University of Gondar

Faculty of Natural and Computational Sciences

Department of Chemistry

Postgraduate Program

“Studies on Assessment of physicochemical and the

concentration of selected metals in drinking water in

Gondar Town”

By

Abera Haile Adello

A thesis submitted to the Department of Chemistry, University

of Gondar for the partial fulfillment and requirements of

Masters Degree in Applied Chemistry

May, 2012

Gondar, Ethiopia

i

Acknowledgement

It is my First and foremost extended sincere thank to the Almighty God keeping all my families

and me safe throughout my educational journey.

I convey my deepest thanks to my major advisor Dr. Alemayehu Abebaw for giving me

constructive pieces of advice and guidance starting from the proposal writing to the completion of

this thesis work. I thank him for his genuine and energetic encouragement, suggestion, insight,

guidance and professional expertise to complete this work.

I also convey my deepest thanks to Gondar city water supply and sanitation staffs and Angered

water treatment servants for their energetic, material, and chemical reagent supports and their

kindness in giving technical and instrumental supports throughout the analysis.

I wish to give my deepest thanks to Dashen Brewery S.C quality assurance servants for their

willingness to support instruments and chemical reagents during the analysis time.

I convey my heartily thanks to Mr. Mekuriaw Alemayehu for his willingness advice, moral and

informational supports and his kindness, his well knowledge of the Environmental chemistry

subject matter and well and clear discussions that enforce me to do my thesis on this area.

Finally I want to give thank for Gondar University chemistry department staffs for their

willingness of supporting different materials and their powerful advice.

ii

Table of content

Contents page no,

Acknowledgement ........................................................................................................................... i

Table of content .............................................................................................................................. ii

List of tables ................................................................................................................................... iv

List of figures .................................................................................................................................. v

LIST OF ACRONYMS AND ABBREVIATIONS ...................................................................... vi

Abstract ........................................................................................................................................ viii

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

1.1. Back ground ..................................................................................................................... 1

1.2. Factor influencing water quality ...................................................................................... 3

1.3. Physicochemical parameters ............................................................................................ 3

1.4. Study of Selected metals in water .................................................................................... 5

1.5. Drinking water standards ................................................................................................. 9

1.6. Statement of problems .................................................................................................... 10

1.7. Scope of the study .......................................................................................................... 11

1.7. General objective ............................................................................................................... 12

1.7.1. Specific objectives.......................................................................................................... 12

2. MATERIALS AND METHODS .......................................................................................... 13

2.1. Description of Study Area .............................................................................................. 13

2.2. Collection of Samples .................................................................................................... 15

2.3. Determination of Physicochemical Parameters.............................................................. 15

2.5. Reagents and Standard Solution ..................................................................................... 20

2.6. Instrumental Calibration Procedure ............................................................................... 20

2.7. Recovery Test ................................................................................................................. 21

iii

2.8. Method Detection Limit ................................................................................................. 22

2.9. Statistical Analysis ......................................................................................................... 23

3. RESULTS .............................................................................................................................. 24

3.1. Physicochemical Variables of Water ............................................................................. 24

3.2. Heavy Metals Concentration in Water ........................................................................... 26

4. Discussion .............................................................................................................................. 28

4.1. Physicochemical quality of water .................................................................................. 28

4.2. Selected trace and heavy metals ..................................................................................... 38

5. Conclusion and recommendation .............................................................................................. 46

5.1. Conclusion .......................................................................................................................... 46

5.2. Recommendation ............................................................................................................ 46

6. Reference ............................................................................................................................... 47

APPEDIX 1: The Regration carves of metal elements such as Ni, Mn, Cu, Pb, Cr, Zn and Fe. .. 53

APPEDIX 2: Optimization procedure of sample and the method detection analysis................... 56

Appendix 3:- Different chemical reagents used in Wagtech Photometer for determination of

chemical parameters in the water sample. .................................................................................... 58

Appendix4:- Table of drinking water guide line value of drinking water .................................... 59

iv

List of tables Table: 2.1. Instrumental conditions for the flame analysis of BUCK SCIENTIFIC AAS 29

Table: 2.2. Standard solution for metals analysis and correlation values 20

Table: 2.3.Theinstrumental detection limit and method detection limits. 23

Table: 3.1a. The Average (± SD) value of some physicochemical properties such as temperature,

PH, turbidity, conductivity, TDS, TSS and total solids in Gondar Town drinking water at the

five sampling sites in three months 24

Table: 3.1b. The average (± SD) value of some physicochemical properties in drinking water at

the five sampling sites in June Month 25

Table: 3.2a. Concentration of dissolved metals in Gondar drinking water at the three month

for five sampling sites (mg/L) From AAS reading 26

Table: 3.2b: The comparative study for the concentration of Copper, Iron and Manganese

and Aluminum, Calcium and magnesium metals dissolved in water were determine by

using the PALINETEST 8000 PHOTOMETER 27

Table: 4.2. Shows the WHO hardness fact sheet level and degree of hardness of water 31

v

List of figures

Figure 3.1: Location of Gondar Town, Ethiopia 14 Figure 2.2. The contours around the Angereb damp 14

Figure 2.3: shows the sample sites such as raw water (A), borehole waters (B) and

BFT water (C) of study 15

Figure: 2.4. The recovery value of seven trace metals in the water samples 22

Figure; 4.1: This graph Represents the physicochemical parameters such as PH,

Temperature, Turbidity, conductivity, total solid, total dissolved solid and total Suspended

solids in the analysed water sample and their average value 31

Figure: 4.2. Graphs which represents the concentration of Nitrate, Nitrite, Ammonia

and ammonium ion in analyzed water 33

Figure: 4.3. Graphs which represents the concentration of total alkalinity, total hardiness,

Mg hardiness and calcium hardiness in the drinking water of North Gondar town 34

Figure: 4.4. Graphs which represents the concentration of Sulphate, Phosphate, Chloride,

Free chlorine and Silica in drinking water of North Gondar Town water 36

Figure: 4.5. Graph which represents the concentration of Al, Ca, and Mn in drinking

water of North Gondar Town 39

4.6. Graphs which represent the concentration of trace metals such as Cu, Fe, Ni, Zn in the

drinking water of North Gondar town 41

Figure 4.6. Graphs which shows the concentration of Cr, Pb and Mn in the drinking water

of North Gondar Town 43

Figure: 4.7. Graph represents the concentration of metal elements such as Copper, Iron,

Manganese, Calcium, Aluminum and Magnesium for the comparative studies of metal

\concentration determination in photometer 45

vi

LIST OF ACRONYMS AND ABBREVIATIONS

AAS Atomic Absorption Spectrophotometer

BAP Bioavaliable Phosphorus

BFT Water before treatment

BH Borehole

BH Borehole water

DPD diethyl-p-phenylene diamine

DWAF Department of Water Affairs and Forestry

EC electrical conductivity

EEPA Ethiopian Environmental Protection Agency

FCP Filterable Condensed Phosphorus

FT Sand filtered water

GAESE Guideline Ambient Environment Standards for Ethiopia

GAESE Guideline Ambient Environment Standards for Ethiopia

GCWSSS Gondar City Water Supply and Sanitation Service

GEMS Global Environment Monitoring System (UNEP)

GEMS Global Environmental Monitoring System

GV Guideline values

MDL Method Detection Limit

NTU Nephelometric turbidity unit

PH Common logarithm of hydrogen ion concentration

vii

RADWQ Rapid Assessment of Drinking water Quality

SD Standard Deviation

UN United Nations

UNEP United Nations Environment Programme

UNESCO United Nations Educational, Scientific and Cultural Organization

UNICEF United Nations Children’s Fund

USA United State of America

USEPA US Environmental Protection Agency

WHO World Health Organization

viii

Abstract

Drinking Water quality deterioration in most towns of the country due to various anthropogenic

activities and poor sanitation make the community to depend on unsafe and poor water

consumption, these expose the community for health and other water quality associated risks. The

primary purpose of the study was to assess the significance of the physicochemical parameters and

dissolved metal constituents of drinking water in North Gondar city may have on public health and

quality of this water.

The result obtained revealed that the physicochemical parameters show that all of the

physicochemical parameters such as pH, temperature, electrical conductivity, total alkalinity,

turbidity, TDS, TSS, total solid, nitrate, nitrite, phosphate,, silica, chloride, ammonia, sulphate, free

chlorine and total hardness were analyzed for three months in drinking water of North Gondar

city. All the physiochemical parameters are within the permissible limits of both WHO and

Ethiopian. But the hardness of the water sample is rather moderate hard water than soft. The

concentration of the selected dissolved metal elopements’ such as Cu, Mn, Ni, Pb, Zn, Fe, Cr, Al,

Ca, and Mg were analyzed using Atomic Absorption Spectrophotometer for (Cu, Mn, Ni, Pb, Zn,

Fe, and Cr) and PALINETEST photometer for (Cu, Mn, Fe, Al, Ca, and Mg) for three months.

According to the result of determination concentration of the all metals have been below the

permissive limit of internal and national or Ethiopian standards and in the permissible range of

WHO guidelines.

Key words; drinking water, physicochemical parameters, dissolved met

1

1. INTRODUCTION

1.1. Back ground

Water is basic component of life, needed for living organisms and an essential resource for

sustainability of live on the earth. Human beings do not survive without water next to air for a few

minutes even they may be surviving a few days without meal. This is because of that about, 60 % of

the human body is water and also about 83 % of our blood is water, which helps to digest food,

transport waste and control body temperature and humans must replace 2.4 liters of water every day

through drinking and from foods [1]. About 70% of the earth’s surface is water, and 3% of this is

fresh water. About 97% of earth’s water supply is in the marine; is unfit for human consumption

and other uses because of its salt content. Of the remaining; 3%, 2% is locked in polar ice caps and

only 1% is available as fresh water. Ground water and surface waters are mainly used by man for

drinking and other purpose. Ground water consists dissolved minerals from the soil layer where as

surface water contain organic and inorganic maters which fed algae and bacteria population.

The surface water resource continue to the contaminated with runoff, water from the agricultural

field, and sewage from the cities and rural areas. Millions of people all over the world particular in

developing countries are losing their lives every year from water born disease [2].

In Ethiopia, the dominant source of drinking water used to supply major urban and rural

communities is from wells and springs. Although there are no systematic and comprehensive water

quality assessment programs in the country, there are increasing indications of water contamination

problems in some parts of the country and the major causes of this contamination could be soil

erosion; domestic waste from urban and rural areas and industrial wastes [3].

Drinking water is water whose quality must ensure the perfect health of the end user. Taken from

the natural environment, it must undergo treatments that will render it apt for human consumption

and safe and clean drinking water and sanitation is a human right essential to the full enjoyment of

life and all other human rights [4].

The constant supply of water is needed to replenish the fluid that through the normal physiological

activities such as respiration, perspiration, urination and other day to day activities [5].Water is one

of the most important compound to the ecosystem whereas the quality of water is of upper most

2

importance compared to quantity in any water supply planning and especially for drinking purposes

purity is equally important. The quality of drinking water has been an important requirement for all

human beings regardless of part of world they are living in and the social class they belong to all

human races in our planet need to have clean water for a number of reasons particularly drinking

purpose [6].

The chemical, physical and bacterial characteristics of water determine its usefulness for municipal,

commercial, industrial, agricultural, and domestic water supplies [8]. Since, better quality of water

described by its physical, chemical and biological characteristics. Safe drinking water is human

bright as much a bright as clear air, so an adequate supply of safe drinking water is prerequisite for

health life of a country [9].

People consume fresh water for different purposes such as drinking, cooking food, irrigating crop,

and different agricultural activities. Fresh water bodies are finite essential for agriculture, industry,

human existence and sustainable socio-economic development country is unachievable without

easily obtainable water of sufficient quantity and acceptable quality [10].

As the matter of fact that lack of adequate supply of potable water is critical challenge in most

developing countries. As earth’s population continuous to increase rapidly the growing of human

needs for fresh water,( such as drinking, cooking, washing, bathing, irrigating crop, receiving

sewages and agricultural runoff, recreation and industrial process ) is also increases. These growing

demands for water along with poor water resource management and monitoring pollution level

contribute water quality problem in and around the growing city [11]. The main water pollution

causes in growing countries, particularly in Ethiopia context, are industrial activities, domestic

wastes and agricultural activities. Such like activities may make pollution of rivers, or any water

bodies around the country. The pressure of increasing population, growth of industries,

urbanization, energy intensive life style, loss of forest cover, lack of environmental awareness, lack

of implementation of environmental rules and regulations and environment improvement plans,

untreated effluent discharge from industries and municipalities, use of non-biodegradable

pesticides/fungicides/ herbicides/insecticides, use of chemical fertilizers instead of organic manures,

etc are causing water pollution. The pollutants from industrial discharge and sewage besides finding

their way to surface water reservoirs and rivers are also percolating into ground to pollute

groundwater sources [12], my affect the quality of water supplied.

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1.2. Factor influencing water quality

The quality of any body of surface or ground water is a function of either or both natural influences

and human activities. Without human influence, water quality would be determined by the

weathering of bedrock minerals, by the atmospheric process of evapotranspiration and the

deposition of dust and salts by wind, by the natural leaching of organic matter and nutrients from

soil, by hydrological factors that leads to runoff, and by biological process within the aquatic

environment that can alter the physical and chemical composition of water.

In developing countries, several disease outbreaks are associated with the use of untreated surface

water, contaminated well water, treatment plant deficiencies or not proper treatments and

contaminated distribution systems [13, 14].

The quality of drinking water may be controlled through a combination of protection of water

sources, control of treatment processes and management of the distribution and handling of the

water. Guidelines must be appropriate for national, regional and local a circumstance, which

requires adaptation to environmental, social, economic and cultural circumstances and priority

setting by [15].

Water quality is defined in terms of the chemical, physical and biological properties of water that

determine its fitness for a specific use. The water quality of rivers and lakes changes with the

seasons and geographic areas, even when there is no pollution present. Water quality guidelines

provide basic scientific information about water quality parameters and ecologically relevant

toxicological threshold values to protect specific water uses [16].

Various workers in world have carried out extensive studies on water quality on physicochemical

characteristics and heavy or trace metal concentration.

1.3. Physicochemical parameters

Assessing the physico chemical parameter of drinking water is important for determining the

quality of drinking water for the public health. The physicochemical parameters of water sample is

analyzed and measured in terms of turbidity, temperature, pH, residual chlorine, nitrates and others

[17].

Many researchers have been investigating the physicochemical quality of water in the world.

4

The study about the physicochemical quality of water in Legos Nigeria was conducted and its

applicability for drinking purpose was determined [19] and the studies aboutconcerning on seasonal

change in physicochemical parameters in drinking water such as temperature, PH, TDS, total

alkalinity free chloride and dissolved minerals their effects on water quality was detected in

industrial are of in Khed (LOTE)[19].

The physico-chemical parameters, Temperature, pH, electrical conductivity, CO2 content, total

dissolved solids, hardness, dissolved oxygen, Ca2+, Mg2+, Cl-, nitrate, phosphate and Sulphate and

selected heavy metal ions of Huluka and Alaltu Rivers of Ambo, Ethiopia have been determined

[20]. The result of study shows that all most all the physico- chemical and nutrient parameters and

measured metal ions were increased trend from the upper stream to downstream and the water

quality of river was deteriorated. This is due to the human pressure associated with domestic,

municipal sewage waste water and agricultural activities.

The study about examining the quality of water in Ife–North Local Government of Osun State

Nigeria by determining the physico–chemical parameters of and the content of dissolved trace

metals was conducted. The results obtained for the physical parameters agreed with the limits set by

both national and international bodies for drinking and domestic water with few exceptions [21].

The studies about evaluating the quality of Lake Edku water and regional and seasonal variations of

some physico-chemical parameters (nutrient salts, total nitrogen, total phosphorous and silicate, in

addition to pH, and total alkalinity in Alexandria, Egypt was determined[22].

The study about physical and major chemical parameters of Malir River (Within Karachi) Pakistan

was conducted[24]. The result of study reported that all the parameters were found within the range

of the observed values of stream and river, except total dissolved solid, total alkalinity, sodium,

manganese, Lead and chromium. However among all the chemical constituents, quantities of total

iron, manganese, lead, chromium and PH were also found beyond the standard value of these factor

give n by WHO for drinking water.

The study about physico-chemical variables (temperatures, pH, TDS, and conductivity) and some

selected trace metals (Cd, Cu, Co, Ni, Pb, and Zn) analysis of the water and surface sediments from

river Big Akaki and Little Akaki were conducted with a view of assessing the quality of the river

water as well as identifying the potential contaminated areas was stated[23].The result of this study

5

shows that the levels of dissolved trace metals in these rivers were found to be below the detections

limit of the method except for Zn and indeed Ni and Co in some sampling sites of the rivers and

levels of dissolved metals in both rivers are below the South Africa guidelines fixed for irrigational,

domestic and livestock watering purposes.

The assessment of physico-chemical and microbiological quality of drinking water from sources to

house hold in selected communities of Akaki-kaliti sub city, Addis Ababa City Administration were

conducted[24].

Determining correlation of physicochemical parameters and bacteriological quality of drinking

water was studied [25]. The result of this study conclude that distributing water without treatment

and uncontrolled physicochemical parameters led to lower free chlorine distribution and contribute

to occurrence of high population bacteria in water. Study about investigated the physico-chemical

characteristics of drinking waters collected from tap, well and sachet in Sokoto metropolis in North

Western Nigeria was studied [26]. This investigation shows that the concentration of

physicochemical parameters fall under the permissible limits of WHO guidelines for water quality

except conductivity of all water samples greater than the permissible limits of water quality

standard guidelines.

The study about investigating the physicochemical water quality of Ona River and well water

samples [30]., and results that the highest value of physico-chemical parameters (compared with

wells) was obtained in Ona River, but the results obtained fell within the maximum allowable limit

set by World Health Organization for drinking water except for water from Ona river.

1.4. Study of Selected metals in water

The study of heavy metals contamination in water sample has been done by many researchers. It

involves a few types of water like water from the river, sea, tap water, lake, dam and others. Most

of the results have shown that heavy metals exist in these samples of water but the concentrations of

their contamination are different and some of the results do not detect the existence of heavy metals

in water samples. The study about the determination of concentration of heavy metals in tap water

samples was studied. The result of the study indicate that metal ion concentrations values in tap

water at Shah Alam which is the main city in Selangor was exceed the recent proposed criteria for

6

water quality and exceed safety baseline levels of the World, European, American Chemical

Standards [27].

Over the past two decades, the term “heavy metals” have been used increasingly in various

publications and legislation related to chemical hazards and the safe use of chemicals. It is often

used as a group of name for metals and metalloids that have been associated with contamination

and potential toxicity and ecotoxicity. Usually the term heavy metals used inconsistently to replace

the name of trace metals [28].

Heavy metals in water refers to the heavy, dense, metallic elements that occur in trace levels, but

are very toxic and tend to accumulate, hence are commonly referred to as trace metals. The major

anthropogenic sources of heavy metals are industrial wastes from mining sites, manufacturing and

metal finishing plants, and domestic waste water and run off from roads. Many of these trace metals

are highly toxic to humans, such as Hg, Pb, Cd, Ni, As, and Sn. Their presence in surface and

underground water at above background concentrations is undesirable [29].

Trace metals may be present in natural groundwater or surface water. The sources of these trace

metals are associated with either natural processes or man's activities. Two important natural

processes contributing trace metals to natural water are chemical weathering and soft leaching.

Decaying vegetation can also affect the concentration of trace metals in water. Many plants are

known to concentrate various elements selectively. As a result, trace metals may become available

during the decay of the plants. Thus, the penetration and movement of rainwater through sod may

pick up these available trace metals and affect the groundwater resource. Likewise, runoff resulting

from rainfall may transport trace metals to surface-water. Mining and manufacturing are other

important sources of trace metals in natural water [30].

Large populations are repeatedly exposed to potentially toxic contaminants in the drinking water in

minute amounts over many months or years, or over whole lifetimes. The sources of inorganic ions

in groundwater, surface water, water treatment chemicals, and from the storage and distribution

system are considered along with the health effects resulting from the total intake from food, air,

and water[31].

7

Adequate water resources for future generations are not only a regional issue but also a global

concern. Our country’s fresh water wealth is under threat due to variety of natural and human

influences [32].

The study on physicochemical water quality and heavy metal concentration in sediment at selected

sites of Sungai Kelantan was carried out. The Result of water quality analysis (physico-chemical)

indicated that Sungai Kelantan is characterized by excellent water quality and comparable to

pristine ecosystems such as the National Park and Kenyir Lake and the river is free from the

pollution [33].

The study of heavy metal pollution load index and distribution of heavy metals (Nickel, lead,

cobalt, zinc, iron, copper and cadmium) have been reported in the surface sediments from Haldi

and Rupnarayan tributaries of Hugli estuary in West Bengal was stated. Trace metal pollution

occurs in aquatic environments, especially in rivers and oceans, due to anthropogenic activities.

Industrial effluent, urban run-off, atmospheric deposition as well as upstream run-off are absorbed

into deposits and incorporated into the surface sediments were major sources of pollutants [34].

The studied on Heavy metal analysis and interim recommended limits for botanical dietary

supplements was carried out and recommended that manufacturers of orally consumed botanical-

containing dietary supplements establish specifications under good manufacturing practice for

specific maximum quantitative limits of inorganic arsenic, cadmium, lead, and methyl

mercury[35]The study about determination ofsome heavy metals (Cd, Cr, Cu, Fe, Ni and Pb) in

water, sediment and some tissues of Cyprinus carpio from Avsar Dam Lake, which is an important

water source for irrigation and drinking in Turkey. From this study, the result shows that the

average values of Iron in water samples were higher than the respective reference values for fresh

water. Results for levels in water were compared with national and international water quality

guidelines, as well as literature data reported for the lakes [36].

The studies about ascertaining water quality for human consumption, major and minor ions were

evaluated in the drinking water supplied to the city of Yozgat and its surrounding villages in Turkey

and reports that The concentrations of investigated parameters in the drinking water samples from

Yozgat were within the permissible limits of the World Health Organization drinking water quality

guidelines and the Water Pollution Control Regulation of the Turkish authorities [37].

8

The studies that the evaluation of level of heavy metals in the drinking water from the Tokat-Black

Sea Region of Turkey and The values this study found the present work for the heavy metal

contents of the drinking water samples of Tokat, Turkey were below the maximum tolerable limits

set by the World Health Organization (WHO) and the Water Pollution Control Regulation of the

Turkish authorities [38].

The studies about determine the content of cadmium (II) and lead(II) in drinking spring and well

waters from rural part of south Serbia, as in a tap water.The result of the study indicates that water

samples in rural parts of municipality of Leskovac show that the quality of natural well’s and

spring’s water are at high quality level concerning heavy metals, Pb and Cd [39].

The result of this investigation indicate that Total concentrations of heavy metals, Pb, Cd, Cu and

Zn, were below maximally allowed concentrations in accordance with EPA and WHO, with

concentrations of lead in the upper maximally allowed limit.

The study of determining the seasonal water quality variations of the major springs of the Yarmouk

Basin of North Jordan. The result of this study indicates that analyzed heavy metals in some water

samples exceeded the Jordanian. Overall, the results showed that the water springs of the Yarmouk

Basin in North Jordan are contaminated with heavy metals that might affect human health as well as

the health of the ecosystem [40].

The study about the determination of heavy metal pollutants of the Alaro river within the Oluyole

industrial area in Ibadan Southwestern Nigeria. The researcher concludes that As long as water is

polluted, it will not only affect water-dwelling organisms, but also terrestrial organisms that feed on

aquatic organisms. The animals who in turn feed on these terrestrial animals will also be affected.

Thus, pollution can cause effects even to animals and humans that are not directly dependent on the

specific water area. These effects include decreased source of food as well as magnified substance

level higher up in the nutrition chain [41].

The studies on the heavy metals in drinking water and their impacts on human health in Egypt in

Cairo area was carried out and the researcher concludes that the contents of metallic contents in the

cave waters is higher than what is expected and exceed baseline levels of the World, European,

American Chemical standards and the Egyptian Chemical Standard of Ministry of Health [42].

9

The studies on evaluating the heavy metals contamination of copper, zinc, manganese, iron,

chromium, nickel, lead and cadmium, and to assess the environmental quality of the coastal area

from Mahajanga town in Madagascar and reported that the high level of metals from soil erosion in

costal sediment threaten marine organisms. The researchers conclude that the sources of the metals

in the sedimentary coastline were caused either seaport activities or non- treated sewages from

different source [43].

1.5. Drinking water standards

The purpose of drinking water standards is to ensure protection from acute poisoning and from

long-term, or "chronic," effects. A drinking water quality guideline value represents the

concentrations of a constituent that those not result in any significant health risk to the consumer

over a lifetime. The amount by which and for how long, any guideline value can be exceeded

without endangering human health depends on the specific substance involve. The quality of the

earth’s water is vital to our existence. The supply of clean water on the earth is finite, and it is being

threatened by water pollution. Water pollution is a serious problem today, in spite of our efforts to

control it [44]. The international organizations, e.g. World Health Organization (WHO) have major

functions to propose regulations, guidelines, and recommendations in order to realize human right

to have access to an adequate of safe drinking water independently of their stage of development

and their social and economic conditions [45].

The primary purpose of the Guidelines for Drinking-water Quality is the protection of public health.

Water is essential to sustain life, and a satisfactory (adequate, safe and accessible) supply must be

available to all. Improving access to safe drinking-water can result in tangible benefits to health.

Every effort should be made to achieve a drinking-water quality as safe as practicable. Safe

drinking-water, as defined by the Guidelines, does not represent any significant risk to health over a

lifetime of consumption, including different sensitivities that may occur between life stages. Those

at greatest risk of waterborne disease are infants and young children, people who are debilitated or

living under unsanitary conditions and the elderly. Safe drinking-water is suitable for all usual

domestic purposes, including personal hygiene. 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

10

Guidelines. The Guidelines describe reasonable minimum requirements of safe practice to protect

the health of consumers and/or derive numerical “guideline values” for constituents of water or

indicators of water quality [46].

The government of Ethiopia has mandated the Ethiopian Environmental protection Authority (EPA)

to set such standards and Guideline Ambient Environment Standards for Ethiopia (GAESE)

represents the guideline standards with respect to the ambient environment. In practice, standards

can be set from either first principles or based on the existing national or international guidelines.

Driving such standards from first principle requires classification, and prioritization of pollutants,

derivation of pollutant exposure processes and their ecological effects [47].

There are many standard guidelines for drinking water in the world. Among these standards

Ethiopia accept the drinking water guidelines of the International Health Organization (WHO),

guidelines for drinking water quality. In table 2.1 below the international and national standards for

drinking water qualities of physicochemical and concentration of dissolved metal elements are

given including Ethiopian drinking water quality standards.

1.6. Statement of problems

Lack of access to safe and clean water is locked in the heart of the poverty. Even though the issue of

water is observed as a general problem for both the urban and the rural population, women bear the

greatest burden because of their social gender roles including collecting water for their households.

Because of their task of water provision at the households, women and children suffer from disease,

have limited participation in education, and both income generating activities and engagement in

cultural and political issues are often compromised[48].

The health and wellbeing of population is directly affected by the coverage of water supply.Gondar

is one example of town where the rate of urbanization, the rate of population growth the availability

of waste removal facility is unbalanced. The impact of human population on surface and

groundwater is increasing with the development of industries and the growth of population size in

and around the North Gondar [49].

The fast growth of the city, in terms of, population number; the rate of urban expansion is

demanded huge increase in the extraction of resources and release of huge volume of wastes to the

environment of the city. In contrast to the high rate of expansion of urbanization, high rate growth

11

of population and growth of industry and, the growth of sewage disposal facility is stagnant.

Because of inequality between population growth, urbanization and the development of the waste

removal facilities, majority of people and industries of city have no access for controlled sewage

disposal. These poor domestic and industrial waste removal and wide spreading uncontrolled waste

disposal have risk on pollution of water by toxic chemicals. Water contamination by heavy metals

in some areas is particularly due to the natural process (weathering of rocks) and anthropogenic

activities such as industrial, agricultural and domestic influents [12].

1.7. Scope of the study

This study is expected to give baseline information on Angereb dam of surface water and borehole

water quality of drinking water supply in north Gondar town. It will provide a framework to assess

the on-going vulnerability of the supply to contamination and the major operational or

infrastructure problems that may make future contamination likely. Moreover, it provides a hint on

the relationships of physicochemical parameters like temperature, pH, free chlorine residual and

turbidity one other and with the level of essential and toxic metals will be determined in this study.

A).The study of this research is to ensure the quality of water for drinking purpose and the

importance of this water for the population health according to its mineral composition and their

concentration.

B). In the fact that the presence of heavy metals in human body can affect health for a long period

of time. It is important to know the concentration of heavy metals in drinkingwater because it is the

main source of water that people consume every day.

C). Therefore, monitoring these metals is important for safety assessment of the environment and

human health in particular.

D).The physico-chemical characteristics pH, total dissolved solids, the conductivity; free chlorine

and other parameters drinking of water are determined and the suitability of this drinking water for

human and animal health and applicability of it for different social affairs are recommend.

12

1.7. General objective

➢ The main objective of this study is to undergo the assessment of major physicochemical

parameters and level or concentration of selected metals on drinking water of north Gondar

town, and to compare the values with the national and international organization (WHO)

recommended drinking water standards.

1.7.1. Specific objectives

✓ To assess physicochemical water quality parameters like temperature, conductivity, total

dissolved solids, turbidity, water hardness, total alkalinity, concentration ofsulphate, nitrate,

phosphate and ammonia in the drinking water sample in North Gondar Town.

✓ To determine trace metals (Zn, Cu, Ni, and Fe) contents of the water sample.

✓ To determine concentration of Mg, Ca and Al in water sample.

✓ To investigate the concentration of toxic heavy metals (Cr, Pb, and Mn) from the drinking

water sample of Angereb dam and borehole water.

✓ To compare the concentration of physicochemical parameters and selected metals with

national and international recommended drinking water standards.

13

2. MATERIALS AND METHODS

2.1. Description of Study Area

Gondar is well known historical city in Ethiopia which located in 760Km North of Addis Ababa.

Gondar town is located in the northwestern part of Ethiopia and its varied landscape, dominantly

covered with ragged hills and plateau formations, imparts variable temperatures largely favoring a

wide range of illnesses. Gondar is an old town, which is not properly planned, zoned, and has no

sufficient sanitation facilities. The geographic location of Gondar extends from 13°9’57’’ to

13°19’58’’ north latitude and from 37°54’48’’ to 38°24’43’’ east longitudewith an elevation of

2133 m3 above the sea level. The temperature varies from 120C to 300C and annual rainfall around

1200 mm [51].

The study was implemented in Gondar city which is one of the growing cities in north Ethiopia.

Gondar is well known historical city in Ethiopia which located in 760Km North of Addis Ababa.

Now a day Gondar is fast growing Ethiopian country in different infrastructures such as Hotel

industry, transportation and different activities. The study was implemented in Gondar city which is

one of the growing cities in north Ethiopia.

Angereb Dam is 420 m long and 33.5m high with a total base width of about 159.25m at the

maximum section and crest width of 6.5m. It is built in compacted earth and stone fragments and

the outer most portion of the upstream body of the dam is built in dumped rock and gravel which is

further protected by a layer of dumped riprap. However, after the construction of the dam it was

observed that a significant amount of silt is being accumulated within the dam and also caused in an

increase of turbidity of raw water which resulted in high chemical consumption in the treatment

processes. Most of the wells drilled in the surroundings of Gondar are abandoned following the

implementation of Angereb Dam and treatment plant because of their lower yields. However, the

eight boreholes found in Angereb Valley are relatively in good condition and they are one of the

main water sources for the city and they are recently under rehabilitation works[52].

14

Figure 3.1: Location of Gondar Town, Ethiopia

Figure 2.2. the contours around the Angereb damp Source: From GCWSSS

15

Figure 2.3: shows the sample sites such as raw water (A), borehole waters (B) and BFT water (C) of study. (Source: Abera H.)

2.2. Collection of Samples

The three replicated water samples were collected from five different points of same station using

polyethylene sampling bottle which is previously washed by HNO3 and deionized water during the

sampling. These water sample collection was from five different sites which were level as

The raw water from the surface water was collected poly ethylene bottle leveled as A, water from

the underground (Borehole) source will be collected in polyethylene bottle which is leveled as B,

water from the center or mixing point of underground and surface water will be collected in

polyethylene bottle leveled as C, water sample at the sand filter will be collected in polyethylene

bottle leveled as D. the water sample after sand filter or filtrated water will be collected in

polyethylene bottle leveled as E for the identification of water sample.

The water samples were filtered through Watch man 541 filter paper immediately after the samples

have been transported to the laboratory. The filtered samples were acidified with HNO3 and were

kept at 4 0C prior to analysis.

2.3. Determination of Physicochemical Parameters

Physicochemical analysis: The water sample collected was analyzed for turbidity, PH, total

alkalinity, total dissolved solid, electrical conductivity, total hardness, free chlorine, nitrate ion,

silicate and other parameters which are explained later on.

B A C

16

The following physicochemical variables of water were determined in situ at the five sampling sites

using the instruments indicated in parenthesis; temperature, pH and conductivity were determined

by using (HORIBA, Ltd. Water Checker, Model U-10, (MFG. 2008) PH meter at the sampling site

in Angereb water treatment laboratory.

The concentration of total alkalinity, total hardness, magnesium and calcium hardness, nitrate,

nitrite, sulphate, phosphate, ammonia, chloride, free chlorine and silica were measured by using

PLAINETEST PHOTOMETER 8000. The reagents and photo programs used for determination of

these chemical parameters are represented in appendix 3.

➢ Alkalinity: the alkalinity of water was determined by Alkaphot testing method. Alkaphot

test is based on colorimetric method and uses single tabled reagent. The color produced in

the test indicative of alkalinity of water and measured by using photometer.

➢ Aluminium: the concentration of aluminium in the sample was determined by Colorimetric

(Eriochrome Cyanine R method). In this method Al reacted with Eriochrome Cyanine R and

develops red pink colored complex in acidic condition. The intensity of color developed is

directly proportional to concentration of Al in given sample.

➢ Ammonia: the concentration of ammonia present in water sample was based on an

indophenols method. In this method, in the presence of chlorine, ammonia reacted with

alkaline salcylate and produce green blue indophenols. The intensity of color produced was

proportional to the concentration of ammonia concentration and was measured by using

photometer.

➢ Chloride: the concentration of chloride was determined base on tablet reagent system

containing silver nitrate. The measurement was carried out under acidic and oxidizing

condition to eliminate interface from any reducing substances or complexing agents. The

concentration of chloride present in the sample was determined depending on degree of

turbidity due to the insoluble silver chloride.

➢ Free Chlorine: the determination of free chlorine was carried out by DPD method. The free

chlorine present in the sample react with DPD in buffered solution and develop pink color.

The intensity of developed color is directly proportional to the concentration of free chlorine

present

17

➢ Copper: determination of copper preset in sample was carried out by coppercol method. In

this method copper salts were reduced to cuprous form by reducing reagents and react with

2,2-Biquinoline-4-dicarboxylic salt and form purple colored complex for free copper

measurement and decomplexing reagent was used to measure total copper present.

➢ Total Hardness: hardness of water was measured by using unique colorimetric method.

Under the controlled condition of measurement calcium ions and magnesium ions were

reacted with hardicol reagent and develop purple colored solution. The intensity of light

transmitted is directly proportional to amount of hardness.

➢ Magnesium and Magnesium hardness were assessed by using magnecol method. In this

method magnesium was reacted with yellow colored organic reagent and produce orange

colored complex. The concentration of magnesium and its hardness was measured by using

intensity of developed color in different photo programs which indicated in appendix 3.

➢ Manganese: since manganese occurs in water in various valency states, previously Mn in

lower valency state oxidized to permanganate by oxidizing reagent. Then the permanganate

reacted with leucomalachite green and develops intense turquoise colored complex. Then

the intensity of color produced is measured to determine the concentration of Mn present in

sample.

➢ Nitrate and Nitrite: both nitrate and nitrite determined by using nitratest method. In this

method nitrate was reduced in to nitrite in the presence of nitratest powder (zinc-base

powder). The nitrite reacted with sulphanic acid in the presence of N-(-naphyl)-ethyldiamine

reagent and develops reddish color. The concentration of both nitrate and nitrate were

measured by using transmitted light intensity in selected photo programs which is presented

in appendix 3.

➢ Phosphate: the concentration of phosphate present in the water samples were .determined

based on Vanado molabdate method. In this method, phosphate present in sample reacted

with ammonium molabdate in the presence of ammonium vanadate reagent and produce

yellow colored compound (phosphovanadomolabdate) and the intensity of developed color

measured at selected light wave length as indicated in appendix 3.

➢ Silica:the concentration of silica pressed in samples was also determined by using

colorimetric method. In this method ammonium molabdate reacted with silica under acidic

condition and produce molabdic acid. This molabidic acid was reduced in to blue colored

18

complex in the presence of reducing agent. The intensity of color in the test is proportional

to silica concentration and measured by photometer.

➢ Sulphate: the concentration of sulphate present in water samples were determined by

turbidity method. In this method sulphate present in the sample reacted with sulphate turb

reagent and form insoluble barium sulphate. Light absorbance of the BaSO4 suspension is

measured by a photometer and sulphate concentration is determined by comparison of the

reading with a standard curve

Total dissolved solids, suspended solid (SS) and total solid of the water were determined by

gravimetric method in the laboratory.

Determination of total sold (TS) and TDS in the water sample will be determined by using

gravimetric method. This will be done by using evaporating dish which will dried in oven at the

temperature of 103 -105 0c, and weighting of evaporating dish.

Ts (mg/L) = 𝑊2−𝑊1

𝑉𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒 mg X 1ooo (1)

Where W2= weight of residue + evaporating dish

W1= weight of dry evaporating dish

Vsample= ml of water sample used for measurements

Total dissolved solid (TDS) gm/L = 𝑊2−𝑤1

𝑉𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒mg/L X 1000 (2)

Where: W2= weight of residue + evaporating dish

W1= weight of dry evaporating dish

Vsample= ml of filtrated water used for measurements

Suspended solid was determined by subtracting amount of TDS from amount of total solid.

2.4. Analysis of trace and heavy Metals

The analysis of selected trace and heavy metals were carried out by using BUCK SCIENTIFIC

MODEL 210VGP, atomic absorption spectrometer equipped with deuterium arc back ground.

19

Concentration of Cu, Pb, Ni, Cr, Cd, Mn, Fe and Zn were determined in water sample. The analyses

of metals in water samples were carried out by BUCK SCIENTIFIC FLAME ATOMIC

ABSORPTION SPECTROPHOTOMETR 210VGP.

The Buck 210VGP atomic absorption spectrophotometer is designed to measure the concentration

of elemental metal in solution. It improves integrated measurements on absorbance or emission

intensity as well as sample concentration compression to standard solution. For major analysis of

commonly available Welder’s grad acetylene required fuel for use with the model 210VGP and

most common oxidant air which can be obtained from accomplished air cylinder.

In order to develop an optimum procedure for the analysis of water samples, different digestion

methods were tasted and the procedures that produce clear, consumed minimal reagent volumes,

and required shorter digestion time was selected from the different alternatives. The optimum

procedure for digestion of water sample was done by using 100 ml of water, 12 ml of HNO3, and 4

ml of HClO4 at 3000c for 2:30 hours. The different alternatives procedures tasted are given in

appendix (2).

Metals such as Pb, Ni, Cr and Zn were demined only using Atomic Absorption Spectrometric

method and metals Such as Ca, Mg and Al were determined only using Wagtech photometer.

Whereas metals such as Cu, Mn, and Fe were determined using both AAS analysis and Photometric

analysis

Table: 2.1. Instrumental conditions for the flame analysis of BUCK SCIENTIFIC AAS

Elements Wavelength in nm Slit width Current

of lump

Detection

Limit

Lump Oxid/fuel

Copper 324.8nm 0.7A0 1.5mA 0.005 HCL Air-C2H2

Cadmium 228.9nm 0.7A0 2.0mA 0.01 HCL Air-C2H2

Chromium 357.9 nm 0.7A0 2.0mA 0.04 HCL Air-C2H2

Iron 248.3 nm 0.7A0 7.0mA 0.05 HCL Air-C2H2

Lead 217.0 nm 0.2A0 3.0mA 0.04 HCL Air-C2H2

Manganese 279.5 nm 0.7A0 3.0mA 0.03 HCL Air-C2H2

Nickel 231.9 nm 0.2A0 3.0mA 0.05 HCL Air-C2H2

20

Zinc 213.9 nm 0.7A0 2.0mA 0.005 HCL Air-C2H2

2.5. Reagents and Standard Solution

All the chemicals used were of analytical reagent grade. De-ionized water was used for all dilutions

throughout the study. Nitric acid, HNO3 (68% - 70%), and Perchloric acid 70% (HClO4

ALDRICH, A.C.S. REAGENT, Germany), were used for digestion. Working standards were

prepared by diluting concentrated stock solution of 1000 ppm for Cu, Cr, Cd, Mn, Ni, Pb, Fe and

Zn in deionized water. Standard 1000ppm stock solution is prepared from the metal powders or

salts of each metal element of Cu, Cr, Cd, Fe, Ni, Mn, Pb and Zn 1gm of each metal in 1000ml of

de ionized water. The working solution of standard solution each metal was prepared by diluting the

stock solution of each metal in deionized water as needed.

2.6. Instrumental Calibration Procedure

To ensure the accuracy of the instrumental readings and to determine the reliability of the result

obtained it is necessary to perform calibration of instrument. The Calibration curves for each heavy

metal were set to ensure the accuracy of the atomic absorption spectrophotometer and to confirm

that the results of determination were true and reliable. The calibration of the 210VGP Atomic

Absorption Spectrophotometer was made with standard solutions. Four working calibration

standards were prepared by serial dilution of concentrated stock solution of 1000 mg/L for copper,

zinc, nickel, lead, cadmium, manganese, chromium, and iron. These solutions and blank were

aspirated into AAS. A calibration curve of Absorbance Vs concentration was established for each

metal and used for determination of metal concentration in the samples of fish and water. The

concentrations of standard solutions that were used to calibrate the 210VGPAAS give in table blow.

Table: 2.2. Standard solution for metals analysis and correlation values

Metals Standard concentration of

AAS calibration

Correlation value or

(R2) value

Copper 0.1, 0.2, 0.4, 0.8 0.99964

Chromium 0.05, 0.1,0.2, 0.4 0.99757

Iron 0.1, 0.5, 1.0, 5.0 0.99889

21

2.7. Recovery Test

The digestion method and AAS analysis were validated by measuring the recovery of copper, lead,

nickel, chromium, manganese, Iron, and zinc spiked to water samples. The known volume and

concentration of standard solutions were employed on the samples in order to determine recovery.

The intermediate concentration of 10ml volume of each metal element added to spike in water

sample and 250ml of spiked sample was digested. The amount of spiked metals recovered after the

digestion of spiked samples was used to calculate percentage recovery using Burns the formula as

sited in [93].

RECOVERY = 𝐶𝑂𝑁𝐶𝐸𝑇𝑅𝐴𝑇𝑂𝑁𝑂𝐹𝑆𝑃𝐼𝐶𝐾𝑆𝐴𝑀𝑃𝐿𝐸−𝐶𝑂𝐶.𝑂𝐹𝑈𝑁𝑆𝑃𝐼𝐶𝐾𝐸𝐷𝑆𝐴𝑀𝑃𝐿𝐸

𝐶𝑂𝑁𝐶𝐸𝑇𝑅𝐴𝑇𝐼𝑂𝑁𝑂𝐹𝐴𝑁𝐴𝐿𝑌𝑇𝐸𝐴𝐷𝐷𝐸𝐷 X 100% (3)

The recovery percentage of spiked water sample obtained shown in figure (4) the results of

percentage recoveries for the studied metal elements in water samples were within the acceptable

range (87.33-114.92%. Therefore, this verifies that the optimized digestion procedure was valid for

water sample analysis.

Lead 0.05, 0.1,0.2, 0.4 0.99800

Manganese 0.03, 0.05, 0.1, 0.2, 0.4 0.99969

Nickel 0.05, 0.1, 0.2, 0.4 0.99917

Zinc 0.1, 0.2, 0.4, 0.8 0.99969

22

2.8. Method Detection Limit

The MDL is a statistically derived expression of theoretical method detection capability. Method

detection limit (MDL) is defined as the minimum concentration of analyte that can be identified,

measured and reported with 99% confidence that the analyze concentration is greater than zero, and

is determined from analysis of a sample in a given matrix containing the analyte and MDL values

are determined by performing the complete analytical procedure (extraction/digestion, cleanup, and

instrumental analysis) on replicate spiked samples (7 or more) in an otherwise clean, interference-

free matrix representative of the environmental matrix to be tested.[54]. The determination of

method detection limits, blank solutions were prepared. For metal analysis, reagents were mixed

Copper Chromium Iron Manganes Lead Nickel Zinc

0

20

40

60

80

100

120

114.

92±2

.504

163

103.

02±0

.288

675

99.0

8±0.

3818

81

88.5

±1.7

3205

1

93.3

3±8.

6216

78

87.

33±2

.309

401

104.

25±10

.678

05

Va

lue

of

reco

ve

ry

metal elements

Recovery

Figure: 2.4.. The recovery value of seven trace metals in the water samples

23

and digested with the optimum procedure, cooled, filtered and diluted. After digestion of seven

blank solutions such metal then seven readings were obtained shown in appendix (2)

According to USEPA, MDL is determining by using equation [55]

MDL = (t) X (s) (4)

Where:

n = number of replicate spike determinations at 1 to 7 times the estimated MDL,

s = standard deviation of measured concentrations of n spike determinations,

t = Student’s t value at n–1 degrees of freedom and 1–α (99 percent) confidence level.

When n=7 and α=0.01, then t=3.14, and

α= level of significance.

Table: 2.3.Theinstrumental detection limit and method detection limits.

Metals IDL (mg/L) MDL (mg/L)

Copper 0.005 0.00508

Chromium 0.04 0.0426

Iron 0.05 0.0521

Lead 0.04 0.0432

Manganese 0.03 0.033

Nickel 0.05 0.051

Zinc 0.005 0.00513

2.9. Statistical Analysis

Statistical analysis of data was carried out using Microcal origin6.0 statistical package and

Microsoft offices excelprograms. The concentrations of all metals in the water concentrations are

expressed in mg/L.

24

3. RESULTS

The result of obtained from experimental analysis of water sample such as; Raw water from the

dam, Borehole water, Infiltrated or Water at the clarifier, filtrated or Sand filtered water at

treatment and potable or water that distributed from reservoir were give below in the table 3.1a and

3.1b depending on their measurement.

The accessibility of domestic use of potable water needs is influenced by physicochemical

parameters such as pH, electrical conductivity, temperature, solids, and inorganic minerals,

nutrients, mineral concentrations as well as the concentration level of heavy metals.

3.1. Physicochemical Variables of Water

The analytical result of physicochemical parameters in drinking water samples of different sampling

sites in Gondar Town are given in table 3.1a and table 3.1a below.

Table: 3.1a. The Average (± SD) value of some physicochemical properties such as temperature, PH,

turbidity, conductivity, TDS, TSS and total solids in Gondar Town drinking water at the five sampling

sites in three months

Physicochemical

parameters

Sample sites

Raw BH BFT FT Potable

PH 7.48±0.71 7.56±0.47 7.02±0.76 6.833±0.671 7.41±0.62

Temperature

(0C)

22.87±3.87 23.733±1.29 22.3±2.458 22.0±3.081 21.5±2.5

Turbidity (NTU) 311.73±128.46 2.34 ± 0.92 7.243±.361 0.77±0.07 1.47±0.05

Conductivity

(µs/cm

270.33±20.04 440.33±7.24 279.33±33.39 278.33±30.07 317.0 ±21.1

TDS (mg/l) 155.53±17.71 242.2±3.9 159.32±6.86 153.82±17.05 523.6±6.19

TSS (mg/l0 298±366.54 2.65±2.117 18.017±3.155 6.36±2.57 5.27±2.99

TS(total solid)

(mg/l)

449.67 ± 154.2 211.5 ± 47.1

166.25±11.62 158.51±12.86 186.07±3.91

25

The result of the study shows that the pH of water sample ranges from 6.833±0.671 to 7.56±0.47,

the temperature of water in the range of 22.0±3.081to 23.733±1.29, the turbidity is in the intervals

of 0.77±0.07 to 180 units and conductivity of water sample is in the range 270.33±20.04 to

440.33±7.24 µs/cm.

In the other hand this study shows that potable or distributed water for drinking purpose consists

highest concentration of total dissolved solids than other source of water and sand filtered water

consists lowest concentration of dissolved solids. And also raw water from dam consists highest

amount of total solids; whereas the concentration of total solid in sand filtered water is lowest

among the studied water sample sources.

Table: 3.1b. The average (± SD) value of some physicochemical properties in drinking water at the five

sampling sites in June Month

Physicochemica

l parameter

Sample sites

Raw water BH water BFT water FT water Potable water

Free chlorine 0.00 0.00 0.18±0.05 0.15±0.032 0.87±0.045

Total Hardness 122.6 ± 8.95 118.2 ± 15.36 125.5± 12.04 128.9±5.21 117.8± 13.8

Calcium

Hardness

51.0 ± 1.5 47 ±4.08 56.0 ±8.04 49.33±13.12 52.33±9.03

Mg. Hardness 50.4 ± 2.1 64.6±1.6 52.5± 1.7 31.5±1.9 42.67 ± 1.21

Total alkalinity 131.67±11.5 163.3 ± 30.26 164.7±45.2 136.0 ± 16.5 126.7± 7.64

Nitrate 0.66± 0.12 2.21±0.91 0.83±0.05 0.78±0.08 1.32±0.37

Nitrite 0.05±0.01 0.04±0.002 0.018±0.001 0.012±0.002 0.033±0.002

Sulphate 4.33±0.92 11.33±4.24 33.67±9.04 41.00±12.89 43.00±11.38

Phosphate 10.3±0.712 15.1±2.5 5.0 ±0.2 14.7±4.1 6.9±2.9

Ammonia 0.2±0.015 0.00 0.02 ±0.004 0.026 ±0.002 0.02±0.002

Ammonium ion 0.026±0.002 0.0 0.026±0.003 0.038±0.003 0.026±0.004

Chloride ion 10.83 ±0.85 9.03± 1.27 6.4±1.59 10.77±2.34 24.67 ±6.60

26

Silicate 14.3±3.02 13.0 ±2.7 12.17±0.46 15.87±1.24 14.13±1.51

3.2. Heavy Metals Concentration in Water

This study was conducted by determining concentration of metals using atomic ABSOPTION

SPECTROPHOTOMETER and instruments. These different instruments are used to indicate the

parallel study results with North Gondar water source management and sanitary office that used

PALINETEST PHOTOMETER to test distributed potable water in country, and ABSOPTION

SPECTROPHOTOMETER is used to indicate the accurate concentration of metals and to sensitivity of

plaint photometer measurements towards these metals. The result of study in AAS photometer indicates

that the potable drinking water accounts high concentration of copper (0.245±0.044) and the minimum

concentration of nickel (0.0013±0.0002) where as lowest concentration of manganese

(0.037±0.005mg/L) and maximum concentration of magnesium (12.34±2.549mg/L) was detected in

plainetest photometer measurements.

Analytical results of trace and heavy elements in various samples of drinking water obtained from

different sampling site of Gondar Town are given table 4.2.1a and b, below.

Table: 3.2a. Concentration of dissolved metals in Gondar drinking water at the three month for five

sampling sites (mg/L) From AAS reading

Metals Sample sites

Raw Water BH Water BFT Water FT Water Potable Water

Copper 0.285±0.023 0.194±0.017 0.295±0.174 0.285±0.051 0.245±0.044

Chromium 0.036 ± 0.001 0.013±0.002 0.011±0.004 0.001±0.0004 0.001±0.0003

Iron 0.012±0.002 0.0024±0.0001 0.985±0.025 0.989±0.075 0.97±0.14

Lead 0.0089±0.0013 0.0098±0.0020 0.012±0.001 0.013±0.002 0.011±0.002

Manganese 0.031±0.001 0.034±0.003 0.031±0.001 0.029±0.001 0.037±0.001

Nickel 0.0033±0.0002 0.0 0.0016±0.00003 0.0023±0.0002 0.0013±0.0002

Zinc 0.205±0.042 0.16±0.02 0.16±0.023 0.145±0.021 0.155±0.006

27

Table: 3.2b: The comparative study for the concentration of Copper, Iron and Manganese and

Aluminum, Calcium and magnesium metals dissolved in water were determine by using the

PALINETEST 8000 PHOTOMETER.

Metal

Elements

Sample Sites

Raw Water BH Water BFT Water FT water Potable Water

Copper 1.3±0.4 0.6±0.3 1.31±0.8 1.26±0.58 1.103±0.298

Iron 0.4±0.05 0.09±0.01 0.73±0.10 0.69±0.04 0.59±0.04

Manganese 0.027±0.006 0.013±0.002 0.036±0.012 0.02±0.006 0.037±0.005

Calcium 20.7±0.3 22.9±1.9 20.58±4.63 20.1±6.3 20.93±4.42

Aluminum 0.044±0.011 0.001 0.048±0.006 0.057±0.003 0.065±0.003

Magnesium 14.74±3.397 15.67±3.552 17.63±2.4097 14.38±4.582 12.34±2.549

28

4. Discussion

4.1. Physicochemical quality of water

PH: International Standards for Drinking-water suggested that pH less than 6.5 or greater than 9.2

would markedly impair the potability of the water. No health-based guideline value is proposed for

pH. Although pH usually has no direct impact on consumers, it is one of the most important

operational water quality parameters, the optimum pH required often being in the range 6.5–9.5

[56].

The pH of the Raw, Bore Hole, BFT, clarified and potable water samples are 7.48±0.7,7.56±0.47,

7.02±0.76, 6.83±0.67 and 7.41±0.62 respectively. The optimum value of pH according to Ethiopian

standard is 6.5 to 8.5. The result of pH of obtained from analytical data indicates that the PH of

water sample falls between the range of both international and national standards of drinking water.

TURBIDITY: The most turbid water is good condition for different pathogens propagation and

great chance for water born disease. This is because contaminants like virus and bacterias can

become attached to the suspended solid and are protected by these solids from disinfection by

chlorination. Turbidity is important because it affects both the acceptability of water toConsumers,

and the selection and efficiency of treatment processes, particularly the efficiency of disinfection

with chlorine since it exerts a chlorine demand and protects microorganisms and may also stimulate

the growth of bacteria. It is recommended that, for water to be disinfected, the turbidity should be

consistently less than 5 NTU by WHO, [5, 57].

According to the results obtained in this study, the turbidity Raw, Borehole, BFT, sand filtrated and

potable water samples are 32.34±0.92, 11.73±38,7.24±2.36,0.77±0.05, 1.47±0 .65 respectively.

From this study, it was observed that Borehole, and filtrated water samples exhibited a higher

quality of drinking water. But raw water and BFT water sample exhibited lower quality which is

unsatisfactory compared to the national and international water quality standards.

TDS: The potability of water with a TDS level of less than 600 mg/litre is generally considered

to be good; drinking-water becomes significantly and increasingly not potable at TDS levels greater

than about 1000 mg/litre. The presence of high levels of TDS may also be objectionable to

consumers, owing to excessive scaling in water pipes, heaters, boilers and household appliances.

29

Concentrations of TDS in water vary considerably in different geological regions owing to

differences in the solubility of minerals. Reliable data on possible health effects associated with the

ingestion of TDS in drinking-water are not available, and no health-based guideline value is

proposed. However, the presence of high levels of TDS in drinking-water may be objectionable to

consumers. A recent conceptual model links higher bulk conductivities at hydrocarbon impacted

sites to higher total dissolved solids (TDS) resulting from enhanced mineral weathering due to acids

produced during biodegradation. In this study, we evaluated the above model by investigating the

vertical distribution of bulk conductivity. The TDS values displayed by the conductivity/TDS meter

are calculated from the specific conductance of ground water and can be approximated by the

following equation [57, 58].

The result obtained from the analysis indicates that the total dissolved solids in each water sample

are acceptable according to the international drinking water standards.

Total solid: The total solid of water sample was the amount of residual solids that incorporates

dissolved solid and suspend solid in water. The international drinking water standards gives the

Permissible value of total solid in drinking water is 500mg/l and the excess value of total solid in

drinking water is 1500mg/l respectively [59].

The result obtained from the analysis of all water samples in table: 4a, indicate the total solid in this

water sample is below the permissible limit value of WHO standards. This indicates that all sources

of water of different simple sites are good for dirking purpose. But the total solid of raw water is

high enough and the value nearly closest with permissible values of drinking water. This is due to

that the upper stream of water holds maximum amount of suspended solids from the surrounding of

city in summer months

Temperature: Many aquatic organisms are sensitive to changes in water temperature. Temperature

is an important water quality parameter and is relatively easy to measure. There is no any

permissibility level in provisional values WHO guidelines of temperature for drinking water, but

the Canadian drinking water standard indicates that temperature of drinking water is less than

15℃.The investigation of temperature demonstrated that the average temperature of raw, borehole,

BFT, filtrated, and potable water samples were measured to be22.87±3.87, 23.73±1.29, 22.30±2.46,

30

22.00±3.10, and 21.50±2.48 respectively. The result of analysis indicates that all of the water

sample temperature was below the room temperature.

Conductivity: Specific conductance yields a measure of water’s capacity to convey an electric

current. This property related to the total concentration of the ionized substances in water and the

temperature at which the measurement is made the nature of the various dissolved substances, their

actual and relative concentrations, and the ionic strength of the water sample vitally affects the

specific conductance. Conductivity, the ability of water to carry an electric charge, is a proxy

indicator of dissolved solids and is therefore an indicator of the taste/salinity of the water (a

conductivity of 1400 μS/cm is equivalent to 1000 μg/L total dissolved solids). Although there is

little direct health risk associated with this parameter, high values are associated with poor taste and

hence customer dissatisfaction and complaints. If conductivity changes over time, or if conductivity

values are high, this can indicate that the water is contaminated [60].

From the study the conductivity values of water samples such as Raw, Borehole, BFT, and potable

are 270.33±20.04 µs/cm, 440.33±7.2342 µs/cm, 279.33±33.39 µs/cm, 278.33±30.07 µs/cm and

317±15.87 µs/cm respectively. This indicates that Borehole water sample contain large amount of

dissolved salts than other water samples. The international standard high permissive value of

conductivity of drinking water is 1000ms/cm. the summary of physicochemical parameters such as

temperature, pH, total solid, TDS, TSS, conductivity and turbidity of water samples were given figure

5 below.

31

Figure; 4.1: This graph Represents the physicochemical parameters such as PH, Temperature,

Turbidity, conductivity, total solid, total dissolved solid and total Suspended solids in the analysed water

sample and their average value

Table: 4.2. shows the WHO hardness fact sheet level and degree of hardness of water

Hardness in mg/L Hardness level Clark’s degrees

0- 20 Soft water 0-3.5

20-40 Moderately soft water 3.5-7.0

40-60 Slightly hard water 7.0-10.5

60-80 Moderately hard water 10.5-14.0

80-120 Hard water 14.0-21.o

>120 Very hard water >21

Source: WHO hardness factsheet

The hardness values shown in table: 4b.The values for sample from point were lower than the

prescribed limit. But even if the hardness of water sample is not higher than that of WHO standards,

it is not soft water but it is moderately hard water

Nitrate and nitrite: Nitrates in drinking water as such are not toxic to health and about 85% of

ingested nitrates are rapidly adsorbed from gastrointestinal tract in normal healthy individuals and

PH Temprature turbidity condactivity total silid TDS TSS

0

100

200

300

400

500

600

quan

titat

ive

valu

s of

par

amet

ers

Physicochemical parameters

Raw Water)

BH Water)

BFT water)

FT water)

Pot. water)

32

adsorbed nitrates are excreted by the kidneys. But, if the nitrates are converted into nitrites which

occur commonly, then toxic effects are encountered and may cause potential health hazards. Nitrate

is one of the most ubiquitous chemical constituents/contaminants of water bodies worldwide as it is

derived from human activities, particularly from the disposal of human and animal wastes and the

use of nitrogenous fertilizers in agriculture [61].

Nitrates occur naturally in many water-supplies and may also find access to them directly or

indirectly through, for example, the discharge of raw sewage, purified sewage effluent, or barn-yard

drainage. The danger of nitrates to human health is limited to some infants under one year of age.

The maximum permissible concentration of nitrate in drinking water is 50mg/l according to both

WHO and Ethiopian standards [62].

The average concentration of nitrate and nitrite in all water samples were raw water, (0.626±0.2),

BH water, (2.21±0.91 mg/L), BFT water, (0.83±0.05 mg/L), FB water, (0.78±0.008 mg/L) and

potable water (1.32±0.37 mg/L)and raw (0.05±0.001), BH water (0.04±0.002), BFT water

(0.018±0.001), FT water (0.012±0.002) and potable water (0.033±0.002) respectively. This result

indicate that all water sours are not polluted by nitrogen contain domestic wastes.

According to fig. 6, the concentration of nitrate and nitrite obtained from laboratory analysis, BH

water contain maximum amount of nitrate and raw water contain minimum amount of nitrate. The

concentration of both nitrate and nitrite in all sampling sites are below the permissible limits of

WHO Gvs.

Ammonia/Ammonium: From the results obtained from the laboratory analysis, the average value

of ammonia/ammonium for the five sample sites namely raw, BH, BFT, Ft and potable water were

below WHO and draft Ethiopian drinking water allowable concentration of 1.5mg/l and 3mg/l

respectively. According to fig. 6, the result of ammonia/ammonium concentration obtained from

laboratory analysis, BH water is under the instrumental detection limit and the concentration of

ammonia maximum at FT water.

33

Figure: 4.2. Graphs which represents the concentration of Nitrate, Nitrite, Ammonia and ammonium ion

in analyzed water

Total alkalinity:Alkalinity of water is its capacity to neutralize a strong acid and it is normally due

to the presence of bicarbonate, carbonate and hydroxide compound of calcium, sodium and

potassium [62].

Total alkalinity values for all the investigated samples were found to be less in samples Raw,BH,

BFT, FT and potable than the value prescribed by WHO.

Total hardness: Hardness is the property of water which prevents the lather formation with soap

and increases the boiling points of water. Hardness of water mainly depends upon the amount of

calcium or magnesium salts or both. International Standards stated that the maximum permissible

level of hardness in drinking-water was 500mg/l [63]. The hardness values shown in table: 4b.The

values for sample from point were lower than the prescribed limit. But even if the hardness of water

sample is not higher than that of WHO standards, it is not soft water but it is moderately hard water.

Nitrate Nitrite Ammonia Ammonium

0.0

0.5

1.0

1.5

2.0

2.5

Conce

ntr

atio

n o

f par

amet

ers

Chemical parameters

Raw water BH water BFT water FT water potablewater

34

Hardness is expressed as the equivalent amount of calcium in parts per million (mg/l) and Clark’s

degrees, and the amount of hardness is expressed in terms of range as shown in table 4.2.1below.

Figure: 4.3. Graphs which represents the concentration of total alkalinity, total hardiness, Mg

hardiness and calcium hardiness in the drinking water of North Gondar town

Sulphate: Sulfates are discharged into water from mines and smelters and from kraft pulp and

paper mills, textile mills and tanneries. Sodium, potassium and magnesium sulfates are all highly

soluble in water, whereas calcium and barium sulfates and many heavy metal sulfates are less

soluble. Atmospheric sulfur dioxide, formed by the combustion of fossil fuels and in metallurgical

roasting processes, may contribute to the sulfate content of surface waters [106].The permissible

limit of sulphate in both international and Ethiopian standards is 250mg/l and 250mg/l respectively.

The result of analysis show in table: 4b, above indicates there is no water sample have sulphate

Total Hardness Calcium Hardness Mg. Hardness Total alkalinity

40

60

80

100

120

140

160

180

Conce

ntr

atio

n o

f

par

amet

ers

Chemical parameters in the water

Raw water BH water BFT water FT water Potable water

35

concentration above the both WHO and Ethiopian standard of drinking water quality. Therefore all

sources of water in this study are suitable for drinking purpose.

Free chlorine: Free chlorine is the most commonly used disinfectant, with a target residual

concentration in the range of 0.2 to 1 mg/L. There are no specific adverse health effects of exposure

to free chlorine [61], but all chemical disinfectants have the potential to produce unwanted organic

or inorganic by-products that may be of health concern. The first recognized disinfection by-

products (DBPs) were the trihalomethane, which are produced by the reaction of free chlorine with

natural organic matter. WHO has conservatively set a GV of 5 mg/L, that well above the taste and

odour threshold for most consumers. From the analytical result of this work the concentration of

free Chlorine was under the ranges of WHO norms.

Phosphorus: phosphorous is an essential nutrient to living organisms (see total phosphorus). In

unpolluted waters, phosphorous can enter a water system from the weathering of phosphorous

baring rocks and minerals. In areas of high volcanic activity, phosphorous may be naturally

abundant in the soils. Manmade sources of phosphate in the environment include domestic and

industrial discharges; agricultural runoff where fertilizers are used, and changes in land use in areas

where phosphorous is naturally abundant in the soil. Phosphate may occur in surface water as a

result of domestic sewage, detergents, and agricultural effluents with fertilizers [49, 64]. The

international and national guidelines of drinking water quality standards do not indicate the

maximum permissible limits of phosphate but the analytical data shown in table: 4b, indicates small

amount of phosphate is in the each water sample

Silicate: It is an important factor as a major nutrient for diatoms, and brought from the rivers or

sewage outfall. The regional distribution of the reactive silicate concentration varies from season to

season and time to time. The lowest silicate values were recorded in the winter season for all

stations. This may bedue to the uptake of silicate by phytoplanktons well as to the slow rate of

regeneration of silicate from the sediments. The higher concentrations of reactive silicate were

directly proportional to drainage water discharged in to the Lake. Decomposition and death of

diatom, in addition to the increase of generation rate from underlying sediments, are factors

influencing silicate variability and the fact that in very badly oxygenated area the decomposition of

siliceous compounds increases under the effect of aerobic bacteria [65].The concentration of silicate

in all water sample represented in table: 4b, ranges from 12mg/L to 15mg/Lin each water samples.

36

Chloride:- Chloride is often associated with sodium since sodium chloride is a common constituent

of some water sources, especially well water. Levels above 140 ppm are considered to be toxic for

plants [65]. However, a value of 600 mg/l has been set as the tolerance limit for irrigation water.

The WHO guidelines and Ethiopian standards show that the permissible value of chloride in water

is 250mg/l and 258mg/L respectively as shown in table 4.1.1b. But the concentration of chloride in

water sample of all points is lower than the expected limit.

Figure: 4.4. Graphs which represents the concentration of Sulphate, Phosphate, Chloride, Free chlorine

and Silica in drinking water of North Gondar Town water.

In general chemical parameters and inorganic nutrients in the drinking water of North Gondar town

were determined in this study by using Wagtech, Photometer (7100).

Sulphate Free chlorine Chloride Phosphate Silica

0

10

20

30

40

50

37

The result of chemical parameters analysis of (free chlorine, Chloride, sulphate, phosphate, silica,

total hardness, calcium hardness, magnesium hardness, total alkalinity, nitrate, nitrite, ammonia and

ammonium,) shows that, the concentration of all parameters are compatible with national and

international drinking water quality standards. This experimental value is the indication of good

quality of this water for drinking proposes and other domestic uses. The summary for the average

concentration of these parameters are graphically represented in figure (9) below.

Figure: 9graphs which represents the concentration of chemical parameters in drinking water source

of North Gondar Town

Free

chlo

rine

Total

Har

dnes

s

Cal

cium

Har

dnes

s

Mg.

Har

dnes

s

Total

alkal

inity

Nitr

ate

ion

Nitr

ite io

n

Sulph

ate

ion

Phosp

hate

Amm

onia

Amm

oniu

m io

n

Chl

orid

e io

n

Silicat

e0

20

40

60

80

100

120

140

160

The

conce

trat

ion o

f par

amet

ers

Chemical parameters

Raw water

borehole water

BFT water

filtrated water

potable water

38

4.2. Selected trace and heavy metals

Aluminum: Coagulation is suitable for removal of certain heavy metals and low-solubility organic

chemicals, such as certain Organochlorine pesticides. For other organic chemicals, coagulation is

generally ineffective, except where the chemical is bound to humic material or adsorbed onto

particulate. Chemical coagulation-based treatment is the most common approach for treatment of

surface waters and is almost always based on the following unit processes. Chemical coagulants,

usually salts of aluminum or iron, are dosed to the raw water under controlled conditions to form a

solid flocculent metal hydroxide WHO. Aluminum is widely used in raw water treatment by adding

the aluminum Sulphate (alum) in coagulation and flocculation processes to ensure safe drinking

water for human consumption by minimizing the levels of organic matter, microorganism, colour

and turbidity. The concentration of aluminum in natural waters can vary significantly depending on

various physicochemical and mineralogical factors and the Aluminum levels in drinking-water vary

according to the levels found in the source water and whether aluminum coagulants are used during

water treatment. There for aluminum concentration of 0.2 mg/L in drinking-water provided a

compromise between the practical use of aluminum salts in water treatment and discoloration of

distributed water [66]

In this study, the average concentration ±SD in the water sample of Raw, BH, BFT, FT and potable

water were 0.044±0.037, 0.001±0.0, 0.048±0.065, 0.057±0.063 and 0.065±0.065 respectively.

The results lower than the national and international permissible limit of Guide line Values for

drinking water standard.

Calcium and Magnesium:-Both calcium and magnesium are essential to human health. Inadequate

intake of either nutrient can impair health. Over 99% of total body calcium is found in bones and

teeth, where it functions as a key structural element. The remaining body calcium functions in

metabolism, serving as a signal for vital physiological processes, including vascular contraction,

blood clotting, muscle contraction and nerve transmission.

Inadequate intakes of calcium have been associated with increased risks of osteoporosis,

nephrolithiasis (kidney stones), colorectal cancer, hypertension and stroke, coronary artery disease,

insulin resistance and obesity. Magnesium is the fourth most abundant cation in the body and the

second most abundant cation in intracellular fluid. Low magnesium levels are associated with

39

endothelial dysfunction, increased vascular reactions, elevated circulating levels of reactive protein

and decreased insulin sensitivity. Low magnesium status has been implicated in hypertension,

coronary heart disease, diabetes mellitus and metabolic syndrome. Individuals vary considerably in

their needs for and consumption of these elements. While the concentrations of calcium and

magnesium in drinking-water vary markedly from one supply to another, mineral-rich drinking-

waters may provide substantial contributions to total intakes of these nutrients in some populations

or population subgroups [66].The result of study in table (4.2.1b) shows, concentration of calcium

and magnesium ranges from 20.10± 0.63 to 22.90±1.87 and 12.34± 2.55 to 17.63±7.41 of calcium

and magnesium respectively. This result is lower than GVs of WHO, 75mg/L of calcium and

150mg/L of magnesium for drinking water qualities.

Figure: 4.5. Graph which represents the concentration of Al, Ca, and Mn in drinking water of North

Gondar Town

Copper: Copper is both an essential nutrient and a drinking-water contaminant. Commercially, it is

used to make pipes, valves and fittings and is present in alloys and coatings. Copper sulfate penta

Aluminum Calcium Magnesium

0

5

10

15

20

25

Conce

ntr

atio

n o

f tr

ace

met

als

(Photo

met

er)

Trace metal elements in the water

Rawwater BH water BFTwater FTwater Potablewater

40

hydrate is sometimes added to surface water for the control of algae. Copper concentrations in

treated water often increase during distribution, especially in systems with an acid pH or high-

carbonate waters with an alkaline pH. Food and water are the primary sources of copper exposure in

developed countries WHO [67].The maximum permissible concentration of copper in drinking

water is 2mg/L WHO [68]. In this study the level of copper from methods, AAS and photometer

analysis, in table (4.2a) and (4.2b) is lower, than maximum permissible level of WHO norms.

Iron: Iron is one of the most abundant metals in the Earth’s crust. It is found in natural fresh waters

at levels ranging from 0.5 to 50 mg/L. Iron may also be present in drinking-water as a result of the

use of iron coagulants or the corrosion of steel and cast iron pipes during water distribution. Iron in

drinking water is present as Fe2+ or Fe3+ in suspended form. It causes staining in clothes and imparts

a bitter taste. It comes into water from natural geological sources, industrial wastes, and domestic

discharge and also from byproducts. Excess amount of iron (more than 10 mg/kg) causes rapid

increase in pulse rate and coagulation of blood in blood vessels, hypertension and drowsiness. Iron

stains laundry and plumbing fixtures at levels above 0.3 mg/L; there is usually no noticeable taste at

iron concentrations below 0.3 mg/L, and concentrations of 1–3 mg/L can be acceptable for people

drinking anaerobic well water [27, 67].

The average values of the laboratory analysis for iron shows that the concentration of iron in raw

and borehole water sample were lower than that of permissible limit of WHO GVS. In contrast the

concentration of iron in BFT, FT and potable water is higher than the WHO norms. This high

concentration of iron is may be come from rusting of pipeline.

Nickel:- Nickel is used mainly in the production of stainless steel and nickel alloys. Food is the

dominant source of nickel exposure in the non-smoking, non-occupationally exposed population;

water is generally a minor contributor to the total daily oral intake. The inhaled nickel compounds

are carcinogenic to humans. However, there is a lack of evidence of a carcinogenic risk from oral

exposure to nickel. Maximum permissible concentration of nickel in drinking water is 0.02mg/L, in

provisional GV of WHO [67]. The result of laboratory analysis shown in table: 4.2.1a indicates that

the average concentration of zinc present in all water samples were below the WHO norms.

Zinc: Zinc is very essential micronutrient in human being and at very high concentration; it may

cause some toxic effect. Zinc compounds are astringent corrosive to skin, eye and mucous

41

membrane.They cause special types of dermatitis known as “Zinc pox”. Zinc is also irritating to

digestive tract causing nausea and vomiting. The maximum permissible concentration of zinc in

drinking water is 3mg/L according WHO [67].

The average values of the laboratory analysis for zinc concentration of all sampling sites were

below the permissible limits of WHO GVs, and Ethiopian standards of drinking water.

Figure: 4.6. Graphs which represent the concentration of trace metals such as Cu, Fe, Ni, Zn in the

drinking water of North Gondar town.

Chromium: Chromium is trace element that occurs in several forms in environment. The most

important are Cr(III) and Cr (VI) species. These two forms are very different in physical properties

and health impacts. Cr (III) is relatively none toxic, occurs in nature and is in the fact essential trace

element for human beings, Chromium is also essential for organism as a micronutrient in traces

from fat and carbohydrate metabolism. In contrast Cr (VI) has several health impacts, mostly occurs

in environment due to anthropogenic activities and human carcinogenic when inhaled. But there are

many controversies on health impact of Cr(VI) when ingested. Because of ongoing controversies of

CU Fe Ni Zn

0.0

0.2

0.4

0.6

0.8

1.0

Conce

ntr

atio

n o

f tr

ace

met

als

by

AA

S

Trace metals in water

Raw water BH water FT water BFT water Potable water

42

Cr (VI) in drinking water, WHO has kept provisional GV at 0.05mg/L for total chromium [67].The

result of study shows that the average concentrations of total chromium in these water samples were

ranged from 0.01mg/L to 0.036mg/L. This result shows that the concentration of Cr in all sampling

sites is below the WHO norms and there is no chromium contaminant in this water source.

Lead:- Lead is rarely present in tap water as a result of its dissolution from natural sources; rather,

its presence is primarily from household plumbing systems containing lead in pipes, solder, fittings

or the service connections to homes. The amount of lead dissolved from the plumbing system

depends on several factors, including pH, temperature, and water hardness and standing time of the

water, with soft, acidic water being the most plumb solvent. Toxic level of lead in human body is

500 ppm beyond which it causes anemia, brain damage and vomiting. The maximum permissible

concentration of lead in drinking water is 0.1mg/L WHO [67].

The result of study shows that the concentration of lead in five sampling sites, raw, BH, BFT, FT

and potable water samples were 0.0089±0.0013, 0.0098±0.0020, 0.012±0.001, 0.013±0.002,

0.011±0.002 respectively. This indicates that the lead concentration in raw and BH water samples

are below the permissible limit GVs of WHO. In contrast the concentration of lead in BFT, FT and

potable water samples exceed the WHO norms.

Manganese: Manganese is naturally occurring in many surface water and groundwater sources,

particularly in anaerobic or low oxidation conditions, and this is the most important source for

drinking water. The exposure in high level of manganese can lead to adverse neurological effect.

Because of possible health risks, WHO has set maximum permissible concentration GVs in

drinking water is 0.4mg/L [67].

The result of the analysis shown in table: 4.2.1a and 4.2.1b, indicates that the concentration of

manganese in all water samples range from, 0.029mg/L of sand filtered water to 0.o37 mg/L of

potable water according to AAS measurement and from 0.013 mg/L of borehole water to

0.037mg/L of potable water in photometer result respectively. This result showed that the

concentration of Mn in all water samples were below WHO and Ethiopian norms.

43

Figure 4.6. Graphs which shows the concentration of Cr, Pb and Mn in the drinking water of North

Gondar Town

In general the levels of selected metals such as Cu, Cr, Fe, NI, Mn, Ca, Mg, Zn, Pb and Al from

drinking water samples were determined by using AAS and Photometer analytical method. The

result in table 3.2a and 3.2b showed that all of the selected metals were present in all the water

samples. The concentration of selected metals showed in table 3.2a and 3.2b were lower than

permissible limits of WHO GVs, except Iron and lead. Iron and lead were present in all the water

samples, and their concentration in raw and BH water samples were lower than permissible limits

of WHO GVs. In contrast their concentration in BFT, FT and potable water samples exceeds the

WHO GVs. In potable water sample concentration of Lead exceeds the WHO GVs by ±0.001mg/L

deviation.

The summary of these selected metals concentration in the entire water samples analyzed by both

methods (Atomic Absorption Spectro photometric and Wagtech Photometric methods)were

graphically represented in figure (13a) and (13b) below.

Cr Pb Mn 0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

Conce

ntr

atio

n o

f

Hea

vym

etal

s

Heavy metals in the water

Raw water BH water BFT water FT water Potable water

44

Figure: 13a the graph represents the concentration results of selected metals obtained from Atomic

Absorption Spectrophotometer (AAS).

CU Cr Fe Pb Mn Ni Zn 0.0

0.2

0.4

0.6

0.8

1.0

The

con

centr

atio

n o

f m

etal

s obta

ined

fro

m A

AS

Metal elements analyzed by using AAS

Raw water BH water BFT water FT water) Pot. water

45

Figure: 4.7. Graph represents the concentration of metal elements such as Copper, Iron, Manganese,

Calcium, Aluminum and Magnesium for the comparative studies of metal concentration determination in

photometer.

CU

FE

Mn

Ca

Al

Mg

0 5 10 15 20

The concentration of metal elements obtained from Photometer

Met

al e

lem

ents

an

alyse

d b

y u

sing p

alin

etes

t photo

met

er 8

000

Raw water) BH water BFT water FT water) Potable water

46

5. Conclusion and recommendation

5.1. Conclusion

The current study revealed that the quality statuses of drinking water in the city of North Gondar

highly related with the physicochemical and selected dissolved metal concentration and their health

impacts. The researcher concludes that the physicochemical constituents of all water samples were

acceptable according to national and international WHO GVS. Hardness of water sample ranges

from 118.16 mg/L of BH water to 128.9 mg/L of FT water sample as shown in the table 4.1.1b.

This result showed that all the water samples were hard except BH water which is moderately hard

according to WHO hardness fact sheet. This hardness of water has adverse effect on boilers,

cooking equipments and boundaries.

The concentration of selected metals present in all the water samples were fall under the permissible

limits of WHO guide line values..

5.2. Recommendation

The researcher recommends that, to ensure general quality and purity of this water for drinking and

domestic uses, the bacteriological water quality, dissolved organic chemicals, heavy metals

adsorbed in sediments of water and pesticide assessment needs further investigations.

Determination of trace metals in the water is imperative as the water is used for drinking Purposes

by the residents. The concentrations of dissolved trace metals in all water samples were found to be

below the maximum permissible limit of WHO for domestic and drinking purposes, but the

concentration of lead and iron in BFT, FT and potable water source deviates with WHO GVs.

Therefore, it is recommended that further studies are required to locate the exact source of this

metals and concerned body to check out the present condition of pipelines.

The study was carried out within three months; this makes lack of compressiviness, there for it is

recommended that further studies are required in different season of the year including other

parameters.

The hardness of water has adverse effect on the laundries and boilers. Therefore, it is recommended

further studies are required to minimize and to point out the source of hardness causing chemicals.

47

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coliform bacterial in water coolers at various location in Uitm Shah Alam, 8, 12

2. Satyajit R. and Sukalyan D. (2012). Assessment of water quality around mine sites. National

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3. Gebrekidan M. and Samuel Z., (2005). Concentration of Heavy Metals in Drinking Water

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4. United Nation Children Fund (UNICEF) and World Health Organization (WHO) (2011).

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5. Shalom N. C., Obinna C. N., Adetayo Y. O., Vivienne N. E.(2011). Assessment of water

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8. Yadav R. N., Dagar N. K., Yadav R, and Gupta P., (2011). Assessment of Ground Water

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physico-chemical parameters tamdalge tank in Kolhapur district, Maharashtra. Department

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53

APPEDIX 1: The Regration carves of metal elements such as Ni, Mn, Cu, Pb, Cr,

Zn and Fe.

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

Abso

rban

ce o

f M

n

Standard Concentration of Mn

R2= 0.99969 Y= 4.88879E-4x + 0.16738

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

Abso

rban

ce o

f N

i

Standard concentration of Ni

R2= 0.99917

y= 1.30435E-4x + 0.3327

54

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

0.00

0.02

0.04

0.06

0.08

0.10

0.12

Abso

rban

ce o

f P

b

Standard Concentration of Pb

R2= 0.99889 y= 1.6667E-4x + 0.1414

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.00

0.02

0.04

0.06

0.08

0.10

Abso

rban

ce o

f C

u

Standard concentration of Cu

R2= 0.99964

y= 4.34783E-4x + 0.12017

55

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

0.22

Abso

rban

ce o

f C

r

Standard concentration of Cr

R2= 0.99757 Y= 0.00478x + 0.50817 +

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

Abso

rban

ce o

f Z

n

Standard concentration of Zn

R2 = 0.99969 Y= 0.00143x + 0.08783

56

APPEDIX 2: Optimization procedure of sample and the method detection

analysis

Table 2.1Optimization procedure of digestion of water sample

Sample in (ml) HNO3 (ml) HClO4 (ml) Temperature(℃) Time observation

100ml 3ml 1ml 250 3hr Turbid and

slightly clear

100ml 6ml 2ml 250 3hr Clear

100ml 9ml 3ml 250 2.30hr Turbid clear

100ml 12ml 4ml 250 2.30hr Clear

0 1 2 3 4 5

0.00

0.02

0.04

0.06

0.08

0.10

0.12

Abso

rban

ce o

f F

e

Standard concentration of Fe

R2= 0.9997 Y= 0.00225x+ 0.02349

57

Table 2 .2 the method detection limit value and seven replicated reading of blank samples

No,

Replication

Metallic elements absorbance, and concentration

Cu Zn Mn Pb Cr Ni Fe

Sample 1 0.006 0.001 0.032 0.04 0.04 0.053 0.05

Sample 2 0.004 0.003 0.043 0.0405 0.041 0.052 0.052

Sample 3 0.003 0.004 0.03 0.064 0.064 0.084 0.054

Sample 4 0.001 0.005 0.034 0.056 0.073 0.0502 0.086

Sample 5 0.004 0.006 0.054 0.041 0.0411 0.065 0.055

Sample 6 0.002 0.005 0.032 0.06 0.061 0.055 0.086

Sample 7 0.004 0.004 0.054 0.072 0.062 0.089 0.051

Average Conc. 0.001618

347

0.0016

32993

0.0105

2661

0.01296

3777

0.01355

8568

0.01613

7091

0.01648

2314

t value 3.14 3.14 3.14 3.14 3.14 3.14 3.14

MDL value 0.00508

0.00513

0.033

0.0432

0.0426

0.0507

0.0521

58

Appendix 3:- Different chemical reagents used in Wagtech Photometer for determination of

chemical parameters in the water sample.

No, Chemical Parameters Chemical Reagents Wave length of

transmittance

Selected photo

program

1 Total Alkalinity Alkaphot tablet 570 nm Photo 2

2 Aluminium Aluminium no. 1 tablet

Aluminium no. table

570 nm Photo 3

3 Ammonia Ammonia no. 1 tablet

Ammonia no. 2 tablet

640nm Photo 4

4 Calcium hardness Calcicol no. 1 tablet

Calcicol no. 2 tablet

570 nm Photo 12

5 Calcium metal Calcicol no. 1 tablet

Calcicol no. 2 tablet

570 nm Photo 60

6 Chloride Acidifying CD tablet

Chloridol tablet

520 nm Photo 51

7 Free Chlorine DPD 520 nm Photo 7

8 Copper Coppercol no. 1 tablet

Coppercol no. 2

decomplexing tablet

520 nm Photo 10

9 Total Hardness Hardcol no. 1tablet

Hardcol no. 2 tablet

570nm Photo 15

10 Magnesium hardness Magnecol tablet 520 nm Photo 61

11 Magnesium metal Magnecol tablet 520nm Photo 21

12 Manganese Manganese no. 1 tablet

Manganese no. 2 tablet

640 nm Photo 20

59

12 Nitrate Nitratest powder

Nitratest tablet

Nitricol tablet

570 nm Photo 23 for N

Photo 63 for

nitrate

14 Nitrite Nitricol tablet 520 nm Photo 24 for N

Photo 64 for

nitrite

15 Phosphate Phosphate HR tablet 490 nm Photo 29

16 Silica Silica no. 1 tablet

Silica no. 2 tablet

Silica PR tablet

640 nm Photo 31

17 Sulphate Sulphate Turb table 520 nm Photo 32

Source: Palintest®, Palintest USA and Palintest Australia are registered trademarks of Palintest

Ltd.

All of the chemical parameters stated in this appendix were measured by using reagents stated in

this table and the procedure for measurement was derived from Photometer 8000 System for Water,

Analysis manual.

Appendix4:- Table of drinking water guide line value of drinking water

1 Standards for Physicochemical parameters

Parameters EPA standards WHO standards UN standards USA standards Canada

standards

Temperature (℃) --- --- ------ ------ 15℃

EC. (μS/cm) 1000 1000 ------- ------- --------

pH 6-9 6.5-8.5 6.5-8.5 6.5-8.56 6.5-8.5

TDS(mg/l) ------- 1000 ------- 500 500

TSS(mg/l) ----- ------- ------- ------ -------

TS (mg/l) ------- 500-1500

------ ------ ------

60

Turbidity (TNU) ------ 5 4 0.5-1.0 5

Ammonia

(mg/l)

1.5

Ammonium

(mg/L)

0.2 ------- 0.5 ----- ----

Chloride (mg/L) 250 250 25 250 250

Free chlorine

Nitrate (mg/L) 50 50 50 ----- ------

Nitrite (mg/l) ----- 3 0.1 -------- -------

Sulphate (mg/L) 200 250 250 250 500

Phosphate (mg/L) 0.25 --------- --------- --------- ------

Total alkalinity ------ 200 ------ ------- ------

Total hardness ------- 500 -------- ----- -------

2 Standards For trace and heavy metals

Calcium (mg/L) -------- 75 -------- ------- --------

Magnesium

(mg/L)

--------- 150 --------- ---------- ----------

Aluminium(mg/l) ------- 0.2 0.2 ------ -------

Copper(mg/l) ------ 2 0.1-3 1.0 1.0

Chromium ------ 0.05 0.05 0.1 0.05

Iron (mg/l) 0.4 0.3 0.2 0.3 0.3

Manganese(mg/l) 0.5 0.5 0.05 0.05 0.05

Lead (mg/l) ------- 0.01 0.05 0.015 0.05

Nickel (mg/l) ----- 0.02 0.05 --- ---

Zinc (mg/l) ------ 3 0.1-5.0 5 5