5. Common microorganisms in water
Viruses such as Entero viruses, Hepatitis A virus
and Rota virus
6. Water treatment
Conventional methods of water treatment can’t
remove some pollutants
concentrations in water.
persistent
at
lower
7. Water treatment
Disinfection process removes microorganisms from
drinking water.
Ozonation, Chlorination and UV-radiation are
effective disinfection methods.
8. Ozonation
Ozone is highly corrosive and toxic colourless gas
and powerful oxidant capable of oxidising organic
and inorganic compounds in water.
9. Ozonation
Ozone is formed by combining an oxygen atom with
oxygen molecule (O2).
10. Ozonation
Ozone reacts with substrate or organic and inorganic
compounds by direct oxidation and oxidation of
compounds by hydroxyl free radicals.
11. Ozonation: applications
Bleaching process
Drinking water treatment such as improvement
of flocculation,
removal
de
coloration,
taste/odour
12. Ozonation: applications
Waste water treatment processes such as elimination
of tensides, phenols, COD, cyanides and sludge
reduction.
13. Ozonation: applications
Process water such as cooling water, swimming pools
and product polishing such as chemical modification
of food and shelf-life improvement of food.
14. Ozonation: applications
Water treatment process to remove bacteria,
viruses, organic and inorganic pollutants and
hazardous chemicals.
15. Ozonation: applications
Ozonation process is also applied in the treatment of
waste water contaminating milk and
chemically treated municipal wastewater.
physico-
16. Ozonation
Ozone attacks bacterial membrane either through the
glycoproteins or glycolipids or through certain amino
acids and ozone reacts with nuclear material affecting
pyrines and pyrimidine in nucleic acids.
17. Ozonation
Ozone acts on viral capsid to inactivate viruses and
high concentration of ozone dissociates the capsid
completely.
18. Ozonation
Ozone inactivates RNA and DNA of the viruses.
Protein capsid is affected by ozone attack which
releases nucleic acid and inactivates DNA.
19. UV radiation
Disinfection from UV radiation removes organic
compounds.
No
production of
compounds (VOCs).
odour and
volatile organic
20. UV radiation
Improves taste of water.
Do not require storage of hazardous waste and
requires minimal space for treatment.
21. UV radiation
Growth and reproduction of micro-organism is
inhibited by UV light induced genetic material
disruption.
22. UV radiation
UV light is capable of penetrating microbe’s cell wall
without producing toxic side effects.
Optimum wave length requirement to destroy
bacterial activities lies between 250nm to 270nm.
23. UV radiation
Special lamp to produce a spectrum of radiation is
used in disinfection process.
24. UV radiation
Presence of high levels of suspended solids,
turbidity, colour and soluble organic matter creates
unsuitable
environment
for
UV-radiation
disinfection process.
25. UV radiation
Dose Requirement is crucial in UV radiation
process. Required level of radiation dose to
disrupt and destroy microorganisms must be
maintained for the effectiveness.
26. UV radiation
Radiation concentration, proper wavelength, exposure
time, water quality, flow rate, the micro-organism’s
type, source and its distance from the light source
determine the effective dose requirement.
27. Chlorination
In Chlorination process, hypochlorous acid acts as
disinfecting agent. Hypochlorous acids are formed
when chlorine hydrolizes in water. When
hypochlorous acids splits into H+ and OCl- ions,
bacteria and viruses are inactivated and enzymatic
activities are inhibited.
29. Chlorination
Chlorination can be applied in drinking water
operations such as treatment of ground
water,
industrial
process
water,
chilling
water, cooling tower systems, drip irrigation systems.
30. Chlorination
In the chlorination process, chlorine has two forms in
water: free chlorine and combined chlorine. Sodium
hypochlorite or chlorine gas produces free chlorine
when added to water. When free chlorine and
ammonia reacts, combine chlorine is formed which
includes monochloramine and dichloramine.
32. Chlorination
Chlorine gas (Cl2) is highly toxic and liquefied under
pressure.
Chlorinated lime (CaO2CaCl2O3H2O) is corrosive dry
white powder.
33. Chlorination
Sodium
hypochlorite (NaClO) is corrosive and
yellowish liquid solution, commonly called “liquid
bleach” and calcium hypochlorite (Ca (ClO)24H2O) is
corrosive inflammable powder or granules and tablets.
34. Chlorination
Sodium hypochlorite (NaClO) produces hypochlorous
acid (HClO) and hypochlorite (ClO-) ions, in water
which affects bacteria and viruses by inactivating and
inhibiting enzymatic activities.