3.Water purification..pptaaaaaaaaaaaaaaaaaaaaaaaa

water purification

1. PURIFICATION OF WATERPURIFICATION OF WATER

Purification on large scale.Purification on large scale.

Purification on small scale.Purification on small scale.

2. Large scale PurificationLarge scale Purification

Water must be safe & wholesome.Water must be safe & wholesome.

Method depends on raw water.Method depends on raw water.

Ground water needs no treatment.Ground water needs no treatment.

Surface water needs extensive treatment.Surface water needs extensive treatment.

3. ComponentsComponents

Storage.Storage.

Filtration.Filtration.

Disinfection.Disinfection.

4. STORAGESTORAGE

Drawn from source & stored.Drawn from source & stored.

Further pollution excluded.Further pollution excluded.

Considerable purification occurs during Considerable purification occurs during
storage.storage.

Three types of purification in storage.Three types of purification in storage.

Physical, Biological, Chemical.Physical, Biological, Chemical.

5. Physical Purification.Physical Purification.

Quality improves.Quality improves.

90% suspended impurities settle down.90% suspended impurities settle down.

Water becomes clearer.Water becomes clearer.

Penetration of light reduces work of Penetration of light reduces work of
filters.filters.

6. Chemical PurificationChemical Purification

Aerobic Bacteria oxidize the organic Aerobic Bacteria oxidize the organic
matter present in water with dissolved matter present in water with dissolved
oxygen.oxygen.

Ammonia content reduced.Ammonia content reduced.

7. Biological Purification.Biological Purification.

Drop of bacterial count during storage.Drop of bacterial count during storage.

Pathogenic organisms gradually die out.Pathogenic organisms gradually die out.
90% drop in 5 - 7 days storage.90% drop in 5 - 7 days storage.
Optimum period of storage for river Optimum period of storage for river
water 10-14 days.water 10-14 days.

8. FILTRATIONFILTRATION

Second stage in purification.Second stage in purification.

98-99% bacteria removed during 98-99% bacteria removed during
filtration.filtration.

Other impurities.Other impurities.

9. Types of FiltersTypes of Filters

BIOLOGICL OR SLOW SAND FILTRS.BIOLOGICL OR SLOW SAND FILTRS.

MECHANICAL OR RAPID SAND FILTERS.MECHANICAL OR RAPID SAND FILTERS.

10. Biological or Slow Sand FiltersBiological or Slow Sand Filters
ELEMENTS.ELEMENTS.


Supernatant (raw) Water.Supernatant (raw) Water.

Bed of graded sand.Bed of graded sand.

Under drainage system.Under drainage system.

Control valvesControl valves..

11. Supernatant WaterSupernatant Water

Depth 1 -1.5 meters above sand bed.Depth 1 -1.5 meters above sand bed.

To over come the resistance of filter To over come the resistance of filter
bed.bed.

Waiting period 3- 12 Hours.Waiting period 3- 12 Hours.

Partial purification by sedimentation & Partial purification by sedimentation &
oxidation.oxidation.

Level kept constant.Level kept constant.

12. Sand BedSand Bed

Thickness 1 -1.5 meters.Thickness 1 -1.5 meters.

Sand grains carefully chosen.Sand grains carefully chosen.

Diameter 0.2 -0.3 mm.Diameter 0.2 -0.3 mm.

Clean sand free from clay & organic Clean sand free from clay & organic
matter.matter.

Sand layer supported by graded gravel Sand layer supported by graded gravel
layer. Thickness 30-40 cm.layer. Thickness 30-40 cm.

Water percolates through sand bed.Water percolates through sand bed.

13. Sand bed (Contd)Sand bed (Contd)

Mechanical straining.Mechanical straining.

Sedimentation.Sedimentation.

Adsorption.Adsorption.

Oxidation.Oxidation.

Bacterial Action.Bacterial Action.

0.1 - 0.4 cubic mts/hour/sq.meter.0.1 - 0.4 cubic mts/hour/sq.meter.

14. VITAL LAYERVITAL LAYER

Surface of the sand covered by slimy Surface of the sand covered by slimy
growth.growth.

Called Schmutzdecke,Vital,Zoogleal or Called Schmutzdecke,Vital,Zoogleal or
Biological layer.Biological layer.

Consists of Thread like Algae,Plankton, Consists of Thread like Algae,Plankton,
diatoms,& bacteria.diatoms,& bacteria.

15. Vital layer (contd)Vital layer (contd)
Ripening. Formation of vital layer.Ripening. Formation of vital layer.

Takes several days for formation.Takes several days for formation.
Extends 2-3 cm into top portion of sand.Extends 2-3 cm into top portion of sand.

Heart of filters.Heart of filters.

Removes organic matter & Bacteria.Removes organic matter & Bacteria.

16. 
DRAINAGE SYSTEM.DRAINAGE SYSTEM.

FILTER CONTROL. (VENTURI METER.)FILTER CONTROL. (VENTURI METER.)

17. Filter cleaningFilter cleaning

Works for weeks or months.Works for weeks or months.

Scraping.Scraping.

1-2 cm sand bed removed.1-2 cm sand bed removed.

18. AdvantagesAdvantages

Simple to construct & Operate.Simple to construct & Operate.

Cost is cheaper.Cost is cheaper.

Quality of filtered water good.Quality of filtered water good.

99.99% free from Bacteria.99.99% free from Bacteria.

19. RAPID SAND FILTERSRAPID SAND FILTERS
TWO TYPES.TWO TYPES.

GRAVITY TYPE (PETERSON’S)FILTER.GRAVITY TYPE (PETERSON’S)FILTER.

PRESSURE TYPE(CANDY’S)FILTER.PRESSURE TYPE(CANDY’S)FILTER.

20. StepsSteps

COAGULATION.COAGULATION.

RAPID MIXING.RAPID MIXING.

FLOCCULATION.FLOCCULATION.

SEDIMENTATION.SEDIMENTATION.

FILTRATION.FILTRATION.

21. COAGULATIONCOAGULATION

Raw water treated with coagulant ALUM.Raw water treated with coagulant ALUM.

5-40 mg/Liter.5-40 mg/Liter.

Depends on Depends on
turbidity, colour, temperature, & PH of turbidity, colour, temperature, & PH of
water.water.

22. Rapid mixingRapid mixing

Treated water subjected for rapid Treated water subjected for rapid
violent agitation.violent agitation.

In mixing chamber for few minutes.In mixing chamber for few minutes.

Alum is thoroughly mixed.Alum is thoroughly mixed.

23. FLOCCULATIONFLOCCULATION

Slow & gentle stirring.Slow & gentle stirring.

Flocculation chamber for 30 mts.Flocculation chamber for 30 mts.

Slow gentle stirring results in formation Slow gentle stirring results in formation
of thick copious, white flocculent of thick copious, white flocculent
precipitate Aluminum Hydroxide.precipitate Aluminum Hydroxide.

24. SedimentationSedimentation

Sedimentation chamber.Sedimentation chamber.

Water flocculent detained for 2-6 hours.Water flocculent detained for 2-6 hours.

Impurities & bacteria settle down.Impurities & bacteria settle down.

95% Flocculent removed before filtration.95% Flocculent removed before filtration.

25. FILTRATIONFILTRATION

Partly clarified water is now subjected Partly clarified water is now subjected
for filtration.for filtration.

26. FILTER BEDFILTER BED

Surface 80-90 square mts.Surface 80-90 square mts.

Sand as filter medium.Sand as filter medium.

Size of sand particles 0.4 -0.7 mm.Size of sand particles 0.4 -0.7 mm.

Depth of sand 1 meter.Depth of sand 1 meter.

Graded gravel (30-40cm) below sand.Graded gravel (30-40cm) below sand.

Depth of water above sand 1-1.5 mts.Depth of water above sand 1-1.5 mts.

Rate of filtration 5-15 cu.mts/hr/sq.mtr.Rate of filtration 5-15 cu.mts/hr/sq.mtr.

27. Filter bed (contd)Filter bed (contd)

Alum flocculent not removed in Alum flocculent not removed in
sedimentation, held back on sand bed.sedimentation, held back on sand bed.

Forms a slimy layer comparable to Forms a slimy layer comparable to
biological layer in SSF.biological layer in SSF.

28. BACK WASHINGBACK WASHING

Needs frequent washing.Needs frequent washing.

Flow of water is reversed.Flow of water is reversed.

Dislodges impurities &cleans up bed.Dislodges impurities &cleans up bed.

Takes 15 mts time.Takes 15 mts time.

29. Advantages.Advantages.

Deals raw water directly.Deals raw water directly.

No storage needed.No storage needed.

Filter beds occupy less space.Filter beds occupy less space.

Filtration rapid,40-50 times more than Filtration rapid,40-50 times more than
SSFSSF

Washing filter is easy.Washing filter is easy.

More flexibility in operation.More flexibility in operation.

30. Comparision RSF &SSFComparision RSF &SSF

Space Little space Large spaceSpace Little space Large space

Rate 5-15 cu. mts 0.1-0.4 c mtsRate 5-15 cu. mts 0.1-0.4 c mts

Size 0.4-0.7 mm 0.2-0.3 mmSize 0.4-0.7 mm 0.2-0.3 mm

Pre.TT. Chemical alum Plain Pre.TT. Chemical alum Plain
sedimentation.sedimentation.

Washing Back wash Scraping.Washing Back wash Scraping.

Operation Skilled less skilledOperation Skilled less skilled

Turbidity good goodTurbidity good good

Color good fair.Color good fair.

Bacteria 98-99% 99.9-99.99%Bacteria 98-99% 99.9-99.99%

31. THANK YOU.THANK YOU.