2. Reference
• Kawamura, Susumu. 1991. Integrated Design
of Water Treatment Facilities. USA: John
Wiley & Sons
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Irna Rahmaniar - Universitas Bakrie
3. Size of the Water Treatment Plant
• The capacity of a Water Treatment Plant (WTP) is
determined by the maximum daily demand placed
on the system
• Future water demand of the area being served should
also be taken into account when calculating the size of
the plant and the site area included
• Additional issues: the reliability of the water supply
and the cost effectiveness of supplying water from one
large plant vs two or three medium sized plants at diff
locations and elevation
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Irna Rahmaniar - Universitas Bakrie
4. • The required available site area for a
conventional plant may be estimated by the
following formula:
– A = area (acres)
– Q = ultimate plant capacity (mgd)
Size of the Water Treatment Plant
𝐴 ≥ 𝑄0,6
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5. Treatment Plant Site
• Evaluation of the treatment plant site is
primarily based on:
– The distance from the intake
– The layout of the treatment process units
– The environmental impact of the treatment plant
– Method of water distribution (gravity or pumping)
5
6. Treatment Plant Site
• Following items to evaluate:
1. Geographical location
2. Information obtained from the geological study
3. Availability of electric power and utilities
4. Accessibility to major highways
5. History of flooding or the presence of earthquake faults
6. Construction costs
7. Site maintenance costs
8. Operator safety and the safety of neighboring homes
9. Provisions for future plant expansion
6
7. Preliminary Engineering Study
• Once the construction phase has decided to proceed, a
preliminary engineering study, including planning must
be initiated
• This study address the following issues:
1. Quality and treatability of the raw water
2. Objectives for the finished water quality
3. Additional goals and objectives
4. Restrictions and constraints on plant design
5. Alternative treatment processes
6. Preliminary design criteria for treatment unit processes
7. Hydraulic grade across the plant
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8. Preliminary Engineering Study (cont..)
• (cont..) This study address the following issues:
8. Geotechnical considerations
9. Structural design conditions and criteria
10. Plant waste handling and disposal
11. Various schemes for instrumentation and control
12. Preliminary cost estimates
13. Recommended treatment processes
14. Plant layout and architectural design
15. Management planning of the design phase
16. Environmental impact statement (EIS) for the new
plant
8
9. Quality and Treatability of Raw Water
• The treatability of the raw water may be
evaluated through the use of bench scale test and
pilot study
• Surface water
– Data quality over period of time (5-10 years)
• Physical, chemical, microbiological, radiological
characteristics
– Risk assessment
• Possible contamination of water supply by chemical spills or
radioactive wastes
– Present and future land development in the
watershed must be studied
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10. Quality and Treatability of Raw Water
• Groundwater
– Apply same considerations associated with surface water
– Geological conditions,
– water table
– the drawdown of the water table as the result of pumping
– Seawater intrusion
– Potential leaching of industrial wastes
– Domestic wastes
– Agricultural chemicals and fertilizers into the groundwater
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11. Treatment Process Selection
• Depend on:
– The characteristics of the raw water and the
finished water quality goals
– Availability of major equipment
– Post-installation services
– The capability of operators and maintenance
personnel
– Waste handling requirements
– The availability and cost of water treatment
chemicals
11
12. • Final of the most appropriate treatment
process:
– Reliability
– Constructability
– Ease of operation
– Simple maintenance
– Cost
Treatment Process Selection
12
13. • 3 basic water
treatment
purification
processes:
1. Conventional
complete
treatment
2. Direct filtration
3. In-line filtration
Treatment
Process Selection
13
14. • Two modified schemes:
1. high-level complete
2. two-stage filtration
Treatment Process Selection
14
15. Treatment Process Selection
• Applicable raw water qualities for the basic
treatment processes
Parameter
Conventional Two-Stage Direct In-Line
Complete Filtration Filtration Filtration
Turbidity (NTU) <5000 <50 <15 <5
Color (apparent) <3000 <50 <20 <15
Coliform (#/mL) <107 <105 <103 <103
Algae (ASU/ml) <105 <5 x 103 <5 x 102 <102
Asbestos Fiber (#/mL) <1010 <108 <107 <107
Taste and Odor (TON) <30 <10 <3 <3
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16. Geotechnical Considerations
• Greatly influence the entire construction cost,
the duration of construction, and plant
maintenance
• Issues that can be obtained:
– Soil pressure
– Data on excavation and fill
– Groundwater level
– Site seismicity
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17. Intake System
• A WTP ceases to function when the intake system
fails to supply water
• Where and How?
– Located in an easily accessible location
– Designed and built to supply a specified quantity of
the best available quality of water
– The source should be reliable
– No interruption under any condition
– Combined with grit chamber and raw water pumping
station.
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18. Intake System
• Essential factors:
– Reliability
– Safety
– Minimal operation
– Maintenance costs
• Others:
– Water rights
– The quality of water source
– Climatic conditions
– Fluctuations in the flow rate and water level
– Regulations
– Water navigation
– Geographical and geological informations
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19. River Intakes
• Most river intake structures are constructed as
shore intakes: an intake system and raw water
pumping station.
• Others: submerged intake, intake tower,
suspended intake, siphon intake, floating
intake, and movable intake.
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20. Lake and Reservoir Intakes
• Tower intakes and submerged intakes are two
typical types of lake and reservoir intake.
• Submerged intakes are generally less
expensive to build than the intake towers
• Others: shore shaft
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21. Groundwater Intakes
• Includes artesian wells, deep infiltration
galleries or pipes, shallow wells and deep
wells
• Quality and quantity of the water should be
investigated by a test well or other methods
• All conventional treatment processes, except
chlorination, may be eliminated
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