i

TITLE

THE MANAGEMENT OF WASTEWATER IN NAIROBI: PROPOSAL

ON THE USE OF BIOLOGICAL TREATMENT SYSTEMS

A PROJECT PAPER PRESENTED TO

THE DEPARTMENT OF REAL ESTATE

AND CONSTRUCTION MANAGEMENT

OF THE UNIVERSITY OF

NAIROBI

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE

OF BACHELOR OF QUANTITY SURVEYING

BY

ODHIAMBO COSMAS ONYANGO

B66/0330/2009

MAY 2013

ii

DECLARATION

I, ODHIAMBO COSMAS ONYANGO, hereby declare that this report is my original work

and to the best of my knowledge, it has not been submitted for any degree award in any

University or Institution.

Signed……………………… (Author) Date…………………………

ODHIAMBO COSMAS ONYANGO

DECLARATION OF THE SUPERVISOR

This research has been submitted for examination with my approval as a University

Supervisor.

Signed………………………… (Supervisor) Date …………………………..

ARCH. PETER NJERU NJUE

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DEDICATION

First, I dedicate this research work to Almighty God who has brought me this far. I

dedicate this project to my dear family and friends who have believed in me and whose

love, support, sacrifice and encouragement has been my constant motivation. I thank you

for your unrivaled support and prayer throughout my education up to this far.

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ACKNOWLEDGEMENT

I would like to take this opportunity to thank those who have helped me complete my

project successfully by providing the technical information and ideas and in providing the

materials I required. I apologize to anyone not included and any errors are mine.

First, I would like to thank my supervisor Mr. Njeru for his guidance throughout the

project. His comments and ideas throughout the project period have helped make the

project a success.

The members of staff of the department of Real Estate and Construction Management who

guided and assisted me in my studies have also been great pillars of my education whose

contribution cannot go unappreciated.

I am also grateful to the help extended by my classmates throughout my course of Bachelor

of Quantity Survey at University of Nairobi. They have helped me be the person I am

today.

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ABSTRACT

There has been an increasing demand for water for both domestic and industrial use mostly

in the urban areas. The water resources available in towns are not sufficient enough to cater

for this growing demand. There has also been the problem of environmental pollution

caused by waste water from buildings. This study was set to come up with ways of

reducing environmental pollution through wastewater in the best economical way possible

and also come up with ways that can be used to minimize the problem of water shortage.

The study involves coming up with a system that is going to cater for the problems of

water shortage and pollution.

The term "wastewater" is a broad, descriptive term. Generally it includes liquids and

waterborne solids from domestic, industrial or commercial uses as well as other waters that

have been used (or "fouled") in man's activities, whose quality has been degraded, and

which are discharged to a sewage system. The term "sewage" technically denotes any

wastewaters which pass through a sewer. Waters that are used for drinking, manufacturing,

farming, and other purposes are degraded in quality as a result of the introduction of

contaminating constituents. Organic wastes, suspended solids, bacteria, nitrates, and

phosphates are pollutants that commonly must be removed. The objective of sewage

treatment is to produce a disposable effluent without causing harm to the surrounding

environment and prevent pollution. The project aims to explore the use of biological

technologies in order to make wastewater treatment cheap, sustainable and effective. The

objective is to treat the wastewater to a high quality that can be safely re-used in buildings.

An improved system combining the use of algae(chlorella vulgaris )and bacteria in a

photo-bioreactor has been discussed.

Algae are responsible for the Oxygen (O2) production used by aerobic bacteria to

biodegrade organic pollutants with Carbon Dioxide (CO2) release that on its turn will be

used by microalgae to grow (Wolfaardt et al 1994).

The efficiency and advantages of biological system has been discussed. It is expected that

Biological system will reduce the said contaminants to a level that can allow safe disposal

and domestic re-use.

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LIST OF TABLES

Table 1: Characteristics of wastewater and source 16

Table 2: Constituents of wastewater and their effects. 18

Table 3: Factors influencing algae growth 29

Table 4: Tabulated response rate of Questionnaires administered 45

Table 5: Distribution of Housing Units 46

Table 6: Water Availability 47

Table7: Prevalence of Diseases 48

Table 8: Urban Centers in Kenya with Sewerage Treatment Facilities 59

Table 9: Access to Recycled water 60

Table 10: Comparison between centralized and decentralized wastewater systems 67

vii

LIST OF FIGURES

Figure 1: Trickling Filter 22

Figure 2: Lagoon 24

Figure 3: A pictorial diagram of a polishing pond 25

Figure 4: Microalgae and heterotrophic bacteria interactions. 31

Figure 5: Nairobi Division 22

viii

LIST OF CHARTS

Chart 1: Housing Distribution 55

Chart 2: Rate of water availability 56

Chart 3: Disease Prevalence 57

Chart 4: Water Recycling 61

ix

LIST OF ABBREVIATIONS

AWWS - Alternative Waste Water Systems

BOD – Biological oxygen demand

COD – Chemical oxygen demand

DeSa/R Decentralized Sanitation and Reuse

DO – Dissolved oxygen

EPS – Exopolymeric substances

NCC - Nairobi City Council

NEMA – National Environmental Management Authority

NWSC - Nairobi Water and Sewerage Company

PBR – Photobioreactor

Total N – Total nitrogen

Total P - Total Phosphorous.

WHO - World Health Organisation.

WW - Wastewater

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Table of Contents

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

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

ACKNOWLEDGEMENTS..................................................................................................... iv

ABSTRACT.............................................................................................................................v

L IST OF TABLES..................................................................................................................vi

L IST OF FIGURES.................................................................................................................vii

L IST OF CHARTS..................................................................................................................viii

TABLE OF CONTENTS..........................................................................................................x

1 CHAPTER ONE .................................................................................................................1

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

1.1 BACKGROUND OF THE STUDY ........................................................................1

1.2 PROBLEM STATEMENT ......................................................................................4

1.3 OBJECTIVES OF THE STUDY .............................................................................6

1.4 HYPOTHESIS OF THE STUDY ............................................................................7

1.5 SCOPE OF THE STUDY ........................................................................................7

1.6 JUSTIFICATION ................................................................................................ .....7

1.7 SIGNIFICANCE OF THE STUDY .........................................................................8

1.8 LIMITATIONS OF THE STUDY ...........................................................................9

1.9 ORGANIZATION OF THE STUDY.......................................................................9

2 CHAPTER TWO ................................................................................................................10

LITERATURE REVIEW.........................................................................................................10

2.1 INTRODUCTION ....................................................................................................10

2.2 DEFINITION OF TERMS .......................................................................................10

2.3 WHY WE NEED TO TREAT WASTEWATER .....................................................12

2.4 BIOLOGICAL TREATMENT OF WATER ............................................................13

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2.5 WHY RECYCLING SYSTEMS ARE NEEDED .....................................................13

2.6 THE BENEFITS OF RECYCLING WATER ...........................................................15

2.7 WASTEWATER GENERATION .............................................................................16

2.8 WASTEWATER CHARACTERISTICS AND ITS EFFECTS.................................16

2.8.1 Characteristics of wastewater and source.........................................................16

2.8.2 Effects of Wastewater on the environment ......................................................19

2.9 TREATMENT TECHNOLOGIES AVAILABLE.....................................................20

2.9.1 Preliminary Treatment......................................................................................20

2.9.2 Primary treatment .............................................................................................21

2.9.3 Secondary treatment .........................................................................................21

2.9.4 Tertiary treatment .............................................................................................24

2.9.5 Advanced WW treatment .................................................................................24

2.10 BIOLOGICAL TREATMENT SYSTEMS ............................................. ...............28

2.10.1 Algal and Bacterial Technology .....................................................................28

2.10.2 Algal- bacteria system.....................................................................................30

2.10.3 Photo-bioreactor Technology .........................................................................32

2.10.4 Filtration Technology .....................................................................................34

2.11 CONCLUSION..........................................................................................................35

3 CHAPTER THREE...............................................................................................................36

RESEARCH METHODOLOGY ..............................................................................................36

3.1 INTRODUCTION .....................................................................................................36

3.2 BACKGROUND TO THE STUDY ..........................................................................37

3.3 DATA COLLECTION ..............................................................................................40

3.4 DATA ANALYSIS ....................................................................................................43

4 CHAPTER FOUR ................................................................................................................45

DATA ANALYSIS, FINDINGS AND PRESENTATION.......................................................45

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4.1 INTRODUCTION .....................................................................................................45

4.1.1 Field Study Response .......................................................................................45

4.2 FINDINGS FROM THE RESIDENTS OF NAIROBI .............................................46

4.3 FINDINGS FROM THE CONTRACTORS AND PROPERTY MANAGERS .......49

4.4 DATA FROM NAIROBI CITY WATER & SEWERAGE COMPANY .................51

4.5 ROLES OF THE NAIROBI CITY COUNCIL .........................................................53

4.6 CHALLENGES FACED IN THE RESEARCH STUDY..........................................54

4.7 DATA ANALYSIS AND PRESENTATION ...........................................................45

5 CHAPTER FIVE ..................................................................................................................63

CONCLUSION AND RECOMMENDATIONS.......................................................................63

5.1 INTRODUCTION ......................................................................................................63

5.2 CONCLUSION ..........................................................................................................63

5.2.1 Water Recycling................................................................................................64

5.2.2 Decentralized or Centralized Wastewater Systems? ........................................66

5.2.3 Biological wastewater treatment ......................................................................68

5.3 HYPOTHESIS TESTING ...........................................................................................69

5.4 RECOMMENDATIONS ............................................................................................69

5.4.1 Decentralization of wastewater treatment system ............................................69

5.4.2 Adoption of Biological treatment systems .......................................................69

5.4.3 Recycling of the waste water ...........................................................................70

5.4.4 Need to Change the waste water collection Systems .......................................71

5.4.5 Need for Government Involvement in ensuring proper standards in

wastewater management are met .....................................................................71

5.4.6 Need for Community Involvement ..................................................................71

5.4.7 Reduction in wastewater build-up ..................................................................72

5.4.8 Need to Improve the financing of wastewater management Projects .............72

xiii

5.5 AREAS OF FURTHER RESEARCH .......................................................................73

REFERENCES .........................................................................................................................74

APPENDIX 1: Questionnaire to residents .............................................................................. xiv

APPENDIX 2: Questionnaire to the staff of NWSC................................................................ xvii

APPENDIX 3: Questionnaire to Contractors........................................................................... xxi

APPENDIX 4: Questionnaire to Estate Agents ....................................................................... xxiv

1

1 CHAPTER ONE

INTRODUCTION

1.1 BACKGROUND OF THE STUDY

One of the main ways of dealing with water shortage in towns is through recycling of

wastewater. To make wastewater acceptable for reuse or for returning to the environment,

the concentration of contaminants must be reduced to a non-harmful level, usually a

standard prescribed by a body called National Environmental Management Authority

(NEMA). Restoration of water quality is accomplished through the use of a variety of

pollution control methods. In urban areas, municipal wastewaters (sewage) generally are

conveyed to a central point of treatment through sanitary sewers. Climate change,

urbanization and increasing demands on resources are placing pressure on traditional forms

of water management. Traditional centralized, “big pipes in, big pipes out”, wastewater

systems have come under pressure to meet new objectives in cities adopting an evolving

sustainability agenda (Newman, 1993). The new agenda encourages cities to look at how

they supply water when traditional measures, such as building dams, are no longer viable

or sustainable options (SWS, 2002). These pressures are encouraging cities to develop

alternative wastewater systems Alternative Waste Water Systems (AWWS), with a

paradigm shift towards decentralized AWWS occurring (Dillon et al ., 2004).

According to the 2009 population census report, Kenya’s population is expanding at a high

rate; it currently stands at 38,610,097. Substantial numbers of people live in urban centers

like Nairobi and up-and-coming towns with infrastructural advantage that attracts

settlement (Thika being a prime example).Nairobi alone has a population of 3,138,369.

This has led to an increase in construction of buildings, residential houses and

infrastructure thus leading to an increased demand for water for domestic and industrial

use and subsequently high production of municipal wastewater (Nairobi City water and

sewerage company manual, 2011). With the current emphasis on environmental health and

water pollution issues, there is need to solve the problems associated with wastewater. This

2

led to the question: what is the best way to treat and dispose of this wastewater safely and

beneficially and in the most economical way?

Properly planned use of municipal wastewater provides an effective means of alleviating

surface water pollution problems and conserves valuable water resources (Cunningham et

al, 1990)

The available Wastewater treatment technologies: Primary and secondary treatments

produce effluent of low quality i.e. effluents containing high levels of Nitrogen,

Phosphorus, Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD).

Further treatment through advanced treatment processes are often costly making it

unaffordable (Viessman ,1998).

There is need for adoption of Biological systems which often use natural resources such as

algae and bacteria. Algal activity is influenced by the presence of light as algae are

photosynthetic. In darkness, the rate of algal growth is substantially reduced and so is their

role in removing nutrients from wastewater. In addition, algae’s production of Carbon

dioxide at night inhibits the activities of aerobic bacteria (Hammer 2001).

Nitrogen and Phosphorous are essential nutrients for plants and are common components

of WasteWater (WW) treatment plants’ effluents. When discharged to the environment in

high concentration can result in environmental pollution. They commonly cause excessive

growth of biomass- a condition known as eutrophication.

BOD and COD are common indicators of water pollution. High levels indicate high

concentration of organic matter in the water. The micro-organisms in water will deplete the

water of oxygen leading to death of aquatic life ( Kruger 1997).

The great potential of algae in wastewater treatment has frequently been noted and utilized

in the form of using suspended algae to remove inorganic nutrients and organic matter

(Grossi et al. 2001; Lee and Lee 2001; Mallick 2002; ) they reported on the performance of

an algal aquaculture wastewater treatment system using the green algae Scenedesmus spp.

and Chlorella vulgaris.

3

A research by M.A. Aziz and W.J. Ng (National University of Singapore) on the

feasibility of using an activated-algae reactor to treat both domestic sewage and industrial

wastewaters from a pig farm and a palm oil mill indicated that algae was able to remove

80–88% of BOD, 70–82% of COD, 60–70% of nitrogen and 50–60% of phosphorus.

Removal rates of organics and nutrients correlated significantly with loading rates. The

activated-algae process was therefore found feasible for treating both domestic sewage and

industrial wastewaters.

Many countries have embraced wastewater re-use as an important water resource planning.

For this to be effective, there is need to first decentralize the wastewater management

system. Countries like Australia and USA use wastewater in agriculture relieving high

quality for supplies and for portable use. Some countries e.g. Heshimite Kingdom of

Jordan and Saudi Arabia have a national policy to reuse all treated wastewater. Efficient

wastewater treatment and re-use is justified on agronomic, social and economic grounds

and must be taken to minimize health and environmental impacts (Dillon et al., 2004).

1.2 PROBLEM STATEMENT

Wastewater pollution has always been a major problem throughout the world. The lack of

suitable water used for drinking, agriculture, farming and other functions has declined

through the years. With a shortage of water throughout the world, proper method of

treating and recycling water is the key goal in sustaining our limited water resource supply

(Newman, 1993). Outside of the laboratory there is no such thing as "pure" water. Even

rain water, for example, will take on gases, solid particles and other "impurities" as it falls

through the air to the earth. As water strikes the ground and flows across or through the

surface of the earth, as would be expected, it takes on the characteristics of the materials it

has encountered. For example, minerals are dissolved and contribute to the dissolved salts

that are normally found in waters. At the same time organic matter from decomposed

vegetation or from the soil, will also dissolve or be carried along within the water. Thus,

waters will have many natural impurities. Generally these impurities do not detract from

utilization of the water for, drinking and washing. The problems of water treatment and

management are mainly faced by overpopulated regions (Okun, 2002)..

4

Following its founding in 1902, Nairobi took roughly 40 years to exceed a population of

100,000 people. By Independence, 20 years later it had reached around 350, 000 people

(Olima, 2001). Rapidly increasing population has been ongoing since, surpassing one

million in the 1980s and now slightly over three million residents(NEMA 2003). A

growing economy and swelling population numbers from both in-migration and natural

growth are continually increasing the city’s size. This growing population is one of the

main forces driving the city’s overwhelming environmental challenges. Ongoing rural to

urban migration, high natural birth rates, and poor or inappropriate city planning conspire

to continue degrading the city’s water and air quality, In turn, environmental degradation

has impacts on human health and economy. Several factors compromise the city’s water

quality, ranging from natural phenomena such as the high fluoride content in groundwater,

to anthropogenic factors such as poor wastewater treatment and environmental degradation

both within the city and its surrounding ( Nairobi water company profile, 2011).

The City’s wastewater management has not kept up with increasing demands from the

growing population and is inadequate to treat the amount of industrial and municipal

effluent entering the Nairobi river and other surface waters. Nairobi has changed from a

“place of cool waters” to one in which the water is no longer portable or fit for many other

useful purposes. The Nairobi River receives improperly treated effluents from the Dandora

Sewage treatment plant and several drainage channels that gather waste effluents from

Nairobi City. Domestic garbage from informal settlements that have no public waste

collection services also finds itself into the river as does sewage from pit latrines and other

on-site sewerage-disposal methods. Improperly treated sewerage and uncollected garbage

have contributed to a vicious cycle of water pollution, water-borne diseases, poverty, and

environmental degradation. Water pollution carries environmental and health risks to

communities within Nairobi, especially the poor who may use untreated water in their

homes and to irrigate their gardens (H.W. Pearson, 1996).

The Researcher’s main concern was with waters that have been used by man and then

discarded. While such waters have in the past been commonly referred to as sewage, over

the more recent years they have come to be called "Wastewaters". There are two general

categories of wastewaters: domestic wastewaters and industrial wastewaters. Domestic

5

wastewaters originate principally from domestic, household activities but will usually

include waters discharged from commercial and business buildings and institutions as well

as ground water. Surface and storm waters may also be present. Domestic wastewaters

are usually of a predictable quality and quantity. Industrial wastewaters, on the other hand,

originate from manufacturing processes, are usually of a more variable character, and are

often more difficult to treat than domestic wastes (P.F.Cooper, 2001). While domestic

wastewaters can be dealt with in general terms with respect to character and treatment,

industrial wastewaters must be examined on an industry-by-industry basis. The researcher

primarily dealt with domestic wastewaters, its management and treatment. Sewage

treatment is the process of removing contaminants from wastewater. Its objective is to

produce an environmentally safe fluid waste stream (treated effluent) and a solid

waste(treated sludge) suitable for disposal or reuse, usually as a farm fertilizer.

There are many ways of treating domestic wastewater, this mainly involves the use of

water treatment plants. Most of these plants are expensive to construct and require too

much labor and energy to run these plants. Due to the poor economic situation in the

country, the researcher’s work study involves the development of a system which is

affordable to the user and friendly to the environment. The ultimate goal of wastewater

treatment should be managing wastewater effectively and in an economically friendly way.

Treated waste water can be re-used in buildings in activities such as flushing of toilets,

general cleaning of the house and irrigation of flower beds and grass. The re-use of this

water helps in saving of the fresh water (municipal/borehole water) usage in buildings.

This water can thus be used in activities such as cooking and bathing (Connell, Rich,

2008).

The research study was focused on the use of Biological treatment methods in the

treatment of wastewater. While a number of methods are currently being used for sewage

treatment and industrial wastewater treatments at sewage treatment plants and effluent

treatment plants, these are very expensive methods that rely on high-cost chemicals and

heavy inputs of energy. With an emphasis on sustainable wastewater treatment in

developing cities such as Nairobi and all over the world, industries are keen on pursuing a

method that can be cost effective and can provide a sustainable long-term solution for

6

treatment of wastewater and sewage. They are keen on exploring bioremediation as an

important route by which to clean up wastewater. Bioremediation uses naturally occurring

microorganisms and other aspects of the natural environment to treat wastewater of its

nutrients (Arms, Karen, 1990). Such an avenue provides an economical and

environmentally sustainable treatment method.

Algae are an important bioremediation agent. The role that algae can play in wastewater

remediation is a very important role. The use of algae helps us to solve two major

problems: increased use of chemicals and high equipment and energy costs. This makes

algae-based waste water treatment a powerful avenue for sustainable wastewater treatment

(Fallowfieldet al. 1996). This research focuses on the potential of Biological wastewater

treatment and provides critical inputs and expert intelligence on current efforts, costs and

challenges facing wastewater treatment.

1.3 OBJECTIVES OF THE STUDY

1. To research on the state of wastewater management in Nairobi and offer solutions

of water shortage through recycling of water.

2. To examine the effects of poor wastewater management on the various attributes of

the socio-economic environment and explain the various stages of wastewater

treatment.

3. To propose and recommend more feasible wastewater management solution and its

efficiency, this is through an efficient low-cost method of treating domestic

wastewater using biological means.

1.4 HYPOTHESIS OF THE STUDY

The current wastewater management systems put in place in the City of Nairobi are not

sufficient enough to serve the residents of the City adequately.

1.5 SCOPE OF THE STUDY

A field study was conducted and questionnaires were prepared and filled with residents

from different parts of the Nairobi City. Sampling techniques were utilized in collecting

data. This research project covered different ways of wastewater treatment. It showed the

7

different stages that the wastewater has to go through before ensuring its safety for re-use.

Research was also done on the merits and demerits of using other treatment systems

compared to the use of algae-bacteria method.

The Biological treatment methods were explained in detail, their functioning and

importance. Questionnaires were also filled with residents, Contractors and property

managers in the City. Data was also collected from the staff at Nairobi Water and

Sewerage Company. This research also gives an overview of the current status of

wastewater treatment in towns and more specifically Nairobi. The findings were discussed

and presented graphically and in tables. Recommendations were given to provide on how

best to solve the problem of wastewater treatment and water shortage.

1.6 JUSTIFICATION

The need for an efficient Wastewater treatment is of huge importance to buildings and their

environment, but some conventional methods suffer from both high cost and the

incapability of sufficiently reducing the level of contaminants. Thus, there is a need for an

efficient low-cost method of treating wastewater that is also environmentally friendly.

With increasing volume of wastewater production coupled with the inability of bacteria to

break down organic compounds under darkness (due to limited oxygen caused by reduced

photosynthesis) there need for a system to provide a constant source of light. This ensures

that treatment is continuous and not stalled at night time.

Conclusively, efficient wastewater treatment is justified on agronomic, social and

economic grounds and must be taken to minimize health and environmental impacts.

Concerning the health factors of the society, consideration must be taken into account for

the number of innocent people that are affected by the polluted waters. These health factors

include the effects on humans due to toxins and hazardous pollutants in the water system

(Cunningham, 1999). Many waterborne diseases such as cholera and typhoid have affected

Nairobi and other cities in Kenya for the past several years through contaminated sewage

water.

8

As for the economical concerns, there is need to take into consideration the total cost to

build or fund new projects on wastewater treatment plants. By building a wastewater

treatment plant, the land the land availability has to be flexible enough to establish areas

with new treatment facilities. By doing so, parts of land that already have existing

farmlands, settlements and industries will be displaced to compensate for the new

development sites. This would also affect the economy negatively (Huber, 2004).

To Improve the water quality to a maximum, technical aspects must be reviewed. These

technical aspects on proposing an acceptable wastewater treatment method include the

types of treatment that can be used for treating wastewater, the efficiency of the

wastewater treatment plants by observing the effluents produced, project duration and the

practicality of using the different types of wastewater treatment. Considering the social,

environmental, economical and technical aspects concerning the wastewater treatment

systems, the use of algae-bacteria system is a suitable way to deal with the wastewater

pollution problem.

1.7 SIGNIFICANCE OF THE STUDY

Wastewater treatment systems are a significant issue for water quality management

planning in developing countries such as Kenya. Proper sewage treatment systems prevent

raw sewage discharges and increase property values without costly infrastructure. The

researcher sought to help us appreciate the need of a suitable system which is both energy

saving and economical to the public, A natural system which reduces environmental

pollution and saves on water demand through recycling of water. The algae-bacteria

system makes use of natural resources such as bacteria, algae and sunlight thus making it

friendly to the environment.

1.8 LIMITATIONS OF THE STUDY

First hand collection of data from the field was faced with many challenges such as some

respondents failing to fill in the questionnaires, inability to access some areas and

inadequate co-operation from some respondents. Since the research was done hand in hand

with university lectures, it was difficult to undertake regular visitations to the sampling

areas and the locations where wastewater treatment was being done.

9

Emphasis on wastewater management has not been a well established area in the country

and has therefore not been well supported, financed and developed. This hence carries a lot

of setbacks in terms of support from the relevant respondents who show little concern or

interest. Collection of relevant information was therefore a huddle to deal with.

1.9 ORGANIZATION OF THE STUDY

This study is organized into 5 chapters. This chapter gives a brief introduction to the

research topic. It laid down the research problem, the objectives of the study, the

hypothesis, scope and significance of the study and gives justification of conducting the

study. The limitations of the study have also been discussed.

Chapter Two takes a deeper look at wastewater management by examining what has been

written about this field of study. Definitions used in this field have been outlined. From

this literature review, characteristics of wastewater and treatment systems available have

been discussed as well as the Importance of wastewater treatment. Biological treatment

Systems and its importance have been also discussed.

Chapter Three describes the procedures which were followed in conducting the study and

the methods used in data collection, analysis and presentation.

Chapter Four presents and analyzes the data collected from the field.

Chapter Five lays down the findings of the study, tests the hypothesis and gives

recommendations on how best wastewater management can be done. It recommends the

adoption of Biological wastewater treatments systems. Areas for further research have also

been indicated.

10

2 CHAPTER TWO

LITERATURE REVIEW

2.1 INTRODUCTION

This chapter outlines the characteristics of wastewater; the effects of wastewater on

environment; the stages of wastewater treatment and treatment technologies available; the

algal-bacterial technology of wastewater treatment.

2.2 DEFINITION OF TERMS

Waste

The world health Organization defines waste as being something which the owner no

longer wants at a given place and time and which has no current perceived market value,

(Suess and Huissman,1993). Waste in this context will be taken to refer to the market

waste that are discarded as useless. These materials may either be of liquid, gaseous or

solid nature.

Management

It is a cyclical process of setting objectives, establishing long term plans, programming,

budgeting, implementation and maintenance, monitoring and evaluation, cost control,

revision of objectives and plans. Waste management should be approached from the

perspective of the entire cycle of material use. This will include production, distribution

and consumption as well as waste collection and treatment if necessary or disposal

(Hawkes H.A, 1963).

Wastewater Management

It is the collection and treatment of wastewater, including such ancillary matters as

administration and financing, engineering planning and design, operation and maintenance

and monitoring and evaluation of overall performance (Dixon et al, 1999)

11

Waste Treatment

It is a series of chemical, physical or biological processes to remove dissolved and

suspended solids from wastewater before discharge. It is any process to which wastewater

or industrial waste is subjected to make it suitable for subsequent use or acceptable for

discharge to the environment (Andrew J.F, 1974).In a broader sense, waste treatment

encompasses the treatment and disposal of solid waste as well as wastewater.

Wastewater Treatment Plant (WWTP)

It is an arrangement of devices and structures for treating wastewater, industrial wastes and

sludge. Synonymous with waste treatment plant, sewage treatment plant or wastewater

treatment works. It can also be referred to as a water pollution control plant. It is a facility

engineered and constructed to remove pollutants from a predominantly liquid medium

(Buzzi R.A, 1992).

Recycled Water

Reclaimed water or recycled water, is former wastewater (sewage) that is treated to

remove solids and certain impurities, and used in sustainable landscaping irrigation or to

recharge groundwater aquifers. The purpose of these processes is sustainability and water

conservation, rather than discharging the treated water to surface waters such as rivers and

oceans.

The definition of reclaimed water, as defined by Levine and Asano, is "The end product of

wastewater reclamation that meets water quality requirements for biodegradable materials,

suspended matter and pathogens." In more recent conventional use, the term refers to water

that is not treated as highly in order to offer a way to conserve drinking water. This water

is thusly given to uses such as agriculture and sundry industry uses

Cycled repeatedly through the planetary hydrosphere, all water on Earth is recycled water.

But, typically when we hear the term "recycled water" or "reclaimed water" it means

wastewater that is sent from our home or business through a pipeline system to a treatment

facility where is treated to a level consistent with its intended use. It is then routed directly

12

to a recycled water system for uses such as irrigation or industrial cooling (Murray M.Y

and Graham J.F, 1978)

2.3 WHY WE NEED TO TREAT WASTEWATER

In addition to water that we want to recycle, wastewater contains pathogens (disease

organisms), nutrients such as nitrogen and phosphorus, solids, chemicals from cleaners and

disinfectants and even hazardous substances. Given all of the components of wastewater, it

seems fairly obvious that we need to treat wastewater not only to recycle the water and

nutrients but also to protect human and environmental health. Many people, however, are

not very concerned about wastewater treatment until it hits home. They can ignore it until

bacteria or nitrates show up in their drinking water, the lake gets green in the summer and

the beach is closed, or the area begins to smell like sewage on warm days. Sometimes

residents discover they can’t get a building permit or sell their home without a septic

inspection or upgrade, or they find out there is no room on their property for a new or

replacement septic system. Often when one home owner has a sewage treatment problem,

others in the neighborhood have the same problem. People don’t always talk to their

neighbors about sewage problems for a variety of reasons, including risk of enforcement

actions (Brower et.al, 1990) .

2.4 BIOLOGICAL TREATMENT OF WATER

Biological wastewater treatment, in its simplest form, is the conversion of biodegradable

waste products from municipal or industrial sources by biological means. Natural low-rate

biological treatment systems are available for the treatment of organic wastewaters such as

municipal sewage and tend to be lower in cost and less sophisticated in operation and

maintenance (Otis, 1996). Although such processes tend to be land intensive by

comparison with the conventional high-rate biological processes already described, they

are often more effective in removing pathogens and do so reliably and continuously if

properly designed and not overloaded. Among the natural biological treatment systems

available, stabilization ponds and land treatment have been used widely around the world.

13

2.5 WHY RECYCLING SYSTEMS ARE NEEDED

Around the world there is a movement for cities to be more sustainable and to encourage

sustainable practices. Along with this push, some cities are facing shortages in the supply

of potable water due to various factors including climate change, water demand issues and

urbanization pressures (Newman, 1993, Dillon etal, 2004).

Added to a shortage of potable water is the increasing need to consider environmental

requirements (WRC Gardner, 2004; and Chung, 2005). The recognition of the effects of

current water management practices on the environment, in particular the effect on

wetland and river dependent organisms in Wetland areas, has seen the environment

become an important consideration when determining future water supply options, thereby

placing pressure on traditional water supply practices.

There have been a number of sewage overflows in Nairobi City, There have been several

cases of bursting main water pipes in areas such as Kayole and Eastleigh areas, Incidences

such as these are becoming commonplace demonstrating a need for major maintenance

and/or system upgrades. In light of these factors the adoption of Alternative Waste Water

Systems (AWWS) is growing in popularity. Overseas, there has been an increase in the

implementation of AWWS. For example in Germany, the concept of decentralized

sanitation and reuse (DeSa/R) is being promoted. This concept involves the separation and

treatment of different wastewater streams for optimal reuse (Huber, 2004). There will be

many challenges implementing AWWS.

a) Climate change

Global weather patterns are shifting and the effects of global warming are yet to be

determined. International model-based predictions indicate lower rainfall events

worldwide (Hochstrat et al, 2005; Lockyer, 2005). Since severe droughts in the 2000s,

Nairobi has experienced repeated episodes of below average rainfall frequency and

intensity; this has seen potable water resources stretched. Decreasing rainfall places

pressure on groundwater extraction levels as water is drawn to replace the lower dam

levels in the water catchment areas.

14

In 2009 the dry season was longer than usual and the reservoir of the Thika Dam, which

has a storage capacity of 70m cubic meters, held only 26m cubic meters of water at the

height of the drought. Environmentalists attributed the low water levels not only to the

failed rains, but also to the destruction of forests in the Aberdare Range Erosion reduces

the storage capacity of the reservoir and water quality has been reduced by pesticide

runoff. The Nairobi water utility drilled emergency wells during the drought and connected

them to the piped network, relying again on groundwater about a decade after the utility

had closed down its last well field.

Wastewater recycling is one option available to help secure potable water supplies in times

of drought (Okun, 2002). Efficient forms of Wastewater treatment can provides water for

non-potable uses, such as toilet flushing and garden irrigation; this reduces demand for

potable water and relieves the need to expand the existing centralized infrastructure.

b) Water Demand

Our water use has been so wasteful that in many respects the problem is not one of water

shortage, but of wasteful, unsustainable and environmentally irresponsible management of

water (COA, 2004 p86).

Everybody needs water, we drink it, wash our clothes, bathe ourselves, and water can be

manipulated to generate electricity and flush away our waste. Water helps drive all forms

of industry and farming, and globally, cities are facing water demands that outstrip their

ability to supply (Anderson, 2005). The natural environment also needs water allocations.

The environmental flows required to protect surface and groundwater systems, and their

dependent ecosystems, need to be balanced with the needs of our own (WRC, 2004;

Gardner and Chung, 2005).

The Kenyan water economy, like many developing countries, has been hampered in the

ability to increase the volume of water supply by economic and environmental factors,

such as catchment volume variability and capped catchment and aquifer withdrawal levels,

yet there has been no diminishing demand for water; in most cases demand has been

increasing.

15

2.6 THE BENEFITS OF RECYCLING WATER

There are many benefits to recycling water. Recycling water provides an alternative

supply of water, where potable water is not necessary, such as public open space irrigation

and car washing (McKay and Hurlimann, 2003). Alternative sources of water reduce

demand on potable water supplies, thereby reducing the need to expand existing

infrastructure (Hermanowicz and Asano, 1999; McKay and Hurlimann, 2003). In some

cases recycling of wastewater represents the only opportunity (apart from desalination) of

adding a substantial and sustainable water yield (COA, 2004). Recycling reduces the

amount of wastewater disposed off into the environment via ocean outflows; it can also be

returned to the environment to enhance environmental flows. By not pumping water to

ocean outflow s there is also a net saving of water; as water is not required to flush waste

long distances; this also reduces energy consumption (Hermanowicz and Asa no, 1999;

Hurlimann and McKay, 2005).

2.7 WASTEWATER GENERATION

Every increase in water use leads to increased wastewater generation necessitating the

management of higher volumes of wastewater as the depleted fraction of domestic and

residential water use is only in the order of 15 to 25%. Most countries do not compile

annual statistics on the total volume of municipal wastewater generated, transported and

treated. In developing countries, rates of sewerage are very low for rural areas of Africa,

Latin America and Asia, where septic tanks and latrines predominate. For ‘improved

sanitation’ (including sewerage + wastewater treatment, septic tanks and latrines), almost

90% of the population in developed countries, but only about 30% of the population in

developing countries, has access to improved sanitation (Jouravlev, 2004; World Bank,

2005a, b).

Estimates for Methane (CH4) and Nitrogen oxide (N2O) emissions from wastewater

treatment require data on degradable organic matter (BOD; COD) and nitrogen. Nitrogen

content can be estimated using Food and Agriculture Organization (FAO) data on protein

consumption, and either the application of wastewater treatment, or its absence, determines

the emissions. Aerobic treatment plants produce negligible or very small emissions,

whereas in anaerobic lagoons or latrines 50–80% of the CH4 potential can be produced and

16

emitted. In addition, one must take into account the established infrastructure for

wastewater treatment in developed countries and the lack of both infrastructure and

financial resources in developing countries where open sewers or informally pond

wastewaters often result in uncontrolled discharges to surface water, soils, and coastal

zones, as well as the generation of N2O and CH4. The majority of urban wastewater

treatment facilities are publicly operated and only about 14% of the total private

investment in water and sewerage in the late 1990s was applied to the financing of

wastewater collection and treatment, mainly to protect drinking water supplies (Silva,

1998; World Bank 1997).

2.8 WASTEWATER CHARACTERISTICS(PHYSICAL, CHEMICAL AND

BIOLOGICAL) AND ITS EFFECTS

2.8.1 Characteristics of wastewater and source

Table 1: Characteristics of wastewater and source

CHARACTERISTIC SOURCE

Physical properties

Color

Odor

Solids

Temperature

Domestic and industrial wastes: natural

decay of organic material

Decomposing matter in wastewater

Domestic water supply, domestic and

industrial

Wastes

Domestic and industrial wastes

17

Chemical constituents

Organic:

Carbohydrates

Fats, oils and grease

Pesticides

Phenols

Proteins

Surfactants

In organic:

Alkalinity

Chlorides

Heavy metals

Nitrogen

Domestic, commercial and industrial wastes

Domestic, commercial and industrial wastes

Agricultural wastes

Industrial wastes

domestic and commercial wastes

Domestic and industrial wastes

Domestic wastes, domestic wastewater

supply, groundwater infiltration

Domestic water supply, domestic wastes,

Ground water infiltration, and water

softeners.

Industrial wastes

Domestic and agricultural wastes

18

pH

phosphorus

sulfur

toxic compounds

gases:

hydrogen sulfide

methane

oxygen

biological constituents:

animals

plants

prostista

viruses

Industrial wastes

Domestic and industrial wastes, natural run

off

Domestic water supply, domestic and

industrial wastes

Industrial wastes

Decomposition of domestic waste

Decomposition of domestic wastes

Domestic water supply, surface water

infiltration

Open water courses, and treatment plants

Open water courses, and treatment plants

Domestic wastes, treatment plants

Domestic wastes

Source (Becker 1988)

19

2.8.2 Effects of Wastewater on the environment

Table 2: Constituents of wastewater and their effects

Contaminant Suspended solids Can lead to development of sludge deposit

and anaerobic conditions when untreated

wastewater is discharged in the aquatic

system

Biodegradable organics Composed of proteins, carbohydrates and

fats

Measured commonly in BOD and COD

When discharged in aquatic system their

biological stabilization can lead to depletion

of natural oxygen and lead to septic

condition.

Pathogens Transmit communicable diseases

Nutrients Both N and P. When discharged in aquatic

system can lead to undesirable aquatic life.

When discharged in excess can cause

ground water pollution

Refractory organics They tend to resist conventional WW

treatment methods. They include-

surfactants, phenols and agricultural

pesticides

Heavy metals Usually added from commercial and

industrial activities. They must be removed

if the WW IS TO be re used.

Dissolved in organic solids Include: Ca, Na, SO4, They must be

removed if the WW is to be re used.

Source (Becker 1988)

20

2.9 TREATMENT TECHNOLOGIES AVAILABLE

The features of wastewater treatment systems are determined by; The nature of the

municipal and industrial wastes that are conveyed to them by sewers and The amount of

treatment required to preserve and/or improve the quality of the receiving bodies of water.

Wastewater contains contaminants that include organic wastes, suspended solids, bacteria,

nitrates, and phosphates that should be removed. In order to make wastewater acceptable

for reuse or for safe disposal into the environment, the concentration of contaminants must

be reduced to a non harmful level; usually a standard prescribed by the National

Environmental Management authority (NEMA) and WHO standards. According to India

Waste Management Portal in 2011, there is need for separating grey water from black

water and tapping its reuse potential could be an ideal strategy for urban wastewater

management. This is because the black water, which is only 30% of the total wastewater

produced, contains most of the pollution load whereas the grey water constituting 70% of

wastewater has fewer pollutants in it and is easy to reuse; in certain applications it is

suitable for reuse even without treatments. The blackwater should be subjected to

treatment before it is disposed of.

In urbanized areas, municipal wastewaters (mainly sewage) generally are conveyed to a

point of treatment through sanitary sewers, whereas storm waters are conveyed to their

receiving bodies of water through storm drainage networks. Essentially, discharges from

treatment plants usually are disposed by dilution in rivers, lakes, or estuaries (Newman,

1993).

2.9.1 Preliminary Treatment

Preliminary treatment of wastewater includes screening, grinding, grit removal, flotation,

equalization, and flocculation. Screens, grinders and grit removal are provided for the

protection of other equipment in the treatment plant. Pre-chlorination or pre-aeration may

be required to prevent odor problems and to eliminate septic conditions where wastewater

has abnormally long runs to the plant. Equalization structures are used to dampen diurnal

flow variations and to equalize flows to treatment facilities.

21

2.9.2 Primary treatment

It is the second step in the wastewater treatment process beyond the preliminary treatment

of headworks, involves the physical separation of suspended solids from the wastewater

using primary qualifiers. This consists of grit and floating oil removal, pH neutralization,

etc., takes care of most of the pollutants and toxic chemicals that can be easily removed

from raw wastewater at this stage. Primary Treatment also reduces the Biological Oxygen

Demand (BOD) levels in the waste stream. Such pretreatment creates conditions suitable

for secondary treatment. Processes which can be used to provide primary treatment include

the following: Primary sedimentation, also called clarification; Microscreens and Imhoff

tanks.

2.9.3 Secondary treatment

Secondary treatment processes can remove up to 90 percent of the organic matter in

wastewater by using biological treatment processes. The process consists of removing or

reducing contaminants or growths that are left in the wastewater from the primary

treatment process. Usually biological treatment is used to treat wastewater in this step

because it is the most effective type of treatment on bacteria, or contaminant, growth

This is accomplished by bringing together waste, bacteria and oxygen in trickling filters or

the activated sludge process. Bacteria are used to consume the organic parts of the

wastewater.

It removes major pollutants to achieve the disposal quality, is designed to substantially

diminish the pollutant load. SS, emulsified oil, and dissolved organics are the major

pollutants removed at this stage.

Trickling Filter

A trickling filter is a bed of media (typically rocks or plastic) through which the

wastewater passes. The media ranges from three to six feet deep and allows large numbers

of microorganisms to attach and grow. Older treatment facilities typically used stones,

rocks, or slag as the media bed material. New facilities may use beds made of plastic balls,

22

interlocking sheets of corrugated plastic, or other types of synthetic media. This type of

bed material often provides more surface area and a better environment for promoting and

controlling biological treatment than rock. Bacteria, algae, fungi and other microorganisms

grow and multiply, forming a microbial growth or slime layer (biomass) on the media. In

the treatment process, the bacteria use oxygen from the air and consume most of the

organic matter in the wastewater as food. As the wastewater passes down through the

media, oxygen-demanding substances are consumed by the biomass and the water leaving

the media is much cleaner. However, portions of the biomass also slough off the media and

must settle out in a secondary treatment tank (Fallowfield al. 1996)

Figure 1: Trickling Filter

Source (Fallowfield al. 1996).

23

Suspended Growth Processes

Examples of these processes include activated sludge, oxidation ditches and sequencing

batch reactors.

Suspended growth processes are designed to remove biodegradable organic material and

organic nitrogen-containing material by converting ammonia nitrogen to nitrate unless

additional treatment is provided. In suspended growth processes, the microbial growth is

suspended in an aerated water mixture where the air is pumped in, or the water is agitated

sufficiently to allow oxygen transfer. The processes speed up the work of aerobic bacteria

and other microorganisms that break down the organic matter in the sewage by providing a

rich aerobic environment where the microorganisms suspended in the wastewater can work

more efficiently. In the aeration tank, wastewater is vigorously mixed with air and

microorganisms acclimated to the wastewater in a suspension for several hours. This

allows the bacteria and other microorganisms to break down the organic matter in the

wastewater. The micro-organisms grow in number and the excess biomass is removed by

settling before the effluent is discharged or treated further. Now activated with millions of

additional aerobic bacteria, some of the biomass can be used again by returning it to an

aeration tank for mixing with incoming wastewater (Larsdotter, 2006).

Lagoons

A wastewater lagoon or treatment pond is a scientifically constructed pond, three to five

feet deep, that allows sunlight, algae, bacteria, and oxygen to interact. Biological and

physical treatment processes occur in the lagoon to improve water quality. The quality of

water leaving the lagoon, when constructed and operated properly, is considered equivalent

to the effluent from a conventional secondary treatment system. However, winters in cold

climates have a significant impact on the effectiveness of lagoons, and winter storage is

usually required.

24

Figure 2: Lagoon

Source (Fallowfieldet al. 1996).

2.9.4 Tertiary treatment

These are mainly advanced treatment processes that go beyond conventional secondary

treatment and include the removal of recalcitrant organic compounds, as well as excess

nutrients such as nitrogen and phosphorus. Water reclamation is achieved in varying

degrees, but only a few large-scale plants are reclaiming water to near-pristine quality.

(Arms et al, 1990).

2.9.5 Advanced WW treatment

Advanced wastewater treatment encompasses several individual unit operations, used

separately or in combination with other processes, to achieve very high overall treatment

efficiencies. The advanced wastewater treatment processes employ physical, chemical and

biological treatment methods. The objective is to improve the removal of suspended solids,

organic matter; dissolved solids, and nutrients. These may be achieved by the following:

Polishing ponds.

Polishing ponds are used to obtain increased organic and suspended solids removal

efficiencies up to 20 percent from existing treatment. Treatment by polishing ponds can be

aerobic or facultative (a combination of aerobic and anaerobic biological activity).

Polishing ponds are also used to allow dissipation of chlorine residual to make discharge

compatible with shellfish. (Fallowfield al. 1996).

25

Figure 3: A pictorial diagram of a polishing pond

Source (Fallowfield al. 1996).

Post-aeration.

Post-aeration is required a when a certain effluent dissolved oxygen level must be

maintained. Post-aeration can be achieved by diffused aeration, mechanical aeration, or

cascade aeration.

Diffused aeration - carried out in tanks 9-15 ft deep and 10-50 ft wide (depth: width ratio is

maintained at< 2), with detention time of 20 min.

Mechanically aeration-basins are 8 ft deep and 15 to 50 square ft per aerator. Surface

aeration is the most efficient mechanical aeration in terms of required hp (0.1 hp per 1,000

gallons of effluent) (Wolfaardt, 1994).

Micro-straining.

Microstraining is an effective effluent polishing device and is applied for the removal of

additional suspended solids and associated biochemical oxygen demand. It involves

physical straining of solids through a screen with continuous backwashing, using a rotating

drum to support the screen (Fallowfieldet al, 1996).

Wastewater is fed into the inside of the drum and filters radially outward through the

screen, with the mat of solids accumulating on the screen inside the drum.

26

The solids are flushed into a removal trough at the top of the drum by a pressurized

backwash system. From this trough, the solids are returned to the head of the system

Filtration.

Filtration is an effective method for achieving additional suspended solids and biochemical

Oxygen demand removal after conventional treatment processes. Filtration can also

partially remove phosphorous. Filtration can be applied directly to secondary effluents

with or without sedimentation and pretreatment by chemical addition (Hawkes H.A, 1963).

Adsorption with activated carbon.

The Carbon Adsorption is a method to treat wastewater in which activated carbon removes

trace organic matter that resists degradation. It accomplishes filtration as well as

adsorption. The primary function of carbon adsorption as a wastewater treatment process is

the removal of dissolved organics. It can be applied as advanced treatment to adsorb non-

biodegradable organics, or as a secondary treatment replacing conventional biological

treatment. However, carbon adsorption does not remove certain such as methanol, formic

acid and sugars (Parker D.S, 1973).

Phosphorus removal.

Phosphorous may be removed from wastewater through conversion of polyphosphates to

soluble forms of phosphorous and then to insoluble forms, and subsequent separation of

the insoluble phosphorus forms from the wastewater a through chemical precipitation

using lime or mineral additives such as alum or ferric chloride.. The process involves

chemical addition, mixing, Flocculation and sedimentation (Hawkes H.A, 1963).

Nitrogen removal.

Nitrogen may be removed from wastewater by the following processes: air stripping,

biological treatment, and breakpoint chlorination. Biological nitrification-denitrification is

the most common method used. It involves the biological oxidation of ammonia to nitrate

followed by anaerobic denitrification, with nitrogen released from wastewater as nitrogen

gas. Nitrification can be achieved as a single stage combined with the activated sludge

process or as a separate stage (Hawkes H.A, 1963).

27

Denitrification is a separate operation and may be achieved from "suspended growth” or

"attached growth” configuration. Here, nitrate is reduced to carbon dioxide, water and

nitrogen gas following addition of methanol which provides the carbon source.

Objectives of advanced wastewater treatment

The main objective of advanced wastewater treatment is to provide for additional organic

and suspended solids removal, These are those solids that failed to undergo removal in the

previous stages. Its second objective is to provide a medium for removal of nitrogenous

oxygen demand (NOD). This stage is also used for nutrient removal especially for

phosphorous and nitrogen. Advanced wastewater treatment is also purposed to cater for the

removal of toxic material. (Fallowfield al, 1996)

Benefits of advanced wastewater treatment

The main benefit of advanced wastewater treatment is that it enables effluents to be

recycled directly or indirectly hence may increase the available domestic water supply.

Effluents from advanced wastewater treatment plants in industries may also be re used for

industrial process or cooling water supplies.

Advanced wastewater treatment also produces effluents of high quality that has reduced or

no effect on the receiving water bodies.

Limitations of various Advanced WW treatment systems

Initial capital required is high.

Advance waste water treatment systems require various operational units e.g. membrane

filtration units, micro-filters, biological nutrient removers, chemical precipitation units etc

which are expensive to acquire and install.

High costs of operation and maintenance.

The systems require chemicals (Chemical coagulation), high energy (Micro-screening) and

skilled labour which are costly hence making the system unaffordable.

28

2.10 BIOLOGICAL TREATMENT SYSTEMS

2.10.1 Algal and Bacterial Technology

Micro algae in the treatment of WW

Microalgae are rapid growing photosynthetic organisms that use sunlight as a source of

energy and use nutrients such as nitrogen and phosphorous to grow. Several microalgae

may even act as heterotrophic organisms in conditions where light is not available (Becker

1988). These metabolic capacities make the microalgae great candidates for wastewater

treatment. They remove the nitrogen and phosphorous by incorporating this nutrients in

their biomass as they grow. The fact that microalgae use the light as energy source renders

these organisms suitable for removing nutrients when organic carbon, a chemical energy

source, is not available in sufficient amount.

Microalgae accumulate heavy metals in its biomass, thus removing them from the water,

which poses a great advantage for treating water contaminated with these toxic

contaminants. PH and temperature increase of the water due to photosynthesis of

microalgae may also contribute to the elimination of pathogenic bacteria (Fallowfieldet al.

1996).

The microalgae systems offer other operational advantages. As they consume CO2 and

produce O2, they may be used to oxygenate water with low DO, improving posterior

heterotrophic biological treatment with aerobic microorganisms and eliminate the need for

aeration (Oswald 1988). This eliminates the elevated costs of aeration which may represent

45-75% of the total energy consumption of the treatment plant (Larsdotter, 2006). The

production of O2and consumption of CO2 makes this system carbon negative rendering it

more environmentally friendly by contributing to the reduction of the greenhouse gases,

and gaining CO2 credits in the CO2 emissions market. Microalgae treatment also eliminates

the need of additional treatments with other chemicals which leads to a reduction in sludge

production. The microalgae sludge has the advantage of being an energy and nutritionally

rich sludge, making it suitable for energy (Brennan and Owende, 2010), fertilizer or

feeding (Spolaoreet al. 2006, Mata et al. 2010) downstream applications. The possible use

29

of this type of sludge may reduce even further the operational costs of the microalgae

system.

Table 3: Factors influencing algae growth (Becker 1988)

(Source : Becker 1988)

Bacteria in the treatment of WW

Bacteria are single-cell organisms. Bacteria metabolize the organics in wastewaters with

the production of new microbial cell mass. While most bacteria in wastewater treatment

systems utilize organics for their metabolism, there is an important group of bacteria that

utilize inorganic compounds for their metabolism. As a net result, the two groups of

Type Factor

Abiotic Light

Temperature

Nutrient concentration

O2

CO2

pH

Salinity

Toxic chemicals

Biotic Pathogens

Predation

Competition

Operational Mixing

Dilution rate

Depth

Harvesting frequency

30

bacteria in wastewater do not compete with each other for their nutrients and both grow in

the same environment (Becker 1988).

Normal municipal wastewaters contain between 105 and 107 bacteria/ml. Bacteria use

soluble food to reproduce by binary fission. They are about 0.5 to 1.0 micron in diameter

(Wolfaardt, 1994).

Their shape falls in three categories:

Spherical (cocci),

Cylindrical (bacilli)

Helical (spirilli); the spiral forms may be 15 microns long.

Metabolically, most bacteria in wastewater are heterotrophic. The autotrophic forms obtain

energy by oxidation of inorganic substrates such as ammonia, iron and sulfur. There are a

few autotrophic photosynthetic bacteria also. Depending on their organic metabolism

reactions, the bacteria may be anaerobic or facultative (Wolfaardt, 1994).

2.10.2 Algal- bacteria system

This symbiotic relation has been found to produce good results for the removal of organic

matter, ammonium, phosphorous (de Bashan et al. 2002) and other pollutants as salicylate

and phenols (Bordeet al. 2003, Safonovaet al. 2004, Chavan and Mukherji 2008).

Microalgae are responsible for the O2 production used by aerobic bacteria to biodegrade

organic pollutants with CO2 release that on its turn will be used by microalgae to grow.

Microalgae are also known to secrete EPS that may provide conditions for heterotrophic

bacteria to attach and serve also as food source (Muñoz and Guieysse 2006). On the other

hand, pH and temperature increase due to phototrophic activity may have a negative

impact on heterotrophic bacteria (Oswald 2003). Microalgae and bacteria are known to

secrete a wide range of compounds which may have effects on the relation between them.

Microalgae produce toxins that affect other organisms, like bacteria, compromising their

growth (Oswald 2003) but also secrete other metabolites that enhance growth (Wolfaardt,

31

1994). Concomitantly, bacteria also secrete compounds that enhance microalgae growth

and activity, as seen in studies using Azospirillumbrasilense (de-Bashan et al. 2004).

However, bacteria may also secrete algaecides that inhibit microalgae (Fukami, 1997).

As discussed, within this system, O2 production by microalgae is often considered the

limiting factor for contaminants removal, which is due to the slower growing rate of

microalgae compared to the growing rate of heterotrophic bacteria (Munoz et al. 2004).

Due to this, high O2 production microalgae should be used to generate better results. This

treatment can be done through lagoons, activated sludge process or in a photo-bioreactor as

discussed below.

Figure 4: Microalgae and heterotrophic bacteria interactions

(Source: Fukami,1999)

Why Micro algae chlorella vulgaris and bacteria

Microalgae chlorella vulgaris combined with bacteria form biofilms that are more resistant

to toxic compounds and high ammonium concentrations. The low biodegradability of the

organic matter present makes the microalgae very suitable for the treatment. However, the

32

few biodegradable organic matter has to be removed, which is accomplished by the

bacteria within this system. The inhibitory action of some pollutants may be minimized by

the symbiotic relationship which, as mentioned above, speeds up the biofilms development

due to algae growth promoters produced by bacteria. (Lin et al. 2007).

2.10.3 Photo-bioreactor Technology

Photo-bioreactor system

A photo-bioreactor is a controlled system that incorporates some type of light source. The

term photo-bioreactor is more commonly used to define a closed system, as opposed to an

open pond. A pond covered with a greenhouse could also be considered an unsophisticated

form of photo-bioreactor, Because these systems are closed, everything that the algae need

to grow, (carbon dioxide, water and light) need to be introduced into the system

(Tredici.M.R 1999).

Important Design Parameters for Photo-bioreactors

Algal use in wastewater treatment using a bioreactor is dependent on many environmental

parameters including light intensity, CO2/O2 balance, temperature, salinity, nutrients, PH

value and turbulence (Spolaore 2006).

Light inside the Photo-bioreactor

The advantage of the illumination intensities is the rate of photosynthesis is directly

proportional to light intensity. On the other hand, too high illumination intensities can

damage photosynthetic receptor system occurs within a few minutes (photo-inhibition).

The total light energy supplied per unit volume of photo-bioreactor (Et/V), is the most

appropriate measure of photobioreactor performance. Linear growth rates of algae

decreased with an increase in depth of the Photo-bioreactor (Ogbonna & Tanaka, 1997)

Salinity, nutrients and pH value

PH has an effect on solubility of carbon dioxide and minerals in the medium, so directly or

indirectly influences the metabolism of the algae. There are some factors that influence pH

of algal cultures, such as composition and buffering capacity of medium, amount of

33

dissolved CO2 solubility and metabolic activity of algal cells. Ammonia stripping and

precipitation of calcium phosphate can be occurring in alkaline pH. For optimal

photosynthesis sufficient nutrient supply for microalgae is a precondition. The shortage of

nutrients will cause disorder in metabolism and disproportionate production of

intermediates of photosynthesis. Deviations from the optimum osmotic conditions and

salinity will cause physiological reactions and productivity problem (Decker, 2008).

Temperature

This is a major parameter which effect growth of microalgae and photosynthetic reactions

in algal medium. The influence of temperature is insignificant, when carbon dioxide or

light is limiting for photosynthesis. At high temperatures, efficiency of photosynthesis

declines. This effect can worsen in suspension cultures by the difference in decrease of

CO2 and O2 solubility at increased temperatures (Spolaore 2006).

Turbulence and Mixing

Turbulence is important for photosynthetic reactions which have an important effect on

light distribution in algal medium while mixing;

i. keeps cells in suspension

ii. distributes the nutrients

iii. keeps generated heat in within the reactor

iv. improves CO2 transfer into the reactor

v. strips the photosyntheticaly produced O2

vi. improves mass transfer between cells and the liquid milieu

vii. facilitates the movement of cells in and out of the illuminated part of the reactor

CO2/O2 Balance

The natural CO2 concentration in air only 0.03 % is too low to sustain optimal growth and

high productivity. Algae require an inorganic carbon source to perform photosynthesis.

Thus, CO2 must be supplied in algal cultures while increasing O2 has to be removed before

reaching inhibitory concentrations. Oxygen may become a problem in algal cultures of

high cell densities not only because of the limitation of the rate of photosynthesis but also

34

upon radiation with appropriate energy, oxygen radicals may develop during the

respiratory gas exchange and cause toxic effects on cells due to membrane damage

(Spolaore 2006).

Light for the bioreactor

Sunlight is the main source of light however an artificial source maybe provided.

2.10.4 Filtration Technology

This involves use of sand and other media filters to remove constituents from wastewater

primarily through a physical process of filtering out particulates from the water. The media

type used and its grain size distribution determine how small of a particle is filtered out.

Coarser sands have larger pore spaces that have high flow-through rates but pass larger

suspended particles. On the other hand, very fine sand, or other fine media filter, has small

pore spaces with slow flow-through rates and filter out smaller total suspended solids (TSS)

particles. Some media, such as peat-sand mix, may also provide ionic adhesion or

exchange for some dissolved constituents which further enhance effluent quality. (Bell and

Stoke et al, 1996)

Sand filters are beds of granular material, or sand, drained from underneath. The typical

sand filter is a lined watertight box, generally concrete- or plastic-lined, and filled with a

specific sand material. Types of sand filters include:

Intermittent sand filter- which wastewater is applied periodically to a 24- to 36-inch-

deep bed of sand that is under drained to collect and discharge the effluent. The bed is

underlain by graded gravel and collecting tile. Wastewater is applied intermittently to the

bed’s surface through distribution pipes.

Re-circulating intermittent sand filter-This filters wastewater by mixing filtrate with

incoming wastewater effluent and re-circulating it several times through the filter media

before discharging it to a final land application system. This filter’s components are similar

to the intermittent sand filter components.

35

Treatment Criteria.

A sand filter purifies the water in three ways:

a) Filtration where particles are physically strained from the incoming wastewater.

b) Chemical sorption, in which contaminants stick to the surface of the sand and to

the biological growth on the sand surface.

c) Assimilation, in which aerobic microbes eat the nutrients in the wastewater. The

success of treating wastewater depends on these microbes. Air must be available

for these microbes to live.

Sand Filter Performance

This is dependent upon aeration and temperature (Hammer and Mark et al, 2001). Oxygen

needs to be available within the pores so that microbes can break down the solids in the

wastewater. If the filter has poor air movement, such as when it is covered with heavy clay,

the system can clog. Temperature directly affects the rate of microbial growth, chemical

reactions, adsorption mechanisms and other factors that contribute to the stabilization of

wastewater. Lower temperatures usually slow the rate of material breakdown.

Maintenance requirements for sand filters depend on the type of filter. They can be

maintained regularly and regenerated if the media become clogged over time. The sand

filter can become clogged because of physical or biological factors. Physical clogging

occurs when solid materials accumulate within or on the sand surface. Biological clogging

is caused by excessive microbial growth within the filter. The filter clogs faster when

biological slimes accumulate and wastewater contaminants entrapped there decompose

slowly.

2.11 CONCLUSION

Water quality is essential to public health. Although water treatment is a common practice

for supplying good quality of water from a source, maintaining an adequate water quality

throughout a distribution system is never an easy task. It is important to develop a system

which is efficient and reliable in wastewater management. A lot has been previously

written about waste management but emphasis has not been on wastewater and its

management through biological treatment systems.

36

3 CHAPTER THREE

RESEARCH METHODOLOGY

3.1 INTRODUCTION

This chapter describes the procedures which were followed in conducting the study, that is,

an explanation of the research design, the population, the sampling technique and sample

size, data collection instruments and techniques and the methods of data analysis and

presentation. The research was carried out through collection of data followed by an

analysis of the same. Data used in this research project is both primary and secondary,

gathered through consultations and studies on wastewater and sanitation related issues. A

qualitative research approach was used to investigate the research questions. Qualitative

research focuses on understanding a situation, rather than trying to predict or control it, and

is used when trying to research social phenomena or to understand stakeholder perceptions

and attitudes to a situation (Nachmias and Frankfort-Nachmias, 1992; Neuman, 2000).

Within a qualitative framework, this research used exploratory design and key informant

techniques. Exploratory research is used in subject areas that are ill defined or poorly

researched. It is the initial research that build s to a deeper understanding of the problem

or concept being studied (Neuman, 2000; Routio, 2004).

Questionnaires were prepared and given to various individuals in the City of Nairobi.

Some of the Questionnaires and interviews were done on the real estate managers and

estate agents of buildings and apartments within the City. Some questionnaires were also

prepared for Contractors who are mainly in-charge of putting up the water treatment plants.

The other type of questionnaires was prepared for the residents of Nairobi city in order to

identify the rate of water related issues affecting the residents, this range from water

shortage to water-borne diseases. The main samples were taken from Karen, Muthaiga and

Kileleshwa which represented areas for wealthy people. Then Kibera, Mathare and

Eastleigh regions belonging to low income earners. Other regions were Embakasi, Langata

and South B which mostly comprise of average income earners. As seen these regions are

widely spread within Nairobi. This was done to allow proper distribution of samples for

37

better results. Both descriptive and Inferential statistical methods were used. Descriptive

statistics is concerned with describing or summarizing a sample. Inferential statistics is

concerned with going beyond the sample to make predictions about the population from

which the sample is drawn.

3.2 BACKGROUND TO THE STUDY

Geography

Nairobi is located about 140km South of the Equator and some 500km from the Coast. Its

geographical coordinates are 1° 17' 0" South, 36° 49' 0" East. The City is not only the

principle urban center of population but also the social, economic and communication hub

of the country. In terms of land-use a single major employment center, composed of central

commercial area and adjacent industrial and residential areas, characterizes Nairobi.

Topography

The land in Nairobi region falls from the edge of the Rift-valley in the West at an elevation

of 2300m to 1500m to the east of the city, with the centre of the city standing at 1,700

metres . The eastern side is characterized by grassland plains of poorly draining black

cotton soils. The city area of Nairobi measures 684 sq kilometres alone, with the larger

metro area covering 3,000sq. km.

Geology and soils

The geological history of Nairobi was dominated by volcanic activity associated with the

development of the Riftvalley. The soils have generally formed as product of weathering of

volcanic rocks. The majority of the soils in the area northwest of the city centre consist of

strong brown to yellow clays and dark to light red clays that have developed from lava,

volcanic tuff and ashes. These soils often referred to as red coffee soils have a relatively

good drainage capacity.

38

Climate

Although Nairobi is less than 1.5◦c South of the Equator, its altitude of about 1700m

results in an equable climate. The characteristic features of the climate are;

a) Very small seasonal change of temperature

b) Considerable daily range of temperature

c) Existence of definite wet and dry seasons

d) Marked daily range of relative humidity

Nairobi receives two types of rainfall. The long rains occur in the months of March to Mid-

May. These rainfalls are intense with occasional thunderstorms especially in April. There

is Mid-October to Mid-December season known as the short rains because it is short in

duration and the amount of precipitation is relatively light as compared to the other season.

The mean annual range of rainfall is between 250mm to 1250mm.

Population

Nairobi has experienced one of the highest growth rates of any city in Africa. Since its

foundation in 1899, Nairobi has grown to become the largest city in East Africa, despite

being the youngest city in the region. The growth rate of Nairobi is currently 4.1%. It is

estimated that Nairobi's population will reach 5 million in 2025.

These data fit remarkably closely (r^2 = 0.9994) to a logistic curve with t(0) = 1900,

P(0)=8500, r = 0.059 and K = 8 000 000. This suggests a current (2011) growth rate of

3.5% (the CIA estimate of 4.5% cited above would have been true in 2005). According to

this curve, the population of the city will reach 5 million in 2025, and will be below 4

million in 2015.

Water supply and sanitation

94% of the piped water supply for Nairobi comes from rivers and reservoirs in the

Aberdare Range north of the city, of which the reservoir of the Thika Dam is the most

important one. Water distribution losses - technically called non-revenue water are 40%,

and only 40% of those with house connections receive water continuously. Slum residents

39

receive water through water kiosks and end up paying much higher water prices than those

fortunate enough to have access to piped water at their residence. In the middle of a severe

drought, the board of the Nairobi City Water and Sewerage Company was sacked July

2009 for "malpractices", following the publication of a report by Transparency

International-Kenya and the Kenyan NGO Maji Na Ufanisi (Water and Development). The

report had found cases of bribery for illegal connections, tampering with meter readings,

and diversion of water from domestic users to industries in five cities, with the highest

incidence of bribery in Nairobi.

Figure5:Nairobi

(Source :The Internet)

40

3.3 DATA COLLECTION

Sampling Techniques

These may be described as methods by which the researcher can derive a sample from a

population. Naturally, if the aim of a certain study is to learn things about a certain

population, the optimum methodology is to test all members of that population. However

this was not possible since it was time consuming and expensive. In this case, a small

sample was sufficient to allow me make reasonable conclusions. What was required to be

done was to select a sample of the population and make inferences from that sample. This

required going beyond the available information. It Involved generalizing from the sample

to the population.

To facilitate sampling, a list of all the households in the different parts of the city was

compliled. This list served as the sampling frame. The sample was taken in a such a way

that the ratio of buildings in each street, avenue or road is reflected in the sample.

Systematic sampling could not be used since samples were being collected from different

regions in the City. Simple random sampling technique was used to select the Interviewees

who were mainly property managers, contractors and residents. Simple random sampling

technique was used to select the interviewees. This ensured the following:

1. Each member of the population had the same chance of selection, and

2. The relative chance of selection of any two members of the population was not

affected by the knowledge of whether a third member had or had not been selected.

In practice, this essentially means drawing names out of a hat or some other

random method.

Sample

A sample is a small group of items selected from a larger group to represent the qualities of

the characteristics of the larger group. It is important that, in any research, the sample

should not be too large or too small but it should be optimum in order to fulfill the required

reliability , efficiency and flexibility and achieve representation.

41

In This study, a total of 80 households form the accessible population. Due to this size of

accessible population, a total of 60 households will be studied. This will be done through

collecting the relevant data from the residents or tenants, property managers of these

households where applicable and various contractors. Information has also been collected

from the Nairobi City Water and Sewerage Company.

Primary Data

Primary data was obtained through the following sources:

a) Direct observation and use of checklist during site visits.

b) Social Interviews with the residents and the organizations involved.

c) Use of questionnaires administered to the benefactors and beneficiaries of water

and sanitations projects in the area.

d) Photographs

Observation and use of Checklists

Observation sheets were used to draw conclusions on the water and sanitation situation in

the area. These were filled during regular site visits. This method of data collection

involved going through round the area and physically inspecting water points, sanitation

facilities and wastewater treatment facilities available. This helped in getting the first hand

information on the area. This method however had shortcomings, which included the fact

that it is superficial and physical inspection did not provide all that needed to be known

regarding the situation.

Social Interviews

These were conducted with relevant authority in the NGO, CBO and Council, and also

with the residents to supplement any information given in the questionnaires which may

not have been clear or needed to needed to be expounded on.

Interviews with the locals had an ultimate goal of establishing how much water they use,

the waste water collection systems used, method of treatment if any, and any water borne

42

diseases affecting the residents. The residents gave their opinion on what type of waste

water management procedures should be adopted.

Determination of the locals to be interviewed was through simple random sampling,

mostly at those staying in apartments and privately owned estates.

Questionnaires

Three types of respondents were involved in obtaining primary data, these were the

Nairobi residents, the estate agents, the staff of Nairobi Water and Sewerage Company and

the Contractors. Questionnaires enabled collection of relevant data concerning the way in

which improvements in the wastewater and sanitation situation are carried out, problems

experienced, government help offered, general dweller participation and contribution, other

ways of waste water management that can be adopted. The answers given were not

elaborate enough and information gathered was backed up by the checklist and the

secondary data collected.

i) Residents

Initially, systematic sampling was intended to be used, where two households from each

apartment or estate in the selected regions from the city. It however proved difficult to find

all the intended interviewees. In some of the households those who were present were

either not willing or able to answer the questionnaires satisfactorily for a number of

reasons. Some households only had small children present, while in some cases the

members of the households were suspicious of the interviewer. Some actually demanded

for payment for answering questions. In some cases the questionnaires had to be left

overnight for collection the next day, at which point in time some were still not filled, if at

all they existed. This led to the use of both random route and opportunity sampling

techniques.

ii) Property Managers/ Owners

Most of the property managers were giving biased information since they didn’t want to

share information which exposed their failures and duties on proper wastewater

43

management procedures. Some manager or Property owners were unavailable or were not

willing to be questioned or interviewed.

iii) Contractors

The Contractors are directly involved in putting up the water treatment plants located in the

city or putting up connections to the municipal sewer for the communal treatment of the

wastewater by the municipal council. Most of the Contractors were unavailable though the

data was acquired through their representatives.

Photographs

Use of photographs was necessary in order to bring out the situation more explicitly. It also

served as illustrations of improvements carried out. Photographs backed up the oral

interviews and information gathered through questionnaires.

Secondary Data

Numerous researches have been done on water and sanitation. Literature used in this

research was obtained from the following sources:

1) Journals

2) Seminar reports e.g Global water supply and sanitation assessment 2000 report

(UNICEF, WSSCC & WHO)

3) Newspapers

4) Previous research papers and thesis.

5) Government publications e.g Ministry of water resources sessional paper No.1 of

1999 on the National policy on Water Resources Management and Development.

6) Electronic media e.g Internet and the community development library.

These sources yielded information on how improvements were done, problems

encountered, maps of the area, quantities such as population of the area, etc. Historical data

recorded had the shortcoming of being outdated.

44

3.4 DATA ANALYSIS

For data analysis, two methods were used:

a) Descriptive method

b) Simple Statistic Method

Descriptive Method

This was used for analyzing qualitative data e.g locals opinion on the current situation,

what they could attribute these changes to, e.t.c Such data was obtained primarily through

observation, questionnaires and secondary data gathered. The use of photographs was

deployed to help illustrate qualitative data.

Simple Statistical Method

This was used for quantitative data that was obtained mostly through the questionnaires.

Such was analyzed using simple statistics and was tabulated after being converted into

percentages where applicable. Presentation of this data was in the form of pie charts and

histograms.

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4 CHAPTER FOUR

DATA ANALYSIS, FINDINGS AND PRESENTATION

4.1 INTRODUCTION

This chapter examines the current water, sanitation and wastewater management situation

in Nairobi. The main participants in these areas were the residents, Contractors, Estate

agents and staff from the Nairobi City Water & Sewerage Company Ltd. Data was

obtained through:

a) Questionnaires filled by the residents, Contractors and Estate agents.

b) Interviews

c) Photographs

d) Observation

4.1.1 Field Study Response

The main source of data collection used was through Questionnaires and Interviews. The

table below portrays the response rate.

Table 4.0 Tabulated response rate of Questionnaires administered

(Source: Field Survey March 2013)

Respondents No.

Administered

No. of

Respondents

Percentage

Response (%)

Residents 60 41 69

Contractors 6 4 67

Estate Agents 12 8 67

Staff of the NWSC

4 3 75

46

From the data in the table above, it could be concluded that the response rate was fair. The

Questionnaires were distributed fairly in a sample format throughout the City. The City

was divided into 12 samples and each sample was presented with at least 5 questionnaires

to residents or households and at least 1 questionnaire for an estate agent. The response

rate from the questionnaires was fairly good as seen from the table above. As the

questionnaires were being distributed, interviews were also used to collect data. Most of

the respondents showed little interest in giving out information through this system.

Physical Observation and the use of photographs were also useful throughout the data

collection period. The Contractors contacted were those who mainly operate in Nairobi and

they were of different classes. Getting audience from the contractors was an issue since

most of them claimed to be too busy. Some also referred the questionnaires to their junior

staff who some may had little knowledge to the topic of research and therefore their

answers were not viable enough.

4.2 FINDINGS FROM THE RESIDENTS OF NAIROBI

Housing

From the data obtained, it is clearly shown that most of the people living in the City stay in

tenements build for rentals. They stay in multi-dwelling units where we have a one single

building owner who charges rent from the residents. This can be noted in the table below.

(Table 5.0) Distribution of Housing Units

(Source: field study March 2013)

Type of

Dwelling

Private

Ownership

Tenancy Total Percentage (%)

Apartments 10 25 35 58

Single-housing

units

9 16 25 42

Total 19 41 60 100

Percentage ( ) 32 68 100

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Water Shortage

As can be noted from the table below, most of the people benefiting from a high rate of

water availability are the ones residing in single housing units. These are mainly the

residents located in Plush areas such as Muthaiga, Karen, Kileleshwa e.t.c, these are areas

associated with the wealthy. Residents residing in slums mostly depend on water kiosks for

water supply, but most of these kiosks are regularly closed due to water scarcity.

(Table 6.0) Water Availability

Rate of water

Availability

Single-unit

housing

Apartments TOTAL

Daily 3 0 3

2 or 3 times a

week

15 6 21

Weekly 5 20 25

Once or twice a

month

2 9 11

TOTAL 25 35

(Source: field study March 2013)

Quality of Water

Nearly all respondents named the source of their tap water as the Nairobi City Council,

which they assume is treated. They however expressed fear in its Quality because some of

the distribution pipes lay in open earth trenches and other unsanitary locations. Despite

this, most do not take any extra precautions. Most people drink water directly from the

taps, they claim that the cost of boiling the water is too expensive. Most of the dwellers in

the apartments rely on external sources such as from small scale water sellers who use

wheel barrows for water transport or water kiosks. The water is mostly sold in 20 litre

jerricans which are hardly cleaned by the sellers. According to residents who rely on water

kiosks, water is highly contaminated, smells, has a weird color and has particles inside,

because old, rusty pipes often break and water is polluted by the open drainage lines and

sewage lines which run parallel to the water network.

48

(Table 7.0 Prevalence of Diseases)

Type of Housing No. of cases of sickness

e.g typhoid, Diarrhea

Percentage (%)

Single-House Units 5 20

Apartments 20 80

Total 25 100

(Source: field study March 2013)

Wastewater Collection

Most of the residents staying in individual residential units do not have a system of

collecting wastewater. The wastewater is deposited deep down the earth and allowed to sip

inside the earth surface. This is the same principle as what happens in the case of latrines.

From the data, The Researcher was able to find out that most residents staying in multi-

housing units such as the multi-storey apartments are not aware of the mode of wastewater

collection done in their areas of residence. Those who had an idea believed that the

wastewater was being collected in a septic tank before being carried away by a tanker or

the wastewater was being directed into the town’s main sewer line.

Wastewater treatment

Most of the residents residing in Individual units and allow the wastewater to sip deep

inside the earth do not treat their wastewater. This wastewater is allowed into the earth

without any form of treatment. Those staying in multi-housing units where the wastewater

is being streamed into the main sewer line reported that the wastewater was being treated

but most had no idea of any form of treatment that the wastewater could be undergoing.

The type of treatment technology that is known to most residents is the chemical mode of

treatment and specifically chlorination, this is after separation of solid particles through

sedimentation and filtration. From the data collected, it is observed that most residents are

not aware of any mode of biological wastewater treatment. People are not aware of the

algae and bacteria method of wastewater treatment and they’ve never had of its

application.

49

Water-borne diseases and wastewater related problems

Incidences of water-borne diseases were more prevalent to residences staying in multi-

housing units. An example of the disease that was mostly reported was Cholera. Though

the cases were not severe, still there is need to provide solutions. Other problems that were

identified mostly in multi-housing units was the leakage or bursting of drainage lines. This

acted as a source of discomfort to the residents and a threat as a source of diseases and

infections.

4.3 FINDINGS FROM THE CONTRACTORS AND PROPERTY MANAGERS

Water Supply

From the data collected it is observed that most buildings in Nairobi gets its water supply

from the Nairobi City water and sewer company. This water is mainly available to

residents residing in areas associated with wealthy people. The rate of water supply

depends with the locality of the residence. In most of the slums in Nairobi such as Kibera,

water supply is through water kiosks. Some of the property managers are the owners of

these kiosks and therefore benefit when there is water shortage in their buildings. Some of

the water available to residents are from boreholes or wells dug deep inside the ground.

Most wells are operated by industrial enterprises, hotels, farms for flower production in

greenhouses, and private houses in parts of the city that receive only intermittent supply

e.g. Langata and Karen. Many private well owners are also connected to the mains water

supply network and use groundwater as a back-up supply. Natural groundwater quality is

good.

Wastewater treatment

Most of the wastewater treatment being done in the city is through a centralized system

where the water is being streamed into the public sewer line then collected into a central

point for treatment. The wastewater could also be transported to the public sewer by road

after collection from septic tanks. The other mode of wastewater treatment that is done is

through direct treatment of the wastewater from the septic tank. After treatment the

wastewater is mainly disposed through ground infiltration or to surface water bodies.

50

Recycling of water is rarely done, areas where it is done is mostly in posh apartments,

where the rich reside. The wastewater is collected to a septic tank which is connected to a

treatment plant where treatment takes place. The Contractors are in charge of constructing

the septic tank and treatment plants. The property managers are in charge of managing the

plant. The most common way of wastewater treatment done after primary and secondary

treatment is chemical treatment which includes chlorination among other processes.

Wastewater Recycling

The wastewater that is being relayed into the public sewer line is not directly recycled into

that building after treatment from the public sewage treatment plant. Where we have

decentralized on-site treatment in form of septic tanks, recycling is rarely done since the

wastewater only undergoes minimal treatment and separation before it is released into the

earth. Direct recycling can be found where we have privately owned treatment plants such

as in apartments or estates which are managed by property managers or real estate

agencies. These apartments which have their own treatment plants have this water recycled

for non-portable functions such as flushing the toilets, irrigation or general cleaning. Those

dwellers staying in slums do not have their wastewater recycled.

Problems associated with the wastewater treatment plants

From the data collected, One of the main problems or limitations associated with the

wastewater treatment plants is the issue of costs. They are costly to construct and operate.

Chemical treatment plants will require the supply of chemicals regularly in order for the

system to meet its objectives. The materials and equipment required for setting up these

treatment plants are also expensive. Some chemical treatment plants also require energy to

operate, this may be in form of electricity or fuel. These are additional costs for operating

these plants.

The other issue affecting the setting up of these treatment plants is the issue of land

requirement. Land has to be set aside for the purpose of location of the treatment plant. The

treatment plant should not be too close to the homes. This becomes an issue because the

estate or apartment owners are not ready to set aside the finance for acquiring this land.

51

Areas where we have individual homes located far way from each other, the option of the

sewer system is too expensive to install due to the need for lengthy sewer lines.

The other limitation affecting the use of wastewater treatment plants is the cost of labour

for the personnel who will be monitoring the functioning of the treatment plant. The labour

is also expensive due to the need of skilled labour to carry out these functions adequately.

Labour will also be needed incase of maintenance and repair on the system. Maintenance

should be done regularly to ensure durability of the plant.

4.4 DATA FROM NAIROBI CITY WATER & SEWERAGE COMPANY

About the Company

The Nairobi City Water & Sewerage Company Limited (NCWSC) was incorporated in

December 2003 under the Company's Act CAP 486. Nairobi Water Company is a wholly

owned subsidiary of the Nairobi City Council (NCC). The Company's formation arose

from the enactment of the Water Act 2002, which created new institutions to manage water

resources in Kenya. The Company, therefore, took over the provision of water and

sewerage services within Nairobi and its environs from the Water and Sewerage

Department of the Nairobi City Council. The Nairobi Water Company has been appointed

by the Athi Water Services Board (AWSB) to provide water and sewerage services to its

residents under an agreed framework specified in the Service Provision Agreement ( SPA)

that ensures adequate and quality supply of water, affordable tariffs, and maintenance and

improvement of water and sewerage infrastructure.

Challenges facing the Nairobi City water and Sewerage Company

One of the main challenges facing the company is overpopulation in the City of Nairobi.

The demand for water and sewerage services is higher than what the company can offer.

The population in Nairobi is continuously growing thereby leading to a high water demand

in the city as well as high amount of wastewater production. Overdependence on the

Centralized treatment system by this huge population has also added as a challenge to the

company. The labour and resources that are available to the company are not sufficient

enough to serve the city adequately.

52

The other issue affecting the company is the issue of low population densities in some

areas of the City. Houses in these regions are sparsely spaced and located at far distances

from each other. This becomes too expensive for the company to connect sewer lines to

these areas. This is because it becomes costly connecting the sewer lines from one

household to the other. This will also imply that the services of repair and maintenance

will also be equally expensive since a larger area will be covered.

One of the other main problems challenging the progress of Nairobi City water and

sewerage company is the issue of their connection lines being destroyed by the road

construction companies. It has become a common phenomenon that whenever roads are

being constructed that there is tampering or destroying of the water or sewer lines. Some

cases are severe that the road construction agencies through ministry of public works have

requested for the relocation of the water or sewer lines.

The other main problem is the collapse of sewer lines, bursting or clogging of the sewer

lines. This can be easily seen on various occasions across the city. One of the main

purposes of collapse of sewer lines is the tree root incursion which weakens the pipe wall.

Tree roots seeking out water are attracted to the available moisture in the sewer line and

grow into the pipe through joints. As the roots grow they weaken the joint allowing

wastewater to escape and erode the soil around the pipe creating a belly that results in

collapse. The other factor that may lead to the collapse of building is the build-up of drain

clogs. These may be caused as a result of disposal of some materials in the households.

Sewer clogs are caused by the flush of items like cotton swabs, gauze, tampons, maxi pads,

diapers, paper towels and heavier materials because those materials aren't designed to

break down easily. Other materials that can create problems include harsh chemicals, paint,

oil or grease-based products. They may go down the toilet with seeming ease, but that

doesn't mean they won't cause problems farther down the line (Mwangi J.K 1993).

In terms of Management, Nairobi Water and Sewerage Company faces big challenges in

water supply in the face of the mushrooming of unplanned settlements. The infrastructure

development was neglected for many years and there was general inefficiency in services

provision. Unaccounted for water, poses one of the biggest challenges as the company has

53

to address illegal connections, vandalism and sabotage, huge unpaid bills and a poorly

maintained infrastructure which results in huge technical losses of water through

leaks and busts along the pipelines. Water production levels to the city are below

demand as the dams do not operate at full capacity. (Kimuyu C.M 1998)

Accessibility is one of the other challenges facing the company. Most of the slums in

Nairobi are not laid in an orderly manner and because of this, there are no developed roads

or streets. The network of roads, pathways in slum settlements develops gradually as the

need for circulation and access increases. In some places, so many overlapping pipes are

observed, some stemming from one location.

4.5 ROLES OF THE NAIROBI CITY COUNCIL

The roles listed below are placed upon the Nairobi City Council. The council is required to

do the following:

a) Connections

Those who wish to be connected send applications. There has been a general increase in

the number of connections, for both sewer lines and water lines despite the continuing

water shortage

b) Maintenance and Repair

Maintenance of the water and sewerage works is poor with those responsible only giving it

a blind eye. Repairs are minimal especially because leakages are all over. 30% of the water

distributed is lost through leakages (Kimuyu C. M. 1998). The problems of water shortage

are felt by both the City Council and the City residents. To the council, the problem is one

of the financial shortfalls while to the residents its one of gross incompetence and

slothfulness.

c) Billing

This is the process of preparing bills and forwarding them to consumers. According to the

council interviews, the process is effective 70% of the time, only that the blueprint for

54

establishing meter readings is not known. Sometimes bills are exaggerated while at times

they are understated. Bills could be delayed for up to 4 months and are thus prepared only

4 times in a twelve monthly period. The labour and facilities within the council e.g

computers are not enough to cater comfortably for the whole population. Due to these

limitations, outside contracting has been introduced.

d) Collections

This is the process of receiving proceeds from the consumers. All metered consumers are

required to pay their bills at City hall. Most Clients are usually discouraged by the long

queues that are found at this place. Collections are prompt and disconnections are effected

if payment is delayed. 60% of the bills are not paid up.

e) Inspections

Over 40% of the revenue expected from the water sales by the city council in each year is

never recovered. Inspections ought to be carried out to ensure correct meter progress.

These are cases of interference with the meter reading, which leads to misleading billing.

This leads to incorrect collections.

4.6 CHALLENGES FACED IN THE RESEARCH STUDY

Since the researcher was not present during the filling of the questionnaires, personal

guidance could not be provided to the respondents on how to tackle come of the questions

addressed to them. This led to some respondents addressing different issues in ambiguous

and sometimes contradictory ways. This was noticed to have been especially the case with

the open-ended questions. They, therefore, went ahead to fill the questionnaires giving

vague and sometimes contradictory responses. The researcher pre-empted this problem in

the design of the questionnaires and attempted to alleviate it by giving definitions of the

technical terms.

Other minor problems encountered during the survey were non-responsive respondents. 4

of the firms initially identified refused to accept the questionnaires for filling. The

researcher, therefore, had to identify four others to replace these. 3 of the firms which had

accepted the questionnaires for filling did not return them and after several phone calls and

55

visits to their offices, the researcher decided to abandon them and base the analysis on the

24 that were returned.

In some of the respondent firms or Contractors, the questionnaires were given to the junior

members of staff to complete as they were deemed by their bosses to be ‘less busy’. Some

of these junior employees were fresh graduates who were still learning the strings of the

job. Their ability to offer viable answers, therefore, not expected to be as incisive as that of

a more experienced member of staff.

4.7 DATA ANALYSIS AND PRESENTATION

Housing In Nairobi

From (table 4.0) in the findings above, this data could be easily presented in a pie chart as

shown below.

(Chart 1.0) Housing Distribution

(Source from Field Study, March 2013)

Population (%)

Apartments (58%)

Single-house Units (42%)

56

From the pictorial presentation above, it can be easily be deduced that a higher percentage

of people are residing in apartments. This population is mainly composed of the average

earning Kenyans. Apartments are also located in slum regions such as eastleigh, Mathare,

Githurai and others. In regions where we have the wealthy residing, apartments are less

compared to the areas above.

It can also be noted from the above pie chart that though the number of single-housing

units is less than that of the apartments, the number of people staying in single-housing

Units is relatively high. This has also been contributed to the small housing units found in

slum regions. These are small dwellings mainly built of iron sheets. The other contributor

to this percentage is the single-housing units belonging to the wealthy. This can be seen in

regions like Kileleshwa, Karen, Lavington estates among many others.

Water Shortage

From the data in table 6.0 above, we can come up with a bar-chart as shown below.

(Chart 2.0) Rate of water availability

(Source from Field Study, March 2013)

0

2

4

6

8

10

12

14

16

18

20

Daily 2 or 3 times a week

weekly Once or Twice a month

Single-house Units

Apartments

57

From the presentation in the graph above, we can conclude that the population residing in

single-house units benefit the most by getting water more number of days in a week than

any other residential units. These are mainly people from the wealthy estates.

Most of the population that stays in multi-housing units or apartments in Nairobi gets

water once a week or once in two weeks. This population mainly depends on water from

water kiosks or any other source that the water is paid for. Those who get water twice or

once a month are mainly those residing in slums. These regions are the most affected

regions by water shortage.

Water Quality

According to the Pie-Chart drawn below whose data is from the table of number of cases

of sicknesses related to water-borne diseases above, we can conclude that most people who

are exposed to water of low quality are the population of people staying in multi-housing

units such as apartments.

(Chart 3.0) Disease Prevalence

(Source from Field Study, March 2013)

Cases of Water related Diseases (%)

Single- House units

Apartments

58

It should also be noted that the majority are housing units that do not get regular supply of

tapped water. They mainly depend on water that they have to pay for such as from water

kiosks. As stated earlier, this water is not properly treated or may be exposed to unhygienic

conditions, such as improperly cleaned containers. Apart from one case, all the other cases

reported from the single housing units were from slum dwellings. It should also be noted

that most of the slum dwellers do not get accessibility to tapped water. This may be the

main reason why they have cases of water-borne diseases due to their exposure to

untreated or poor quality water.

According to the Public Health Office in Ruiru District, in year 2010 the majority of cases

with diarrheal diseases (typhoid, amoebiasis, etc) were between 30 and 40% of all the

patients seeking medical care. Diarrhea is a leading cause of death in children. Unlike

diarrheal diseases, Malaria was highest during the wet months of the year and was lowest

during May, June and July when it was relatively dry. The rate of hospital visits

because of water borne diarrheal diseases was most frequent in Githurai where on

average person was treated once every 3 months.

In Kahawa Sukari, which is a more affluent residential area, the average resident was

treated for diarrheal diseases once every 3.5 year while in Kahawa Wendani the

time interval between hospital visits was 2 years. Infection with intestinal worms was less

frequent. In Kahawa Sukari and Kahawa Wendani residents completed 5 years without

worm infections. In Githurai these infections occurred once in 4 years.

Wastewater treatment

The most commonly used types of domestic wastewater collection are two: one is where

the water is collected in a septic tank and upon filling, it is transported by road to a central

location where it is treated. As stated above, there are few instances where the wastewater

is treated on-site. Secondly is where the individual sewer lines are connected to the main

sewer line which transports the wastes to a central treatment plant. According to the data

collected from the city council staff, The system includes drains, man-holes, trenches,

junction boxes, sumps, lift stations, and/or weirs. Waste water streams from different

points throughout the system normally enter the collection system through individual

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drains or trenches connected to a main sewer line. The drains and trenches are usually open

to the atmosphere. Junction boxes, sumps, trenches, lift stations, and weirs will be located

at points requiring waste water transport from one area or treatment process to another.

Areas that have sewage system were easily identified by the presence of man-holes or

Inspection Chambers.

As discussed in Literature Review, it was also confirmed during data collection that

Treatment systems are divided into 3 categories: primary, secondary, or tertiary, depending

on their design, operation, and application. In primary treatment systems, physical

operations remove floatable and settleable solids. In secondary treatment systems,

biological and chemical processes remove most of the organic matter in the waste water. In

tertiary treatment systems, additional processes remove constituents not taken out by

secondary treatment. In its secondary and tertiary treatments, the city council mainly uses

mechanical and chemical systems for the wastewater treatment. Chemical compounds are

added at various stages of the wastewater treatment.

It has also been noted that a large number of urban households are not connected to public

sewerage systems for disposing of sewage, this may be due to poverty and the proliferation

of informal settlements. This can be seen in the table below:

Table 8.0: Urban Centers in Kenya with Sewerage Treatment Facilities

Population

Range (In

thousands)

Urban centers

with sewerage

Facilities

Centers without

Sewerage

Facilities

Total

Greater than 300 2 0 2

100 – 300 8 0 8

20 – 100 16 8 24

Below 20 4 177 181

Total 30 185 215

(Source; wastewater magazine 2005)

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Wastewater Recycling

In the data collected, it can be seen that around only 15% of the wastewater collected in

Nairobi is treated to a standard where it can be safely re-used. This can attributed to the

expensive techniques used for wastewater treatment and recycling. This could be the

reason why recycling was found to be mostly done in multi-housing units than in single-

house units where the individual will be solely responsible for the treatment plant. This

means that a lot of wastewater that could be safely re-used goes into wastage. It should

also be noted that this water that is being recycled, the sewage had to be treated to high

standards as required by law and the treated water is be used for non-portable uses such as

flushing of toilets and gardening.

The table and the Chart below shows the percentage of residences that have access to

recycled water.

(Table 9.0 )Access to Recycled water

Type of Housing No. of residences with

access to recycled water

Percentage (%)

Single-House Units 2 22

Apartments 7 78

Total 9 100

(Source: field study March 2013)

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(Chart 4.0) Water Recycling

(Source: field study March 2013)

Groundwater Contamination

However, within Nairobi, introduction of polluted wastewater into the small streams, has

seepage into the groundwater system. The untreated wastewater is effluent products of

industrial waste containing many chemicals and pesticides. Ground water is used for

irrigation, industry, drinking, and rural home and stock watering (Benarde, 1989). The

beneficial aspect of ground water is that it requires no treatment to safeguard its quality.

Since ground water is pulled beneath the surface due to gravity, safe drinkable water exists

virtually anywhere within the ground. Since Nairobi City has a population of 3 million

people, groundwater resources are vital for water consumption. However, with the

industrial wastewater pollution containing pesticides contaminating the groundwater, the

mass consumption of unhealthy water can be severe to the population’s health. The

chemical-contaminated groundwater can affect the human nervous system in various ways.

Groundwater containing chemicals has been indicated to have carcinogens and endocrine

Wastewater Recycling (%)

Single-House Units

Apartments

62

disrupters (Benarde,1989).. Carcinogens are substances that attack normal cells causing

them to be cancerous. While endocrine disrupters have been researched to indicate

blocking of the normal passage of hormones into their receptors and mimicking the

hormone itself, and enter the receptors in lieu of the hormone (Statement, 1995). As you

may know, there is a water shortage-taking place right now in the urban, industrial, and

agricultural sectors within Kenya. To help alleviate the water shortage within Kenya,

wastewater treatment plants will help increase the supply of usable water, improve the

environment, and reduce water pollution.

Water Pollution

Water pollution is the contamination of water by undesirable foreign matter. The little

water that is available in Nairobi often gets polluted as a result of various human

activities. Therefore, as is the case in many other cities in the world, Nairobi is

experiencing a steady decline of available freshwater. This is because there is also a

steady increase in population. Urban population often grows as a result rural-urban

migration by people looking for better living standards (Grau and Alde, 2007). Informal

settlements accommodate 60% of Kenya’s urban population (Antao, et al., 2007). An

example of a suburb in Nairobi, Githurai is not classified as an informal settlement, it

has characteristics of an informal settlement. It discharges wastewater without any

form of treatment. Industries in Githurai discharge effluents that do not comply with

Kenya’s standards for discharge into the environment; and the wastewater is allowed to

either percolates into the ground where it contaminates groundwater or flows into the

natural drainage system causing surface water pollution. This is what happens in most of

the areas in Nairobi.

From the study, most pit latrine users from Nairobi, indicated that some wastewater

empties into storm sewers, soak-aways and cess pits designed for kitchen waste. The

discharge of wastewater without treatment may cause microorganisms, in rivers, lakes and

even seas to which they send, consumes the dissolved oxygen and cause depletion of the

oxygen concentration in them.

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5 CHAPTER FIVE

CONCLUSION AND RECOMMENDATIONS

5.1 INTRODUCTION

From the research we can conclude that the wastewater management systems currently put

in place in The City of Nairobi are not sufficient enough to serve adequately the growing

population in Nairobi. The increased urbanization of Nairobi is placing pressure on the

aging centralized wastewater system. The level of wastewater production is higher than

what the systems can manage. It was also established that poor wastewater management

leads to health problems as well as environmental pollution. Investment on proper

wastewater treatment systems is minimal because the costs associated with wastewater

treatment systems are high. This is mainly because as established in the research most of

the systems mainly use chemicals and are dependent on power e.g electricity.

5.2 CONCLUSION

The study is aimed at establishing the state of wastewater management in the City of

Nairobi and show the importance of biological wastewater management system. This

research paper highlights the present wastewater treatment and management aspects and

the status of wastewater reuse in the city of Nairobi. An attempt has been made to identify

the relevant management strategies to improve the wastewater reuse and management in

the city. From the research it is established that most residents depend on the Centralized

Sewerage treatment system for the management of their systems. Combined sewers can

cause operational problems at a treatment plant. Unfortunately, most plants with combined

sewers are not designed to handle the increased flow loads during storms and usually cause

a decrease in plant efficiency. During high flow periods, detention times are decreased,

solids may be washed out of the secondary system and large amounts of grit, sand and silt

may be washed into the plant. . Since the Centralized system is unable to accommodate

this demand, there is need to decentralize the system and utilize more economical systems

for wastewater management.

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The objectives originally sought in wastewater treatment include:

1. Protection and maintenance of sources for use as domestic water supplies.

2. Prevention of disease and spread of diseases.

3. Prevention of nuisance conditions.

4. Maintenance of clean waters for bathing and other recreational purposes.

5. Protection and maintenance of the environment.

6. Conservation and protection of water for industrial and agricultural uses.

7. Prevention of silting in navigable channels.

Water recycling has been recognized as a key approach to alleviate water shortage in

Kenya, which has now become a worldwide issue. A wastewater treatment plant is

designed to remove from the wastewater enough organic and inorganic solids so that it can

be disposed of without contravening or affecting the objectives sought. Treatment devices

merely localize and confine these processes to a restricted, controlled, suitable area or

environment and provide favorable conditions for the acceleration of the physical and

biochemical reactions. The ultimate goal of wastewater treatment should be managing

wastewater effectively, economically, and ecologically.

5.2.1 Water Recycling

From the research it has been established that wastewater recycling is very minimal in the

city thus the residents are not able to enjoy the benefits of recycling water. Alternative

sources of water such as recycled water reduce demand on potable water supplies, thereby

reducing the need to expand existing infrastructure (Hermanowicz and Asano, 1999;

McKay and Hurlimann, 2003). Recycling reduces the amount of wastewater disposed off

into the environment via lake or river outflows; it can also be returned to the environment

to enhance environmental flows. By not pumping water to these outflow s there is also a

net saving of water; as water is not required to flush waste long distances; this also reduces

energy consumption (Hermanowicz and Asa no, 1999; Hurlimann and McKay, 2005). One

65

of the best ways to solve the problem of pollution due to wastewater and reduce waste

shortage is through water recycling.

Challenges to Wastewater Recycling

The main barriers to reuse of water in Nairobi are issues of public confidence, health, the

environment, reliable treatment, storage, economics, the lack of relevant regulation, poor

integration in water resource management and the lack of awareness

Pricing: Water is sometimes seen as a “free” resource. Often the end user pays for the

cost of service delivery only and not the associated costs such as infrastructure, storage and

disposal (Thwaites, 2003). Therefore, pricing of water doesn’t reflect the scarcity of the

resource or the environmental impacts of the water supply systems. The cost of recycled

water to the consumer is not the only pricing issue. Added costs to developers for initial

infrastructure, treatment measures, the financial commitment to maintenance, monitoring

schedules and cross connection checks (Anderson, 1996; Shelef and Azov, 1996) are costs

that need to be considered when choosing which AWWS to implement.

Technology: Decentralized Alternative waste water systems are emerging technologies

and there are few people who are qualified to install, operate and maintain these systems

and fewer AWWS maintenance services available. The greatest health concern associated

with the recycling of wastewater is that it can contain pathogenic micro-organisms

(Higgins et al ., 2002; Khan et al ., 2004). A major concern lies in the ability of

technologies to remove such contaminants and their ability to ensure continuity of a

contaminant free water supply.

Costs : The costs incurred are also one of the major factors discouraging people from

investing in water recycling systems. The initial capital may be too high for some people.

Legislation: There are those safe standards set by different legislative bodies that have to

be met for recycled water. This and many other legislations discourage the investment into

water recycling.

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5.2.2 Decentralized or Centralized Wastewater Systems?

As established in the research, Centralized systems have been the norm in water supply

and wastewater removal. This is also the case in the City of Nairobi. Centralized system is

where the wastewater management system is dependent on one institution such as the case

of Nairobi, we have Nairobi City Water and Sewerage Company. Decentralized is where

the management of the wastewater is done by in Private or by individual building owners.

Due to its systems and mode of operation, I also gathered that Centralized system is more

expensive to a decentralized system. Centralized sewerage infrastructure is capital

intensive and once built, creates a lock-in effect by binding capital for long periods of time.

This makes strategy or management changes difficult to implement and discourages

innovation (Tillman et al ., 1999).

Decentralized wastewater management is not just about the disposal of wastewater and the

public health. It has the potential to contribute to the formation of an infrastructure to

sustain watershed integrity. By treating the water in a decentralized manner, neighborhood

assets requiring irrigation can receive the treated discharge, which in-turn can percolate

underground and help refill aquifers. Large-scale sewage treatment plants are often unable

to make use of the treated water and instead of being recycled and returned to the aquifers

upstream, much of it is discharged into rivers.

A comparison between centralized and decentralized systems is shown in Table below.

From this table we can see that decentralized systems offer more competitive operating and

management costs, better source contamination control, better environmental outcomes

however it faces legislative challenges.

(Table 10.0) : Comparison of benefits and shortcomings between centralized and

decentralized wastewater systems (Adapted from Anda and Ho, 2004; with additional

references Douglas 1998; Mattila, 2003; Livingston et al., 2004, Otterpohl et al., 2005)

67

Centralized Decentralized

Source. The wastewater comes from

various origins, including industry, which

contains various contaminants that increase

the costs of treatment and disposal.

Source. Communities have a certain amount of

control over the inputs into the systems and

contamination by toxic substances can be limited,

whilst wastewater reuse onsite can further reduce

costs.

Ownership. The water service provider

controls ownership of unit: designing,

constructing, operating or maintaining

systems are considered too complicated to

be in the control of homeowners. Not

much flexibility in delivery and disposal

options.

Ownership. Ownership and management are

options available to the homeowner. Units can be

altered to be site specific to allow for environmental

factors and can be effective solutions for

ecologically sensitive areas.

For example, in the USA town of Jericho, 95% of

homeowners rely on individual on-site sewage

systems to help protect groundwater and surface

water quality.

Cost. Initial cost average Aus$ 5,000 to

10,000 per property, with the majority (up

to 80%) of the cost is in the set up of pipes and

pumps. $/unit decreases as number of units

increases economies of scale.

Cost. Initial cost average Aus$ 5,000 to 10,000 per

system. (Mainly in the treatment unit and reuse or

disposal land area). $/unit decreases as number of

units increases economies of scale.

Nutrients. Safe disposal of treated

wastewater is primary objective. This may

leave nutrients within the wastewater that can

cause problems for the receiving water bodies;

further treatment is increasingly being

required. To reuse this treated water additional

plumbing at additional cost will be necessary.

Nutrients. Onsite reuse of treated wastewater is

generally the objective of onsite systems with

nutrients being recycled back onto land. The

opportunity to reuse the sludge residue on-site via

additional processes such as vermin-composting is

possible, with the end product becoming a useful

garden fertiliser.

Stormwater can cause sewerage overflow,

this may cause health or environmental harm.

Stormwater management incorporated into a

system can recharge local groundwater supplies,

reducing the risk of environmental harm.

Source: (Anda and Ho, 2004)

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5.2.3 Biological wastewater treatment

From the research it is established in order to minimize the problems related to wastewater

management systems there is need for vast adoption of biological wastewater treatment

systems. Biological treatment methods should dominate the secondary wastewater

treatment sector as it is the most effective and eco-friendly option of the available

treatment processes. The demand for the biological wastewater treatment equipment is on

growth path which is catalyzed by the need to meet obligatory wastewater treatment

standards, imposed by environmental legislation to municipalities and industries in the vast

part of developed countries.

The main benefits of biological wastewater treatment are as follows:

a) Low capital and operating costs compared to alternatives such as chemical-

oxidation processes

b) True destruction of organics, versus mere phase separation, such as with air

strippingor carbon adsorption

c) Oxidation of a wide variety of organic compounds

d) Removal of reduced inorganic compounds, such as sulphides and ammonia, and

total nitrogen removal possible through denitrification

e) Operational flexibility to handle a wide range of flows and wastewater

characteristics

f) Reduction of aquatic toxicity.

The biological treatment equipment segment has dominated the wastewater treatment

equipment European market over the past decade with aspects such as nutrient removal

and sludge reduction gaining increasing acceptance among both municipal and industrial

customers. This is what needs to be adopted by the African market as they seek to

introduce Biological wastewater systems and equipment into the market. Therefore the

focus for Nairobi would be seeking for new solutions and investing in research to provide

high efficient technologies on the one hand - meeting regulatory standards, on the other -

reasonable priced - will be crucial to win the opportunities of the market.

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5.3 HYPOTHESIS TESTING

The hypothesis that ‘The current wastewater management systems put in place in the City

of Nairobi are not sufficient enough to serve the residents of the City adequately’ tested

Positive. This has been shown by the various Challenges that have identified to associate

with the management of wastewater in the city. Recommendations proposed for solving

these problems have been discussed below.

5.4 RECOMMENDATIONS

5.4.1 Decentralization of wastewater treatment system

As observed from the research, for many small and medium enterprises and housing

estates, conventional wastewater treatment systems are too technically sophisticated and

costly. These conventional systems often require high energy inputs for operation and rely

on extensive maintenance services to ensure continuous operation. By incorporating into

the existing centralized system, decentralized treatment units, wastewater can be

introduced into new markets as a source of water supply for non-potable use.

The government needs to play a major role in adoption of decentralized units by putting

legislative measures to ensure the public adopts these mechanisms, offering training

services and offering sponsorships and incentives towards the adoption of these systems.

This can also range from friendly reminders to residents about proper maintenance, to a

government entity or homeowners association actually taking ownership and maintaining

individual onsite systems. Wastewater to decentralized units can be easily treated

biologically to suitable standards than when all the wastes flow into a single centralized

unit in the City.

5.4.2 Adoption of Biological treatment systems

The principal objective of wastewater treatment is generally to allow human and industrial

effluents to be disposed of without danger to human health or unacceptable damage to the

natural environment. As discussed earlier, Biological wastewater treatment follows

mechanical treatment and is mainly the use of bacteria or microorganisms to degrade and

70

decompose organic materials during treatment. The Government should promote the use of

biological systems as compared to other conventional systems. They can do this by

creating awareness, offering training programs and adopting these systems in their own

facilities.

Among the natural biological treatment systems available are activated sludge process,

stabilization ponds and land treatment which have been used widely around the world and

a considerable record of experience and design practice has been documented. There is

need for investment in the above systems as well as new systems such as the use of algae

and bacteria in a photo-bioreactor, Membrane Biological Reactor (MBR) Systems,

Sequencing Batch Reactors (SBR) among many others. The use of algae and bacteria in a

photo-bioreactor system has been discussed earlier in the literature review. Adoption of

these biological systems in the decentralized units will help to minimize the limitations

presented by other conventional treatment methods.

5.4.3 Recycling of the waste water

There is need to recycle wastewater to a standard that it can be recycled for different non-

portable uses. As earlier said, Waste water from baths, showers, washing machines,

dishwashers and sinks is often referred to as Grey water. Waste from toilets is known as

Black water. Untreated grey water can be used for garden watering if used immediately

after it is produced. The waste water from kitchen sinks and dishwashers is not usually

collected for this purpose as it is too heavily contaminated. Soil is very effective at filtering

out many contaminants in grey water. However water containing soap or detergents does

have the potential to cause soil, especially clay based soils, to lose their structure.

The wastewater that had to undergo treatment should be recycled for non-portable uses in

the facilities. Recycling of this water for these uses help to reduce demand on water and

minimize the problems of water shortage. Recycling is also easier and cheaper when the

treatment system is decentralized. Recycled water should be distributed with a dual piping

network that keeps the recycled water pipes completely separate from potable water pipes.

71

5.4.4 Need to Change the waste water collection Systems

As noted from the research is that the City has a combined system of collecting water. This

means that both the storm water and sewage flow are in the same drainage. There is a need

to introduce a separate system of wastewater collection so that storm water from different

areas can be tapped for irrigation plants. When the system is separated it means that the

treatment work would be more efficient since they are able to deal with less waste

materials from the waste water.

5.4.5 Need for Government Involvement in ensuring proper standards in

wastewater management are met

The Government should ensure the establishment of standards and guidelines for

municipal waterworks, wastewater and storm drainage facilities. This is an integral part of

the regulatory program directed at ensuring public health and environmental protection.

The main body concerned with ensuring that these safe standards are met in Kenya is

NEMA (National Environment Management Authority). In addition to their regulatory

role, there is need by NEMA and other regulatory bodies to create awareness towards the

importance of the water from the treatment facilities meeting the set standards.

5.4.6 Need for Community Involvement

The planning, location, design and construction of facilities have traditionally been carried

out by Government agencies and officials without the involvement of the eventual users

and with limited, if any consultation with them. Infrastructure systems planned for low-

income communities, by outside agencies familiar with local needs, customs and

aspirations and without community involvement, have frequently proved to be

inappropriate for and unacceptable to the users. Consequently, these systems have rapidly

fallen into disuse, and communities have had no interest in the continuing success of what

they perceive as a government responsibility. Community Interest and Involvement are

implicit in user participation and essential for project success.

72

Community participation should be encouraged right from conceptualization, operation

and maintenance stages of the project. This gives the community a sense of ownership.

Meaningful community involvement is more than the supply of free labour and local

material or even contributions. Where public awareness of the need for a given service is

low for example sewage disposal, the use of special promoters can prove useful in

mobilizing community support. The consultation process with the users requires time and

the recruitment of additional staff but the returns are massive in terms of less wastage of

resources which outweigh the implied increase in planning costs.

5.4.7 Reduction in wastewater build-up

Water contamination occurs both at the point of collection and at the point of use. Even in

areas that make use of municipal piped water, the water becomes contaminated due to

inadequately maintained pipes, intermittently delivery and many other factors. It is

recommended that households take responsibility for making sure that the water is not

contaminated. They might view this as an extra expense, but the money saved such as

hospital bills may be worth the time and effort. Policies that aim to improve water quality

through source improvements may be compromised by post-collection contamination.

Safer household water storage and treatment is recommended to prevent this, together with

point-of-use water quality monitoring.

5.4.8 Need to Improve the financing of wastewater management Projects

As identified in the research, there is need to rehabilitate the existing mechanical treatment

systems that we have in the city. There poor state has also been accelerated by insufficient

funds. There is need to convince donors such as World Bank and other NGO’s of the need

to assist in upgrading the wastewater treatment plants. The various problems and

recommendations identified in the research require huge amounts of finance and thus need

to contact NGO’s and other funding Organizations. The budget set aside by the City

Council also needs to be increased to meet these demands.

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5.5 AREAS OF FURTHER RESEARCH

A. This study was primarily done in an urban region, The geographical coverage was

confined to Nairobi. There is need to also conduct a similar investigation in the

rural areas where we have informal settlements, since the manner of waste handling

in these areas is different from that in the City center.

B. Due to time and financial constraints, the study was limited to the study of the state

of wastewater management. A study should also be done on the state of solid waste

management with reference to their effects to the environment and efficient ways of

managing the solid waste.

C. A further study can be done on other ways of wastewater treatment apart from

biological treatment of the waste.

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Hawkes H.A (1963); The Ecology of Wastewater Treatment, Pergamon Press, Oxford.

75

Hammer Mark J. Sr., and Mark J. Hammer Jr. (2001) Water and Wastewater

Technology, 4th ed. Englewood Cliffs, NJ: Prentice Hall, 2.

Horan N.J. (1990), Biological Wastewater treatment Sytems Theory and Operation, John

Wiley and Sons Ltd, Chichester England.

Isaa P.C (1972), Water Research England.

Lin L, Chan GYS, Jiang BL, LAN CY. (2007), Use of ammonia cal nitrogen tolerant

microalgae in landfill leachate treatment. Boca Raton, University of Florida.

Metcalf, & Eddy Inc., (1991), Wastewater Engineering Treatment Disposal and Reuse,

(3rd ed.). McGraw-Hill, Singapore.

Moresby A.L and Curtis M (1959), Goodmand Downings Domestic Sanitation, London.

The Estate Gazette Limited, London.

Murray M.Y and Graham J.F. (1978) Wastewater treatment and utilization. Pergamon

Press Ltd, Oxford.

Metcalf, & Eddy Inc., (1991), Wastewater Engineering Treatment Disposal and Reuse,

(3rd

ed.). McGraw-Hill, Singapore.

Ogbonna, J.C., & Tanaka, H. (1997), Industrial-size Photobioreactors. Enfield New

Hampshire.

Parker D.S. (1973), Water and wastes Engineering. Nature Publishing Group.

Republic of Kenya (2002), The Water Act 2002. Kenya Gazzette Supplement No. 107,

Government Printers Nairobi.

Republic of Kenya (2005), The Water Sector Reforms, Government Printers, Nairobi.

Republic of Kenya (1972), Public Health Act Cap 242, Government Printers, Nairobi.

Standard Analytical Procedures for Water Analysis (SAP),(1999), Standard Methods

for the Examination of Water and Wastewater’ (Standard Methods), 19th edition, APHA,

AWWA, WEF, Technical Assistance in Waste Water Engineering.

76

Shuval H.I (1970), Development in Water Quality Research. Ann Arbor Science

Publishers, England.

Walters J.K and Wint A (1981) Industrial Effluent Treatment Applied Sciences

Publishers, England.

Wolfaardt GM, Lawrence JR, Roberts RD, Caldwell DE. (1994), The role of

interactions, sessile growth, and nutrient amendments on the degradative efficiency of a

microbial consortium. Can. J. Microbiol.

Yahya S.S (1987) Review of Building Codes and Regulations, A manual on Kenya’s

Experience. University of Nairobi, Nairobi.

xiv

APPENDICES

Appendix 1: Questionnaires to Residents

Odhiambo Cosmas Onyango

School of the Built Environment

Department of Real Estate and Construction Management

UNIVERSITY OF NAIROBI

P.O BOX 30197-00100

NAIROBI

February 23, 2009

To

Respondent

I am a student at the University of Nairobi, conducting a research on “The management

of wastewater: The proposal on the use of Biological treatment systems” as part

fulfillment for the award of B.A. Degree in Quantity Survey. I intend to administer

questionnaires to you as a tool for data collection.

DECLARATION

THE INFORMATION COLLECTED THROUGH THE USE OF QUESTIONNAIRE(S),

INTERVIEWS AS WELL AS YOUR IDENTITY SHALL BE TREATED AS

CONFIDENTIAL AND SHALL BE USED FOR RESEARCH PURPOSES ONLY.

INSTRUCTIONS

Please tick and/or state the appropriate answer in the space(s) or box(es) provided. More

than one answer may be ticked or stated where applicable.

Your assistance will be highly appreciated

Thanks

Cosmas Onyango (Researcher)

xv

UNIVERSITY OF NAIROBI

QUESTIONNAIRES

Questionnaire 1 to Residents

1. Place of residence

………………………………………………………………………………………

………………………………………………………………………………………

2. Type of residence a) apartment….. b) estate…..c) any

other(specify)………………………………………………………………………

……………..

3. Is the residence Privately Owned or is it a tenancy? .............................................

4. Where do you get your water supply from

………………………………………………………….

5. Are there any problems of water shortage? ..........................................................

6. If Yes, how often is the water supply a) once a week b) twice a week c) specify

any other ………………………………………………………………………….

7. How is the waste water collection done a) communally……..

b) Individually…………

8. Is the waste water being treated or not a) Yes….. b) No…… c) No

idea………………

9. If Yes, are you aware of the treatment technology being used? a) yes …. b) No……

10. If Yes, which

one……………………………………………………………………………………

……………..…………………………………………………………………………

11. Is water recycling being done? A) Yes…………… B) No………….

12. Have there ever been any problems associated with waste water in your place of

residence? A) Yes………. B) No…………..

13. If Yes, what was the nature of the problem?

……………………………….………………………………………………………

………………………………………………………………………………………

xvi

14. Was the Problem a one-time case or was it frequent? ................................................

15. Do you have suggestions on any mode of treatment that should be adopted for

treating waste water?

………………………………………………………………………………………

………………………………………………………………………………………

16. If Yes, which one(s)

………………………………………………………………………………………

……………….……………………………………………………………………..

17. What reasons can you give for your answer in (16) above

…………………………………………….

18. Are you aware of the use of the algae and bacteria method of waste water

treatment?

a) Yes…………. b) No……………

19. If Yes, are you aware of any places in the country where this method is being used?

(specify the location)

………………………………………………………………………………………

……………….……………………………………………………………………..

xvii

Appendix 2: Application for Research Authorization to NWSC

Odhiambo Cosmas Onyango

School of the Built Environment

Department of Real Estate and Construction Management

UNIVERSITY OF NAIROBI

P.O BOX 30197-00100

NAIROBI

February 23, 2009

The Chief Engineer

Nairobi Water and Sewerage Company

P.O.BOX 30656-00100 NAIROBI

Dear Sir,

RE:APPLICATION FOR A RESEARCH PERMIT

I am a student at the University of Nairobi, conducting a research on “The management

of wastewater: The proposal on the use of Biological treatment systems” as part

fulfillment for the award of B.A. Degree in Quantity Survey. I intend to administer

questionnaires to you as a tool for data collection.

DECLARATION

THE INFORMATION COLLECTED THROUGH THE USE OF QUESTIONNAIRE(S),

INTERVIEWS AS WELL AS YOUR IDENTITY SHALL BE TREATED AS

CONFIDENTIAL AND SHALL BE USED FOR RESEARCH PURPOSES ONLY.

.

Your assistance will be highly appreciated

Thanks

Cosmas Onyango (Researcher)

xviii

UNIVERSITY OF NAIROBI

QUESTIONNAIRES

Questionnaire 2 to the staff of NWSC

1. What are the Obligations and responsibilities of the Nairobi Water and sewerage

Company?.....................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

2. Are there training programs that are offered to the staff

Yes [ ] No [ ]

3. How regular does Nairobi Water and Sewerage Company carry out maintenance

programs to its system?

Weekly [ ] Monthly [ ]

Quarterly in a year [ ] Yearly [ ]

Any other (specify)…………………………………..

4. How is Collection of Wastewater

done?............................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

5. What are the problems faced in the wastewater collection (if any)?

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

6. What type of treatment mechanism is mainly applied during the treatment

works?....................................................................................................................... ...

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

xix

7. What are the problems faced in the treatment works (if any)?

......................................................................................................................................

......................................................................................................................................

8. Are there any dangers encountered during the treatment works?

Yes [ ] No [ ]

9. If Yes, which ones

………………………………………………………………………………………

………………………………………………………………………………………

10. Is there any application of Biological treatment mechanisms?

Yes [ ] No [ ]

11. Are you aware of any Biological treatment mechanisms

Yes [ ] No [ ]

12. If Yes, which ones

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

13. Is Water Recycling done?

Yes [ ] No [ ]

14. If Yes, to what extent is it done (what proportion of the population has access to the

recycled water)

………………………………………………………………………………………

………………………………………………………………………………………

15. Does Nairobi Water and Sewerage Company offer educational programs to the

people about sewage and sewage handling?

Yes [ ] No [ ]

16. In your Opinion is the management of wastewater in Nairobi adequate?

Yes [ ] No [ ]

17. If yes, what measures do you suggest to improve the management of wastewater

………………………………………………………………………………………

xx

………………………………………………………………………………………

………………………………………………………………………………………

xxi

Appendix 3: Questionnaires to Contractors

Odhiambo Cosmas Onyango

School of the Built Environment

Department of Real Estate and Construction Management

UNIVERSITY OF NAIROBI

P.O BOX 30197-00100

NAIROBI

February 23, 2009

To

Respondent

I am a student at the University of Nairobi, conducting a research on “The management

of wastewater: The proposal on the use of Biological treatment systems” as part

fulfillment for the award of B.A. Degree in Quantity Survey. I intend to administer

questionnaires to you as a tool for data collection.

DECLARATION

THE INFORMATION COLLECTED THROUGH THE USE OF QUESTIONNAIRE(S),

INTERVIEWS AS WELL AS YOUR IDENTITY SHALL BE TREATED AS

CONFIDENTIAL AND SHALL BE USED FOR RESEARCH PURPOSES ONLY.

INSTRUCTIONS

Please tick and/or state the appropriate answer in the space(s) or box(es) provided. More

than one answer may be ticked or stated where applicable.

Your assistance will be highly appreciated

Thanks

Cosmas Onyango (Researcher)

xxii

UNIVERSITY OF NAIROBI

QUESTIONNAIRES

Questionnaire 3 to Contractors

1. What is the class of the firm? ……………………………………………………….

2. Where is the location of the firm? ..............................................................................

3. Is the firm involved in putting up of Commercial and residential buildings?

Yes [ ] No [ ]

4. How is water obtained in most of the buildings?

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

5. Has the firm been involved in putting up of Wastewater treatment plants?

Yes [ ] No [ ]

6. If Yes, which systems of treatment plants were mainly used?

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

7. Who was responsible for making the decision on the type of treatment mechanism

used in most of the projects?

a) The Client [ ] b) The Contractor [ ] c) Any other (specify)

……………………………………………………………………

8. Were there any reasons given behind the type of treatment mechanism used?

...................if yes, what were the reasons?

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

9. In the majority of the projects, is wastewater being recycled?

Yes [ ] No [ ]

xxiii

10. Are you aware of the most used type of wastewater treatment mechanism?

.................... If yes, Which one

……………………………………………………………………………….

11. Can you suggest the reasons for the popularity of the mechanism in the answer

above

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

12. Are there any standards set by the Government for the quality of the recycled

water?

Yes [ ] No [ ]

13. Do you have any suggestions of the type of treatment mechanism that should be

mostly used in the City

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

14. What are the reasons for the answer above?

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

15. Are you aware of any Biological treatment systems?

Yes [ ] No [ ]

16. If Yes, Which ones?

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

xxiv

Appendix 4: Questionnaires to Estate Agents

Odhiambo Cosmas Onyango

School of the Built Environment

Department of Real Estate and Construction Management

UNIVERSITY OF NAIROBI

P.O BOX 30197-00100

NAIROBI

February 23, 2009

To

Respondent

I am a student at the University of Nairobi, conducting a research on “The management

of wastewater: The proposal on the use of Biological treatment systems” as part

fulfillment for the award of B.A. Degree in Quantity Survey. I intend to administer

questionnaires to you as a tool for data collection.

DECLARATION

THE INFORMATION COLLECTED THROUGH THE USE OF QUESTIONNAIRE(S),

INTERVIEWS AS WELL AS YOUR IDENTITY SHALL BE TREATED AS

CONFIDENTIAL AND SHALL BE USED FOR RESEARCH PURPOSES ONLY.

INSTRUCTIONS

Please tick and/or state the appropriate answer in the space(s) or box(es) provided. More

than one answer may be ticked or stated where applicable.

Your assistance will be highly appreciated

Thanks

Cosmas Onyango (Researcher)

xxv

UNIVERSITY OF NAIROBI

QUESTIONNAIRES

Questionnaire 4 to Estate Agents

1. Name of your Agency

……………………………………………………………………...

2. What is your area of location?

.…………………………………………………………….

3. How long have you worked for the agency?

1-3 years [ ] 4-7 years [ ] Above 7years [ ]

4. Where do you get your water supply from?

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

5. Are there any problems of water shortage in your Estate?

Yes [ ] No [ ]

6. How is wastewater collected in your Estate?

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

7. Is the wastewater treated (this apply to where wastewater collection is not piped to

public sewers otherwise the response should be not applicable)

Yes [ ] No [ ]

Not applicable [ ]

8. If the response above is Yes, which treatment mechanism is used?

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

9. Are you aware of any Biological wastewater treatment mechanisms

Yes [ ] No [ ]

xxvi

10. If yes which one (s)

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

11. Is water recycling done in your Estate?

Yes [ ] No [ ]

12. Are there any cases of water related diseases in your Estate

Yes [ ] No [ ]

13. Are the cases : frequent [ ] Not frequent [ ]

14. What advice or proposals can you give as relating to wastewater management?

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………