ENVIROMENTAL
MODELS
Wells
• A well is a hole in earth, sunk or excavated
to fetch ground water
Dug Tube
wells wells
Wells
DUG WELLS
• Are excavated
manually
–1.5 m in diameter
–9 m in depth
DUG WELLS
• Are of 3 types
STEP
KUCHCHA PUCCA
WELLS
TUBE WELLS
• Consist of pipe or tube sunk into
earth to reach a water bearing
stratum
• Consists of 3 parts
– Strainer (lower part)
– Galvanized pipes
(middle part)
– Pump (upper part)
SANITARY WELL:
• Sanitary well is one which is properly
located, well constructed & protected
against contamination with a view to yield
a supply of safe water.
SALIENT FEATURES
• The following point should be taken in to
consideration :
– Location
– Lining
– Parapet
– Platform
– Drain
– Covering
– Hand-pump
– Consumer responsibility
– Quality
• Location:
–A sanitary well should be located
atleast 15 m away from possible
source of contamination.
–It should be located a higher level
than nearby sources of
contamination.
–It should be located within 100m from
the people’s house.
• Lining :
–The inside of the well should be lined
with bricks upto a depth of 6 m
–This is done to ensure water enter
from the bottom , not from the sides.
–Lining should be continued till about
60-90 cm above the ground level.
• Parapet wall:
–Parapet wall should be upto 70-75 cm
above the ground level.
• Platform:
–A cement concrete platform should be
constructed around the well with the
radius of at least 1m in all directions.
–The margin of the platform should
have a drain for collecting the spilled
water.
• Drain:
– The spilled water should be channeled away
from the well using a proper drain system.
– It should be connected to the public drain
system or to the drainage pit located
outside the cone of filtration of the well.
• Cover:
– A proper cement concrete cover is essential
for maintaining the quality of water of the
well
–It increases the bacterial quality of
the well water considerably.
• Hand pump:
–It is should be installed to draw the
water from the well
–It should be of good quality
–It should be regularly serviced.
• Consumer responsibility:
– Certain precautions should be taken to
ensure the quality of water.
– Should not dump waste. Washing of
clothes and animals in the vicinity of the
well should be prohibited.
• Quality :
– The physical, chemical and biological
parameters of the well water should
conform to acceptable standards.
PUBLIC HEALTH USE
–For safe drinking water.
–For domestic use.
INSANITARY WELL
(Sources of contamination)
SANITARY WELL INSANITARY WELL
• Clean and vegetation • Not clean and
growth absent vegetation growth
• A proper cement present
concrete cover is • No proper concrete
present cement cover
• Water is safe for • Water is
drinking contaminated.
• No Contact between • Contact is there
human • Chlorination is not
• Chlorination is done done
• Regularly cleaned. • Not regularly cleaned
SHALLOW & DEEP WELL
SHALLOW WELL
• Shallow wells tap subsoil water i.e. the
water from above the first impervious layer
in the ground (25 feet).
– They yield limited quantities of water.
– Water is notoriously liable to pollution unless
care is taken in well construction.
– Most of the wells in India are shallow types.
– Shallow wells are therefore a health hazard to
the community, if they are not made sanitary.
DEEP WELL
• A deep well is one which taps water from
water-bearing stratum below the first
impervious layer in the ground ( 50 feet-
400feet deep).
• Deep wells are usually machine-drug and
may be several hundred meters deep.
• Deep wells furnish the safest water, and
are often the most satisfactory sources of
water supply.
SHALLOW WELL DEEP WELL
• Taps the water from • Taps the water from
above the first below the first
impervious layer.
impervious layer.
• Chemical quality is
moderately hard • Chemical quality is
• Grossly much hard.
contaminated. • Taps pure water.
• Usually goes dry in • Provides a source of
summer.
constant supply.
WATER PURIFICATION
• Slow sand filters
• Rapid sand filters
Screening & Primary
sedimentation
Coagulation & flocculation
Secondary sedimentation
Filtration
Chlorination
SLOW SAND FILTERS
• Slow sand filters were first used for water
treatment in 1804 and subsequently in London.
• Even today, they are accepted as the standard
method of water purification.
• Elements of slow and sand filter are:
1. Supernatural (raw) water.
2. A bed of graded sand.
3. An under-drainage system.
4. A system of filter control valves.
SLOW SAND FILTERS
• Principle features:
–Enclosure tank
–Filter medium
–Support medium
–Under drainage system
ENCLOSURE TANK
• Arranged side by side
in rows
• Rectangular in shape
• Size:
– 30*60 m
• Occupies a large area
(may be upto 1 acre)
ENCLOSURE TANK
• Holds supernatant water: above the sand bed , depth
varies from 1-1.5m
– Provides constant head of water to overcome the resistance of
the filter bed-promote the downward flow of the water through
sand bed.
– Provides waiting period of some hours (3-12 hrs) for the raw
water to undergo partial purification by sedimentation and
oxidation and particle agglomeration.
FILTER MEDIUM
• Bed of sand: 60-90 cm in thickness
• Sand particles are relatively fine
– Upper 15 cm even finer
– Support the vital layer of the filter
SUPPORT MEDIUM
• Foundation of graded gravel
• Size decreases from below upwards
• Thickness: 30 cm
UNDERDRAINAGE SYSTEM
• Lies on the floor of enclosure tank
• Consists of perforated pipes leading to
central drain where filtered water collects
MECHANISM OF ACTION
Filter
Physical Biological
water
MECHANISM OF ACTION
• Physical action:
– Mechanical filtration
• Whereby suspended particles are strained out by
bed of sand
– Adsorptive action
• Colloidal particles get adhered to sand grains
– Electrical action
• Oppositely charged ionized particles are attracted
& arrested by sand particles
MECHANISM OF ACTION
• Biological action
– By “ZOOGLEAL/ VITAL” layer
– Appears as
• Slimy, gelatinous adhesive film resting on surface of
sand
– Made up of
• Living objects like algae, plankton, diatoms and
bacteria
• Formation of this layer is known as RIPENING of the
filter which may take several days to fully develop
– Function
• Holds back bacteria & releases bacteria free water
PERFORMANCE
• Rate of filtration
–100-200 L of water per hour per
square meter of filter area
• Removes 99.9-99.99% bacterial
flora
CLEANING OF SSF
With
continuing Resistanc Eventually,
operation, e to becomes
Efficiency
thickness water clogged &
decreases
of vital flow non
layer increases functional
increases
CLEANING OF SSF
Disconnect Scrap 1-2 Virtually
Now fit for
the filter cm of sand removing
reuse
unit bed vital layer
With continuous use thickness of sand bed progressively reduces,
& when decreases to 40-45cm new bed to be prepared
• Advantages :
–Simple to construct and operate.
–Cheaper.
–Physical, chemical and
bacteriological quality of water is
very high.
–Reduces bacterial count by 99.9%
and E.coli by 99%.
• Disadvantages :
–Old fashioned and outdated method
of water purification
–Initial cost is low but maintenance
cost is much more than rapid sand
filter.
–Needs a lot of space
RAPID SAND FILTER (RSF)
• Principle features
–Enclosure tank
–Filter medium
–Support medium
–Underdrainage system
STEPS OF RSF
–Coagulation
–Rapid mixing
–Flocculation
–Sedimentation
–Filtration
COAGULATION
• Coagulants are trivalent salts of metals which
release ions carrying high positive charge.
• Coagulation
– Starts when positively charged coagulant particles
attract negatively charged colloidal particles
– Coagulant is the nucleus and surrounded by colloidal
particles
– These enlarged particles coalesce to form a
gelatinous precipitate that runs through as a spongy
mass called “FLOC”
– Bacteria get entangled to meshes of floc
– As the size of floc increases, it descends and settles
at the bottom of sedimentation tank .
• Two types of coagulants used:
– Alum coagulants
• Alum (aluminium sulphate): most commonly
used
• Activated alum
• Sodium Aluminate
– Iron coagulants
• Ferrous sulphate
• Ferric Sulphate
• Ferric chloride
• Able to remove colour & odour
• But are corrosive & expensive
FLOCCULATION
• Process of gentle stirring of
water for thorough mixing of
the coagulant
• Ensures uniform distribution of
coagulant & accelerates floc
formation
SEDIMENTATION
• Takes 2-6 hours
• Essential features of
sedimentation tank:
–Rectangular tank / Circular tank/
Hopper bottom tank
–Inlet and outlet
–Water flow (horizontal)
–Sludge drainage
FILTRATION
• Each unit has a surface of 80-90 m3
• Supernatant water -1 to 1.5 mt
• Depth of sand bed 1 mt
• Effective size of the sand particle is
0.4-0.7mm
• Supported graded gravel- 30-40cm
• Filtration rate 5-15 m3 / m2 /hr
MECHANISM OF ACTION
• Primarily Mechanical
– Sand bed arrests suspended particles
mechanically
• Floc particles which escape sedimentation,
collect on surface of rapid sand filter &
form slimy layer comparable to vital layer
of SSF
– This adsorbs bacteria & purifies water
METHOD OF CLEANING OF RSF
Filter becomes Loses its
Unit is closed
clogged with use efficiency
Clean water
injected under Called
pressure in backwashing
reverse direction
It shakes the sand & dislodges the clogging
material which is then easily removed by Back-
washing
PERFORMANCE
• Filter 3000-6000 L of water/hour/
square meter of filter area
• Removes colouring and colloidal
substances effectively
• Decreases bacterial load by:
– 98-99%
• ADVANTAGES
–Deal with raw water.
–Occupies less space
–Filtration is rapid
–Washing of filters is easy.
–More flexibility in operation
• Disadvantages :
–Relatively high skill operation
–Costlier
–Removes bacteria by 98-99%
BERKEFELD FILTER
• It is a water filter made
of diatomaceous earth .
• It is invented in
Germany in 1891 and by
1922 was being
marketed in UK by
Berkefeld Filter co.
WORKING PRINCIPLE
Bottom of the
Consists of two The water is forced
upper cylinder has
cylinders (metal or through the filters
fitted porcelain
plastic) by gravity
filter columns (1-4)
Tapped off as It trickles down to
Where it is stored
required the lower cylinder
PASTEUR-CHAMBERLAND FILTER
• It is a porcelain water filter invented
by Charles Chamberland in 1884.
• It is similar to the Berkefeld filter in
principle.
WORKING PRINCIPLE
It consists of an unglazed porcelain tube called bisque
Contains a ring of enameled porcelain through which the
inflow pipe fits
The core of the porcelain is made up of a metal pipe with
holes through which water flows out and is collected
Inflow is pressurized so filtration occurs under force
USES
• It is a good bacterial water filter used
mainly as a high volume water filter
• The filter works more quickly when the
water supplied is under pressure.
• It cannot filter very small particles like
viruses or mycoplasma .
• It is used in removal of organisms from a
fluid culture in order to obtain the bacterial
toxins.
INCINERATOR
INCINERATION :
• It is a process of control and complete
combustion , for burning solid wastes. It leads
to energy recovery and destruction of toxic
wastes.
• In these plants the recyclable material is
segregated and the rest of the material is
burnt.
• It can be used to reduce the original volume
of combustible solid waste by 80-90%
Incineration process
USES
• Volume reduction
• Stabilization of wastes
• Recovery of energy from waste
• Sterilization of waste
SMOKELESS
CHULHA
Vents smoke
THE SMOKELESS CHULHA out of room
with a chimney.
Vents smoke out of
room with a chimney.
Two pot holders
80% of heat
cooking
It traps smoke 20% of heat
and heat inside Keeping
food warm
MATERIALS NEEDED FOR SMOKELESS
CHULAH CONSTRUCTION
Bricks or mud made out of
• Clay – 1 Part
• Sand – 5 part
• Bhoosa or paddy husk or
cow dung.
Chimney made from cement pipe.
(Metal pipes will get too hot and plastic pipes may melt)
Cap on the chimney top, to protect from rain, animals and
sparks
LAXMI STOVE 50%
less
fuel
50%
less
smoke
Two dishes can be cooked at same time
Any household pot
Chimney 60% heat can be placed on
40% heat top of the stove
Pots sit flush on the
potholes, so the
gases do not escape
into the kitchen
Manufactured by
local worksphops
that own a mold
Price of Mold: INR
Fixed Cement stove 2000
AN IMPROVED SAMPOORNA
SMOKELESS CHULHA FROM PHILIPS
Indoor access for Chimney made from
cleaning several sections, easier
to manufacture and
transport and clean
90%
Stack of clay tablets that less
clean the exhaust smoke
BENEFITS OF SMOKELESS
CHULHA
• Reduces deforestation
• Reduced risk of carcinogenic fumes
• Thermal efficiency increased by 25%
• Affordable and made with local
materials
• Reduced risk of eye injuries
• Risk of burns reduced from open
flames.
THANK YOU
THANK YOU
