investigation of utilizing rainwater as alternate source of water in tejgaon industrial area

7/31/2019 Investigation of Utilizing Rainwater as Alternate Source of Water in Tejgaon Industrial Area

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INVESTIGATION OF UTILIZING RAINWATER AS ALTERNATE SOURCE OF WATER

IN TEJGAON INDUSTRIAL AREA

MAHIR ASEF

S.M.MUNTASIR MASUM

SOUMITRA PAUL

DEPARTMENT OF CIVIL ENGINEERING

AHSANULLAH UNIVERSITY OF SCIENCE AND TECHNOLOGY

MAY, 2012


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INVESTIGATION OF UTILIZING RAINWATER AS ALTERNATE SOURCE

OF WATER IN TEJGAON INDUSTRIAL AREA

A Thesis

Submitted By

Mahir Asef (08.01.03.003)

S.M.Muntasir Masum (08.01.03.029)

Soumitra Paul (08.01.03.047)

In partial fulfillment of the requirement for the degree of

Bachelor of Science in Civil Engineering

Under the supervision of

Dr. Abdullah Al-Muyeed

Associate Professor

Department of Civil Engineering

AHSANULLAH UNIVERSITY OF SCIENCE AND TECHNOLOGY

May, 2012


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CE 450

Project & Thesis

Approved as to style and content by

Dr. Abdullah Al-Muyeed

Associate Professor, Department of Civil Engineering, AUST


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DECLEARATION

We hereby declare that the Project work submitted here has been performed by us and

this work has not been submitted for any other degree.

Mahir Asef

S.M.Muntasir Masum

Soumitra Paul


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ACKNOWLEDGEMENT

We would like to express our sincere appreciation and gratitude to our supervisor

Dr. Abdullah Al-Muyeed for his unending assistance, valuable suggestion, co-

operation and encouragement. The Project could not have been prepared in such a

manner without his ultimate advice and direction.

We are highly thankful to Dr. Md. Anwarul Mustafa, Head, Department of Civil

Engineering for his exemplary character that inspires us throughout the whole track of

this thesis work.

We are also thankful to Bangladesh Meteorological Department, Dhaka Water Supply

& Sewerage Authority (DWASA), Bangladesh Power Development Board (BPDB)

and their official web site for their informative documents and data sheet. It saved a

lot of time to visit those offices physically.

We would also like to express our thankfulness to the official members of ACI

Limited and Runner Group of Companies for providing us all the information needed

for the survey work.

We would also like to appreciate the staff members of Civil Department, Engineering

section members, and our co-workers in helping us to complete the research work.

Finally, we are grateful to GOD that our research has been completed successfully

and within schedule time.


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ABSTRACT

In many developing countries, the stress of rapidly growing populations,

mismanagement of resources and changing climate has created a burden on already

compromised water resources. In Bangladesh, where a significant proportion of the

population is without access to improved water source, the urgency for clean available

water sources to sustain healthy and productive human and natural populations has

become a priority. Rainwater harvesting is a familiar term for Bangladesh. People in

areas that lack drinking water, particularly the coastal areas and the rural areas in the

country, practice rainwater harvesting. The high annual rainfall in the country makes

rainwater harvesting a logical solution for the arsenic contamination of ground water

in Bangladesh (Rahman et al, 2003). Most of RWH literature is centered on the

potential and implementation of rainwater harvesting systems, however not much

focus has been placed on examining the demand satisfaction of these systems. This

study investigates the reliability of rooftop rainwater harvesting (RRWH) as a key

priority source of water supply for residential and industrial uses. This research work

aims to develop a guideline for economical RWH in the urban areas. For this purpose

Dhaka city was selected as the model town representing urban areas of Bangladesh.

An experiment, carried out on the rooftop of AUST to prove that RWH can easily be

adopted for the urban buildings. The experiment was followed by a survey on the

industrial areas to justify that not only residential area but also the industrial areas can

be considered for RWH. The research project also highlights on the physical and

chemical properties of harvested rainwater, which was tasted in laboratory. Analysis


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on cost-benefit, storage capacity of AUST, ACI Limited and Runners Group of

Companies are also done in this study. A statistical analysis is also added in this

research to correlate different parameters of this research work. In the end different

results gained from this research work are represented through GIS, to prove

economical effect of rainwater harvesting in the residential and industrial areas of

Bangladesh and establish RWH as an alternative source of safe water.


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Contents

ACKNOWLEDGEMENT ...................................................................................................... v

ABSTRACT ..................................................................................................................... vi

List of Tables ...................................................................................................................... x

List of Figures ..................................................................................................................... xi

List of Abbreviations ............................................................................................................ xiii

CHAPTER 1 ...................................................................................................................... 1

INTRODUCTION ................................................................................................................... 1

1.1 General ...................................................................................................................... 2

1.2 Background of the Study (RWH) .................................................................................... 4

1.3 Rationale of the study ...................................................................................................... 6

1.4 Purpose of the study ........................................................................................................ 7

1.5 Objective of the Study ..................................................................................................... 7

1.6 Hypothesis ...................................................................................................................... 8

1.7 Limitations of the Study .................................................................................................. 8

CHAPTER 2 ...................................................................................................................... 9

LITERATURE REVIEW ....................................................................................................... 9

2.1 Rainwater Harvesting .................................................................................................... 10

2.2 RRWH Potential and Reliability ................................................................................... 13

2.3 Adoption of RWH ......................................................................................................... 16

2.3.1 Asia......................................................................................................................... 16

2.3.2 Other Regions of the World ................................................................................... 17

2.3.3 Bangladesh ............................................................................................................. 19

CHAPTER 3 .................................................................................................................... 22

METHODOLOGY ................................................................................................................ 22

3.1 METHODOLOGY ........................................................................................................ 23

3.1.1 DATA COLLECTION PROCEDURE .................................................................. 24

3.1.1.1 Survey ......................................................................................................... 24

3.1.1.1.1 Study Approach ................................................................................. 24

3.1.1.1.2 Condition of Rainfall in Dhaka City.................................................. 28


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3.1.1.1.3 Study Area ......................................................................................... 29

3.1.1.2 Small Scale RWHS ..................................................................................... 30

3.1.1.2.1 Experimentation................................................................................. 30

3.1.1.2.1.1 Equipment ................................................................................ 30

3.1.1.2.1.2 Installation Process..............................................................31-33

3.1.1.2.1.3 Cost Measurements .................................................................. 34

3.1.1.2.2 Trials.................................................................................................. 35

3.1.1.2.3 Sample Collection & Storage ............................................................ 36

3.1.1.2.3.1 Sampling Procedure ................................................................. 37

3.1.1.2.3.2 Collection and Storage of Research Project Sample ................ 39

3.1.2 DATA ANALYSIS ................................................................................................ 40

3.1.2.1 Test the quality of sample ........................................................................... 41

3.1.2.2 Compare Sample Data With Standards ....................................................... 42

3.1.2.3 Analysis of Survey Data & Storage Calculation ......................................... 43

3.1.2.3.1 Storage capacity Calculation ............................................................. 44

3.1.2.3.2 Contribution to Groundwater Recharge............................................. 47

3.1.2.3.3 Cost Benefit Analysis ........................................................................ 483.1.3 RESULT................................................................................................................. 51

3.1.3.1 Water Sample Quality ................................................................................. 51

3.1.3.2 Storage Capacity Comparison ..................................................................... 55

3.1.3.3 Statistical Analysis: ..................................................................................... 57

CHAPTER 4 .................................................................................................................... 61

GIS PRESENTATION .......................................................................................................... 61

CHAPTER 5 .................................................................................................................... 66

CONCLUSION .................................................................................................................... 66

5.1 CONCLUSION ............................................................................................................. 67

5.2 MAJOR FINDING of THE STUDY............................................................................. 68

5.3 FUTURE SCOPE of STUDY ....................................................................................... 69

References .................................................................................................................... 70

APPENDIX ...................................................................................................................... a

Questionnaire ...................................................................................................................... b


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List of Tables

Table 2.1: Coefficient of runoff for common roof types (Kumar, 2004) 14

Table 3.1: Prediction of population and water demand in Dhaka urban area 25

Table 3.2: Historical data of water supply 27

Table 3.3: Cost of equipments 34

Table 3.4: Harvested Sample Quality 41

Table 3.5: University (AUST) Water Sample Quality 41

Table 3.6: Comparison with standard values 43

Table 3.7: Storage Comparison between AUST, ACI limited and

Runners Group of Companies 55

Table 3.8: One-Sample Test 57

Table 3.9: Paired Samples Correlations 58

Table 3.10: Paired Samples Test 58


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List of Figures

Figure 3.1: Showing water demand and supply with growing population 25

Figure 3.2: Groundwater depletion with time (years) 26

Figure 3.3: Monthly average rainfall of Dhaka 28

Figure 3.4: Study Area (AUST, block-c) 29

Figure 3.5(a): Layout of the project 32

Figure 3.5(b): RWHS on AUST 33

Figure 3.6: Components (a,b) & Layout of the Filter bed (c,d) 36

Figure 3.7: Comparison of Costs-Benefits Analysis 50

Figure 3.8: Comparison of pH 51

Figure 3.9: Comparison of Turbidity (JTU) 52

Figure 3.10: Comparison of TDS (mg/l) 53

Figure 3.11: Comparison of Iron (mg/l) 53

Figure 3.12: Comparison of between AUST, ACI limited and Runners Group of

Companies 56

Figure 3.13: One sample t test 59

Figure 3.14: Paired Sample Correlation 59


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Figure 3.15: Comparison of Significance (One & Paired Sample) 60

Figure 4.1: Rainfall Intensity 63

Figure 4.2: Summarized Information Comparing the Study Areas 65


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List of Abbreviations

AUST Ahsanullah University of Science and Technology

BPDB Bangladesh Power Development Board

BS Bangladesh Standard

CARE Co-operation for American Relief Everywhere

CWSSP Community Water Supply and Sanitation Project

DASCOH Development Association for Self-reliance Communication and

Health

DPHE Department of Public Health Engineering

DRWH Domestic Rainwater Harvesting

DWASA Dhaka Water Supply & Sewerage Authority

IWM Institute of Waste Management

NGO Non-governmental organization

RWH Rainwater Harvesting

RWHS Rainwater Harvesting System

RRWH Rooftop Rainwater Harvesting

UNICEF United Nations International Children's Emergency Fund

UNEP United Nations Environment Programme

WHO World Health Organization

WASA Water Supply & Sewerage Authority


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CHAPTER 1INTRODUCTION


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1.1 General:

Bangladesh is a developing country of South Asia. The development of any country

depends largely on, how they use their natural resources. Among natural resources

gas, oil, coil, lime are mainly named. But sea, river, forest, snow/rainfall are also

important elements of natural resource for any country. But with the increasing

demand and excessive use these resources are on the verse of decay.

Water is essential to sustain life, and a satisfactory supply must be available to all. But

in Bangladesh there has been acute scarcity of safe drinking water for recent years.

Because of excessive use of ground water the country is now facing arsenic problem.

Discovery of the presence of arsenic in the drinking water in Bangladesh has been a

cause of red alert in the public health arena. According to Bangladesh Arsenic

Mitigation and Water Supply Project out of 4 million tube-wells installed in

Bangladesh, 1.2 million have been found contaminated with arsenic

(www.bamwsp.org). What is startling is that the arsenic concentration level in 30-40

percent wells of the affected area is over 500 ppb or 50g/liter (World Bank, 2001).

For Bangladesh, it is estimated that 27 to 60% of the population is at risk from arsenic

exposure (Smith, Lingas and Rahman, 2000). This is equivalent of 28-50 million

people in Bangladesh and most of them live in rural areas.


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Rainwater Harvesting and storage do not constitute a new technology. It has been

used for domestic, agricultural, runoff control, air-conditioning etc. for a long time in

different parts of the world. However, rainwater harvesting is not a common practice

in Bangladesh. Only 35.5 percent households have been found to use the rainwater as

drinking water source during the raining seasons in coastal areas having high salinity

problems (Hussain & Ziauddin, 1989). In the backdrop of arsenic contamination in

groundwater of Bangladesh, rainwater has been considered as a potential source of

arsenic free water.


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1.2 Background of the Study (RWH):

Rainwater has been harvested in Bangladesh from time immemorial. Traditional

rainwater collection was very simple and was usually done by tying an old saree or a

sheet to four posts in the yard and collecting the water in a traditional earthenware

pot, a Motka. The introduction of handpumps in the 1970s and the widespread

installation of shallow well handpumps through the private sector in the 80s and 90s,

brought water close to the home in many areas of Bangladesh. In the coastal belt of

Bangladesh groundwater is often saline and so, where deep tube wells that would

yield sweet water were not possible, rainwater harvesting was practiced. Several

NGOs were active during the Decade and community-wide rainwater harvesting in

Dacope upazilla, completed with the assistance of the Bangladesh Agricultural

University in 1988, was reported in Waterlines in 1992.

In 1994 UNICEF developed an interest in rainwater harvesting and in support of the

Department of Public Health Engineering; a pilot activity was undertaken in

Chittagong. It was thought that rainwater harvesting would be useful in the

Chittagong Hill Tracts and to expand water supply in areas with saline water in the

coastal belt. Very few systems were built, mainly due to costs and rainwater

harvesting never took off.

Rainwater harvesting regain its emphasis in the last years of twentieth century, mainly

because of the increasing awareness about the adverse effect of arsenic. In 1998,

while looking for alternative solutions for people who were losing their safe water

supply due to the contamination of their well with arsenic, WHO argued for


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consideration of rainwater as a potential replacement. Initially there was little

response, as rainwater was considered not to be adequate all year round, systems

would be too expensive, and doubts existed about the water quality. Several meetings

were convened with various parties that had once supported rainwater harvesting and

slowly interest was developing among the professionals. A Swiss technology transfer

agent, SKAT, came to support NGO Forum for Drinking Water Supply and Sanitation

and indicated the feasibility.

WHO and SKAT collected up-to-date information from the Lanka Rainwater

Harvesting Forum and an action-research proposal was prepared. By June 2000, NGO

Forum received support from SDC to undertake a 3 year project. At the same time,

International Development Enterprises, Bangladesh, a NGO focusing on developing

affordable technologies, locally, for the poor, at a fair market price, through a private

sector supply chain also started a pilot scheme in a community-based water supply

project area where it was collaborating with CARE and Development Association for

Self-reliance Communication and Health (DASCOH) in what is called the Water

Partnership Project. UNICEF and DPHE, through the pilot projects on arsenic

mitigation, have also started again to try out rainwater harvesting again and offer it as

an option in their projects. WHO supported the pilot activities of the various agencies

through regular consultation and technical advice. As it was at least the second time

that rain water harvesting was initiated in Bangladesh, it was imperative to do it right

this time (Han A. Heijnen, Environmental Health Advisor; [email protected]).


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1.3 Rationale of the study:

In Bangladesh rainwater has traditionally been a security in areas where water has

been scarce. Islands or coastal areas may have plenty of water, but most of it will be

saline and not tasty to drink. In hard water areas or where water contains a lot of iron,

people may be more inclined to use rainwater for drinking and cooking purposes.

Hilly wet zone areas, as population pressures increase, people are forced to move

uphill into areas that remained uninhabited before. Water points will be available only

below the level where people live and daily drudgery in collecting water is the

consequence. This does not have to be the case as areas with 2 monsoons can very

well have an excellent water collection regime, even with small roof surface or

storage.

Our study mainly highlights the urban areas of Bangladesh especially Dhaka city.

Rainwater harvesting can ease water crisis in Dhaka. Rainwater could potentially

supply about 15% of citys water requirement. The citys Water & Sewerage

Authority (WASA) has the capacity to produce up to 1800 million liters a day, while

the demand is in excess of 2000 liters. A study carried out by IWM suggested that

around 150000 million liters rainwater could be harvested during the annual

monsoon. So the intensity of this research work is to reduce the problem of safe

drinking water.


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1.4 Purpose of the study:

The purpose of the study is to develop a rainwater harvesting system on the rooftop of

urban residential and industrial buildings.

1.5 Objective of the Study:

The objectives which are highlighted in the study are-

To study and determine the rainwater harvesting methods of Dhaka city toestablish RWHS as an alternate solution of water supply

To determine the suitability of harvesting rainwater for drinking and otherpurpose in the residential and industrial buildings

To develop a project to assess the feasibility of incorporating rainwater harvestingfrom selected roof area of Ahsanullah University of Science and Technology

(AUST) and estimate its contribution on the total consumption of the university

To meet the ever increasing demand for water, harvest rainwater to recharge thegroundwater and enhance the availability of groundwater at specific places and

time and thus assure a continuous and reliable access to groundwater

To reduce the rate of power consumption for pumping of groundwater anddetermine the cost-benefit ratio


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1.6 Hypothesis:

Hypothesis is important for a research. It is a tentative generalization, the validity

of which has to be tested. It is made in order to find out the correct and valid

explanation of certain phenomena through investigation. Rainwater harvesting in the

urban area is becoming popular day by day. In the research it has been conducted to

give comprehensive insights about harvesting rainwater procedures on the rooftop of

urban area buildings. Based on the research topic a hypothesis has been drawn that

will be tested by statistical data got from the study.

It is more economical to harvest rainwater than ground water pumping

1.7 Limitations of the Study:

There are also some limitations in RWHS and the limitations are-

Maximum output can be gained in the monsoon only Applicable only for buildings Only urban areas would be taken in consideration


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CHAPTER 2LITERATURE REVIEW


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2.1 Rainwater HarvestingWater is essential for all life and used in many different ways, it is also a part of the

larger ecosystem in which the reproduction of the bio diversity depends. Fresh water

scarcity is not limited to the arid climate regions only, but in areas with good supply

the access of safe water is becoming critical problem. Lack of water is caused by low

water storage capacity, low infiltration, larger inter annual and annual fluctuations of

precipitation (due to monsoonic rains) and high evaporation demand.

The capture and utilization of rainwater is an ancient tradition which dates back to

similar techniques used in todays Iraq around 5000 years ago. Modern methods

usually represent improvements with respect to technical variations (Mbilinyi, 2005).

The term rainfall harvesting' is broadly defined as the collection of any form of

precipitation from a catchment (Babu and Simon, 2006). Rainwater harvesting

(RWH) is the process of collecting and storing rainwater from rooftops, land surfaces

(steep slopes, road surfaces and rock catchments) using simple components (pots,

tanks, cisterns) or more complex methods (underground dams) ( Zhu et al, 2004).

RWH can be categorized according the catchment method used as: in-field RWH

(IRWH), ex-field (XRWH) and domestic RWH (DRWH). In IRWH, part or all of the

target area is used as the catchment area. In XRWH the catchment area is separate

from the target area and harvested water is transported through channels to the target

area (Kahinda et al, 2007). In DRWH, rainwater is collected on rooftops or other

compact surfaces and stored in underground (UGTs) or aboveground tanks (AGTs)

for domestic uses and other small-scale activities (Kahinda et al, 2007).


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RWH can also be divided into two major systems: runoff rainwater harvesting and

rooftop rainwater harvesting. In the former system, water collected is of a low quality

as it follows a similar route as surface water in that area (Kahinda et al, 2007) and

thus requires an added effort on treatment of harvested water before domestic use.

Studies show that of the two systems, rooftop rainwater harvesting, RRWH, yields

harvested waters with contaminants in levels acceptable by international drinking

water standards (Kahinda et al, 2007; Zhu et al, 2004) and is thus thought to be a

superior option when considering domestic water supply, in particular potable water.

Components of a typical RRWH system are the catchment (roof area), down pipe and

gutters and storage tank.

RWH has become a popular option for obtaining a relatively clean, accessible water

supply in many areas with limited water supply. Other than as a direct source of water

for human consumption, RWH often serves as an artificial recharge (AR) to

groundwater that has been over exploited (Sundaravadivel, 2007). Lowering of the

water table due to depletion of groundwater can cause environmental problems like

land collapse, loss of vegetation, desertification and soil erosion.

In the case of groundwater pollution, such as episodes of arsenic contamination in

India (Pandey et al, 2003), rainwater can be used to dilute contaminants within the

aquifer (Sundaravadivel, 2007). Using RWH to replenish groundwater is considered

the most cost efficient way of storing rainwater (Sundaravadivel, 2007).


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Albeit RWH is an old tradition, scientific interest in the design and improvement of

these systems recently expanded after open predictions of global water crisis arose.

For this reason, most literature on the topic lightly focuses on past uses and more on

the need to implement RWH within government policy. Some studies discuss the use

of RWH to supplement water supply for agricultural use during dry seasons in parts of

Southeast Asia and Sub-Saharan Africa. Domestic use systems are put in operation in

many countries in Africa, Asia (Sundaravadivel, 2007) and even a few areas in

Eastern Europe and western United States.


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2.2 RRWH Potential and Reliability

Research shows that there is still a considerable amount of untapped rainwater

potential in Africa that can be used to supply adequate water to an immense portion of

the population (UNEP, 2008). However, before adopting RRWH systems, it is

important to verify the RWH potential of the area of interest and conclude whether the

conditional parameters produce a satisfactory reliability for water supply.

The RRWH potential of any region depends on the amount of rainfall, the surface

(rooftop) area used to capture the rainwater and surface runoff coefficient (that is, the

proportion of total rainfall that can be captured). The runoff coefficient used depends

on the type of material of the roof surface (Table 2.1). The potential rainwater supply

of the system is usually deduced by the following equation (Tripathy and Pandey,

2005):

S= R x A x Cr (1) where S is the potential rainwater supply in m3, R is the mean

annual rainfall in m, A is the catchment area in m2 and Cr is the runoff coefficient.

RRWH reliability of a system defines its quality of performance and can be

determined through two equations (Liaw and Tsai, 2004):

(1)the volumetric reliability, that is, the total actual amount of rainwater supply overdemand or

(2)the fraction of time that demand can be met:Re = 1- n/N

Where n is the number of time units (days) when demand exceeds storage while N is

the total number of time units in the time sequence.


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Table 2.1: Coefficient of runoff for common roof types (Kumar, 2004).

Roof Type Runoff Coefficient

Galvanized Iron Sheet 0.90

Asbestos Sheet 0.80

Tiled Roof 0.75

Concrete Roof 0.70

In their study, Tripathi and Pandey in the year of 2005 used the equation 1 to calculate

the rooftop rainwater potential for Zura village in Kutch district in Gujarat, India. The

number of households with different roof areas was used to determine the total

rooftop area which was then multiplied by the annual rainfall and runoff coefficient to

obtain the amount of water stored collectively from the pucca houses in the village.

The researchers then divided the stored water supply by the demand (total population

x daily per capita water demand) to determine the amount of time the collected water

could be used (without replenishing) by the village. Tripathi and Pandey concluded

that the RRWH can be used as a source of domestic water supply for similar water

stressed (500 mm of annual rainfall) villages in arid parts of India.

In another study done by M. Dinesh Kumar in the year of 2004 in the city of

Ahmadabad in a semi-arid part of India, the RWH equation was used to determine the

per capita water harvested for 3 different household stocks; independent bungalow, 3-

story apartment and 10-story apartment. Rooftop areas were dependent on the

household stock and the highest, average and lowest precipitation values with once in

6 years probability of occurrence were used to access the feasibility of RWH in low-


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rainfall areas (Kumar, 2004). The study concluded that the physical feasibility of

RWH in urban areas with low rainfall is less than desirable. In addition government

Subsidies for RWH systems were not recommended for areas characterized with

annual rainfall of less than 400 mm.

These two studies considered both the regional variation of RWH and its dependence

on the social demography of the study area. Several other studies (Kumar, 2007;

Pudyastuti, 2006; Thomas, 1998) show that RWH is suitable in areas that receive

above 1200 mm of rainfall to solely sustain domestic demand. However, the study on

Zura village in India shows that even under low rainfall conditions, the number of

households used in harvesting and the population allowed for a satisfactory water

supply through rooftop harvesting, perhaps due to large roof areas and storage volume

(Kumar, 2007). In addition to storage and demand characteristics, poor roofing

structures, high household density and sparsely distributed houses, typical in many

Asian and African countries, are factors that can greatly reduce the practicality of

RWH in low rainfall areas.


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2.3 Adoption of RWH

As a traditional practice, RWH has gained popularity in the formal settings within the

last decade. The practice, that is still used in many tropical islands and semiarid rural

areas (Tripathi and Pandey, 2005), has been introduced more efficiently into urban

areas and in temperate regions as a way to satisfy higher demand or as a water

conservation method. Although literature on this technique is not extensive, current

literature does highlight the main geographical regions that play key roles in the

development and research of RWH.

2.3.1 Asia

RWH has wide spread adoption throughout Asia. India is leading in rainwater capture

for domestic use in Asia where some variants of RWH have been used for over 8000

years (Pandey et al, 2003). In 2001, India was approaching the level of water stress

with 1,820 cubic meters of annual renewable freshwater per capita which is estimated

to decrease to 1,341 cubic meters by 2025 (Tripathi and Pandey, 2005). The Indian

government has created subsidies to encourage the adoption of DRWH to harness the

rainfall and balance out the declining water table in many parts of the country

(Tripathi and Pandey, 2005). RWH is also commonly implemented as a climate

change adaptation strategy (Pandey et al, 2003). Sir Lanka has practiced RWH since

the 5th Century and even with the introduction of piped systems and boreholes, the

RWH option has once again gained popularity this last decade (Ariyananda, 1999).

With about 1,250 mm of annual rainfall (Sri Lankas main source of freshwater),

harvesting rainwater has been an ideal solution. Over the years, growing population,


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urbanization and deforestation have increased the competition for domestic water

supply hence the country has invested in research to improve the RWH technology.

The government of Sri Lanka in collaboration with the World Bank established the

Community Water Supply and Sanitation Project (CWSSP) that provides water

supply and sanitation infrastructure that can be managed by communities

(Ariyananda, 1999). Initially the CWSSP provided these communities with water

supply through shallow wells, house connections and either hand or motorized pump

wells. Rainwater collected was introduced as a solution to the challenge of providing

water supply to the uphill settlements (Ariyananda, 1999).

2.3.2 Other Regions of the World

Outside of Asia some more developed regions are utilizing RWH to provide partial

supply and reduce the high cost of piped water for a variety of activities such as

gardening, aquaculture, nurseries, domestic supply, and livestock farming for example

(Gould, 1999).

Germany is one of the countries investigating the RWH models in urban areas (Gould,

1999). RWH is an economic way of substituting potable piped water with collected

rainwater for low quality uses such as flushing toilets and laundry (Herrmann, 1999).

Although the utilization of rainwater is a relatively recent focus (within the last 20

years), there has been accelerated use of the technology for private and commercial

sectors. The decentralization of water supply has been accepted and in many cases

subsidized by city councils as it reduces storm overflow (Herrmann, 1999). There

have been efforts by local governments to encourage households to capture rainwater


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for domestic use and divert exceeding amounts to recharge groundwater, however

another objective is to control urban flooding and storm water drainage. Several

places in the country have received grants and subsidies to facilitate this movement

(Gould, 1999).

According to Herrmann in 1999, about 100,000 rainwater storage tanks have been

provided for rainwater storage purposes allowing for the storage of over 600,000m3 of

rainwater. The widespread use of RWH in developed countries such as Australia,

USA and New Zealand, is mainly for the purpose of water supply in the rural and

drier regions. In semiarid and arid Australia, rainwater is collected for use in farming

and domestic activities and more than one million people rely on rainwater as their

solely domestic water supply (Gould, 1999). Large rainwater catchments are utilized

in Western Australia to provide water for livestock farms and small settlements

(Gould, 1999).


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2.3.3 Bangladesh

The recent detection of high level of arsenic concentration in numerous shallow

tubewell water mostly across Bangladesh has caused serious problem for supplying

safe water for drinking and other domestic uses. It is reported that more than 4000

people are suffering from arsenic-related diseases ranging from melanosis to skin

cancer. It has been also reported that about 70 million people are likely to be affected

through probable arsenic contamination of shallow tubewells currently serving as

water points mainly for drinking and cooking purpose. Efforts to develop remedial

solution are still far from making a comprehensive breakthrough. Known arsenic

removal methods work fairly well only under strictly controlled conditions, making

such use impractical at household level. The fate of affected patients in terms of

developing drugs remains even more uncertain. Researchers are, however,

unanimously agreed that the known treatment so far is the immediate cessation from

the use of arsenic-contaminated water and resumption of the use of arsenic-free water.

As arsenic contamination of groundwater becoming widespread, the increasing

awareness of people is enticing them to find a remedial measure. They are looking

forward to an alternative source that is safe, cost-effective, available and acceptable. It

is also evident that though some people recognized rainwater is safe to drink; their

mental preparedness is not adequate to adopt it in their life. However, it is necessary

to popularize the use of rainwater as an alternative source of drinking and cooking

water. Mass awareness building and training programme on the storage procedures

are required. When people will know that a scientific and cheap method is within their


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reach and it is for betterment of their health, it will positively change their attitude and

practice towards multi-uses of rainwater.

Dhaka has a critical water supply problem, one of the worst for a South Asian city.

According to a study by the Institute of Water Modeling based in Bangladeshs

capital city, its groundwater level is falling by three meters per year. Groundwater has

already receded by fifty meters in the past 40 years, bringing the current level to sixty

meters below ground. The supply-demand gap is approximately 500m liters per day.

The situation is so problematic that in the summer of 2010, the Government of

Bangladesh deployed troops to manage water distribution in Dhaka. Since 1963, the

population of Dhaka has grown by thirteen times. When Bangladesh gained its

independence in 1971, Dhaka faced a growing influx of rural-to-urban migration. The

city expanded into the low-lying marshlands at its borders. Historically, most of

Dhakas water supply comes from its two rivers, the Buriganga and the Shitalakkhya.

But as population has increased and industry has expanded, river water has become

contaminated with industrial waste. Today, groundwater is expected to satisfy over

80% of the citys water supply. Infrastructure in Dhaka is not robust enough to

sufficiently recharge groundwater. In a recent seminar, international NGO Water Aid

and Bangladeshs Institute of Engineers concluded that rainwater harvesting needs to

be included in establishing the countrys bylaws. In 2008, it was recommended that

40-50% of building premises should remain unpaved and that half of that area should

be under green cover to allow for natural recharge of aquifers. The caveat though is

that 65% of Dhaka is already paved and the remaining 35% does not ensure natural

recharge of aquifers because top soil in most of these locales consists of clay.


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Rainwater harvesting, low-cost systems that collect and store rainwater for year-round

use, offers a cost-effective and practical solution to ease Dhakas water crisis. It is

estimated that rainwater harvesting (RWH) systems could supply more than 15% of

Dhakas requirements. Since 1997, one thousand RWS have been installed in

Bangladesh, mostly in rural areas. The systems capacities vary from 500L to 3,200L,

at costs in the range of US$50-150. If RWH is undertaken as a serious investment, it

could help conserve groundwater and recharge the water table. About 150 billion

liters of rainwater could be harvested during the monsoon season alone. Water can be

stored for four to five months without bacterial contamination an important fact given

that 110,000 children in Bangladesh die of waterborne illnesses every year.

There has been precedence of public-private partnerships working to establish RWH

in Bangladesh. In early 2008, Coca-Cola Far East Ltd teamed up with Plan

Bangladesh to install RWS in five primary schools in the Mirpur and Borguna Sadar

areas of the country to ensure potable drinking water for school students. In 2009,

Coca-Cola became involved in a new partnership with UN-Habitat called The Safe

Drinking Water and Sanitation Project. It is a two-year project valued at US$300,000.

The goal is to impact six thousand families by demonstrating RWH and other water

conservation and storage systems. RWH will be set up at twenty schools while

drinking water and sanitation systems will be set up at thirty schools. The

commissioned RWH recharge capacity is projected to be 3.25m liters per year. So

rainwater harvesting is one of the most efficient, available and cheap method for

Bangladesh to adopt for solving the acute problem of safe water.


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CHAPTER 3

METHODOLOGY


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3.1 METHODOLOGY:The research project is about introducing a Rainwater Harvesting System for both

residential and industrial area to develop an Alternative source of water for

consumptive purpose. To achieve the research objectives, the methodology of this

research is divided into following parts-

Data Collection Procedure Data Analysis Result

The whole Methodology of the project can be represented through the

Flow chart below -


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3.1.1 DATA COLLECTION PROCEDURE:

The data collection procedure is the collection of work done to collect and store the

water sample. Data collection includes survey. Small scale RWHS setup,

experimentation, trials and collection and storage of water sample. The steps are

briefly described here.

3.1.1.1 Survey:

In civil engineering surveying or land surveying is the technique, profession, and

science of accurately determining the terrestrial or three-dimensional position of

points and the distances and angles between them. These points are usually on the

surface of the Earth, and they are often used to establish land maps and boundaries for

ownership or governmental purposes. In general language it is the initial visit where

the project or experiment will be taken place. The steps followed in the research

project are categorized and explained below.

3.1.1.1.1 Study Approach:

Bangladesh is categorized as a developing country whose economy is rapidly

growing. Dhaka is the capital of Bangladesh. All the activities regarding any

development is Dhaka centered. As a result for a better and safer living people from

all districts are moving towards Dhaka. This makes Dhaka the most densely populated

mega city of this world. With the growing population and development of Dhaka city,

the demand for water is also increasing. Dhaka WASA is finding it difficult to meet

this exponential demand.


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The statistical data showing the relation between population growth, water demand

and shortfall of water supply is given below the Table-3.1 and Figure-3.1:

Table 3.1: Prediction of population and water demand in Dhaka urban area

Figure 3.1: Showing water demand and supply with growing population

(Source: Dhaka WASA)

YearPopulation

(million)Water

Demand(mld)

Shortfall(mld) with

present water

supply(2200 mld)

2010 12.27 2400 2002015 14.93 3050 850

2020 18.04 3686 1486

2025 21.63 4419 2219

2030 25.87 5286 3085

Water Demand and Supply


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Currently, with the help of some 546 water-supply pumps, DWASA supplies about 2.2

million cubic meters (MCM) of water a day against city's daily demand of 2.4 MCM.

Only 15% of the water is supplied from the two surface water treatment plants at

Chadnighat and Syedabad. DWASA is dependent on groundwater for the rest 85%

water demand. This is resulting the groundwater to drop by 3 meter every year.

According to the Dhaka Water and Sewerage Authority (WASA), the Ground water

table was at 11.3m below the surface in the 1970s and at 20m in the 1980s. Dhaka's

groundwater table has gone down by 35m in the past 11 years. However, water level

has drastically fallen since 1996.

The continuous dropping of groundwater table over the past 14 years is graphically

shown in Figure-3.2:

Figure 3.2: Groundwater depletion with time (years)



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This is mainly because the estimated mean annual recharge for Dhaka city is 300

350 MCM, which is much less than the annual abstraction of 700 MCM. After every

few years the pumps has to be relocated or new deeper installation has to be installed.

If this process continues then within few years groundwater depth will not be any

more within pumping depth.

From the past history with the growing demand for water supply was increased which

caused the Deep Tube Well to go from deep to deeper as shown below Table-3.2:

Table 3.2: Historical data of water supply

Year Supply ( MLD ) DTW

1963 130 30

1970 180 47

1980 300 87

1990 510 140

1996 810 216

1997 870 225

1998 930 237

1999 1070 277

2000 1130 308

2001 1220 3362002 1550 394

2004 1437 382

2005 1460 423



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The demand will surely not decrease but due to the shortage of groundwater, supply

will surely decrease. One of the major threats to the city due to declining groundwater

levels is land subsidence, which can be triggered by earthquakes of greater

magnitudes. So, an alternative source of water or a method to recharge groundwater is

of utmost importance in Dhaka city for preserving environmental balance along with

meeting human demand.

3.1.1.1.2 Condition of Rainfall in Dhaka City

Dhaka has a climate. It has a distinct monsoonal season with an average 2075 mm

(1953-2009) of rain every year. Nearly 88% of the annual average rainfall of

1,826 millimeters occurs between May and October. Water logging occurs after 2-

3hrs of continuous raining.

Figure 3.3: Monthly average rainfall of Dhaka

Monthly average rainfall of Dhaka


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3.1.1.1.3 Study Area:

Our study covers the urban areas of Bangladesh, but to carry out the research work

and for setting up RWHS, Tejgaon industrial area of Dhaka city was selected. The

RWHS was setup on the rooftop of Block C of Ahsanullah University of Science &

Technology. An area about 100 sq ft of the rooftop was used for this purpose.

Figure 3.4: Study Area (AUST, block-c)

(Source: AUST)


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3.1.1.2 Small Scale RWHS:

A small scale RWHS was setup on the roof top of AUST. The setup of the RWHS,

experimentation, trials and sample collection & storage are vital part of the Data

Collection Procedure

3.1.1.2.1 Experimentation:

The experimentation process includes setting up of RWHS, installation process and

cost measurements.

3.1.1.2.1.1 Equipment:

Equipments needed to complete the research work are enlisted below-

Gutter: GI sheet made gutter. Dimension of 8ft * 3ft Bricks: For inclination and support to the gutter The First Flush Device: To drain the first fault water. It consists of 6in pvc pipe

along with GI elbow and screw cap at the end

Filtration Drum: Plastic made,15 inch in diameter,15 inch in height Filtration Bed: Consists of four layer,5 cm well graded gravel,5 cm well graded

brick chips,12.5 cm sand, 12.5 cm well graded gravel

Water Storage Drum: Plastic made, Capacity of 30 gallon, dia of 18in,height of 24inch

Steel Frame: Steel made, 24 in square, height of 49 in Outlet Key: 1in Distribution Pipe: 1in


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Aggregate: Sand and Gravels Cement: white cement; to keep the whole structure stableThis equipments may vary with the type of RWHS setup.

3.1.1.2.1.2 Installation Process

The whole project work was done in the month of May and June. Because the

monsoon starts in Bangladesh in the month of May, and generally lasts till September.

The installation process are described below-

Rooftop Water Tank of the university was used to install the GI sheet made gutter The GI sheet made gutter was used as the catchment area At first the gutter was placed on the top of the water tank. In order to drain the

rain water through the gutter, two brick made walls were used. A slope of 1/6 was

maintained between the walls. The gutter was tied with the brick walls to give

stability

Rainwater drains through the first flush device to the collection Pipe The collection pipe opened to the filtration drum Filtration drum was placed on top of the main storage tank with the help of the

extended frame. In order to prevent the filtered water becoming polluted a plastic

paper was used as a shade from the bottom of the filtration bed to the top of the

storage tank. The filtered water can directly enter the storage tank.

A outlet key was placed, 3 in up from the bottom of the storage tank to collectwater


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The layout of the RWHS is given below

Figure 3.5(a): Layout of the project

To view

Front view

Steel sheet

Brick wall

Pipe

Filter bed

Storage

Drum

SupportiveSteel Frame

Isometric view


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Figure 3.5(b): RWHS on AUST


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3.1.1.2.1.3 Cost Measurements

The total cost estimation of the RWHS is given below. The costs may vary with the

market price.

The project cost nearly 7000 BDT.

Table 3.3: Cost of equipments

Item Price in BDT

Gutter 600

Storage drum 650

Filtration drum 450

Steel Frame 3000

6in dia pipe

70tk/ft

1in ball bulb 350

Outlet key 100

Fast flush device 400

Cement 150

Other cost 1000

TOTAL COST 7000


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3.1.1.2.2 Trials:

Based on the quality, water is termed into two types

Portable water : Physically, chemically, and bacteriologically acceptable Palatable water: Free from turbidity, color, taste, odor, and moderate temperature.

In a sense it has to be physically acceptable.

Now to ensure these quality in the harvested water, the filter bed which was installed

initially was given trial as if it can provide physically accepted water or not

Trials onFiltration Bed

To ensure that the harvested water from rain is safe for drinking, filtration bed was

installed. Two trials were given too.

1st

trial:

In the initial or 1st trial (Figure-c) of filtration bed some problems were detected.

Turbidity was found because of the presence of sand in the water sample. Again the

color of the sample was not clear. To solve those problems, 2nd trial was given.

2nd

trial:

In the 2nd trial (Figure-d), course sand was used in the place of fine sand to solve the

turbidity (sand) problem. A pair of thin net was also introduced in the lowest layer

upon the opening of the filter bed. Also well graded layers of stone chips & brick

chips were used instead of gap graded & uniform graded layers in 1st trial.


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In Figure 3.6 different elements ofthe filter bed and the layout are given-

Gravel

Brick chips

Fine sand

Gravel

Filter Bed (1st Trial)Filter Bed (2nd trial)

Well Grade Gravel

Well Grade Brick chips

Course sand

Well GradeGravel

Figure3.6: Components (a,b) &

layout of Filter bed (c,d)

(a) (b)

(c) (d)


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3.1.1.2.3 Sample Collection & Storage:

There are procedure which must be followed while collecting and storing water

sample. In this research the procedures proposed by Minnesota Pollution ControlAgencyare followed.

3.1.1.2.3.1 Sampling Procedure

Sample Holding/Travel Time

Samples must be collected as soon as possible. For water samples, the time from

sample collection to initiation of analysis should be no longer than 24 hours. If time

exceeds 30 hours, results for total and faecal coliform analyses are invalid due to

bacterial stress and die-off.

Sample Containers

Water samples for microbiological examination should be collected in sterilizable,

non- reactive, glass (borosilicate) or plastic bottles. Pre-sterilized plastic bags with

or without DE chlorinating agent, available commercially, may be used. (*Plastic

bottles reduce the possibility of breakage during sample transit.)Bottles should be

carefully washed and rinsed, with a final distilled or deionized water rinse.


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Potable Water Samples taken from tap

Taps used for sampling must be free of aerators, strainers, hose attachments,mixing type faucets and purification devices. Avoid leaky taps.

Always take sample from cold water tap. Flush tap by running water (to waste) for 2-3 minutes; this will allow for

adequate flushing of the pipe between water main and tap.

If tap appears to be dirty, clean with a sodium hypochlorite solution , then

allow water to run for an additional 2 to 3 minutes to rinse

Aseptic Sampling Procedure

Wash hands prior to sampling. Remove lid of sample container with one hand. While holding lid with one

hand, fill bottle with other hand.

Some important points on which emphasis should be given are-

Do not adjust water line or water flow rate before taking sample. Do not rinse bottle prior to sampling.

Be careful not to touch sides or inside lid of bottle to anything. These measures

will prevent sample from becoming contaminated.

Do not overfill sample container. Make sure there is approximately 1 inch of airspace at top of container to allow for adequate shaking prior to analysis.


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Immediately replace lid tightly. If there is any question as to whether or not a sample has become

contaminated, discard and resample.

Samples should be placed on ice/ice packs during transit to laboratory tomaintain temperature below 10C.

3.1.1.2.3.2 Collection and Storage of Research Project Sample

The RWHS was completed at the month of July. The rainfall occurred at 23 rd of

July and the sample was collected at the morning of 24 th July maintaining all above

mentioned procedures. The sample was stored in the freezer at 5C for two days.

An amount of one liter sample water was collected for testing.


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3.1.2 DATA ANALYSIS:

Analysis of datais a process of inspecting, cleaning, transforming, and

modelingdatawith the goal of highlighting useful information, suggesting

conclusions, and supporting decision making. Data analysis has multiple facets and

approaches, encompassing diverse techniques under a variety of names, in different

business, science, and social science domains. Data analysis is a body of methods that

help to describe facts, detect patterns, develop explanations, and test hypotheses.

In this thesis Data analysis is done in three steps-

Test the quality of sample Compare sample with standards Analysis of surveyed data


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3.1.2.1 Test the quality of sample:

To ensure the quality of the harvested water, some tests were run on the collected

sample water. The experiments were done in the universitys Environmental Lab.

The results are enlisted in the table below

Table 3.4: Harvested Sample Quality

Nameof the test pH Turbidity Co2 TDS Iron FreeChloride Conductivity D-ionizer Redoxpotential

Experimented Value

7.20.055JTU

5mg/

l

300mg/l

0.11mg/

l

1.77mg/l

24.3mg/l

0.26mg/l

288mg/l

In addition to our research work, the water of the university (AUST), was also tested.

The university uses ground water for all purposes. The test results are -

Table 3.5: University (AUST) Water Sample Quality

Name of the

testspH Turbidity CO2 Iron Conductivity

D-ionizer

Redox

potential

Experimented

value 6.77

0.044 JTU

(.85 JTU) 37 mg/l

0.13

mg/l 88.5 mg/l

0.18

mg/l 217 mg/l


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3.1.2.2 Compare Sample Data With Standards:

The primary purpose of the Guidelines for Drinking-

water Qualityis theprotection of

public health. The Guidelines are intended to support the development and

implementation of risk management strategies that will ensure the safety of

drinking-water supplies through the control of hazardous constituents of water.

These strategies may include national or regional standards developed from the

scientific basis provided in the Guidelines. World Health Organization (WHO)

generally sets a limit of standard values of different elements of drinking water.

In developing national drinking-water standards based on these Guidelines, it will be

necessary to take account of a variety of environmental, social, cultural, economic,

dietary and other conditions affecting potential exposure. This may lead to national

standards that differ appreciably from these Guidelines. A programme based on

modest but realistic goals including fewerwater quality parameters of priority health

concern at attainable levels consistent with providing a reasonable degree of public

health protection in terms of reduction of disease or reduced risk of disease within

the population may achieve more than an overambitious one, especially if targets

are upgraded periodically. Like many other countries Bangladesh also has standards

for drinking water too.


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The comparison between the BS (Bangladesh Standard) and harvested water sample

and university water sample are enlisted below:

Table 3.6: Comparison with standard values

Name of the TestBangladesh

Standard

Experimented value

(Harvested Rainwater)

Experimented Value

(University water)

pH 6.5-8.5 7.2 6.77

Turbidity 10 JTU .055 JTU (1.04 FTU)0.044 JTU (0.85

FTU)

CO2 5 mg/l 37 mg/l

TDS 1000 mg/l 300 mg/l 278 mg

Iron 0.3-1 mg/l 0.11 mg/l 0.13 mg/l

Free Chlorine 1.77 mg/l 1.68 mg/l

Conductivity 24.3 mg/l 88.5 mg/l

D-ionizer 0.26 mg/l 0.18 mg/l

Redox potential 288 mg/l 217 mg/l

3.1.2.3 Analysis of Survey Data & Storage Calculation

For gathering further information on the thesis topics, a survey work was also

performed. The survey was carried out in two companies

1) ACI Limited2) Runner Group of CompaniesThe data collected from the survey were used to calculate the storage capacity of

those companies and also to Cost-Benefit analysis. The university was also considered

for this calculation.


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3.1.2.3.1 Storage capacity Calculation

To know the amount of water that can be saved through RWHS is impotent. The

efficiency of the RWHS is also calculated through the storage capacity. The total

storage capacity of AUST, ACI Limited and Runner Group of Companies are given

below -

AUST

Total boundary area = 400,000 sq ft

Total rooftop area = 32,530.5 sq ft

Total free rooftop area = 12,500 sq ft

The volume of the underground reservoir = 15000 cu ft

Considering 1/3 of the reservoir water is used daily in AUST for all consumptive

purpose,

Total daily water consumption of AUST = 37,402gallon (US)

Consumption of AUST during the five month of monsoon

= (37402*30*5)

= 5,610,300 gallon

Total precipitation in Dhaka city,

During the monsoon (May- September) = 5016 mm

(Source: http://www.bmd.gov.bd)

So, the volume of rainfall = 1748 cu meter

Now, Considering 30% of the rooftop can be used for rainwater harvesting,

The amount of water that can be harvested = 461773 US gallon


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Using Runoff coefficient table,

Amount of harvested water = 461773 * 0.8

= 369418.4 gallon

So the percent of water that can be saved = (369418.4 /5,610,300)*100

= 6.5 %

So, using only 30% of the free rooftop area of AUST, an amount of 6.5%

ground water can be saved.

ACI Limited

Total Area = 10,200 sq ft

Total rooftop area = 6000 sq ft

Free rooftop area = 6000 sq ft

Considering 30% of the rooftop can be used for RWHS,

Harvested area = 1800 sq ft



So, the volume of rainfall using 1800 sq ft of rooftop

= 839 cu meter

= 221640 gallon

Using Runoff coefficient table,Amount of harvested water = 221640 * 0.8

=177312 gallon

From the survey, daily consumption for all purpose

= 2324 gal

Total consumption in the monsoon = 2324*5*30

= 348,600 gallon


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The percent of water saved = (177312/348600)*100

= 50 %

So, using only 30% of the free rooftop area of ACI Limited, an amount of 50%ground water can be saved.

Runner Group of Companies

Total Area = 9000 sq ft

Total rooftop area = 9000 sq ft

Free rooftop area = 7000 sq ft

Considering 30% of the rooftop can be used for RWHS,

Harvested area = 2100 sq ft



So, the volume of rainfall using 2100 sq ft of rooftop= 979 cu meter

= 258625 gallon

Using Runoff coefficient table,

Amount of harvested water = 109103 * 0.8

= 206900 gallon

From the survey, daily consumption for all purpose

= 1500 gal

Total consumption in the monsoon = 1500*5*30

= 225000 gallon

The percent of water saved = 206900/225000

= 92%

So, using only 30% of the free rooftop area of Runner Group of Companies, an

amount of 92% ground water can be saved.


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3.1.2.3.2 Contribution to Groundwater Recharge

If the system can be used for ground water recharge then a significant amount of

water can be recharged.

Total area of Dhaka City = 1528 km2

(Source: www.rrcap.unep.org/reports/soe/dhaka.../2-1dhaka-Introduction.pdf)

Total population of Dhaka City = 20 million

Total Annual Rainwater = Annual rainfall x Area= 2.1 m x 1528 x 106

= 3208.8 x 106 m3/yr

Assuming 25% of the total rainwater is used in recharging groundwater.

Total water recharge naturally = 0.25 x 3208.8 x 106

= 802.2 x 106 m3/yr

Considering 65% of the area of the Dhaka City is covered by concrete as a continuous

roof.

Actual water recharge in Dhaka = .35 x 802.2 x 106

= 280.77 x 106 m3/yr

= 769,232 liter/day

If half of the covered area can be used for the rain water harvesting and 50% of the

rain water can be recharged,

Additional ground water recharge = 769.23 x 106 x 0.65 x 0.5 x .5 x 0.85

= 106.25 x 106 m3/yr

= 291,100 liter/day


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3.1.2.3.3 Cost Benefit Analysis

A cost benefit analysis is done to determine how well, or how poorly, a planned action

will turn out. Although a cost benefit analysis can be used for almost anything, it is

most commonly done on financial questions. The cost for water in the monsoon for

AUST, ACI Limited and Runners Group of Companies are analyzed in this part

Price of water = 6.34 taka per 1000 liter(Source: www.theindependentbd.com/paper-edition/front-page)

ACI Limited

Demand of water during the monsoon = 348,600 gallon

= 1319594 liter

So, the total cost = (1319594/1000)* 6.34

= 8366 tk

As rainwater can serve 50% of the demand

The savings will be = (8366*50)/100

= 4183 taka

Again, one 10 horse power water pump runs 8 hour per day for lifting water from the

ground and to load the overhead water tanks.

Per unit cost in the industrial area = 8 tk

(Source: BPDB)

So cost for raising water in the monsoon = (10*8)*0.746*8*5*30= 71616 tk

As rainwater can serve 50% of the demand

So, the savings will be = {(71616*50)/100}

= 35818 tk

Now the total savings = 35818+4183

= 40000 tk


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Runners Group of Companies

Demand of water during the monsoon = 198150 gallon

= 750079 liter

So, the total cost = (750079/1000)* 6.34

= 4755 tk

As rainwater can serve 55% of the demand,

The savings will be = (4755*92)/100

= 4375 taka

Again, from the survey it is found that monthly cost for water

= 30000 tk

As rainwater can serve 55% of the demand water

So, the savings will be = {(30000*92)/100}*5

= 138000 tk

Now the total saving = 138000+4375

= 142375 tk

AUST

AUST only uses ground water for all types of consumptive purposes.

Three 9 horse power water pumps run 2 hours per day. 2 of them are used to lift water

from the ground to the main reservoir. And the rest is used to load the overhead water

tank from main reservoir.

So cost for raising water in the monsoon = ((9*3)*2)*0.746*8*5*30

= 48340 tk

(Source: AUST)

As rainwater can serve 3% of the demand water

So, the savings will be = {(48340*6.5)/100}*5

= 15710 tk


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Expances during the monsoon (tk) Savings during the monsoon (tk)

48340

15710

75800

40000

154755142375

Costs-Benefits Analysis

AUST ACI Limited Runners Group of Companies

Figure 3.7: Comparison of Costs-Benefits Analysis

In the research project the adoption of RWHS largely depends on the cost-benefit of

the total system. Analysis shows that RWHS is more economical during the monsoon

than of ground water pumping.


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7.26.77

7.5

pHExperimented value (Harvested Rainwater)

Experimented Value (University water)

Bangladesh Standard

3.1.3 RESULT

The results section is organized to show how the dates are tested; comment on the

research question or hypothesis should also be presented. If the harvested rainwater is

safe for drinking purpose or not, does it meets the Bangladesh Standard water quality,

if it is cost beneficial or not these topics are discussed here.

3.1.3.1 Water Sample Quality

The water quality of the harvested rainwater was tested in the Environmental

Laboratory of AUST. The report collected from the laboratory is arranged in table 3.6.

The comparison of the parameters with BS guideline, whether harvested water is

acceptable as drinking purpose or not are discussed below.

pH

In general, water with a pH < 7 is considered acidic and with a pH > 7 is considered

basic. The normal range for pH in surface water systems is 6.5 to 8.5 and for

groundwater systems 6 to 8.5. Alkalinity is a measure, of the capacity of the water to

resist a change in pH that would tend to make the water more acidic. From the

laboratory test, pH value of the harvested water was found 7.2, which is well inside

the BS. On the other hand the university water pH was found to be 6.77, which is very

slightly acidic. So in the case of pH, the harvested water quality is ok.

Figure 3.8: Comparison of pH


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10

0.055

0.044

Turbidity (JTU)

Bangladesh StandardExperimented value (Harvested Rainwater)Experimented Value (University water)

Turbidity

Turbidity is the suspended matter which can be removed from water through

filtration. On the other hand, is a measure of the amount of light scattered and

absorbed by water because of the suspended matter in the water. Turbidity is the lack

of clarity or brilliance in water. Water may have a great deal of color, and still be clear

and without suspended matter. BS for turbidity is 10 JTU. The harvested water was

found 0.055 JTU from the test. The value is found to be 0.044 JTU from the

university water. So the harvested water is acceptable in the turbidity standards.

Figure 3.9 Comparison of Turbidity (JTU)


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Other Properties

Some other properties of water were also examined. The properties are- CO2, Free

Chlorine, Conductivity, D-ionizer and Redox potential. As Bangladesh Standard does

not provide too much importance in these properties for drinking water, so there is no

such strict limit for these properties. But these properties were found to be in the close

range to the university water.

Comment

The harvested rainwater properties were found acceptable for drinking and other

purpose from the view of pH, Turbidity, TDS and Iron. The color of the sample water

was also found acceptable. But only these properties are not enough to say that it is

safe for drinking purpose. For other purpose it can be accepted. Some important

properties such as Fecal Coliform, Hardness, Sulphate, Carbonate, Nitrate were failed

to be tested because of the limitation of facilities in the laboratory. So without running

these tests the harvested water cannot be used for drinking purpose.


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3.1.3.2 Storage Capacity Comparison

In rainwater harvesting, calculation of supply and demand of water is very important.

Storage is the difference between actual supply of fresh water and the demand. The

amount of water that can be saved through harvesting are enlisted in Table 3.7

Table 3.7: Storage Comparison between AUST, ACI limited and Runners Group of

Companies

AUSTACI

Limited

Runner Group

of Companies

Total boundary area 400,000 sq ft 10,200 sq ft 9000 sqft

Total rooftop area 32,530.5 sq ft 6000 sq ft 9000 sq ft

Total free rooftop area 12,500 sq ft 6000 sq ft 7000 sq ft

Total daily water consumption 37,402gallon (US) 2324 gal 1321 gal

Consumption during the five

month of monsoon5,610,300 gallon

348,600

gallon198150 gallon

Considering 30% of the rooftop

the amount of water that can be

harvested

369418.4 gallon177312

gallon206900 gallon

Total Savings 6.5% 50% 92%


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Totalboundary

area(sq. ft)

Total rooftoparea

(sq. ft)

Total freerooftop area

( sq ft)

Total dailywater

consumption(gallon (US))

Consumptionduring the

five month ofmonsoon( gallon)

Considering30% of therooftop theamount of

water that canbe harvested

( gallon)

Total Savings(percentage)

400,000

32,530.50

12,500

37,402 5,610,300

369418.4

6.5

10,200

6000

6000

2324 348,600

177312

50

9000

90007000

1321 198150

206900

92

Comparison of between AUST, ACI limited and Runners

Group of Companies

AUST ACI Limited Runner Group of Companies

Figure 3.12: Comparison of between AUST, ACI limited and Runners Group of

Companies

Comment

In the research, for calculating storage capacity only 30% of the free rooftop of the

buildings was considered. From table 3.7 it can be said that in the months of monsoon

AUST, ACI Limited and Runners group of Companies can save up to 6.5%, 50% and

92% respectively. In this case it should be mentioned that the data used for calculation

were collected from a survey carried out to those places.


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3.1.3.3 Statistical Analysis:

Statistical analysis means collection, examination, summarization, manipulation, and

interpretation of quantitative data to discover its underlying causes patterns,

relationships, and trends. Statistical analysis refers to a collection of methods used to

process large amounts of data and report overall trends. Statistical analysis is

particularly useful when dealing with noisy data. In the research work the samples of

harvested rainwater and the water used in AUST are compared with the Bangladesh

Standard. Statistical analysis is performed to correlate between the sample properties.

The samples were analyzed through one sample t test and pair sample t test. The

results gained through the analysis may not be too much significant because only two

samples were used to run these tests.

Table 3.8: One-Sample Test

Sample

Test Value = 0

t df Sig. (2-tailed) Mean Difference

Bangladesh Standard 1.026 3 .380 254.8750

University (AUST) Water Sample Quality 1.642 6 .152 49.9462857

Harvested Sample Quality 1.639 8 .140 69.6327778


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Table 3.9: Paired Samples Correlations

Sample N Correlation

Sig.

Pair

1

Bangladesh Standard & University (AUST) Water Sample

Quality3 .349 .773

Pair

2Bangladesh Standard & Harvested Sample Quality 4 1.000 .000

Pair

3

University (AUST) Water Sample Quality & Harvested

Sample Quality7 .943 .001

Table 3.10: Paired Samples Test

Sample Sig. (2-tailed)

Pair

1Bangladesh Standard - University (AUST) Water Sample Quality .285

Pair

2

Bangladesh Standard - Harvested Sample Quality .382

Pair

3University (AUST) Water Sample Quality - Harvested Sample Quality .828


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BangladeshStandard &University(AUST)Water

Sample

BangladeshStandard &Harvested

SampleQuality,1.000

University(AUST)Water

SampleQuality &

Harvested

Paired Samples Correlations

Correlation

BangladeshStandard,

0.38

University(AUST)

WaterSampleQuality,0.152

HarvestedSample

Quality, 0.14

One Sample t Test

Significance

Comment:

From the statistical analysis some decisions can be made, which are-

In Table 3.8 where significances are found from one sample t test, it can be seen that

the significances have decreased. It means singular data cannot represent much

significance all alone.

Figure 3.13: One sample t test

From table 3.9 in which pair sample test have been performed, the correlations

between the samples have much improved. The correlation is found to be 1 in case of

BS and harvested rainwater, which means the sample qualities are the same or does

not differ by much. It is also close to one in case of AUST and Harvested rainwater,

but decreased between BS and AUST samples.

Figure 3.14: Paired Sample Correlation


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BangladeshStandard


SampleQuality

HarvestedSampleQuality

BangladeshStandard -University(AUST)Water

SampleQuality

BangladeshStandard -Harvested

SampleQuality


SampleQuality -Harvested

SampleQuality

0.38

0.152 0.14

0.2850.382

0.828Comparison of Significance

Significance (one)

When Table 3.8 and 3.10 are considered it is seen that, the result of significances

between pair sample and one sample t test the significances have varied. The

significances have improved in case of pair sample test than of one sample test. It

means the samples have much similar qualities when they are tested in a group than of

singular.

Figure 3.15: Comparison of Significance (One & Paired Sample)

From Table 3.8 and 3.9 it is seen that, in the case of pair sample test the correlations

between the samples are more improved than that of one sample t test. The values

have deviated a bit when the samples were compared with the BS. Its because BS

does not provide all standards for water samples which were tested in the laboratory.

So, from the above it can be said that, the results gained from the statistical analysis

are seen to be scattered. It is because of the limitation of collected samples. To get a

stable result or decision more samples are required.


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CHAPTER 4GIS PRESENTATION


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Divisional Rainfall Intensity of Bangladesh

(Source: http://www.bmd.gov.bd)

DHAKA5016mm

SYLHET4136

CHITTAGONG

22976

BARISAL4920

KHULNA4227

RAJSHAHI+

RANGPUR

8414


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0

10000

20000

30000

40000

50000

60000

investigation of utilizing rainwater as alternate source of water in tejgaon industrial area

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