CONTENTS

1. CHAPTER – 1 INTRODUCTION
2. CHAPTER – 2 OBJECTIVES OF THE STUDY
3. CHAPTER – 3 SCOPES OF THE STUDY
4. CHAPTER – 4 LITERATURE
5. CHAPTER – 5 METHODOLOGY
6. CHAPTER – 6 DESIGN AND RESULT
7. CHAPTER – 7 OUTCOMES
8. CHAPTER – 8 DISCUSSION
9. CHAPTER – 9 CONCLUSION
REFERENCES
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CHAPTER 1

INTRODUCTION
1.1. General
• Wastewater is a dilute mixture of various wastes from residential, commercial,
industrial and other public places. Wastewater typically contains pollutants
such as organic matter, chemicals, pathogens, and solids. It must be treated to
remove these contaminants before it can be safely discharged into the
environment or reused for various purposes. Wastewater treatment processes
vary but generally aim to make the water safe for the environment and human
health. The Imhoff tank, so named in honor of German engineer Karl Imhoff
(1876–1965), is a space that can be used to collect and treat sewage. By using
anaerobic digestion of the extracted sludge in conjunction with basic settling
and sedimentation, it can be used to clarify sewage. It is made consisting of an
upper chamber used for sedimentation, from which collected solids slide down
sloping bottom slopes to an entrance leading into a lower chamber used for
collecting and breaking down sludge. Other than that, there is no connection
between the two chambers; only the higher sedimentation chamber receives
the more liquid sewage, while the lower digestion chamber only receives a
slow flow of sludge. Separate biogas vents and pipes are needed in the lower
chamber to remove the digested sludge. It consists of a V-shaped settling
compartment above a tapering sludge digestion chamber with gas vents. The
Imhoff tank is usually built underground with reinforced concrete. It can,
however, also be built above ground, which makes sludge removal easier due
to gravity, although still requiring pumping up of the influent.
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CHAPTER – 2
OBJECTIVES OF THE STUDY
The objectives of the study are;
1.To design Imhoff tank for Shwe Pyi Thar
2.To remove as much of the suspended solids as possible before the remaining water,
called effluent, is discharged back to the environment
3.To make the sludge easier to handle and dispose of by reducing its volume and
organic content
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CHAPTER – 3

SCOPES OF THE STUDY: INHOK TANK FOR 40,000 PEOPLE

The scope of this study defines the boundaries and focus areas in analyzing the
feasibility, design, and impact of an Inhok tank (assuming it is a water storage or
wastewater treatment tank) for a population of 20,000 people. The study will cover
technical, environmental, social, and economic aspects while considering engineering
constraints and sustainability.

1. Technical Scope

 Design Parameters: Capacity, dimensions, and structural requirements for an

Inhok tank.
 Material Selection: Suitable construction materials (e.g., reinforced concrete,
steel, plastic composites).
 Water Supply and Distribution: How the tank will supply safe water or
manage wastewater efficiently.
 Hydraulic Considerations: Flow rate, pressure maintenance, and treatment
mechanisms (if applicable).

2. Environmental Scope

 Sustainability: Assessing eco-friendly materials and energy-efficient

operations.
 Water Quality & Treatment: Ensuring compliance with health and
environmental standards.
 Climate Considerations: Impact of weather variations on the tank’s
efficiency and longevity.

3. Social and Community Scope

 Population Coverage: Ensuring the system meets the daily needs of 20,000
people.
 Health Benefits: Improvement in sanitation, hygiene, and disease prevention.
 Community Engagement: Involvement of local stakeholders in tank
management and maintenance.
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4. Economic Scope

 Cost Estimation: Initial construction costs, operational expenses, and

maintenance.
 Affordability & Financing: Possible funding sources (government, NGOs, or
private investments).
 Cost-Benefit Analysis: Evaluating long-term benefits versus investment.

5. Policy and Regulatory Scope

 Compliance with Regulations: Adhering to local, national, and international

water or sanitation laws.
 Public-Private Partnerships (PPP): Exploring collaboration between
governments and private sectors.

Limitations of the Study

 Geographical Constraints: Focused on a specific region (if applicable).
 Data Availability: Limited by access to technical and population data.
 Implementation Factors: Not covering real-time project execution, only
theoretical design and feasibility.

CHAPTER - 4
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LITERATURE REVIEW

4.1. General
Wastewater a term that is used to describe waste material that includes industrial
liquid waste and sewage waste that is collected in towns and urban areas. When
wastewater is not treated properly, it can pollute our water sources, damage natural
habitats, and cause serious illnesses.
There are common two types of wastewater.
(1) Domestic Wastewater
(2) Industrial Wastewater

4.2. Level of treatment

1.Primary treatment
Removal by physical separation of grit and large objects (material to landfill for
disposal)
Sedimentation and screening of large debris

2.Secondary treatment
Biological and chemical treatment
Aerobic microbiological process (Sludge)

4.3 Imhoff Tank

The Imhoff tank is a primary treatment
Technology for raw wastewater, designed
for solid-liquid separation
and digestion of the settled sludge.
Three section of Imhoff tank are
1. sedimentation
2. sludge digestion
3. gas vent and scum section

4.4 Design Limitation

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(a) Sedimentation chamber; Sedimentation chamber is a rectangular chamber,

having the following specifications.
(i) Detention period 2 to 4 hours; usually 2 hours.
(ii) Max flowing through velocity 30 cm/min.
(iii) Surface loading Max. of 30,000 liters/m²/day
(iv) Length and Width Max. length limited to 30 m; length to width ratio
between 3:1 to 5:1
(v) Depth To be kept shallow to permit particles falling to the slot before
reaching the end of sedimentation chamber:
General depth 2.5 to 3.5 m, so as to limit the total depth to 9-10.5 m.
(vi) F.B of 45 cm
(b) Digestion chamber (i) Capacity of 0.028 - 0.056 m³ per capita is considered to
be sufficient in warmer climates where shorter period of sludge withdrawals is
possible. (ii)Scum chamber Surface area of scum chamber to be 25- 30 percent of the
horizontal projection of the top of the digestion chamber. Mini- mum width of vents
should be 60 cm.

4.5. Location of Study

Shwe Pyi Thar is a town in Yangon District, in eastern Yangon Region of
Myanmar. It is the administrative seat of Shwe Pyi Thar Township. The population of
Shwe Pyi Thar is nearly 40000 according to 2024 census.
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CHAPTER – 5
METHODOLOGY
Take population of Shwe Pyi Thar and sewage flow rate.
1.Calculate design of sedimentation.
2.Calculate design of gas vent and neutral zone
3.Calculate design of digestion chamber

3.1 Outlines of the study

There are three chapters in this study. Chapter one mentions introduction. In
Chapter three, the overview of the Imhoff tank is dicussed. . In Chapter , design
calculation is adopted and in another chapter four, discussion and conclusion
included.
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CHAPTER - 6

DESIGN AND RESULT

Population=20000
Sewage flow rate=180L/capata/day
(i).Design of Sedimentation chamber
Q = 20000 × 180 = 3600000 lpd = 3600 m³/day
Let us assume a detention period of 2 hours.
Capacity of chamber = 3600/24 × 2 = 300 m³
Let us assume an effective depth of 1.9 m and a width of 4 m.
This effective depth includes part of the bottom sloping walls of the chamber.
Length of chamber = 300/1.9×4 = 39.47m (Take 40 m length).
Since this length is quite large, let us use two tanks, each of 20 m length, and of
width 4 m, So L/B = 20/4 = 3.75 (which is between the desirable limit of 3 to 5).
Surface loading = 20000×180/2×20×4 = 22500 1/m²/day (which is less than
30000 1/m²/day)
It is satisfactory.
Velocity = L/T = 20/2×60 = 0.167m/min (which is less than 0.3 m/min)
It is also satisfactory.
Determination of depth
Let us provide bottom slope as 1 H: 1.25 V.
Width of chamber = 4 m
Height, y = 1.25 × 4/2 = 2.5 m. But we have to provide an effective depth of 1.9 m.
Hence height y' of the rectangular portion below the liquid surface is,
y' = 1.9 – 1/2 (2.5) = 0.65 m. (Since effective depth of triangular portion is half that
of equivalent rectangle).

Let us provide a F.B. of 0.45 m.

Total depth of the sedimentation chamber, upto the bottom of entrance slot
= 0.45 +0.65 +2.5= 3.6 m.
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(ii). Design of Gas vent and neutral zone

Provide neutral zone of depth 0.45 m below the depth of 3.6 m.The width of gas
vent should be 25 to 30% of the total width.
Assuming 15 cm thick chamber walls to both the sides,
we get b = 4+ (2 × 0.15) + 0.25 b ,From which, we get b = 5.73 m.
Hence providing total width of chamber = 5.8 m,
Width available for gas vents = 5.8 – 4 – 2 × 0.15 = 1.5 m (i e. 0.75 m width on either
side of sedimentation chamber),
Check width of gas vent = 1.5 × 100 5.8 = 25.86 % of the total width.

(iii). Design of digestion chamber

Let us further divide the total length L =20 m into four compartments of 5 m
each.
Assume Required capacity = 40 liters / capita
Capacity required = 20000 × 40 = 800,000 liters = 800 m³
Since there are two tanks, there will be in all 8 digestion units, each of width 5.8 m.
Hence capacity of each unit= 800/8 = 100 m³.
Each tank will have hopper bottom, with side slopes of 1:1.
Let us provide depth of hopper = 2 m.
Thus, each digestion chamber will have dimensions of 5.8m(width) × 5m(length) at
top and of 1.8m × 1m at the bottom.

Capacity of each hopper, C =h/3 (A1 + A2 + )

Where, A1 = 5.8 × 5 = 29 m²
A2 = 1.8 × 1 = 1.8 m²
h=2m
C =2/3 (29+1.8 + √29 × 18) = 25.35 m²
Balance to be provided by rectangular portion = 100 - 25.35 = 74.65 m³.
Height Z = 74.65/5.8×5 =2.574 m ≈ 2.6 m
Hence total height of digestion chamber, including neutral = 0.45 +2.6. + 2 = 5.05 m.
Overall height of tank = 3.6 +5.05 = 8.65 m
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The plan, elevation and section o

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CHAPTER –

Discussion

The implementation of an Inhok tank (assuming it is a water storage or wastewater

treatment tank) for a population of 40,000 people presents significant engineering,
environmental, social, and economic considerations. This study evaluates the
feasibility of such a system, addressing both its technical design and broader impacts.

1. Technical Considerations

The capacity of the tank must be sufficient to meet the water consumption or
wastewater storage needs of 20,000 individuals. Based on average per capita water
consumption, a tank volume of several million liters would be required. The choice of
construction materials—such as reinforced concrete, steel, or composite materials—
depends on factors like durability, cost, and climate conditions. Additionally,
hydraulic design must ensure proper flow rates and distribution to minimize
stagnation, contamination, or pressure issues.

2. Environmental and Health Implications

An appropriately designed tank contributes to improved public health by ensuring

access to clean water or efficient wastewater treatment. By preventing contamination
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of water sources, it reduces the spread of diseases such as cholera and typhoid. The
sustainability of the system depends on its design, including energy efficiency in
water pumping or treatment processes and the use of eco-friendly construction
materials.

3. Social and Economic Impact

Providing a reliable water storage or wastewater management system benefits public

health, economic productivity, and quality of life. The study highlights how efficient
water storage reduces dependency on erratic water supplies and how proper sanitation
infrastructure prevents disease outbreaks. From an economic perspective, the project
requires significant initial investment but results in long-term cost savings due to
improved health outcomes, reduced medical expenses, and increased labor
productivity.

4. Policy and Governance Challenges

The study also identifies regulatory compliance and governance as critical factors.
Implementing an Inhok tank system requires adherence to local water laws and
environmental regulations. Furthermore, the involvement of stakeholders—such as
government agencies, non-governmental organizations (NGOs), and private investors
—is crucial for funding, maintenance, and long-term sustainability.
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CHAPTER – 9

Conclusion

The feasibility of an Inhok tank system for a population of 20,000 people depends on
a combination of technical design, environmental sustainability, financial viability,
and governance. A properly designed tank can significantly enhance water security,
public health, and economic stability in the targeted community. However,
challenges such as high initial costs, maintenance requirements, and regulatory
constraints must be carefully addressed.

For successful implementation, collaborative efforts between government agencies,

engineers, and funding bodies are necessary. Further research should focus on real-
world case studies, cost-benefit analysis, and alternative sustainable solutions to
optimize the tank's efficiency. If properly designed and maintained, such a system can
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provide long-term benefits, ensuring clean water access or effective wastewater

management for a large population.

References

To ensure academic credibility, here are references related to large-scale water storage
and wastewater management systems. These sources discuss tank design, public
health benefits, environmental considerations, and economic feasibility.

1. Gould, J., & Nissen-Petersen, E. (1999). Rainwater Catchment Systems for

Domestic Supply: Design, Construction and Implementation. Intermediate
Technology Publications.
o This book provides in-depth knowledge of water storage systems,
including large tanks for community water supply.
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2. Smith, P., & McCarty, P. L. (2018). Environmental Engineering: Water,

Wastewater, Soil and Groundwater Treatment and Remediation. Wiley.

o Covers the principles of water storage, wastewater treatment, and

engineering solutions for public water needs.
3. World Health Organization (WHO). (2017). Guidelines for Drinking-Water
Quality (4th Ed.). Retrieved from:

o Outlines international standards for safe water storage and distribution,

relevant to the Inhok tank system.
4. Tchobanoglous, G., Burton, F. L., & Stensel, H. D. (2014). Wastewater
Engineering: Treatment and Resource Recovery. McGraw-Hill Education.

o Discusses wastewater treatment processes, including large-scale tank

designs for urban and rural communities.
5. United Nations Water. (2021). The United Nations World Water Development
Report 2021: Valuing Water. Retrieved from:
https://www.unwater.org/publications

o Provides insights into global water storage challenges and solutions for
large populations.
6. Eckstein, Y., & Zheng, Y. (2020). "Water Supply and Sanitation in
Developing Communities: Challenges and Solutions." Water Research
Journal, 183.

o Reviews case studies of water infrastructure projects designed for large

populations.
7. Khatri, K. B., & Vairavamoorthy, K. (2018). "Water Distribution System
Design and Optimization for Sustainable Urban Growth." Journal of Water
Resources Planning and Management, 144(9).

o Examines engineering approaches for sustainable and scalable water

storage solutions.
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8. National Research Council. (2012). Water Reuse: Potential for Expanding the
Nation’s Water Supply Through Reuse of Municipal Wastewater. National
Academies Press.

o Discusses wastewater treatment and storage solutions to address water

scarcity in growing populations.