. water tolightening and bleaching 1l. water to

compliance with its requirements of compliance with its requirements of GOST 950GOST 950

- 2000 "drinking water".- 2000 "drinking water".

• One method of improving the One method of improving the processprocess    Coagulation is the use of    Coagulation is the use of    high-molecular flocculants.    high-molecular flocculants.    These flocculants are    These flocculants are    activated silicic acid,    activated silicic acid,    alkaline starch, sodium alginate     alkaline starch, sodium alginate andand    A number of synthetic drugs    A number of synthetic drugs    copolymers of acrylic    copolymers of acrylic. .

water Filtrationwater Filtration

Filtration - following the coagulation and Filtration - following the coagulation and sedimentation technique for releasing sedimentation technique for releasing water from the suspended solids are not water from the suspended solids are not detained in the first stages of cleaning.detained in the first stages of cleaning.

Fast filters with two-way filtering (AKH).

Water is supplied at the same time:

•The basic amount of water The basic amount of water is fed through the bottom is fed through the bottom layer of gravel, filter layer of gravel, filter performance abruptly performance abruptly withdrawn-Chivawithdrawn-Chiva

•. .

•Contact clarifier - loaded Contact clarifier - loaded with gravel and sand on with gravel and sand on combines the processes of combines the processes of coagulation, clarification coagulation, clarification and filtration.and filtration.

thank you for your thank you for your attentionattention