Disinfection

Water chlorination

Water treatment can be done
chlorine, sodium hypochlorite obtained
on site in electrolyzers, or direct
wastewater electrolysis.

The estimated dose of chlorine is taken in
dependencies on previous methods
cleaning (after mechanical cleaning -
not less than 10 g/m3, after incomplete
biological - 5 g / m3, after complete
biological - 3 g/m3). Wherein
dose of residual chlorine after 30 minutes
contact must be at least 1.5 g/m3.

Complex of facilities for disinfection
chlorine gas consists of a plant
chlorination, chlorine storage. Mixer,
contact tank.

Chlorine facilities should provide
increase in the calculated dose of chlorine by 1.5
times without changing the storage capacity.

Waste chlorination plant
water is similar to the settings for
water disinfection. Due to the small
solubility of the liquid choir
pre-evaporate, then
gaseous chlorine enters the intermediate
cylinder - mud tank, where they linger
drops of water and other impurities. Next in
filter filled with glass wool
soaked in sulfuric acid, after which
through the chlorinators is supplied to the ejector,
where tap water is supplied. Chlorine
- the gas dissolves in water and the resulting
chlorine water is used for disinfection.

Diagram of a water treatment plant
chlorine gas

Disinfection

1 - intermediate cylinder (mud tank);

2 - filter with glass wool;

3 - reducing valve for reducing
chlorine gas pressure;

4 - manometer;

5 – measuring diaphragm;

6 - rotameter;

7 - mixer;

8 - supply of tap water;

9 - an ejector that creates a vacuum in
chlorinator;

10 removal of chlorine water for dosing;

11 - scales;

12 - cylinder with chlorine.

For dosing chlorine gas
using special devices
called chlorinators. Chlorinators can
be proportional and constant
consumption, as well as automatic,
maintenance in waste water
constant residual concentration
chlorine.

In our country, the most widespread
received permanent vacuum chlorinators
consumption.

To evaporate chlorine cylinder or container
put on the scales and open
valve. Chlorine gas output from one
bottle at room temperature
is from 0.5 to 0.7 kg / h from 1 m2 of the cylinder surface. Boost Output
gas from a cylinder can be heated with warm
water or air.

To mix chlorine water with SF, use
mixers of three types:

At costs up to 1500 m3 / day. – ruff
mixers;
Tray Porshal;
Mechanical or pneumatic.

Contact reservoirs are practiced in
settling tanks (vertical or
horizontal) for the duration of stay 30
minutes, taking into account the time
stay and flow until release.

Water disinfection with active oxygen

The principle of operation of the purification method with the help of active oxygen: an oxygen-containing reagent is injected into the water, which decomposes in the water, releasing oxygen, which reacts with biological contaminants. At one time, this sparing method was very popular in Europe and Russia.

Advantages of disinfection with an oxygen-containing reagent:

quite effectively destroys the harmful microflora living in the pool bath;
does not irritate the mucous membranes of the eyes and skin due to the absence of chloramines;
no harmful by-products are formed.

Disadvantages of disinfection with an oxygen-containing reagent:

expensive compared to chlorination;
oxygen-containing reagent decomposes very quickly in the aquatic environment. As a result, higher doses have to be used;
lower activity compared to chlorination, which again leads to an increase in the dosage of the reagent;
an overdose of an oxygen-containing reagent (hydrogen peroxide) has more unpleasant health consequences than an overdose of chlorine;
still requires periodic chlorination.

According to SanPin 2.1.2.1188-03 “Swimming pools. Hygienic requirements for the device, operation and quality of water”, the water in the pool must correspond to the quality of drinking water. The maximum allowable concentration of hydrogen peroxide in drinking water (as an active substance of active oxygen) is 0.1 mg/l, when using the method of disinfection with active oxygen as the only method of disinfection, the concentration of peroxide is exceeded.

As the only method used, it is not suitable for large public pools and outdoor pools, but is quite effective in small indoor private pools with a low load. Also, the method of disinfection with active oxygen is not suitable for warm pools with temperatures above 28 ° C, since oxidation slows down in warm water.

Additional chemical additives for water treatment

There are a lot of specialized chemistry for swimming pools. Others include flocculants, coagulants, algicides and pH regulators.

In the process of filtering water, sand filters can only retain particles larger than a certain size. Particles smaller than this size cannot be filtered out without the use of coagulation. Coagulation is the process of particles sticking together under the influence of a coagulant. Flocculation is a type of coagulation in which loose, flocculent aggregates are formed. Coagulants differ from flocculants in the shape, density and size of the particles formed. In practice, this distinction is not given much importance, so flocculants are often called coagulants, and vice versa. Under the influence of coagulants, suspended particles become coarser and can be retained by mechanical filters; under the influence of flocculants, suspended solids precipitate in the form of flakes, which are then removed using a filter. In public pools, an automatic dosing station for flocculant or coagulant is installed: periodically injecting these substances into the line in front of the mechanical filter. There is also "shock" coagulation, when the coagulant is added to the pool water with the pump turned off. The sediment that has fallen out after a few hours is removed from the bottom of the pool with a vacuum cleaner.

Algaecides are chemical preparations from the group of herbicides, designed to remove algae and combat the "bloom" of water. Algaecide is a means of selective action, safe for humans, but detrimental to algae. Algae more easily adapt to chlorine and other disinfection, in addition, they can stick to the walls of the pool and pipes, thereby bypassing the disinfection zone. To combat algae, before filling the pool with water, the walls of the pool are treated with an algaecide or a loading dose of the drug is injected into the water. As algicides, copper sulfate, copper ammonia, urea derivatives (diuron, majuron, etc.) are most often used.

An important evaluation parameter is pH - this is the acid-base balance of water. Depending on the content of free hydrogen ions in the water, the environment is determined: pH > 7 - alkaline, pH pH regulators are able to change the pH level in one direction or another.

In summary, public swimming pool water is disinfected using the chlorination method alone or in combination with other disinfection methods. When choosing a pool for swimming, one should prefer one where a combination of disinfection methods is used to disinfect the water, which reduces the amount of bleach used, and therefore reduces the risk of irritation of the skin, mucous membranes and eyes.

So anyway: Chlorine is the breakfast of champions!

Water ozonation

Ozone is a gas that is the most reactive form of oxygen. Ozone is one of the most powerful oxidizers, destroying bacteria, spores and viruses. At its core, water purification with ozone is equivalent to the many times accelerated procedure of natural water purification.

Advantages of the ozonation method:

a wide range of effects on microorganisms (ozone destroys virtually all bacteria, viruses and organic substances), and the activity of ozone is many times higher than that of oxygen and chlorine. For example, pathogenic microorganisms are destroyed by it 15-20 times, and spore forms of bacteria - 300-600 times faster than chlorine. The polio virus dies at an ozone concentration of 0.45 mg / l after 2 minutes, while from chlorine twice the concentration in only 3 hours;
chloramines are not formed, irritating the skin and mucous membranes of the eyes;
ozone, unlike chlorine, does not leave any smell;
ozone treatment makes the water shiny and gives the water a blue tint (chlorination gives a greenish tint);
Overdose of ozone is not a problem, as once the treatment is finished, the ozone is converted back into oxygen.
ozone treatment does not add any additional foreign substances and chemical compounds to the water.

Disadvantages of the ozonation method:

ozone does not have a prolonged action, as it is an unstable gas and quickly decomposes into ordinary oxygen without accumulating in the aquatic environment.
ozonation of water is much more expensive than traditional chlorination;
pool surfaces remain a risk factor, as only the water passing through the device is disinfected;
ozone is toxic when inhaled, at high concentrations of ozone, damage to the respiratory tract, lungs and mucous membranes is observed, and the chronic effects of micro-ozone concentrations on the human body have not been sufficiently studied; In addition, pure ozone is explosive. For these reasons, working with ozone requires careful monitoring of safety precautions.

In public pools, the ozone generator can only be used in combination with a chlorine station. Water treatment by ozonation in conjunction with the chlorination method is an excellent option for large pools. Thanks to ozone treatment, the water in the pool will be transparent, clean and effectively disinfected. It remains only to maintain a small concentration of chlorine to prevent penetration into the pool and the growth of pathogenic microorganisms. At the same time, the formation of chloramines will be minimized, and, consequently, there will be less smell of bleach and irritation of the skin and eyes.

Water disinfection using salt electrolysis

One of the modern methods of water disinfection. In salt electrolysis systems, the chlorine-containing reagent is produced from a solution of ordinary table salt (NaCl) by electrolysis. Electrolysis is a physicochemical process in which a liquid (electrolyte) decomposes into positive and negative ions under the influence of an electric current.

There are two options for water disinfection systems based on salt electrolysis:

Flow electrolysis electrolysis plants. A small amount of salt is added to the pool water in order to produce, through salt electrolysis, a strong disinfectant filled with active chlorine. This oxidizing agent has the ability to turn back into salt after its disinfectant action. Here's how it all happens: "salted" water from the pool passes through the electrolyzer apparatus; when current is applied to the electrolysis cell of the electrolyzer, as a result of an electrochemical reaction, new chemical elements and compounds arise: hypochlorous acid (HOCI), which destroys organic substances (microbes, bacteria, viruses, algae) by oxidation, which is a reaction product hydrogen (H2), which is safely removed from the entire surface area of the pool, and again obtained from the remaining after the reaction of the components NaOH and HCl salt (NaCl) and water (H2O).Salt is then reused in the electrolysis process, and the reaction cycle starts over. Chloramines during their passage near the electrodes are destroyed and release chlorine, which will be reused.
Electrolysis plants that produce chlorine in a separate tank. When using this plant, it is not necessary to add salt to the pool water. Gaseous chlorine is produced by electrolysis of table salt inside a special chamber and is supplied to the pool water in strictly metered portions, where sodium hypochlorite is formed in the water.

Advantages of the disinfection method using salt electrolysis:

effectiveness of chlorine disinfection;
profitability (ordinary salt is used as a consumable raw material);
there is no overdose of chlorine, since chlorine is produced gradually, and not injected in pulses;
maintaining the desired concentration. Thanks to the sensors that are equipped with this type of cleaning systems, the chlorine content in the pool water is monitored and the required amount of chlorine is produced for disinfection;
if salt is added to the pool water, then it is good for health, since the salt contained in the pool water in small doses has a positive effect on the skin and the body as a whole, restoring vitality. In addition, salt water itself is an antiseptic, which greatly simplifies disinfection.

Disadvantage of the disinfection method using salt electrolysis: Pool surfaces remain a risk factor, since only the water passing through the device is disinfected. In the surface of concrete pools, especially in the seams, joints and corners, a lot of bacteria live, which can only be dealt with by shock doses of chlorine.

The disinfection method based on salt electrolysis is used in private and hotel swimming pools, in swimming pools of sanatoriums and healthcare facilities, as well as in public outdoor and indoor swimming pools.

II. By the dose of chlorine.

Normal
chlorination (chlorination
normal doses of chlorine). Dose of chlorine
under normal chlorination is calculated
based chlorine needs
water.
Chlorine requirement
(or
chlorine absorption capacity)
water —
is the amount of chlorine that goes
for the oxidation of organic matter,
contained in water (when chlorine is added
into the water after a while
the number is decreasing because
a certain amount of it, equal to
chlorine needs, goes for oxidation
organic matter). With the introduction
more chlorine than
chlorine demand, it remains in the water.
The chlorine that remains in the water is called
residual.
Usually
after chlorination residual
chlorine is
0.3-0.5 mg/l (provided that no
less than 30 minutes after chlorine application
in water). In this way, Dose
chlorine = water chloride requirement +
0.3-0.5 mg/l (Residual
chlorine). Normal
chlorination is used. most often
on the
waterworks, So
as the water before it passes thoroughly
cleaning and normal doses of chlorine,
providing the specified amount
residual chlorine is sufficient
(considering that the larger the value
residual chlorine the worse the organoleptic
water properties). Sometimes normal
chlorination is applied and v
field conditions.
Hyperchlorination
and
superchlorination
(chlorination
high doses of chlorine). Applies
usually for chlorination v
field conditions
dirty,
suspected of being epidemic
water and is distinguished by the use of high
doses of chlorine. At hyperchlorination
use
doses from 10 to 50 mg/l. Duration
chlorination - 15 minutes in summer, 25-30 minutes
in winter. If found in water (or
suspected) anthrax spores,
then apply superchlorination
and
doses of chlorine are increased to 100 mg/l or more.
When chlorinated in the field
use chloride
lime, two-thirds basic salt
calcium hypochlorite (DTSGK),
which contains 60% active chlorine,
neutral
calcium hypochlorite (NGK)
– 70% active chlorine, as well as individual
facilities - chlorine-containing
tablets ("aquasept",

"sporicide"
Aquacid, etc.). After use
higher doses of chlorine
subsequent dechlorination
water, So
without it, it's almost useless
for consumption but organoleptic
properties. Dechlorination produce
via hyposulfite,
a
also by filtering through activated
coal.

Besides
listed methods of chlorination
separately can be called chlorination
with pre-ammonization at
which before chlorination into water
introduce ammonia. Ammonia with chlorine forms
chloramines that last longer
than just residual chlorine.

TABLE OF CONTENTS

Various
water disinfection methods and their
hygienic assessment (except for chlorination).

For
disinfection of water except for chlorination
The following methods are applied: i. V
large volumes (on the tap
stations).

1. Ozonation
  water. Is
  in use ozone
  which the
  is a strong oxidizing agent. Across
  a few minutes after administration
  residual ozone decomposes with the release
  oxygen, which not only does not worsen,
  but improves organoleptic properties
  water. In addition, ozone is more active
  than chlorine against microbial spores
  and enteroviruses.
2. Irradiation
  UV ray Is an
  one of the best methods of disinfection,
  as pertains to called
  reagentless methods and
  eliminates changes in chemical
  composition of water. The method provides
  rapid death of bacteria, viruses, eggs
  helminths. For UV irradiation of water
  using mercury-quartz lamps
  (PRK), art gosh-quartz lamps (BUV).
  Cleanliness is essential
  (transparency, colorlessness) of water, in
  otherwise suspended particles
  absorb rays. P.
  In small volumes.

1. Boiling.
  Duration
  boiling should be 5-10 minutes.
  Boiling can also be used in
  rather large scale (hospitals,
  schools)
2. Usage
  iodine (2
  drops of 10% tincture of iodine per 1 liter of water,
  iodine tablets)
3. Usage
  special devices,
  which
  purify and disinfect water - "Spring",
  "Tourist", "Gadfly", etc.
4. Disinfection
  ultrasound,
  ultrahigh frequency currents and
  others

TABLE OF CONTENTS

Systems
removal of sewage and waste. Methods
cleaning, disinfection, disposal.

By
V.G. Gorbov all waste is classified
in the following way:

The bactericidal effect of ozone

From a hygienic point of view, the method of ozonizing water has significant advantages due to the high redox potential of bactericidal action.

The dose of ozone required for water disinfection varies depending on the content of organic substances in the water, on the water temperature and on the magnitude of the active water reaction (pH).

Transparent and clean spring water and waters of mountain rivers, slightly polluted with foreign impurities, require approximately 0.5 mg/l of ozone. Water coming from open reservoirs can cause ozone consumption up to 2 mg/l. The average dose of ozone is 1 mg/l.

Experimental studies have shown that with an increase in water temperature, it is also necessary to increase the dose of ozone.

When studying the effect of the active reaction of water on the disinfecting effect of ozone, it was found that an increase in pH over 7.1 was accompanied by a significant decrease in the coefficient of ozone utilization by water.

The duration of contact of the ozone-air mixture with the treated water varies from 5 to 15 minutes, depending on the types of installations and their performance, (as the temperature rises, the contact time increases).

Chlorine and ozone do not affect bacteria in the same way. With an increase in the intensity of chlorination, the progressive death of bacteria occurs. Meanwhile, during ozonization, a sudden bactericidal effect of ozone is detected, corresponding to a certain critical dose, equal to 0.4-0.5 mg / l.For smaller doses of ozone, its bactericidal activity is insignificant, but even as soon as a critical dose is reached, the death of bacteria becomes immediately sharp and complete.

Recent studies of the mechanism of ozonation have shown that its action occurs quickly, provided that the desired concentration is maintained for a certain time. This action is due to the ozonation of the mass of bacterial proteins in the process of catalytic oxidation. Meanwhile, chlorine produces only selective poisoning of the vital centers of bacteria, and rather slowly because of the need for a long time for diffusion in the cytoplasm.

The disinfecting effect of ozone is affected by the color of water, so ozonation of unclarified water is uneconomical and inefficient, since large amounts of ozone are spent on the oxidation of substances that can be delayed by conventional treatment facilities. Water treatment with ozone is advisable only after it has been clarified, as well as filtered (the dose of ozone is reduced by 2-2.5 times than for unfiltered water).

Studies have shown that of the bacteria, Escherichia coli proved to be the most resistant to the action of oxidizing agents from the entire group of intestinal bacteria, it quickly dies when ozonized. It is also effective to use ozonation in the fight against pathogens of typhoid fever and bacillary dysentery.

Chlorination of water in large doses

Named
The method is mainly used in
field practice when limited
choice of water sources and sometimes you have to
use poor quality water.
The essence of the method is that
an increased amount is added to the water
active chlorine, counting on the subsequent
dechlorination. Dose of active chlorine
chosen according to the physical
water properties (turbidity, color),
nature and degree of improvement
water source and from the epidemic
environment. In most cases, she
equals 20-30 mg / l, contact time - 30
min.

Method
has the following advantages:
1) Reliable disinfection effect even
muddy and colored waters containing
ammonia; 2) simplification of the chlorination technique
(it is not necessary to determine the chlorine requirement
water; 3) reduction of water color due to
chlorine oxidation of organic substances
and converting them into uncolored compounds;
4) elimination of foreign tastes and
odors, especially those caused
the presence of hydrogen sulfide, and
decaying vegetable matter
and animal origin; 5) absence
chlorophenolic odor if present
phenols, since it does not form
mono-, and polychlorophenols, which smell
do not possess; 6) destruction of some
toxic substances and toxins
(botulinum toxins); 7) destruction of spore
forms of microorganisms at a dose of 100-150 mg/l
active chlorine and prolonged contact
(2-5 hours); 8) a significant improvement in conditions
for the coagulation process. Listed
positive aspects of the method
its highly valuable for practice improvement
water quality in the field,
especially in connection with the danger of using
bacteriological and chemical
weapons.

TO
The disadvantages of the method are
the need for additional processing
water - dechlorination and increased
the consumption of chlorine and its preparations, which has
value only when processing large
quantities of water in major water pipelines
stations.

V
as a means of dechlorination can
chemicals to be used
binding excess
chlorine, and sorption of chlorine on the corresponding
sorbents. Chemical substances,
converting chlorine into an inactive compound,
usually belong to the group of reducing agents
is sodium thiosulfate, sulfate
sodium, sodium sulfate and sulphide
anhydride. Dechlorination by sorption
made with charcoal
activated.