i

THE IMPACTS OF DUMPSITE AND DOMESTIC WASTE LEACHATE

ON GROUNDWATER QUALITY IN KILIFI TOWN, KILIFI COUNTY,

KENYA

THOMAS OWINO JUMA (BSc)

REG/NO. N50/CE/11412/2008

A Thesis Submitted in Partial Fulfillment of the Requirements for the Award

of the Degree of Master of Environmental Science in the School of

Environmental Studies of Kenyatta University, Kenya

APRIL, 2014

ii

DECLARATION

This thesis is my original work and has not been presented for a degree in any

University or any other award.

THOMAS OWINO JUMA (BSc)

REG/NO. N50/CE/11412/2008

Signature………………….. Date……………………

Supervisors

We confirm that the work reported in this thesis was carried out by the student

under our supervision

1. Dr. Gladys Gathuru,(PhD)

Department of Environmental Science

Kenyatta University

Signature……………………….. Date………………….

2. Prof. Mwakio Tole, (PhD)

Department of Environmental Science

Pwani University

Signature…………………………Date…………………

iii

DEDICATION

This thesis is dedicated to: My wife, Millicent, Daughters; Susan, Mitchell,

Lillian, Carren and Naomi for their support during the course of my studies.

iv

ACKNOWLEDGMENT

I would like to take this opportunity to acknowledge the assistance received from

a number of individuals and institutions towards the successful completion of my

study.

I am greatly indebted to my supervisors: Dr.Gladys Gathuru and Prof. Mwakio

Tole for their tireless supervision and guidance. I am equally grateful to Dr. Kiti,

Prof. Oyoko, Dr. Mwafaida and Dr. Olwendo for their scholarly advice. I would

also like to recognize Mr. David Samoe and Madam Scholarstica Atieno of Pwani

University for taking their time to assist me in undertaking technical analysis in

the laboratories.

Finally, I would like to thank the department of pure and applied sciences of

Pwani University for allowing me to conduct the analysis using the University

facilities. I am also thankful to KEMRI Kilifi through Mr. Kennedy Kawuondo

for assisting in mapping the study area.

v

TABLE OF CONTENTS

TITLE PAGE .................................................................................................................... i

DECLARATION ............................................................................................................. ii

DEDICATION ................................................................................................................ iii

ACKNOWLEDGMENT ................................................................................................ iv

TABLE OF CONTENTS ................................................................................................ v

LIST OF TABLES .......................................................................................................... ix

LIST OF FIGURES ......................................................................................................... x

LIST OF PLATES ......................................................................................................... xii

ABBREVIATIONS AND ACRONYMS .................................................................. xiii

ABSTRACT ................................................................................................................... xiv

CHAPTER ONE: INTRODUCTION ....................................................................... 1

1.1 Background Information.......................................................................................... 1

1.2 Statement of the Problem ......................................................................................... 2

1.3 Research Questions. .................................................................................................. 3

1.4 Research Objectives .................................................................................................. 3

1.5 Research Hypotheses. ............................................................................................... 4

1.6 Research Justification ............................................................................................... 4

vi

1.7 Scope and Limitations of the Study ........................................................................ 5

1.7.1 Scope of the Study.................................................................................................. 5

1.7.2 Limitations of the Study ........................................................................................ 5

CHAPTER TWO: LITERATURE REVIEW ......................................................... 6

2.1 Introduction ................................................................................................................ 6

2.2 Groundwater ............................................................................................................... 6

2.3 Effects of Pollutants on Health. ............................................................................. 10

2.4 Effects of Dumpsite and Domestic Waste Leachate on Groundwater ............. 12

2.5 Previous Studies on Groundwater ......................................................................... 13

2.6 Composition of Domestic Wastewater. ................................................................ 14

2.6.1 Nitrogen in Wastewater ....................................................................................... 15

2.6.2 Organic Matter in Wastewater ............................................................................ 16

2.6.3 Pathogens in Domestic Wastewater ................................................................... 18

2.6.4 Physical and Heavy Metals in Waste Water ..................................................... 18

CHAPTER THREE: MATERIALS AND METHODS ...................................... 20

3.1 Introduction .............................................................................................................. 20

3.2 The study Area ......................................................................................................... 21

3.2.1 Location ................................................................................................................. 22

3.2.2 Climate ................................................................................................................... 23

vii

3.2.3 Geology.................................................................................................................. 23

3.2.4 Hydrology .............................................................................................................. 25

3.3 Research Design ...................................................................................................... 25

3.4 Sampling Procedure and Sample Size .................................................................. 26

3.4.1 In-Situ Measurements .......................................................................................... 26

3.4.2 Analytical Method ................................................................................................ 27

3.5 Data Analysis ........................................................................................................... 29

CHAPTER FOUR: RESULTS AND DISCUSSIONS ......................................... 30

4.1RESULTS .................................................................................................................. 30

4.1.1 PH ........................................................................................................................... 30

4.1.2 Temperature ......................................................................................................... 31

4.1.3 Electrical conductivity ......................................................................................... 32

4.1.4: Lead (Pb) ............................................................................................................. 33

4.1.5: Manganese (Mn) ................................................................................................. 34

4.1.6: Cadmium (Cd) ..................................................................................................... 35

4.1.7: Total Nitrogen (TN) ............................................................................................ 37

4.1.8: BOD ...................................................................................................................... 38

4.1.9: Sulphate ................................................................................................................ 39

4.1.10: Total Coli ........................................................................................................... 40

viii

4.1.11 Escherichia coli.forms ....................................................................................... 41

4.1.12: Levels of Total coli.forms as a Function of Distance from Pit Latrine ..... 43

4.1.13: Levels of Escherichia coli.forms as a Function of Distance from Pit Latrines .... 45

4.1.14 Origins of the Pollutants .................................................................................... 47

CHAPTER FIVE: CONCLUSIONS AND RECOMMENDATIONS ............. 50

5.1 Conclusions .............................................................................................................. 50

5.2: Recommendations .................................................................................................. 51

REFERENCES ............................................................................................................... 52

APPENDIX I:Measurenets of Total coli.forms and Escherichia coli.forms for dry

and wet seasons .............................................................................................................. 56

APPENDIX II:The mean values of pH, Temperature and Electrical conductivity

for dry and wet seasons. ................................................................................................ 57

APPENDIX III:The mean concentrations of Pb, Mn, Cd and Zn ........................... 58

APPENDIX IV: The mean concentrations of BOD, T-N and Sulphates for dry and

wet seasons ...................................................................................................................... 59

APPENDIX V:The Range of pollutants for dry and wet seasons and the

percentage changes due to seasons .............................................................................. 60

ix

LIST OF TABLES

Table 4.2: Principal Component Analysis results. ........................................................... 48

Table 4.3: Total variance of the four components (PC1, PC2, PC3, and PC4) ............... 49

x

LIST OF FIGURES

Figure 3.1 Map showing the study area (Kilifi Town), locations of the sampled

wells, dumpsite and Pit latrines. ..................................................... 22

Figure 4.1: Mean pH values for the ten wells measured during the dry and wet

seasons. ........................................................................................... 30

Figure 4.2: Mean temperatures values for the ten wells measured during dry and

wet seasons...................................................................................... 31

Figure 4.3: The graph of electrical conductivity for the ten wells measured

during the dry and wet seasons ....................................................... 32

Figure 4.4: The graph of Lead for the ten wells measured during the dry and wet

seasons. ........................................................................................... 33

Figure 4.5: The graph of Manganese for the ten wells measured during the dry

and wet seasons. .............................................................................. 34

Figure 4.6: The graph of Cadmium for the ten wells measured during the dry

and wet seasons. .............................................................................. 36

Figure 4.7: The graph of Total Nitrogen for the ten wells measured during the

dry and wet seasons. ....................................................................... 37

Figure 4.8: The graph of BOD for the ten wells measured during the dry and wet

seasons. ........................................................................................... 38

xi

Figure 4.9: The graph of sulphate for the ten wells measured during the dry and

wet seasons. ..................................................................................... 39

Figure 4.10: The graph of Total coli.forms counts for the ten wells measured

during dry and wet seasons. ............................................................ 40

Figure 4.11: The graph of Escherichia coli.forms counts for the ten wells

measured during dry and wet seasons. ............................................ 42

Figure 4.12: Correlation between measurements of Total coli.forms in ground

water wells and distance from pit latrine during wet season. ......... 44

Figure 4.13: Correlation between measurements of Total coli.forms in ground

water wells and distance from pit latrine during dry season. .......... 44

Figure 4.14: Correlation between measurements of Escherichia coli.forms in

ground water wells and distance from pit latrine during wet season.

.......................................................................................................... 45

Figure 4.15: Correlation between measurements of Escherichia coli.forms in

ground water wells and distance from pit latrine during dry season. ..

......................................................................................................... 46

xii

LIST OF PLATES

Plate 2.1: Incineration of Municipal solid wastes at the dumpsite..................................... 7

Plate 3.1: Laboratory Analysis of trace metals using AAS.............................................. 28

Plate 3.2: Incubation of plates for analysis of coli forms ................................................ 28

xiii

ABBREVIATIONS AND ACRONYMS

APHA American Public Health Association

BOD Biochemical Oxygen Demand

CBD Central Business District

EPA Environmental Protection Agency

GoK Government of Kenya

GPS Global Positioning System

KDDP Kilifi District Development Plan

KEBS Kenya Bureau of Standards

KEMRI Kenya Medical Research Institute

KIMAWASCO Kilifi Malindi Water and Sewerage Company

MCLG Maximum Contaminant Level or Goal

MSW Municipal Solid Waste

NEMA National Environment Management Authority

NGO Non-Governmental Organization

PCA Principal Component Analysis

PU Pwani University

SAS Statistical Analysis Software

TCR Total Coli Form Rule

WHO World Health Organization

xiv

ABSTRACT

Kilifi town (study area) is in Kilifi County, Kenya. Groundwater samples were

collected from wells which were close (≤30m) from pit latrines and (≤2.5Km)

from refuse dumpsite. Ten wells, namely wells number (1- 10) were purposively

sampled during wet season (July, August and September, 2011) and also during

dry season (January, February and March, 2012), with the aim of assessing the

physicochemical and biological impacts of the leachate from the dumpsite and the

pit latrines on quality of groundwater in Kilifi town and its environs. The physico-

chemical parameters investigated included: Temperature, pH, Electrical

conductivity and anions So42-

and No3- which were determined using the standard

analytical methods. Trace metals Pb, Cd and Mn were determined using Flame

Atomic Absorption Spectrophotometer. Bacteriological analysis was done as

prescribed by the standard methods for analysis of water and wastewater. The

data obtained was analyzed using Matlab software. The levels of electrical

conductivity (E.C), Manganese (Mn), Cadmium (Cd), No3-, and E.coli found in

Kilifi town are higher than KEBS health based guideline values thus indicating

possible impacts of the dumpsite and pit latrines on groundwater quality. The

measurements of the parameters were as follows: E.C values ranged from 343-

4237 microS/cm against recommended guideline of 120 microS/cm. Cd ranged

from 0.02- 0.03 mg/L against guideline of 0.005mg/l. Mn ranged from 0.09- 0.34

mg/L against the guideline of 0.1 mg/L and 9 out of the 10 wells recorded higher

values than the guideline. NO3- ranged from 7- 40 mg/L against guideline of

1mg/L and 8 out of the 10 wells recorded higher values than the guideline. The

total coli.forms ranged from 180- 18630 counts/100ml against the guideline of 0

counts/100ml and all the sampled wells registered higher values than the

guideline. The results affirm groundwater pollution and indicate possibilities of

toxicities of these pollutants and their threat to human health. The groundwater

had PH within the KEBS acceptable range for drinking water. The seasonal effect

was manifested in that, the levels of pollutants increased in wet seasons as

compared to dry seasons. This could have been caused by the increased

percolation during the wet season. The concentration of Escherichia coli.forms in

groundwater wells had strong negative correlation with distances from the

dumpsite and the pit latrines with r values ≥ - 0.5. Wells 1, 2, 3 and 4 were less

than 15m from the nearest pit latrines. Out of these, wells number 1, 2 and 4

recorded higher counts of coli.forms compared to the rest due their proximity to

pit latrines. Well number 3 recorded less coli.forms despite being equally closer to

pit latrines. This could have been due to other factors like lining of the pit. The

results confirm the need for determining safe distances between wells and waste

disposal sites to abate groundwater pollution.

1

CHAPTER ONE: INTRODUCTION

1.1 Background Information

Groundwater refers to water which originates from the infiltration and percolation

of precipitation through the soil profile and accumulates below the earth’s surface

in a porous layer commonly referred to as the aquifer. It forms part of the

hydrologic cycle and the quantity and quality of water stored in the aquifer is a

function of factors such as type of rocks, rainfall amounts, topography, surface

cover and the state of the environment (Salami, 2012).When precipitation finds its

way into a landfill, it causes the extraction of water soluble compounds from the

decomposed wastes thus forming garbage juice commonly called the leachate

(Salami, 2012). The leachate then seeps and percolates to groundwater aquifers

thus causing groundwater pollution.

Groundwater is increasingly becoming one of the most important valuable

renewable resources for human life in economic development. For example, In

the Coastal region of Kenya where surface sources are minimal, the Swedish

International Development Authority has in the past championed the groundwater

exploitation where hand operated pumps are used to lift water to the surface to

assist the communities to get access to clean water. A number of people and

institutions are exploiting groundwater as a result of the absence of surface

sources or in some cases due to contamination of the surface sources (Abolfazl

2

and Elahe, 2008). Other factors such as low capital cost required for the

development of groundwater resources, convenience in availability to where

water is needed and its natural quality are influencing many developed and

developing nations in changing to sub-surface sources of water, for domestic and

industrial purposes (Tods,1980). Globally, groundwater is threatened by the

unlined and uncontrolled landfills used for solid waste disposal. The threats are

more evident in the developing countries like Kenya where hazardous industrial

waste is co-disposed with municipal wastes (Kumar and Alappat, 2003).

Migration of leachate from landfills to groundwater limits the quality of this

valuable renewable resource especially in areas closer to pit latrines and land fill

sites. Lack of proper management and protection of urban aquifers has been a

major problem in many towns in Kenya because of environmental degradation.

For example, according to Coast Water Services Board (CWSB,2008), Mombasa

city despite being the second largest town in Kenya has only about 30% of its

population covered under the local centralized sewerage system.

1.2 Statement of the Problem

Due to rapid population increase over the last decade, there has been a growing

rise in water scarcity across the country. The immediate solution to water shortage

in Kilifi town has been an increase in exploitation of groundwater sources. The

groundwater quality however, is being compromised by poor disposal of wastes

through dumping as well as use of pit latrines. The dumpsites contain domestic

wastes, vegetable wastes, waste papers; scrap metals, cans for different chemicals,

3

plastic containers, old rags, vehicle tyres, scalpels and human wastes. Some of

these wastes are hazardous and are bound to cause serious health problems if they

enter domestic water supply. Relevant information on the pollution status of the

groundwater over this region is needed to safeguard the current and future

populations.

1.3 Research Questions.

The following were the research questions used in the study:

i. What are the levels of groundwater pollutants as compared to drinking water

guidelines as provided by the Kenya Bureau of standards?

ii. What are the effects of dry and wet seasons on groundwater pollution?

iii. Is there a correlation between groundwater pollution and distance from

dumpsite?

iv. Is there a correlation between groundwater pollution and distance from pit

latrine?

1.4 Research Objectives

The main objective of this study was to determine the impacts of dumpsite and

domestic waste leachate on groundwater quality within Kilifi town.

4

The specific objectives were to establish:

i. The levels of pollutants in groundwater wells as compared to guidelines

provided by Kenya Bureau of standards for drinking water

ii. The effects of wet and dry seasons on groundwater pollution.

iii. The correlation between levels of pollutants in groundwater wells with

respect to distances (0-1.4km) between the wells and the dumpsite

iv. The correlation between levels of pollutants in groundwater wells with

respect to distances (0-30 m) between the wells and pit latrines

1.5 Research Hypotheses.

The research was guided by the following hypotheses;

i. Groundwater is polluted above the guidelines as determined by the Kenya

Bureau of Standards (KEBS,2006)

ii. Groundwater pollution is affected by seasons (wet and dry seasons)

iii. The levels of pollutants in groundwater wells correlate with the distances

between the dumpsite and the wells

iv. The levels of pollutants in groundwater wells correlate with the distances

between the pit latrines and the wells

1.6 Research Justification

Due to the growing population, there is need for more clean water for domestic

and other uses. Groundwater being one of the most viable options among others

such as rainwater harvesting or sea water desalination is faced with challenges

like migration of leachate from dumpsites and pit latrines. The pit latrines and

5

dumpsites when located close to groundwater recharge areas, can easily release

pollutants to groundwater through percolation of leachate. These pollutants get

leached into groundwater through percolation especially when the sources of

pollutants are haphazardly located close to water wells. The research determined

the concentrations of these pollutants with regard to: (a) guidelines as determined

by Kenya Bureau of standards (KEBS, 2006), (b) seasons, (c) distance from

dumpsite and (d) distance from pit latrines. The information obtained can help in

policy formulation on waste management and location of wells in order to abate

groundwater pollution.

1.7 Scope and Limitations of the Study

1.7.1 Scope of the Study

The research was carried out along the coastal region within Kilifi town and its

environs. The main focus was on the effects of dumpsite and domestic waste

leachate on groundwater quality. The study targeted inorganic, organic and

biological pollutants. Sampling was based on ten wells that continuously supply

water during wet and dry seasons without drying up.

1.7.2 Limitations of the Study

This research was an attempt to try and understand the pollution status of

groundwater at a limited space in time. The parameters measured were limited

due to financial constraints hence the results are limited in revealing trends over

time. The findings cannot therefore be used to predict pollution trends for the

study area or any other part of the country.

6

CHAPTER TWO: LITERATURE REVIEW

2.1 Introduction

This chapter reviews the relevant literature to the study. It gives definitions of

terms associated with groundwater, sources of groundwater pollution and

discusses the ill effects of some pollutants of concern to human health and the

associated risks. It also reviews the effects of dumpsite and domestic waste

leachate on groundwater.

2.2 Groundwater

Groundwater is water that exists in the pore spaces and fractures in rocks and

sediments beneath the Earth's surface. It originates as rainfall or snow, and then

moves through the soil profile into the groundwater system, where it eventually

makes its way back to surface streams, lakes, or oceans. It is naturally replenished

from above, as surface water from precipitation, streams, and rivers infiltrate into

the ground. Groundwater is a long-term storage of the natural water cycle as opposed

to short-term water reservoirs like the atmosphere and fresh surface water

(http:www.lenntech.com/drinking/standards, 20th January, 2014.1159hrs). The

pore spaces within which the groundwater is contained are referred to as aquifer.

There are two different types of aquifers based on physical characteristics: if the

saturated zone is sandwiched between layers of impermeable material and the

groundwater is under pressure, it is called a confined aquifer; if there is no

7

impermeable layer immediately above the saturated zone, it is called an

unconfined aquifer. Groundwater table is the surface of the groundwater exposed

to an atmospheric pressure above the surface of the saturated zone (aquifer).

Water tables may therefore vary in elevation from the surface and the depth to

groundwater affects its vulnerability to pollution (Bakis and Tuncan, 2010).

Groundwater pollution is the introduction or presence of organic, inorganic,

biological, radiological or physical foreign substances in water that tend to

degrade its quality. Among heavy metals in Municipal Solid Waste (MSW)

leachate, lead presents the greatest threat for pollution of groundwater that serves

as domestic water supply. Leachate from some MSW landfills contain sufficient

concentrations of lead to cause leachate contaminated groundwater to contain

levels of lead that impair the use of the groundwater for domestic water supply

(Fred and Jones, 2009). Most concern over groundwater pollution has centered

on pollution associated with human activities like haphazard dumping of wastes

followed by incineration of the wastes (plate 2.1).

Plate 2.1: Incineration of Municipal solid wastes at the dumpsite.

8

This practice is meant to reduce the volume of the waste so as to increase the

lifespan of the dumpsite; a practice which increases contamination risk to

groundwater and constitutes potential environmental and public health problems.

It also destroys the organic components and oxidizes the metal wastes and in the

process, enriches the ashes left behind in metal. Odukoye et al., (2001) pointed

out that leachate from such dumpsites constitutes major sources of heavy metal

pollutants to both soil and aquatic environment. Depending on the environmental

conditions, such pollutants reach groundwater aquifers through the infiltrating and

percolating water. The degraded environment thus increases groundwater

pollution.

Saltwater encroachment associated with over drafting of aquifers or natural

leaching from naturally occurring deposits is considered under natural sources of

groundwater pollution and is equally important. The sources of groundwater

pollution include, natural, agricultural, industrial and residential. Natural

groundwater contains some impurities, even if it is unaffected by human activities

(Pickford, 1986). The types and concentrations of natural impurities however;

depend on the nature of the geological material through which the groundwater

moves and the quality of the recharge water. For example, groundwater moving

through sedimentary rocks may pick up a wide range of compounds such as

magnesium, chlorides and calcium while some aquifers naturally have strong

concentrations of arsenic, boron and selenium (Weiner and Mathews,

2007).Agricultural pesticides, fertilizers, herbicides and animal wastes are

9

potential groundwater polluters depending on how they are handled, stored and

used. Examples of these include: using chemicals uphill a few meters of a well;

storage of agricultural chemicals near conduits to groundwater, or storage in

surface depressions where ponded water is likely to accumulate; storage of

chemicals in uncovered areas unprotected from wind and rain or in locations

where the groundwater flows from the direction of the chemical storage to the

well while industrial sources include manufacturing and service industries

(Jorgensen and Johnson, 1989).When businesses, have no access to sewer

systems, they use cesspools or dry holes, or send the wastewater into septic tanks.

Any of these forms of disposal can lead to pollution of groundwater sources. Dry

holes and cesspools introduce wastes directly into the ground. Wastewater

disposal practices of certain types of businesses, such as automobile service

stations, dry cleaners, electrical component or machine manufacturers, photo

processors, and metal platters or fabricators are of particular concern because the

wastes they generate are likely to contain toxic chemicals. Other industrial

sources of pollution include cleaning off holding tanks or spraying equipment on

the open ground, disposing of waste in septic systems or dry wells, and storing

hazardous materials in uncovered areas or in areas that do not have pads with

drains or catchment basins (Odukoye et al., (2001).

Residential wastewater system remains one of the major sources of a number of

categories of contaminants, including bacteria, viruses, and nitrates from human

waste as well as organic compounds like the BOD. Injection wells used for

10

domestic wastewater disposal are of particular concern to groundwater quality if

located close to drinking water wells. Poor disposal of household chemicals such

as paints, synthetic detergents, solvents, oils, medicines, disinfectants, pool

chemicals, pesticides, batteries, gasoline and diesel fuel can lead to severe

groundwater pollution (Osu and Okoro, 2011). When stored in garages or

basements with floor drains, spills and flooding may introduce such contaminants

into the groundwater. When thrown in the household trash, the products will

eventually be carried into the groundwater because community landfills are not

equipped to handle hazardous materials. Similarly, wastes dumped or buried in

the ground can pollute the soil and leach into the groundwater (Buckinggham,

P.L. and Evans, J.C. 2003).

2.3 Effects of Pollutants on Health.

Water naturally contains small amounts of dissolved substances like zinc,

calcium, magnesium and even impurities like silt, sand and microbial substances

under normal circumstances. These quantities are considered safe for human use;

however, when they exceed threshold limits, then the water is polluted (Michael,

2001). Metal ions and their complex exhibit a wide range of toxicity to organisms

ranging from sub lethal to lethal, depending upon time of exposure and the

ambient temperatures. For example, the heavy metals; Pb, As, Cd, Cr, Mn, Ni,

and Hg are highly toxic even in low concentrations (Sangarika, et al., 2010).

Cadmium and lead are some of the heavy metals that are hazardous to human

health for example; long term exposure to lead can cause severe disruption of

11

biosynthesis of hemoglobin and anemia, high blood pressure, damage to kidneys,

miscarriages, brain damage, sperm damage in males and disruption of nervous

system. Mercury can cause brain and kidney damage as well as interference with

the nervous system, birth defects, miscarriages, and damage to DNA; while

elevated manganese levels can disrupt the nervous system and regeneration of

hemoglobin (GSADH, 2005). When these pollutants are dumped haphazardly in

landfills, the resulting leachate easily percolates into groundwater thus causing

groundwater pollution. Leachate from ash landfills is likely to have elevated pH

and to contain more salts and metals than other leachate. Household batteries and

fluorescent tubes make a small quantity of landfill wastes by volume but are a

significant source of pollutants (Odukoye et al., 2001). More than 80% of

mercury in solid wastes can in fact be traced to electronic substances, especially

batteries (Michael, 2001).

The other groundwater pollutants of concern are the pathogens and nutrients.

Pathogens such as coli.forms mainly come from sewage. E.coli as a portion of the

coli form bacteria group originating in the intestinal tract of warm blooded

animals is an indicator of the bacteriological contamination of domestic water

supply. Their presence in domestic water is of great concern because of the many

diseases they cause to human beings. Similarly, nitrogen limits the oxygen

carrying capacity of red blood cells in infants causing a condition referred to as

methemoglobinemia or blue baby syndrome (Osu and Okoro, 2011).

12

2.4 Effects of Dumpsite and Domestic Waste Leachate on Groundwater

Any waste treatment system generates residues that eventually need to be land

filled. The landfill is the only final sink of any waste; nonetheless, it can only hold

on to the title as the ultimate sink for waste as long as it does not release its

leachate. Unfortunately, this is not the case in practice for example, in Tanzania;

sites where agrochemicals were ineptly stored are still polluting water and soil

(NEMC, 1998). According to Kaseva and Mbuligwe (2002), leachate from the

now closed and abandoned Tabata and Vingunguti solid waste disposal sites in

Dar es Salaam City pollute the Msimbazi River more than ten years after the

former was decommissioned. Guidelines and specifications for planning, design,

operation, and closure as well as post-closure care requirements of disposal sites

for all types of wastes are detailed in the literature (Bagchi, 2004; Corbit, 1993

and LaGrega, 1994).Through leaching, contaminants are transferred from a

stabilized matrix such as waste dumpsite to a liquid medium such as water

(LaGrega, et al., 1994). Waste dumpsites and pit latrines are some of the major

sources of pollutants to groundwater. Nitrogen and phosphorous compounds are

present in significant amounts in all domestic waste water and mainly come from

human excreta and detergents. They easily contaminate groundwater through

migration of leachate from pit latrines (Osu and Okoro, 2011).

Worldwide, wastewater emanates from sewage, industrial runoff, agricultural

runoff, storm water and urban runoff among others. It can be a mixture of natural

and manmade organic and inorganic substances. Wastewater can be split into

13

domestic (sanitary) wastewater, industrial wastewaters and municipal

wastewaters. With increasing population, wastewater is bound to increase and a

lot of emphasis is on their pollution effects and the economics for their mitigation.

Variation of groundwater quality is influenced by factors such as biological and

physicochemical parameters. These parameters are influenced by geological and

anthropogenic activities (Subramani, et al., 2005). Studies have shown that impact

assessment of pollution sources of groundwater, have been receiving major

attention both now and in the past (Ozler, 2001; Ikem, et al., 2002; Ebong et al.,

2007 and SiaSu, 2008). Sources of major concern to groundwater pollution

include leachate from pit latrines, solid waste dumpsites, industrial effluents,

domestic wastes, sea water intrusion, agricultural chemicals, and oil spillage.

These sources can generate many types of pollutants including heavy metals,

nitrogen species, chlorinated hydrocarbons phenols, cyanides, and bacteria among

others (Yusuf, 2007).

2.5 Previous Studies on Groundwater

Several studies have been done on the environmental impacts of waste dumpsites

and pit latrines on groundwater quality in Kenya and other parts of the world.

Studies on health implications have shown that high levels of nitrates are quite

toxic to human health and the toxicity is as a result of the natural reduction of

nitrates to nitrites by gastric enzymes. According to Boumediene et al., (2004), it

causes serious disturbances to the exchange system that leads to blue baby

syndrome and formation of nitrosamines which supposedly produce carcinogenic

14

cells in adults. Heavy metals can adversely affect mental and neurological

functions and alter metabolic processes in the human body including impairment

and dysfunctions in blood, cardiovascular, endocrine, immune, reproductive and

urinary system (Okuo, et al., 2007). Leachate from dumpsite has been reported as

a significant threat to groundwater even if it does not contain hazardous wastes.

The use of groundwater for domestic purposes especially from shallow wells in

areas where dumpsites and pit latrines are haphazardly located is of utmost

concern to human health as safe and good quality drinking water is essential for

good health. The heavy metal concentration in drinking water should be kept as

low as possible (Lu, 1985).

Local and national authorities demand that wastewaters are treated by the polluter

to some agreed standards before discharge to local authority sewer or water

bodies. Towns usually have large centralized waste water treatment systems that

are run by the local authorities. In the developing countries, conventional

biological treatment systems like oxidation ditches, activated sludge, septic tanks,

trickling filters and waste stabilization ponds are quite common. These systems

are costly to implement and run and attention has been shifted to the use of onsite

sanitation systems for disposal of domestic wastewater.

2.6 Composition of Domestic Wastewater.

Domestic sewage is composed of black and grey water where black water is that

from the toilets and grey water is from bathrooms and kitchen. These waters are

15

basically composed of organic matter with traces of inorganic substances. The

raw wastewater also contains nutrients such as nitrogen and phosphorous. Such

impurities do pollute groundwater and surface waters through migration to water

bodies. Sewage is about 99.9% water but the specific pollutant composition of

domestic wastewater varies both in the constituents and their concentration (Gray,

2009).

2.6.1 Nitrogen in Wastewater

Nitrogen does exist in wastewater in many forms like organic nitrogen, ammonia,

nitrites and nitrates. Nitrogen is usually measured as Kjeldhal nitrogen. This is the

sum of organic nitrogen and ammonia nitrogen present. Total nitrogen is the sum

of Kjeidhal nitrogen and the oxidized nitrogen. In raw wastewater and settled

wastewater, there is no oxidized nitrogen present and therefore the total nitrogen

is equal to the Kjedhal nitrogen (Gray, 2009). In terms of water quality, the

nutrients are considered pollutants when their concentrations are sufficient to

allow excessive growth of aquatic plants especially algae. It lowers the

attractiveness of the water body as drinking water supply because of its viability

as a habitat for other living things. It leads to Eutrophication of water bodies

through nutrient enrichment which is a big threat to human health when such

sources are used for domestic purposes.

16

The algal blooms that result eventually die and decompose thereby lowering the

levels of dissolved oxygen (DO). The DO can be lowered to levels too low to

sustain normal life forms. The algae and decomposed organic matter add colour,

turbidity, odour and objectionable tastes to the water. The nitrogen in the form of

nitrates in water can be converted into highly toxic nitrites in infant’s intestinal

tracts when consumed (Keter, et al., 1997).

2.6.2 Organic Matter in Wastewater

Most organic materials are water soluble. They may come from natural sources or

they may result from anthropogenic activities. Most natural organics consist of the

decayed products of organic solids while synthetic organics usually come from

agricultural activities. The soluble organics can either be biodegradable or non-

biodegradable. The biodegradable organics are those that can be utilized as food

by naturally occurring micro-organisms within a reasonable time and they usually

consist of proteins, starch, fats, acids, esters, alcohol and aldehydes which may be

end products of initial microbial decomposition of plant and or animal tissues.

Alternatively they may result from industrial or domestic wastewater effluents.

Some of these products cause colour, taste and odour in water but the most

significant problem associated with them is the action of microorganisms on

them. The amount of oxygen used by the microorganisms while utilizing the

organics is referred to as biochemical oxygen demand (BOD).

The organic matter concentration in wastewater is expressed through

measurements of the oxygen consumed during the decomposition. The parameters

17

used in characterizing the amount of organic matter in such wastewaters are the

Biochemical Oxygen Demand (BOD), the chemical oxygen demand (COD), the

Total Organic Carbon (TOC) and the Theoretical Oxygen Demand (ThOD). The

daily per capita output of organic wastes is about 30-50 grams as BOD, and about

half of it is associated with urine and faeces and half with grey water (Pickford,

1986).

The BOD refers to the amount of oxygen consumed over a five day period and is

the parameter used in characterizing the organic matter in wastewater. The five

day test for BOD, is done by placing wastewater samples into two standard bottles

of 300ml. One sample is analyzed immediately to measure the initial amount of

dissolved oxygen in the wastewater often using a Winkler titration (Weiner and

Mathews, 2007).

Chemical Oxygen Demand (COD) is another parameter used for the

characterization of wastewater. It refers to the oxygen equivalent of the organic

matter in wastewater that can be oxidized chemically using potassium dichromate

in an acid solution (usually sulphuric acid). This method is however less specific

since it measures everything that can be chemically oxidized rather than just the

levels of biologically active organic matter but a mathematical relationship is

usually worked out for the particular wastewater to translate COD to the time

consuming BOD (Jorgensen and Johnsen, 1989).

18

2.6.3 Pathogens in Domestic Wastewater

Pathogens are disease causing organisms. Their presence and concentrations in

wastewater is reflected through biological indicators called “indicator organisms”.

The Escherichia coli (E.col) originate from intestinal tract of warm blooded

animals and are usually an indicator of the presence of pathogens in water. In the

United States of America, a standard of no coli form in 100ml of water has been

used as a threshold for safe water (Gray, 2009). The World Health Organization

(WHO, 2006) and the Kenya Bureau of Standards (KEBS, 2006) guidelines of

zero coli form per 100ml are recommended for drinking water. The presence of

coli forms in water does not necessarily mean that pathogenic organisms are

present in the water but is an indicator that such pathogens might be present

(Weiner and Mathews, 2007)

2.6.4 Physical and Heavy Metals in Waste Water

Physical characteristics of waste water are the solid contents, color, temperature

and odour. Domestic water is usually grey to yellow–brown depending on the

time of the day (Gray, 2009). Waste water temperatures do vary with season and

the source but generally they are warmer than the air temperatures except for very

warm months, since the specific heat capacity of water is much greater than that

of air. Raw sewage is turbid and has small but visible particles of organic material

which settles readily from the suspension. Total solids include those materials that

are left behind in a container when water evaporates usually at a temperature of

103-105 degrees Celsius (Weiner and Mathews, 2007). The total solids consist of

19

insoluble and suspended solids and soluble compounds dissolved in water. In

waste water about 40 percent of the solids are suspended. Heavy metals

accumulate in the environment in different geochemical forms that is; water

soluble, exchangeable carbonate-associated, Fe-Mn oxide-associated, organic-

associated and residual forms (Osu and Okoro, 2011). Measurements of metal in

aquatic environments are an important monitoring tool to assess the degree of

pollution (Sangarika, et al., 2010).The toxicity and mobility of heavy metals in

soils depend not only on the total concentrations but also on their specific

chemical form, binding state, metal properties, environmental factors and soil

properties like pH and organic matter content (Osu and Okoro, 2011).

Exposing an individual to concentrations beyond permitted threshold limits

normally leads to toxicity. In Kenya, the Kenya Bureau of Standards

(KEBS,2006), established a concentration of 0.005mg/L as permissible for Cd,

10mg/L for total nitrogen, 400mg/L for suphate, 0.05 mg/L for lead, 0.1mg/L for

manganese, 5mg/L for zinc, 100mg/L for magnesium, (6.5-8.5) for pH and zero

counts per 100ml for coli forms in drinking water. In this study, the variables

cadmium, lead, manganese, magnesium, biochemical oxygen demand, total

nitrogen, Total coli.forms, Escherichia coli.forms, suphate, zinc as well as the

physical parameters temperature, pH and electrical conductivity were measured

and compared with the Kenya Bureau of Standards (KEBS, 2006) guidelines in

order to determine the safety of groundwater within Kilifi town.

20

CHAPTER THREE: MATERIALS AND METHODS

3.1 Introduction

This chapter describes the methods and materials that have been used in this

study. The study was conducted within Kilifi town in Kilifi County, Kenya. The

latest population census estimates that the town has about 70,000 people,

excluding tourists who visit from time to time depending on the season. The area

is facing problems concerning waste disposal and sites of discarded and

unmanaged wastes are common features within the town and its environs. Open

dumpsites and pit latrines are predominantly used for solid and domestic waste

disposal. The town is supplied by tap water through Kilifi Malindi Water and

Sewerage Company (KIMAWASCO) from Baricho water works but frequent

breakdowns and insufficient water supply mainly for domestic uses has forced

many residents to embrace the groundwater option.

In order to avoid mixing sea water with fresh water, the sources of groundwater

over the coastal region, mainly the wells have shallow depths (about 16m deep)

making them highly vulnerable to pollution particularly when located near pit

latrines, dumpsites or soak pits. Limestone and sandy formations are prevalent

within the coastal region and they form the main areas of recharge to the aquifers.

The high permeability and hydraulic conductivity make the aquifers highly

vulnerable to pollution through the leachate produced from pit latrines, soak pits

and dumpsites. The pollution is exacerbated by haphazard dumping of wastes.

21

The local Swahili houses use pit latrines for sewage disposal, and many of these

houses have bathrooms next to the toilets, that drain wastewaters directly into the

pit latrines thus accelerating groundwater pollution. Sewage is associated with

the introduction of pathogens in water that lead to water borne diseases like

cholera, dysentery, typhoid, diarrhea, intestinal worms, skin diseases, eye

infections among others.

3.2 The study Area

The study area is in Kilifi County, Kenya (Fig. 3.1). It is bounded approximately

by longitudes 039 51 E and 039 52 E and latitudes 0336 S and 03 38 S. It is

situated close to the Indian Ocean, approximately 60 km north of Mombasa city

along the Mombasa - Malindi highway and covers about 13Km2 (Fig. 3.1). The

area is densely populated but it is not connected to a centralized sewer system

thus domestic wastes are mainly managed by pit latrines and soak pits while solid

wastes are land filled on dumpsite. The common practice of digging pit latrines to

groundwater table is very popular in the study area and has significant impact on

groundwater quality. The dumpsite is not designed for waste disposal but is used

because of its convenience to the source community. Sites of discarded and

unmanaged wastes are quite common within the town and its environs. The

wastes emanate from residential houses, hotels, health facilities, schools, colleges,

petrol stations, government prison, slaughter houses, wood and metal workshops

and they are collected regularly by the council Lorries for dumping.

22

3.2.1 Location

The study site is located in Kilifi County, Kenya. It is bordered by the Indian

Ocean to the South and to the East. The West is bordered by the Mombasa

Malindi highway which is connected to Kilifi town through the famous Kilifi

Bridge. The dumpsite is situated next to the Mombasa Malindi highway and

covers approximately 700 m2 (Figure 3.1).

Figure 3.1. Map showing the study area (Kilifi Town), locations of the

sampled wells, dumpsite and Pit latrines.

23

3.2.2 Climate

The study area falls within the Kenyan Coast line. The Coast line lies within the

hot tropical region and the weather is influenced by the great monsoon winds

from the Indian Ocean. The Coastal climate is influenced by two monsoon

periods. From March to April the monsoon winds blow in an East to South-

easterly direction bringing in strong incursions of maritime air from the Indian

Ocean that bring heavy rains while from November to March, the Northeast

Monsoon remain dominant bringing in dry weather conditions. From May to

August, the Southeasterly monsoon dominates bringing in comparatively cooler

temperatures (UNEP, 1998b). The Coastal annual rainfall follows a strong

seasonal pattern being influenced by the Inter-Tropical Convergence Systems

(ITCS). The long rains come between March and June while some short rains

come between October and November (UNEP, 1998b). The mean annual rainfall

ranges between 508mm in the Northern hinterland and 1016mm in the wetter

areas. Mombasa town which is within the Coast line, experiences the strongest

winds within the Coastal region (Kensea, 2006) but the relative humidly is high

all the year round along the Coastal region with peaks in April to July.

3.2.3 Geology

The Coastal environment is set up in a passive continental margin which was

initiated by the break-up of the mega continent Gondwanaland in the lower

Mesozoic (Abuodha, 1998). The initial opening of the Indian Ocean was preceded

by doming, extensive faulting and down warping similar to that observed in the

24

Great Valley of East Africa. The tectonic movements formed a north south

trending depositional basin which was exposed to several marine incursions

during the Mesozoic period with well defined marine conditions. It underwent

further faulting and extensive continental erosion throughout the Tertiary with

much older Cretaceous deposits totally removed (Caswell, 1953). The current

coastal configuration has been evolving and is marked by numerous sea level

fluctuations. The Coastal margin is of sedimentary origin and range in age from

Triassic to recent. The older rock formation of the Duruma sandstone series is

represented by the Mariakani and Mazeras sandstones which were deposited

under subaqueous and deltaic conditions that prevailed before the opening of the

Indian Ocean (Caswell, 1956). The Upper Mesozoic is represented by marine

limestone and shale with occasional horizons of sandstones, gravels, and clays.

The Coastal region has three physiographic zones namely; the Nyika plateau that

lies approximately 600m above sea level representing the higher ground covered

by the Duruma sandstone series, the Foot plateau which lies between 140m and

600m above sea level and comprises mainly the Jurassic rocks and the Coastal

plain which happens to be the lowest level rising from the sea level to about

140m. The geomorphology is dominated by a series of old elevated terraces that

make the current Coastal environment with the shore configuration lying on the 0-

5m and the 5-15m sea level terraces (Kensea, 2006). The Coastal region

comprises mainly sedimentary rocks consisting of limestone, sandstones,

siltstones and shale that offer very high infiltration rates and makes the

25

unconfined aquifers below highly vulnerable to pollution especially in areas

where the environment is degraded (Osu and Okoro, 2011).

3.2.4 Hydrology

The hydrology is composed of the drainage patterns of seasonal and permanent

rivers that drain into the Western Indian Ocean basin. The basin has rivers Tana

and Sabaki originating respectively from Mount Kenya and Ngong Hills. Both

rivers are permanent and tap water supplied to Kilifi town is from river Sabaki

which drains into the Indian Ocean through the Sabaki estuary situated to the

north of Malindi town. The rising populations coupled with the economic

activities have serious environmental impacts on the drainage basin as wastes are

discarded anyhow and when they rot, the drainage water easily dissolves the

resulting constituents thereby polluting surface and subsurface sources of water.

3.3 Research Design

Purposive sampling was used in data collection. The first sampling of wells was

done during the dry season in the months of January, February and March, 2011.

Second sampling was done after the long rains in July, August and September,

2012. The pollutants of concern in the water samples included; toxic metals,

pathogens and nutrients. In-situ measurements of PH, electrical conductivity and

temperature were done on freshly collected water samples. A total of ten (10)

wells were identified that covered the entire study area (Figure 3.1).The area was

chosen for this study because of the increased number of wells in use and their

relative closeness to pit latrines and dumpsite. The choices were determined by

26

the general groundwater flow direction and the fact that they do not dry up

during the dry season as evidenced for the last three (3) years. Their distribution

was as follows: three were situated within the low population density residential

area, four within the CBD, and three within the high population density

residential area (Figure 3.1).

3.4 Sampling Procedure and Sample Size

Ground water samples were taken during dry and wet seasons. The samples

were collected at an average depth of 16 m during dry season and approximately

14 m during wet season. The levels of water in the wells had dropped during the

dry season by an average of about 2m. For each season, three samples were taken

from each of the ten wells. A total of sixty (60) samples were collected in the

two seasons. The water samples were collected in two liter sampling bottles.

The bottles were previously cleaned by soaking in 10% nitric acid. The bottles

were rinsed with distilled water and rinsed again three times with the sampled

water at the site. Each sampling container was corked after filling with sampled

water using lids and kept in a cool box for transfer to the laboratory for safe

custody under refrigerated conditions at 40C to avoid sample deterioration.

3.4.1 In-Situ Measurements

The physical parameters; temperature, electrical conductivity and pH were

determined in the field on freshly collected water samples. The pH was measured

using a Jenway model 3100 pH meter. Electrical conductivity (EC) was

27

determined using conductivity meter Jenway model 4076 and both of them had

automatic temperature compensation.

3.4.2 Analytical Method

Samples for microbiological analysis, Sulphate, BOD5, and Total Nitrogen were

collected into sterilized 1-liter plastic bottles making sure that no air bubbles were

present. They were stored in an ice box at 4 0C and taken to the laboratory within

the stipulated time of 6 hours. The analysis was done in the laboratory as

prescribed by the Standard Methods for the analysis of Water and Wastewater

(APHA, 1998). For the bacteriological analysis, the plates were incubated at 35

0C for 24 hours (Plate 3.2). Total coli.forms and Escherichia coli.forms in the

water were enumerated by the membrane filtration technique using M-Endo-Agar

Les at 37 0C and on MFC Agar at 44

0C respectively. Analyses of the metals Pb,

Mg, Mn, Zn, and Cd were done using atomic absorption spectrophotometer

(AAS) Buck Scientific-210 VGP, air-acetylene flame (Plate 3.1). Standard stock

solutions for each metal analyte were prepared using respective analar grade

reagents dissolved in distilled water for each analyte in order to prepare the

calibration curves and the results were given in milligrams per liter (mg/l).

Samples for trace metal analysis were acidified to pH < 7 by adding nitric acid but

the samples for anion analysis were not acidified.

28

Plate 3.1: Laboratory Analysis of trace metals using AAS

Plate 3.2: Incubation of plates for analysis of coli forms

29

3.5 Data Analysis

The data collected was analyzed using Matlab software by comparing the mean

measurements of the pollutants in water samples to the recommended guidelines.

Correlation analyses were done to determine the relationship between the levels

of pollutants in wells as compared to the distances between the wells and the pit

latrines. Principal Component Analysis (PCA) was performed to determine the co

linearity among the variables and the results of the analyses are presented in

tables and graphs.

30

CHAPTER FOUR: RESULTS AND DISCUSSIONS

4.1RESULTS

4.1.1 PH

The groundwater pH for wet and dry seasons versus the Kenya Bureau Of

standards (KEBS, 2006) guidelines is presented in Figure 4.1 below.

Figure 4.1: Mean pH values for the ten wells measured during the dry and

wet seasons.

PH indicates the samples acidity but is actually a measurement of the potential

activity of hydrogen ions (H+) in the sample. The PH measurements run on a

scale from 0 to 14, with7.0 considered neutral. PH below 7.0 is considered acidic

and those above 7.0 are considered bases. The PH is a critical factor determining

the health of a water source as all organisms are subject to the amount of acidity

and function best within a given range. When acidic water comes into contact

1 2 3 4 5 6 7 8 9 100

1

2

3

4

5

6

7

8

9

Wells

pH values

pH lower -KEBS

pH Upper -KEBSdry

wet

31

with certain chemicals and metals, it makes them more poisonous than normal.

The PH of a water body can be affected by many factors. Some of the key factors

include; bedrock and soil composition through which the water moves both in its

bed and as groundwater as well as the amount of plant growth and organic

material within a water body.

The results show that the groundwater remained slightly alkaline during the dry

season in all the wells. Only two wells (wells 3 and 5) were slightly acidic during

the wet season probably due to influx of effluents from pit latrines. The results

show some slight variation in groundwater PH in dry and wet seasons however; in

both seasons the PH was within the acceptable range of 6.5 to 8.5.

4.1.2 Temperature

The groundwater temperature for wet and dry seasons is presented in Figure 4.2

below.

Figure 4.2: Mean temperatures values for the ten wells measured during dry

and wet seasons.

32

From the results, the groundwater temperatures were slightly higher in 50% of the

sampled wells during dry season compared to wet season. The temperatures tend

to increase during drier seasons and thus moderately affect groundwater

temperatures. In both seasons however, the temperatures ranged between 28 0C

and 30 0C. Water temperature is an important factor because it influences the

amount of dissolved chemicals and other pollutants as well as the amount of

dissolved oxygen (DO) in the water. Because the temperature variations were

minimal in the two seasons, its effect on pollution was negligible.

4.1.3 Electrical conductivity

The electrical conductivity for wet and dry seasons as compared to KEBS

guideline is presented in Figure 4.3

Figure 4.3: The graph of electrical conductivity for the ten wells measured

during the dry and wet seasons

33

Conductivity is a measure of the ability of water to pass an electrical current.

Conductivity in water is affected by the presence of inorganic dissolved solids

like nitrate, sulpate and phosphate anions or cations like sodium, magnesium and

iron. Conductivity in groundwater is affected by the geology of the area through

which the water flows. The results indicate that all the wells had very high

electrical conductivity as compared to the guideline thus implying that the water

is not suitable for drinking. The coastal belt generally has higher amounts of

sodium salts due to seas water intrusion and this can account for the high

conductivity in all the sampled wells. The conductivities were higher in 90% of

the sampled wells in wet season compared to dry season. This was caused by

influx of more anions and ions through leaching.

4.1.4: Lead (Pb)

The graph of Lead for wet and dry seasons as compared to KEBS guideline is

presented in Figure 4.4

Figure 4.4: The graph of Lead for the ten wells measured during the dry and

wet seasons.

1 2 3 4 5 6 7 8 9 100

0.1

0.2

0.3

0.4

0.5

0.6

Sapmled Wells

Mg/

L

Concentration of Lead

Pb KEBS

dry

wet

34

Lead is one of the most toxic metals because it affects the nervous system and has

damaging effects on the brain and kidneys. Infants and children who drink water

containing lead in excess of the action level could experience delays in their

physical or mental development. The children could have deficits in attention

span and learning abilities while adults who take such waters could easily develop

kidney problems or high blood pressure. The KEBS recommended guideline limit

in drinking water is 0.05 mg/l. In both seasons the graphs show that the levels of

lead fell below the guideline limit. This implies that the groundwater is not

polluted with lead.

4.1.5: Manganese (Mn)

Figures 4.5 shows the graph of the mean levels of manganese in groundwater as

compared to KEBS recommended guideline limits for drinking water.

Figure 4.5: The graph of Manganese for the ten wells measured during the

dry and wet seasons.

1 2 3 4 5 6 7 8 9 100

0.1

0.2

0.3

0.4

0.5

0.6

Sampled Wells

Mg/

L

Concentration of Manganese

KEB

dry

wet

35

The results indicate that all the wells recorded higher levels of manganese than

the recommended guideline during the wet season while during the dry season,

only one well registered slightly less concentration as compared to the guideline.

This could have been as a result of the distance from the dumpsite (1.2km) or its

relative location to the pit latrine. Manganese is found naturally in groundwater

and can fluctuate seasonally and varies with the depth and location of the well and

the geology of the area. It is also common in areas where groundwater flow is

slow and also in areas where groundwater is polluted with organic matter. The ill

effects of manganese in human via inhalation include neurotoxin causing ataxia,

co-ordination impairment, anxiety, dementia and involuntary movement similar to

Parkinson’s disease. The results imply that the groundwater is not suitable for

domestic purposes.

4.1.6: Cadmium (Cd)

Figures 4.6 shows the levels of cadmium in groundwater for wet and dry seasons

against the recommended KEBS guideline limit of 0.005 mg/l.

36

Figure 4.6: The graph of Cadmium for the ten wells measured during the dry

and wet seasons.

From the graph, all the wells recorded higher levels of cadmium in both seasons.

Wells number 1, 2, 3, 4, 5, and 9 registered same amounts of cadmium in both dry

and wet seasons but wells number 6,7 and 10 registered more cadmium during the

wet season than during the dry season. This suggests that during the wet season,

wells number 6, 7 and 10 received more influx of cadmium through migration of

leachate from the dumpsite as a result of increased moisture. When municipal

waste especially cadmium containing batteries and plastics, or cadmium-plated

steel and electronic wastes are incinerated, the releases can be carried to and

deposited on areas remote from the source. Incineration of such waste is often

practiced at the dumpsite to reduce the volume and this enhances the release of

cadmium ions. Cadmium exerts toxic effects on the kidney, skeletal system and

1 2 3 4 5 6 7 8 9 100

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

0.05

Sampled Wells

Mg/

L

Concentration of Cadmium

KEBS

dry

wet

37

the respiratory system and causes disruption of biosynthesis of hemoglobin. It is

also carcinogenic. The results imply that the source is unsuitable for domestic use.

4.1.7: Total Nitrogen (TN)

Figures 4.7 shows the levels of Total Nitrogen in groundwater for wet and dry

seasons against the recommended KEBS guideline limit of 10 mg/l.

Figure 4.7: The graph of Total Nitrogen for the ten wells measured during

the dry and wet seasons.

The measurements were compared to guidelines as recommended by KEBS.

The results show that during the wet season, 90% of the samples recorded higher

values than the KEBS guideline while during the dry season, only 70% of the

wells had higher values than the KEBS guideline limits. In general, the

38

groundwater recorded more nitrates in wet season which could have been as a

result of increased leaching of the nutrients caused by the rainfall. When nitrates

in domestic water exceed the thresholds, it can result to illnesses like

methemoglobinemia (blue baby syndrome) in children and nitrosamine in adults.

The toxicity of nitrates comes from the natural reduction of nitrates to nitrites by

gastric enzymes in human system. This water source is therefore a health hazard

particularly to pregnant mothers and infants and should not be used for domestic

purposes.

4.1.8: BOD

Figure 4.8 shows the levels of BOD for wet and dry seasons compared to

recommended guidelines as provided by the KEBS.

Figure 4.8: The graph of BOD for the ten wells measured during the dry and

wet seasons.

1 2 3 4 5 6 7 8 9 10

0

10

20

30

40

50

60

70

Sampled Wells

Mg/

L

Concentration of BOD

KEBS

dry

wet

39

The results show that the levels of BOD in groundwater were above the

recommended guideline limits as recommended by KEBS. The measurements of

BOD were higher during the wet season than during the dry season in all the

sampled wells. This was as a result of increased inflow of organic matter from the

pit latrines due to increased moisture. The problem which is associated with BOD

in drinking water is the action of microorganisms on them which results to

reduction in the amount of dissolved oxygen. This implies that the groundwater

remained polluted with BOD in both seasons making it unsuitable for domestic

use throughout the year.

4.1.9: Sulphate

Figures 4.9 shows the levels of sulpate in groundwater for wet and dry seasons

against the recommended KEBS guideline limit of 400 mg/l.

Figure 4.9: The graph of sulphate for the ten wells measured during the dry

and wet seasons.

1 2 3 4 5 6 7 8 9 100

50

100

150

200

250

300

350

400

450

500

Sampled Wells

Mg/

L

Concentration of Sulphate

KEBS

dry

wet

40

The results show that suphate levels were below the KEBS guideline limit of 400

mg/l in both seasons. Higher levels of sulphate concentrations were however

registered during the wet seasons compared to dry seasons in all the wells. This

difference can be explained in terms of increased moisture in the ground that

leached the sulphate into groundwater. The mean range of suphate varied between

37 and 116mg/l during dry season while during wet season the range was between

60 and 166mg/l which represents a percentage increase of between 30% and 38%.

4.1.10: Total Coli

Figures 4.10 shows the levels of Total coli forms in groundwater for wet and dry

seasons against the recommended KEBS guideline.

Figure 4.10: The graph of Total coli.forms counts for the ten wells measured

during dry and wet seasons.

1 2 3 4 5 6 7 8 9 10-2000

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

Sampled Wells

Tot

al C

olifo

rm c

ount

s/10

0 m

l

Total Coliform Cocentration

KEBS

dry

wet

41

The results show that the levels of Total coli.forms counts in groundwater were

higher in wet seasons than in dry seasons in all the wells that were polluted. All

the wells recorded higher levels of total coli.forms in both wet and dry seasons.

The first well (well number 1) which was closest to a pit latrine (10m) recorded

the highest concentration of Total coli.forms counts (18630 and 16453

counts/100ml for wet and dry seasons) while well number ten (10) which was

furthest (30m) from the nearest pit latrine recorded the least amount of Total

coli.forms counts (257 and 180 counts/100ml for wet and dry seasons). This is an

indicator that there is some correlation between levels of pollution and distance

between the well and the pit latrine. Total coli forms are a group of closely related

bacteria that may not necessarily be harmful to human; however Environmental

Protection Agency (EPA) considers them useful indicators of pathogens that need

to be investigated. According to Total Coli form Rule (TCR), these symptoms

comprise a general category referred to as gastroenteritis which may not be

serious for healthy people but can lead to serious complications for people with

weakened immune systems.

4.1.11 Escherichia coli.forms

Figure 4.11 shows the levels of Escherichia coli.forms counts/100ml for wet and

dry seasons compared to the KEBS recommended guideline.

42

Figure 4.11: The graph of Escherichia coli.forms counts for the ten wells

measured during dry and wet seasons.

The graph shows that all the wells except wells number 6 and 7 were polluted

with Escherichia coli.forms in both seasons. Well number one had the highest

level of pollution. During wet seasons, higher levels of the pollutant were

recorded compared to dry seasons. This difference could have been caused by

increased percolation as a result of rainfall. Well number one was situated 10m to

the nearest pit latrine and this could have probably resulted to the higher level of

pollution. Wells number 5 to 10 were situated more than 20 m to the nearest pit

latrines and their levels of pollution were generally lower than the first four wells

that were situated less than 16m to the nearest pit latrines. The results show that

1 2 3 4 5 6 7 8 9 10-500

0

500

1000

1500

2000

2500

KEBS

Sampled Wells

Counts

/100m

L

Escherichia Coliform Cocentration

dry

wet

43

there is a correlation between the levels of pollution and the distance between the

well and the pit latrine. The presence of Escherichia coli.forms in drinking water

is reflected through biological indicators like the total coli.forms. The Escherichia

coli.forms originates from intestinal tract of warm blooded animals and is usually

an indicator of the presence of pathogens in water. Their presence in drinking

water is of great concern because of the many diseases they cause to human

beings.

4.1.12: Levels of Total coli.forms as a Function of Distance from Pit Latrine

T.coli counts were plotted against the distances from the pit latrines to determine

the correlation. The correlation analyses were done in order to gauge the “safe

distance” between the pit latrines and a well. Figures 4.12 and 4.13 show the

correlations between the levels of Total coli.forms in ground water wells as a

function of distance from the pit latrines for wet and dry seasons. Well number

1which was the closet to pit latrine was at a distance of 10m while well number

10 which was furthest from the pit latrine was at a distance of 30m from the pit

latrine.

44

Figure 4.12: Correlation between measurements of Total coli.forms in

ground water wells and distance from pit latrine during wet season.

The scatter plot gives a strong negative correlation coefficient (r = - 0.546)

between the levels of pollutants in the wells against their distances from pit

latrines. There is more pollution when wells are situated closer to pit latrines as

amplified by well number 1at a distance of 10 meters from a pit latrine.

Figure 4.13: Correlation between measurements of Total coli.forms in

ground water wells and distance from pit latrine during dry season.

10 15 20 25 30-5000

0

5000

10000

15000

20000

r = -0.54574

Distance [m]

T.co

li Co

unts/

100m

L

10 15 20 25 30-2000

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

r = -0.54433

Distance [m]

T.co

li Co

unts/

100m

L

45

From Figure 4.13 the correlation coefficient for dry season is r = - 0.544. The

scatter plot gives a strong negative correlation between the levels of pollutants

and the distance from pit latrine and is an indicator of less pollution in wells that

are situated further away from pit latrines. The correlation coefficients (r-values)

for wet and dry seasons show a general decline in pollution as the distance from

the pit latrines to the wells increases (Figures 4.12 and 4.13).

4.1.13: Levels of Escherichia coli.forms as a Function of Distance from Pit

Latrines

Figures 4.14 and 4.15 show the correlation between the levels of Escherichia

coli.forms in ground water as a function of distance from pit latrine for wet and

dry seasons. The levels of Escherichia coli.forms are measured in counts/100ml.

Figure 4.14: Correlation between measurements of Escherichia coli.forms in

ground water wells and distance from pit latrine during wet season.

From Figure 4.14 the correlation coefficient for wet season is r = - 0.587. The

correlation shows a general decline in groundwater pollution as wells situated far

10 15 20 25 30-1000

-500

0

500

1000

1500

2000

2500

r = -0.58738

Distance [m]

E.co

li Co

unts/

100m

L

46

away from pit latrines have less pollutants. Pollution level being quite high in

wells situated 10 meters or less from pit latrines. At a distance of 20m from the pit

latrine, the levels of Escherichia coli.forms reduce to extremely low values.

Figure 4.15: Correlation between measurements of Escherichia coli.forms in

ground water wells and distance from pit latrine during dry season.

From Figure 4.15 the correlation coefficient for dry season is r = - 0.568. The

negative correlation between the levels of Escherichia coli.forms and the distance

from pit latrine shows that there is less pollution in wells situated far from pit

latrines. In general there was more pollution during wet season compared to dry

season which was due to increased infiltration and percolation.

10 15 20 25 30-500

0

500

1000

1500

2000

r = -0.5684

Distance [m]

E.co

li C

ount

s/100

mL

47

4.1.14 Origins of the Pollutants

In order to try and identify the sources of the pollutants, the principal Component

Analysis (PCA) was used to identify the elements with similar geochemical and

physico-chemical behavior. The first four principal components (PCs) had Eigen

values greater than 1, accounting for 67.181% of the total variance. Table 4.7

gives the loadings of the principal components (PCs). The loadings of the first

principal components (PC1) were the greatest for Zn, BoD, T-N and SO4 and their

respective Eigen values were: 0.849, 0.834, 0.759 and 0.718. The loadings for the

second principal components (PC2) had substantial Eigen vector values of: 0.911,

0.907 and 0.755 for Escherichia coli.forms, Total coli.forms and pH respectively.

The loading for the third principal components (PC3) had Eigen vector values of:

0.669 and 0.528 for temperature and depth respectively while cadmium and

electrical conductivity had Eigen vector values of 0.699 and 0.796 respectively in

the fourth principal component (PC4).

48

Table 4.2 shows the Principal Component Analysis with Varimax Rotation

results.

Table 4.2: Principal Component Analysis results.

*The highest contribution of each variable

The latent root criterion for number of factors to derive indicated that there are

four components to be extracted from these values as shown in bold.

variables PC1 PC2 PC3 PC4

Depth -0.494 0.165 0.528 * -0.101

pH -0.351 0.755 * 0.054 -0.294

Temp. -0.408 -0.188 0.669 * -0.317

T.coli 0.147 0.911 * -0.217 -0.057

E.coli 0.147 0.907 * -0.023 0.081

E. cond. 0.209 -0.241 0.135 0.796 *

BOD 0.834 * 0.023 -0.206 0.095

T-N 0.759 * 0.198 0.272 0.280

Sulphate 0.718 * 0.136 0.082 0.275

Lead -0.160 0.167 -0.844 -0.058

Manganese -0.140 0.021 - 0.020 -0.020

Cadmium 0.044 0.169 -0.307 0.699 *

Zinc 0.849 * 0.117 -0.190 -0.131

Magnesium -0.685 0.172 0.071 -0.108

49

From table 4.3, it is clear that the cumulative proportion of variance criteria can

be met with four components to satisfy the criterion of explaining 60% or more of

the total variance since a four components solution explains 67.181 % of the total

variance (Table 4.3).

Table 4.3: Total variance of the four components (PC1, PC2, PC3, and PC4)

COMPONENT % VARIANCE CUMULATIVE %

PC1 29.693 29.693

PC2 19.162 48.855

PC3 10.104 58.959

PC4 8.221 67.181

The pollutants in PC1 (BOD, T-N, SO4 and Zinc) are closely associated with

organic sources. The pollutants in PC2 (Total coli.forms and Escherichia

coli.forms) also reveal groundwater pollution by pathogens. The components of

PC3 (Depth and temperature) shows that the temperature increases with depth

thus depicting geothermal gradient. Many ions tend to dissolve in water at higher

temperatures thus pollutants would dissolve more at lower depths where the

temperatures are higher. The PC4 components (Electrical conductivity and

cadmium), reveal that the groundwater is polluted with cadmium ions as indicated

by the high electrical conductivity.

50

CHAPTER FIVE: CONCLUSIONS AND RECOMMENDATIONS

5.1 Conclusions

In summary the ground water was found to be polluted with nitrogen manganese,

cadmium, BOD and coli forms. The presence of coli forms suggests that there

may be a pathway for pathogens or fecal pollution to the groundwater, making the

groundwater unsuitable for domestic use.

The groundwater recorded more levels of pollutants during wet seasons compared

to dry seasons and this suggests that groundwater pollution is enhanced by wet

seasons.

Finally correlation analyses suggest that ground water pollution is affected by

the distances between the wells and the source of pollutants namely, the pit

latrines and the dumpsite.

51

5.2: Recommendations

The groundwater can be used for other purposes or treated for domestic

use

The pit latrines should be lined to avoid leakage of leachate to

groundwater

Kilifi Malindi water and sewerage company should improve on the

quantity and quality of water supply to reduce dependency on groundwater

supply

The county government of Kilifi through NEMA should enhance

environmental protection by creating awareness on safe disposal of wastes

to mitigate groundwater pollution through leachate production.

Regular monitoring of groundwater quality and further research to develop

a model for predicting pollution status of groundwater wells at different

seasons of the year to abate ill effects.

The county government to enforce proper procedures for siting, design,

operation, monitoring and remediation as well as 30-year post closure care

of dumpsites to preclude groundwater pollution

52

REFERENCES

Abolfazl, M. and Elahe, A.P. (2008). Groundwater Quality and the Sources of

Pollution in Baghan Watershed, Iran. World Aca.of Sc., Eng and Tech

Abuodha, J.O.Z. (1998).Geology, Geomorphology, Oceanography and

Meteorology of Malindi Bay. In: Hoorweg j. (Ed), Dunes, Groundwater,

Mangroves and Birdslife in Coastal Kenya, InL Coastal Ecology Series,

Vol.4: 17-39

APHA, (1998): Standard method for the Examination of Water and

Wastewater, 2nd Edition APHA, Washington D.C.

Bagchi, A. (2004). Design of Landfills and Integrated Solid Waste Management.

New York: John Wiley and Sons, Inc.

Bakis, R. and Tuncan, A. (2010). “An investigation of Heavy Metal and

Migration through Groundwater from Landfill area of Eskisehir in

Turkey”. 176: 87-98

Boumediene, M. and Achou, D. (2004). Desalination, Water Resources Journal,

168,167.

Caswell, P.V. (1953). Geology of the Mombasa-Kwale Area. Report 24, Mines

and Geology Department, Ministry of Environment and Natural

Resources, Nairobi, Kenya: 69.

Caswell, P.V. (1956). Geology of the Kilifi- Mazeras area. Report 34, Mines and

Geology Department, Ministry of Environment and Natural Resources,

Nairobi, Kenya: 45.

Corbit, R. (1993). Handbook of Environmental Engineering. New

York: McGraw-Hill.

CWSB, Coast Water Services Board. (2008). ANNUAL Report, Mombasa,

Kenya.

Fred, G.L. and Anne, J.L. (2009). Electronic Wastes and MSW Landfill Pollution

of Groundwater: California: G.Fred Lee and Associates El Macero.

KEBS(1996).DrinkingWaterStandards

(http://www.lenntech.com/drinking/standards)

53

Ebong, G. A., Akpan, N. M. and Mkepenie, V. N. (2007). E-Journal of

Chemistry, 5, 281.

Gray, N.F. (2009). Water Technology. An Introduction for Environmental

Scientists and Engineers, 2nd

Edition. Elsevier Publishers, Haryana,

India.

GSADH, Government of South Australia, Department of Health, Wastewater

Management Section (2005). Reed bed Systems. St. Adelide, South

Australia 5000.

Ikem, A. Osibanjo, O. Sridhar, M. K. and Sobande, A. (2002). Water, Air, and

Soil Pollution, 140,307.

Jorgensen, S.E. and Johnsen, I. (1989). Principles of Environmental Science and

Technology, 2nd

Ed. Elsevier Science Publishers B.V. Amsterdam. The

Netherlands.

Kaseva, M. E and Mbuligwe, S. E. (2002). Hazardous Waste Management in

Tanzania: Retrospection and Future Outlook. In: Knowledge for

Sustainable Development: An Insight into the Encyclopedia of Life

Support Systems Vol.3,pp 897-926. Oxford, UK: Eolss publishers Co.

Ltd.

Kensea (2006). Environmental Sensitivity Atlas for Coastal Area of Kenya.

http://www.geus.dk

Keter, P.B, Grudman, N.J., Hage, D.S, Carr, J.D (1997). A discussion of water

pollution in the U.S and Mexico with High School laboratory Activities

for analysis of lead, anthrazine and nitrate. Chem.Edu.74 (12), pp1413-

1418

Kumar, D. and Alappat, B.J. (2003). Analysis of leachate contamination potential

of a municipal landfill using leachate pollution index. Workshop on

sustainable landfill management, India, December 3-5: 147-153

LaGrega, M.C., Buckingham, P.L., and Evans, J.C. (1994).Hazardous Waste

Management: New York: MC. Graw-Hill Publishing Co.

Buckinggham, P. L. and Evans, J. C. (2003). Hazardous Waste Management

London: McGraw-Hill. Water Engineering. John Willey and sons inc.,

New York, USA.

54

Lu,J.C.S.(1985).“Leachate from municipal landfills, production and

management”, Noyes Publisher, Park Ridge. Mercado, A. Groundwater,

1985, 23,635

Michael, D. L., (2001).Hazardous Waste Management and Environmental

resource management. California: McGraw Hill International.

NEMC (National Environmental Management Council) (1998). Disposal of

Obsolete Pesticides and Veterinary Waste. NEMC Project Report, Dar

es Salaam.

Odukoya, O., Bamgbose, O., and Arowolo, T. A. (2001). Global Journal of Pure

and Applied Sci., 7:467 – 472.

Okuo, J. M., Okonji, E.T. and Omoyerere, P. R. (2007). Journal of Chem.Soc. 32,

53.

Osu,C. and Okoro, I.A. (2011). Comparative Evaluation of Physical and Chemical

Parameters of Sewage from some selected areas in Port-Harcourt

Metropolis, Rivers State Nigeria. Continental Journal. Water, Air and

Soil Pollution 2(1): 1-14.

Ozler, H. M. (2001). 1st Morocco international Conference on Saltwater intrusion

and Coastal Aquifer Monitoring, Modeling and Management.

Pickford, J. (1986). Water, Wastes and Health in Hot Climates. John Wiley and

Sons, New York, U.S.A.

Sangarika, N., Debyani, S., Rajani, K.S. (2010). Heavy Metal Pollution in a

Tropical Lagoon Chilika Lake, Orissa, India. Continental J. Water, Air

and Soil Pollution. 1: 6-12.

Salami, L. (2012). Leachate characterization and assessment of groundwater

quality: A case of Solous dumpsite in Lagos state. PhD seminar paper,

Lagos state University, Epée, Lagos, Nigeria.

SiaSu, L. G. (2008). American Journal of Environmental Sciences, 4,262

Subramani, T., Elango, T., Damo-darasamy, S. R. (2005). Environ Geol., 47,

1009.

Tods, D.K. (1980).Groundwater Hydrology. 40, 2nd

Ed. New York, John Wiley.

55

UNEP, (1998b).Eastern African Atlas of Coastal resources handbook, Kenya.

Brussels: National Geographic Institute.

Weiner, R. and Mathews. (2007). Environmental Engineering, 4th

.Ed.

Butterworth-Heinemann, an Imprint of Elsevier New Delhi, India.

World Health Organization (WHO). (2006). Guidelines for drinking water

quality. Washington, first addendum to third edition vol.1

Recommendations.

York: McGraw-Hill.

Yusuf, K. A. (2007). Journal of Applied Science, 13, 1780.

56

APPENDIX I

Table 4.1Measurenets of Total coli.forms and Escherichia coli.forms for dry

and wet seasons

Pollutant season W1 W2 W3 W4 W5 W6 W7 W8 W9 W10

T.coli

(Cnt/100ml)

Dry

Wet

16453

18630

2893

3277

180

257

5948

8079

2113

2502

290

349

3240

3749

2117

2428

2000

2383

1800

1934

E.coli

(Cnt/100ml)

Dry

Wet

1900

2390

317

614

169

204

122

147

24

35

0

3

8

14

29

41

30

43

30

40

57

APPENDIX II

Table 6.1: The mean values of pH, Temperature and Electrical conductivity

for dry and wet seasons.

W1 to W10 represent the ten wells

variables

Season

The mean values of pH Temp. and E.cond as measured in 10 wells

W1 W2 W3 W4 W5 W6 W7 W8 W9 W10

pH

Dry

Wet

8.2

8.2

7.5

7.3

7.6

6.6

7.6

7.2

7.7

6.8

7.8

7.3

7.4

7.2

7.6

7.3

7.3

7.3

7.1

7.3

Temp.(0celcius)

Dry

Wet

29

28

30

29

29

29

29

28

30

30

30

30

29

28

29

29

30

30

30

29

E.con(MicS/cm

Dry

Wet

343

693

918

1773

2386

2823

2939

3893

3233

3900

1005

1229

4237

4190

1713

1959

1557

1978

1107

1175

58

APPENDIX III

Table 6.2The mean concentrations of Pb, Mn, Cd and Zn

Pollutant

Season

The mean concentrations of Pb, Mn, Cd and Zn as measured in 10

wells

W1 W2 W3 W4 W5 W6 W7 W8 W9 W10

Pb

(Mg/l)

Dry

Wet

0.03

0.04

0.01

0.01

0.02

0.02

0.04

0.03

0.02

0.02

0.02

0.02

0.03

0.03

0.02

0.03

0.04

0.04

0.03

0.04

Mn

(Mg/l)

Dry

Wet

0.29

0.33

0.30

0.34

0.27

0.31

0.24

0.26

0.27

0.26

0.27

0.32

0.21

0.20

0.21

0.17

0.09

0.20

0.17

0.17

Cd

(Mg/l)

Dry

Wet

0.03

0.03

0.02

0.02

0.02

0.02

0.02

0.02

0.03

0.03

0.02

0.03

0.02

0.03

0.03

0.02

0.02

0.02

0.02

0.03

Zn

(Mg/l)

Dry

Wet

0.05

0.09

0.05

0.09

0.03

0.07

0.08

0.09

0.05

0.07

0.05

0.10

0.05

0.09

0.03

0.07

0.04

0.09

0.03

0.08

59

APPENDIX IV

Table 6.3: The mean concentrations of BOD, T-N and Sulphates for dry and

wet seasons

pollutant season W1 W2 W3 W4 W5 W6 W7 W8 W9 W10

BOD

(Mg/l)

Dry

Wet

16

33

16

28

15

28

16

37

25

39

14

31

22

41

12

26

13

24

18

27

T-N

(Mg/l)

Dry

Wet

13

26

17

33

14

31

18

30

11

20

14

18

21

40

9

14

8

12

7

10

Sulp.

(Mg/l)

Dry

Wet

97

130

116

83

88

166

69

126

67

113

93

118

63

112

37

60

67

123

77

120

W1-W10 represents sampled wells.

60

APPENDIX V

Table 6.4: The Range of pollutants for dry and wet seasons and the

percentage changes due to seasons

Pollutant Range (dry season) Range (wet season) % change

Pb (mg/l) 0.01-0.04 0.01-0.04 (0-0) %

Cd (mg/l) 0.02-0.03 0.02-0.03 (0-0) %

Mn (mg/l) 0.09-0.3 0.17-0.34 (47-12) %

BOD (mg/l) 12-25 24-41 (50-39) %

T.N (mg/l) 7-12 10-40 (30-48) %

Sulphate(mg/l) 37-116 60-66 (38-30) %

T.coli(counts/100ml) 180-16453 257-18630 (30-12) %

E.coli(counts/100ml) 0-1900 3-2390 (100-21) %

Zn (mg/l) 0.03-0.08 0.07-0.1 (57-21) %