Chemistry

1. Purification Of Water
By: Arifa Kiran
Roll No-16
Submitted To:
Dr. Khurram Shehzad

2. Waste water treatment
Methods
of
Cleaning Water

3. What is water?
Definition:
Water is a transparent fluid which forms the world's streams, lakes, oceans
and rain, and is the major constituent of the fluids of living things. As a
chemical compound, a water molecule contains one oxygen and
two hydrogen atom that are connected by covalent bonds.

5. Water chemistry and properties of clean water
• It is the mixture of one oxygen and two
• Hydrogen atoms.
• These hydrogen and oxygen atoms are
• Covalently bonded with each other.
• Between the water molecule hydrogen
• Bonding is present.
Properties
 Colorless
 Odorless
 Tasteless
 Transparent
 Freezing point 0 c ̊
 Boiling point 100 C̊
 Density 1g/cm3
 pH. of pure water is normally 6.8-6.9
Structure of water molecule

6. Types of water
There are two types of water :
 Hard water
 Soft water
Soft water
It is often desirable to soften hard water,
as it does not readily form lather with
soap.
• Soap is wasted when trying to form lather, and in the process, scum forms.
• Hard water may be treated to reduce the effects of scaling and to make it
more
effects of scaling and to make it more suitable for laundry and bathing.
Hard water
Hardness also be defined as water that
doesn’t produce lather (foam) with soap
solutions, but produces white precipitate
(scum).
• Hardness in water can cause water to form scales and a resistance to soap.

7. Types of hardness
There are two types of hardness:
 Temporary hardness
 Permanent hardness
Temporary hardness
This temporary hardness is due to bicarbonates of Ca+2 and Mg+2
Methods for removing temporary hardness
 Boiling
Chemical equations
 Clark’s Method

8. Permanent hardness
Permanent hardness is due to the chlorides and sulphates of Ca+2 and Mg+2
Methods for removing permanent hardness
 Using washing soda:
 Ion exchange method:

9. What is waste water?
Used water …….includes……
• Food scraps,oil and soaps
• Human wastes
• Industrial wastes
Why treat waste water?
 To remove pollutants from waste water for its recycling.
 To promote health concern and public hygine.
 To preserve aquatic life and wildlife habitat.
 To promote recreaction and quality of life.

10. Methods for purifying water or cleaning water
There are different methods which are used for purifying water these are enlisted in
the following:
 Boiling
 Filtering
 Distilling
 Chlorination

12. Stages of treatment
There are different stages which involves in waste water treatment:
1. Primary treatment
2. Secondary treatment
3. Tertiary treatment

14. Primary treatment
The removal of large objects from influent sewage.
By physical separation of grit and large objects(material to landfill for disposal)
The objective is the removal of
Settle able organic and inorganic solids
By sedimentation, and removal of the
Material that will float by skimming.
Around 25-50%of the incoming BODs,
50-70%of the total suspended solids
And 65%of oil and grease are removed
During primary treatment.

15. Secondary treatment
Biological Treatment
Secondary treatment is designed to substantially degrade the biological content of
the sewage
Which are derived from the human waste, food waste, organic contaminants and
binds
Much of the less soluble fractions into floc.
Secondary sedimentation
Microorganisms must be separated from the treated water by sedimentation to
produce
Clarified secondary effluent.
Biological floc is settled out in secondary clarifier and the secondary sludge is then
sent to
Sludge treatment unit.

17. Nutrients Removal
 Wastewater may contain high level of nutrients (N&P compounds)( which
excessive release
to envoirnment may cause eutrophocation.
 Overgrowth of weeds,algae,blue-green algae (cyanobacteria).
 Toxins produced by some algae may contaminate drinking water supply.

18. Nitrogen Removal
Nitrification
 Biological oxidation of nitrogen from ammonia to nitrate.
Ammonia to nitrite using Nitrosomonas
Nitrite to nitrite using nitrobacter ssp.
 De nitrification
Nitrate is converted into nitrogen gas and released into air.
Phosphorous Removal
 Biologically
Using Polyphosphate Accumulating Organism (PAOs)
The process is called Enhanced biological phosphorous removal.
 By chemical precipitation
Using salts of iron (e.g.ferric chloride)or aluminium (e.g. alum) or lime.

19. Tertiary treatment
 Purpose is to provide a final treatment stage for the destruction of
harmful(pathogenic)
microorganisms i.e. disease causing germs.
 Nutrients removal
 Disinfection
to reduce the number of microorganisms
 Chlorination
 Ultraviolet radiation
 Ozone
 Odor control

20. Odor control
Odor emitted by wastewater treatment are typically an indication of anaerobic or
Septic condition.
Generally arises due to hydrogen sulfide.
Controlled by adding iron salt or hydrogen peroxide or calcium nitrate.