The type of handpump technology suitable for a particular area depends on the groundwater level, water quality and hydrogeological conditions. There are some areas like the costal belt in the southern part of Bangladesh, where the conventional shallow and deep tubewlls technologies are not successful due to the high salinity. Alternative water supply options are needed for those areas.

1. Welcome
To The
Presentation
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2. Title Here
Presentation
Environmental Engineering-I
CEN-343
Instructor
Tanaz Islam
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3. Group Members
Name ID
1. Manik Chandra Roy 12206039
2. Md. Shariful Haque Robin 12206049
3. Md. Shifullah 12206051
4. Md. Mahmudujjaman 12206062
5. Arun Chandra Acharjee 12206066
6. Md. Oliullah Sheik 12206067
7. Rajesh Chandra Barman 12206070
8. S. M. Abrar Hossain Asif 12306001
9. Md. Monowar Hosen 13106174
10. Nur Afsar 13106175
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4. Our Presentation Topic: Alternative Water Supply
Technologies
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5. CONTENTS
1. Introduction
2. The important alternative water supply
technologies include:
3. Shallow Shrouded Tubewell (SST) and Very
Shallow Shrouded Tubewell (VSST)
4. Deep Tubewell
5. Dug Well
6. Pond Sand Filters
7. The major limitations
8. Household Filters
9. The important characteristics of household filters .
10.Infiltration Gallery
11.Solar desalination
12.Rainwater Harvesting
13.Advantages and disadvantages of rainwater
collection system
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6. INTRODUCTION
• The type of handpump technology suitable
for a particular area depends on the
groundwater level, water quality and
hydrogeological conditions. There are some
areas like the costal belt in the southern
part of Bangladesh, where the conventional
shallow and deep tubewlls technologies are
not successful due to the high salinity.
Alternative water supply options are needed
for those areas.
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7. The important alternative water
supply technologies include:
Shallow shrouded tubewell (SST)
Very shallow shrouded tubewell (VSST)
Pond sand filters
Household filters
Infiltration gallery
Solar desalination
Rainwater Harvesting
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8. Shallow Shrouded Tubewell (SST) and Very Shallow
Shrouded Tubewell (VSST)
These low-cost handpump tubewell technologies have been
designed and installed in the coastal areas to collect water from
very shallow aquifers formed by displacement of saline water by
fresh water. The SST/VSSTs can be convenient methods for
withdrawal of fresh water in limited quantities. Over-pumping
may yield contaminated water. Installation of low capacity
pumps may prevent over exploitation of shallow aquifers. The
systems may be considered suitable for drinking water supply for
small settlements where water demand is low. The depatment
of Public Health Engineering has sunk a total of 5,904 VSST/SST
to provide water to 0.44 million people in coastal areas (DPHE,
2000).
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9. Deep Tubewell
• In Bangladesh two types of deep
tubewells as shown in Figure 2.4 are
constructed, manually operated small
diameter tubewell similar to shallow
tubewells and large diameter power
operated tubewells called production
well. Some areas of the coastal region
of Bangladesh is very suitable for
construction of deep tubewell.
Department of Public Health
Engineering has sunk a total of 81,384
deep tubewell mainly in the coastal
area to provide safe water to 8.2
million people (DPHE,2000). The
identification of areas having suitable
deep aquifers and a clear
understanding about the mechanism of
recharge of these aquifers are needed
to develop deep tubewell based water
supply systems in Bangladesh.
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10. Dug Well
• Dug well is the oldest method of
groundwater withdrawal for water
supplies. The mechanism of
producing water of low arsenic and
other dissolved minerals
concentration by dug wells are not
fully known. Dug wells are widely
used in many countries of the world
for domestic water supply. The flow
in a dug wells is actuated by lowering
of water table in the well due to
withdrawal of water. Usually no
special equipment or skill is required
for the construction of dug wells. For
construction by manual digging, the
wells should be at least Community
dug wells should be deeper to
provide larger surface area for the
entry of water to meet higher water
demand. Private dug wells are less
that 10m deep but dug wells for
communal use are usually 20-30
metres deep.1.2 meters in diameter.
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12. Pond Sand Filters
• A prospective option for development of surface water
based water supply system is the construction of
community type Slow Sand Filters (SSFs) commonly
known as Pond Sand Filters (PSFs). Slow sand filters are
installed near or on the bank of a pond, which does not
dry up in the dry season. The water from the pond is
pumped by a manually operated hand tubewell to feed
the filter bed, which is raised from the ground, and the
treated water is collected through tap(s). The PSF is a
low-cost technology with very high efficiency in turbidity
and bacterial removal. It has received preference as an
alternative water supply system for medium size
settlements in arsenic affected areas and areas. Although
PSF has a very high bacterial removal efficiency, it may
not remove 100% of the pathogens from heavily
contaminated surface water.
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13. Pond Sand Filter for
Treatment of Surface Water
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15. Collection of safe water by installation of PSF
on the bank of a pond
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16. The major limitations
 Operation and maintenance are difficult;
 Not suitable for heavily contaminated ponds;
 People complained of foul taste in pond water and
many resorted to using it for cooking only;
 Conflicts with fish culture;
 It is difficult to find an appropriate/reserve pond
for installation of PSF;
 Many ponds dry up in the dry season in some parts
of the country;
 Secondary contamination takes place due to lack
of proper maintenance.
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17. Household Filters
• Surface water containing impurities can be clarified by a pitcher
filter unit or a small sand filter at the household level. It is an old
method of water purification, once widely used in rural areas of
Bangladesh. These processes of water treatment at household level
have been phased out with the introduction of tubewells for village
water supply. Pitcher filters are constructed by stacking a number
pitchers (Kalshis), one above the other, containing different filter
media .Raw water is poured in the top Kalshi and filtered water is
collected from the bottom one. In this process, water is mainly
clarified by the mechanical straining and adsorption depending of
the type of filter media used. Small household filters can be
constructed by stacking about 300-450 mm thick well graded sand on
a 150-225 mm thick coarse aggregate in a cylindrical container. The
container is filled with water and the filtered water is collected
from the bottom. Full effectiveness of the filtration process is
obtained if the media remain in water all the time. The pitcher and
other small household filters cannot completely remove micro-organisms
if these are present in large numbers in raw water.
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20. The important characteristics
of household filters are:
Suitable for surface water treatment;
Remove turbidity, color and micro-organisms;
Complete removal of pathogenic micro-organisms
is not guaranteed;
Not suitable for high-turbid water;
Difficulty in cleaning and keeping the
system operational.
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21. Infiltration Gallery
• Infiltration Galleries (IG) or wells can be
constructed near perennial rivers or ponds to
collect infiltrated surface waters for all domestic
purposes. Since the water infiltrate through a
layer of soil/sand, it is significantly free from
suspended impurities including microorganisms
usually present in surface water. Again, surface
water being the main source of water in the
gallery/well, it is free from arsenic. If the soil is
impermeable, well graded sand may be placed in
between the gallery and surface water source for
rapid flow of water.
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22. An Infiltration Gallery by the Side of a
Surface Water Source
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23. Solar desalination
• Solar energy available in Bangladesh can be used
for solar distillation of contaminated water in
crisis areas. Experimental units based on
conventional evaporation-condensation facilities
have been found to produce 0.6 - 2.4 Um2/d. The
water produced by solar distillation in free from
all chemicals including arsenic but cannot produce
enough water at a reasonable cost. The system
requires further development for cost effective
use in water supply in rural areas.
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24. Solar Distillation
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25. Rainwater Harvesting
• Bangladesh is a tropical country and receives heavy
rainfall during the rainy season. In the coastal
districts, particularly in the offshore islands of
Bangladesh, rainwater harvesting for drinking purposes
is a common practice in a limited scale for long time
(Chowdhury et al, 1987). In some areas of the coastal
region with high salinity problem, about 36 percent
households have been found to practice rainwater
harvesting in the rainy season for drinking purpose
(Hussain and Ziauddin, 1989). In the present context,
rainwater harvesting is being seriously considered as an
alternative option for water supply in Bangladesh in
the arsenic affected areas.
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28. Advantages and disadvantages of
rainwater collection system
Advantages Disadvantages
 The quality of rainwater is
comparatively good.
 The system is independent
and therefore suitable for
scattered settlements.
 Local materials and
craftsmanship can be used
in construction of rainwater
system.
 No energy costs are incurred
in running the system.
 Ease in maintenance by the
owner/user
 The initial cost may prevent a
family from installing a
rainwater harvesting system.
 The water availability is limited
by the rainfall intensity and
available roof area.
 Mineral-free rainwater has a
flat taste, which may not be
liked by many.
 Mineral-free water may cause
nutrition deficiencies in people
who are on mineral deficient
diets.
 The poorer segment of the
population may not have a roof
suitable for rainwater
harvesting.
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