CHAPTER ONE

1.0 Introduction

1.1 Background of Study

Wastes can be considered, as those materials no longer required

by an individual, institution or industry. Wastes are thus

regarded as by-products or end products of the production and

consumption process respectively. Solid waste can be defined as:

‘The useless and unwanted products in the solid state derived

from the activities of the society and hence discarded off by the

society.’ Solid waste results from various sources, such as

animal wastes, hazardous wastes, industrial and medical wastes,

food wastes, mineral waste, and nonhazardous wastes.

In the late 1990s, it was estimated that each person in the world

generated 200kg of solid waste per year (UNCHS, 2001) and this

was forecasted to increase with the growth in population. The

quality and generation rate of solid wastes in Nigeria have

increased at an alarming rate over the years with lack of

efficient and modern technology for their management (Babayemi

1

and Dauda, 2009). Solid waste management has remained an

intractable environmental sanitation problem in Nigeria. This

problem has manifested in the form of piles of indiscriminately

disposed heaps of uncovered waste and illegal dumpsites along

major roads and at street corners in cities and urban areas. This

problem is compounded by the rapid urbanization and population

growth which has led to the generation of enormous quantities of

solid waste which are often discarded by open dumping. The rate

of increase in the quantity of waste generated in relation to the

population size can only worsen urban environmental issues and

planning as a whole (Babayemi and Dauda, 2009).

Solid wastes are mainly disposed off to dumpsite, because it is

the simplest and cheapest method of disposing waste (Barret and

Lawler, 1995). Rushbroke (2001) describes open dumping of

municipal solid waste (MSW) as a primitive stage of waste

disposal, practiced by three fourths of countries and territories

round the world. Open dumps are the major causes of environmental

degradation and public health concerns in many developing

countries including Nigeria. These waste dumps may contain a

mixture of general waste and toxic, infectious or radioactive2

wastes and are susceptible to burning and exposure to scavengers.

There are a number of major risks and impacts of the dumpsites on

the environment. For instance, air pollution from open burning,

due to emission of green house gases such as methane and carbon

dioxide; the air emissions and leachates generated as a result of

decomposition of waste may contaminate air, surface and

groundwater sources; fire hazards and explosions cause public

health risks as well. The emission of greenhouse gases, rats and

fly infestation and nuisance effects are among the health and

environmental impacts of poor solid waste management. In

addition, scattering of wastes by wind and scavenging by birds,

animals and waste pickers creates aesthetic nuisance. Malodour

emanating due to the degradation of the waste in the dumpsite has

nuisance effect and decreases the economic and social values in

the locality. In many dumpsites, the waste is directly exposed

due to the absence of daily cover on the dumped waste and this

attracts the animal and human scavengers (Kurian et al, 2004).

According to DEAT (2001), the life and dumpsite and landfill can

be managed if wastes disposed to dumpsites are minimized through

waste recycling and resource recovery and the vision of the3

Polokwane declaration is to reduce solid wastes landfilled to 50%

of current levels by 2012 and to zero by 2022. If resources (both

renewable and non renewable) are salvaged, dumpsites air space

will be more effectively utilized and pollution and environmental

degradation will be reduced.

1.2 Statement of Problem

Over the last three decades there has been increasing global

concern over the public health impacts attributed to

environmental pollution, in particular, the environmental quality

and human health risks associated with the waste dumps. World

Health Organization estimated that about a quarter of the

diseases facing mankind today occur due to prolonged exposure to

environmental pollution (UNEP, 2006). Unfortunately there seems

to be no clear cut guidelines at the national or state levels on

how to deal with these dumpsites in a sustainable manner,

particularly in the developing where ironically the burden of

environmental pollution seems to be highest. It is suggested that

the first task would be to decide on one of three options: if the

dumpsite should be closed, remediated or rehabilitated (Kurian et

al, 2005).. To determine whether to rehabilitate and close or4

remediate, upgrade and operate a dumpsite may require an

environmental impact assessments studies (EIAs) including

consultation with the interested and affected parties,

specifically the adjacent communities. In countries like Nigeria

where the number of existing dumpsites (both legal and illegal)

are many, economic considerations of the evaluation process must

be taken into consideration in recommending a suitable approach

or methodology.

Assessing the relative health and environment hazards posed by

the dumpsites existing throughout the developing countries could

help prioritize, plan and initiate dumpsite rehabilitation

(Kurian et al, 2005).

In order to prolong the life of the current dumpsites and

landfills in the country and optimally manage the new ones, they

need to be redesigned and reconstructed, following the

internationally acceptable standards and regulations. Landfills

(dumps) in the case study (Ogun State) generally were not subject

to the regulations governing modern landfills and were usually

sited for convenience such as the presence of a pre existing hole

5

into which wastes could be deposited. This research seeks to

assess the suitability of dumpsites location within Abeokuta

North and South Local Government area of Ogun state with a view

of identifying suitable areas across the state for future

landfill projects using site selection criteria.

1.3 Research Question

The following questions are intended to be answered by this study

- Where are the designated dumpsites within Abeokuta North and

South Local Government of Ogun State?

- What are the qualities of the waste in the designated dump

site within Abeokuta North and South Local Government of

Ogun state

1.4 Justification/Rationale of Study

The lack of effective waste management strategy is a potential

threat to achieving sustainable development in Nigeria. Studies

that would bring about strategies to manage these wastes are

urgently needed. Hence, the purpose of this study is to provide a

scientific assessment of an existing dumpsite in Ogun state.

Landfills offer promising potentials for both energy as well as

6

raw material recovery. In addition, they offer easiest and

cheapest way of waste disposal. While the predominant reasons for

dumpsite deconstruction and reclamation in the past have been

environmental pollution and degradation. At present and in the

future, the motivation should be their proper location through

constraint mapping, using site selection criteria. If properly

located and constructed, dump sites has many environmental

besides economic benefits. Revenues from recyclable and re-

useable materials (e.g. ferrous metals, aluminum, plastic and

glass) provide people with sustained

Income generation; reclaimed soil used as cover material or sold

as construction fill or sold for other uses. The recovery of

metals from old dumpsites seems also reasonable in respect to the

strongly increasing prices of raw materials (EUWID, 2008)

1.5 Significance of Study

Internationally, landfills have significant waste management

potentials. Proper site selection for dumpsites has potentials

for increasing dumpsite life span protecting the environment from

further pollution from indiscriminate waste dumping and enhancing

conversation of natural resources and virgin materials so as to

7

eradicate poverty through income generation. However, these

benefits are still not fully taken into advantage in Nigeria due

to poor site location for the dumpsites/landfills. This is partly

because the major issues that determine the success of dumpsites

selection and construction have not been earnestly addressed.

That is environmental impact assessment and audit of each dump

site has not been given the much attention it deserved. It will

also provide necessary information for appropriate/suitable site

which in the long run increase the life span of these sites and

reduce the necessity for reclamation in the future.

At present there are hardly any documented experiences with the

use of risk based approaches for the management of dumpsites in

Nigeria. The need for a risk based tool that is suited to the

peculiarities of a developing country and that has been tested

and proven to be useful, scientifically sound and easy to apply

is therefore urgently required, given the number o f waste dumps

in Nigeria and the march towards the achievement of vision 20-20-

20 (the vision of the Nigerian state to become one of the

twentieth largest economies in the world by the year 2020). This

8

study will therefore provide basis for action and suggest

modification for better result.

1.6 Objectives of Study

1.6.1 Broad Objective

The broad objective of this study is to assess the existing

dumpsites in Abeokuta North and South Local Government of Ogun

State.

1.6.2 Specific Objectives

The specific objectives are to:

1) Identify and list all the designated dumpsites in Abeokuta

North and South Local Government of Ogun state

2) Carry out Physical and Chemical characterization of waste at

dumpsites in Abeokuta North and South Local Government of

Ogun state.

9

CHAPTER TWO

2.0 Literature Review

Waste can be loosely defined as any material that is considered

to be of no further use to the owner and is, hence, discarded.

However, most discarded waste can be reused or recycled, one of

the principles of most waste management philosophies. What may be

of no further use to one person and regarded as waste to be

dumped, may be of use to the next person, and is the basis of the

rag picking trade, the sifting through of refuse at landfills for

recovery and resale, a very fundamental historical waste

management practice still functioning in many countries, often

conducted on a highly organized commercial basis.

Waste is generated universally and is a direct consequence of all

human activities. Wastes are generally classified into solid,

liquid and gaseous. Gaseous waste is normally vented to the

atmosphere, either with or without treatment depending on

composition and the specific regulations of the country involved.

Liquid wastes are commonly discharged into sewers or rivers,

10

which in many countries is subject to legislation governing

treatment before discharge.

In many parts of the world such legislation either does not exist

or is not sufficiently implemented, and liquid wastes are

discharged into water bodies or allowed to infiltrate into the

ground. Indiscriminant disposal of liquid wastes pose a major

pollution threat to both surface and groundwater.

Solid wastes are mainly disposed of to landfill, because landfill

is the simplest, cheapest and most cost-effective method of

disposing of waste (Barrett and Lawler, 1995). In most low- to

medium-income developing nations, almost 100 per cent of

generated waste goes to landfill. Even in many developed

countries, most solid waste is landfilled. For instance, within

the European Union, although policies of reduction, reuse, and

diversion from landfill are strongly promoted, more than half of

the member states still send in excess of 75 per cent of their

waste to landfill (e.g. Ireland 92 per cent), and in 1999

landfill was still by far the main waste disposal option for

Western Europe (EEA, 2003). Furthermore, although the proportion

of waste to landfill may in future decrease, the total volumes of

11

municipal solid waste (MSW) being produced is still increasing

significantly, in excess of 3 per cent per annum for many

developed nations (Douglas, 1992). Landfill is therefore likely

to remain a relevant source of groundwater contamination for the

foreseeable future (Allen, 2001).

Solid waste composition, rate of generation and methods of

treatment and disposal vary considerably throughout the world and

largely determine the potential of waste to impair groundwater

quality.

.2.1 Types of Solid Waste

Wastes generated by the full extent of human activities range

from relatively innocuous substances such as food and paper waste

to toxic substances such as paint, batteries, asbestos,

healthcare waste, sewage sludge derived from wastewater treatment

and as an extreme example, high-level (radioactive) waste in the

form of spent nuclear fuel rods. Numerous classifications of

solid wastes have been proposed (e.g. Tchobanoglous et al., 1993;

Ali et al., 1999), and the following represents a simple

classification of waste into broad categories according to its

origin and risk to human and environmental health:

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- Household waste;

- Municipal waste (MSW);

- Commercial and non-hazardous industrial wastes;

- Hazardous (toxic) industrial wastes;

- Construction and demolition (C&D) waste;

- Health care wastes – waste generated in health care

facilities (e.g. hospitals, medical research facilities);

- Human and animal wastes; and

- Incinerator wastes.

Household waste represents waste generated in the home and

collected by municipal waste collection services. Municipal solid

waste (MSW) includes this plus shop and office waste, food waste

from restaurants, etc., also collected by municipal waste

collection systems, plus waste derived from street cleaning, and

green (organic) waste generated in parks and gardens.

Storage of waste in a disposal facility serves to minimise the

effects of waste on the environment. This is achieved by

restricting any effluent derived from the waste to a single

location, where emissions can be controlled. If control is

lacking or inadequate, disposal facilities may become point

13

sources of groundwater contamination. In many regions,

centralised waste disposal has historically occurred by

landfilling, wherein local quarries and gravel pits have been

filled with waste because, in many cases, they simply constituted

an appropriately sized hole in the ground. Such locations

typically offered little protection against contamination of

adjacent groundwater supplies. Legislation, designed to protect

usable groundwater, has helped to reduce the incidence of this

practice in many high to middle income countries (e.g. US EPA,

1974; CEC, 1980; NRA, 1992). Modern waste management practices

involve disposal of waste in specially sited and engineered sites

known as "sanitary landfills".

Waste accepted in municipal waste landfills in developed

countries would normally consist of municipal solid wastes, plus

commercial and non-hazardous industrial wastes, and construction

and demolition (C&D) waste. There is a tendency in many countries

for C&D waste, usually regarded as inert, to be buried on the

construction site where it is generated.

14

However, since downward percolating rainwater may leach heavy

metals from C&D waste, recent waste regulations in some developed

countries requires all C&D waste to be disposed of in landfills.

Hazardous and non-hazardous wastes are differentiated in waste

management legislation of many countries. A range of legal

definitions exist for hazardous waste, but it can generally be

thought of as waste or a combination of wastes with the capacity

to impair human health or the environment due to its quantity,

concentration, or physical, chemical or infectious

characteristics when improperly used, treated, stored,

transported or disposed. In many countries, hazardous (toxic)

industrial wastes (both organic and inorganic), solid incinerator

residues, bottom and fly ash are disposed in special hazardous

waste landfills, and specialized disposal or incineration may

also be practiced for healthcare wastes. In many low- to medium-

income parts of the world, where uncontrolled open dumps are

common, all waste tends to be dumped together, regardless of its

origins or its hazardous nature. A specific characteristic of

leachate from hazardous industrial waste is that it may be toxic

15

to the bacteria naturally present and thus delay biodegradation

of organic substances in leachate.

Human and animal wastes are usually not disposed of in landfills,

although animal carcasses and waste from abattoirs may in some

countries be disposed of in dumps and landfills. Human corpses

are not generally regarded as waste, but they degrade in a

similar way to other organic waste, and also produce leachate in

significant quantities. The majority of corpses are buried in

cemeteries, although a significant proportion are cremated

(incinerated), the proportion varying from country to country

depending on the proportions of different religious groups in the

population and their funeral rites. The main health concern with

human and animal wastes is the high concentrations of pathogenic

organisms associated with this type of waste, and the potential

it has to spread disease.

2.2 Waste Storage, Treatment and Disposal Sites

The processes of storage, collection, transport, treatment and

disposal of wastes all have the potential to pollute the

environment and particularly groundwater due to uncontrolled

migration of fluids (leachate) derived from the wastes. In

16

addition to the potential for groundwater pollution at sites

where wastes are produced and stored prior to collection, sites

associated with the treatment and disposal of wastes, where

leachate may be generated include:

- Landfills (both controlled as sanitary landfill or

uncontrolled as open dumps);

- Scrap-yards;

- Cemeteries;

- Waste collection and processing facilities; and

- Composting facilities.

For situation assessment, landfills are most readily identified

with the pollution of groundwater by waste-derived liquids.

However, any site where waste is concentrated, processed (e.g.

recycled) and stored even for a short period of time, may be a

potential point source of groundwater contamination. Such

processing facilities are often not well regulated or licensed

and frequently occur in urban or semi urban settings, where local

water supply points may be impacted by these activities. An

inventory of these locations, the types of waste handled and

17

management processes for waste products will aid in the

assessment of the polluting capability of such sites.

For situation assessment, a critical criterion in estimating

potential groundwater pollution from waste disposal is the siting

of all of the above mentioned waste treatment and disposal

facilities, particularly sanitary landfills and open dumps. Most

modern landfills in high to medium income countries require

licenses to operate and must be engineered to prevent groundwater

pollution. This generally involves lining the site with an

artificial lining system, but liners leak and degrade with time.

Even if the site is well engineered and managed, with an

artificial lining system installed, and even if or the waste

materials are inert, leachate, which may have the potential to

pollute groundwater, will be produced. It is therefore essential

to assess the capacity of the underlying geology to protect

groundwater in the event of liner failure. The likelihood of

disposed wastes polluting groundwater depends on the thickness of

the unsaturated zone and the attenuation capacity of the

overburden (i.e. any loose unconsolidated material which overlies

solid bedrock) underlying the site, and also on the total and

18

effective precipitation at the site, since the quantity and

concentration of leachate generated is a function of the access

of water to the waste. Thus the potential for pollution of

groundwater will be least at sites carefully selected to take

advantage of the most favourable geological/ hydrogeological

conditions.

'Historic landfills (dumps)' generally were not subject to the

regulations governing modern landfills, and were usually sited

for convenience, such as the presence of a pre-existing hole into

which the waste could be deposited. The general assumption that

an aftercare period of 30 years is adequate to allow for

degradation of waste to an inert state, is now being questioned,

with recent studies (Hjelmar et al., 1995; Wall and Zeiss, 1995;

Kruempelbeck and Ehlrig, 1999; Röhrs et al., 2000; Fourie and

Morris, 2003) suggesting that waste may remain active for many

decades and even hundreds of years, particularly under

moisturedeficient conditions. This includes not only landfills

from regions where evaporation exceeds precipitation, but also

all lined and capped landfills employing the concept of dry

entombment of waste.

19

In the past, hazardous and non-hazardous wastes were not

distinguished so that hazardous substances may be stored in all

of these landfills. For situation assessment, it is important to

locate all waste disposal sites in the drinking-water catchment,

including both currently operating landfills, and historic dumps,

now closed and covered over.

Assessment of all landfills, but in particular historic

landfills, should include age and type of waste, underlying

geology, most importantly type and thickness of overburden and

thicknessof the unsaturated zone. The state of degradation of the

waste can be ascertained by analyzing the leachate and landfill

gases generated, as degradation of waste follows a distinctive

pattern manifested in well-known and documented compositional

variations in liquid and gaseous emissions. All of this, together

with the proximity of all of these sites to sources of drinking

water, can determine the threat to public health posed by waste

disposal.

2.3 Factors governing contamination by disposal of waste into

dumpsites

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Waste deposited in landfills or in refuse dumps immediately

becomes part of the prevailing hydrological system. Fluids

derived from rainfall, snowmelt and groundwater, together with

liquids generated by the waste itself through processes of

hydrolysis and solubilisation, brought about by a whole series of

complex biochemical reactions during degradation of organic

wastes, percolate through the deposit and mobilise other

components within the waste. The resulting leachate, subsequently

migrates from the landfill or dump and has the potential to

contaminate local groundwater either through direct infiltration

on site or by infiltration of leachate-laden runoff offsite. The

risk posed to groundwater-fed drinking water sources by waste

disposal in landfills or dumps can be considered in terms of

three controls:

Waste Composition and Loading;

Leachate Production; and

Leachate Migration - Attenuation and Dilution.

2.3.1 Waste composition and loading

21

The composition and volume of disposed wastes vary nationally and

regionally in relation to the local human activities, and the

quantity and type of products that communities consume. Discarded

waste in lower income areas is typically rich in food-related

waste, i.e. organic (carbon-rich) substances. Although such waste

is not in itself toxic, decomposition of organic matter can alter

the physico-chemical quality of groundwater and enhance the

mobility of hazardous chemicals including metals and solvents.

The proportion of manufactured (e.g. paper) and potentially

hazardous (e.g. textiles, metals, plastics) wastes increases in

relation to income and degree of industrialisation (Table.1), and

waste disposal leachate from highly industrialized settings may

contain a wide range of anthropogenic contaminants. The types of

hazardous substances likely to occur in discarded waste may be

assessed from the types of industry, small-scale enterprise and

other human activity of a particular area.

A major concern in many countries is also of waste import,

particularly of hazardous wastes. Export from industrialised

countries to low-income countries circumvents strict waste

disposal regulations implemented in the country generating these

22

wastes. Often this is highly organized, as informal, though

illegal, transactions between an exporter and importer using

false documentation (e.g. Mackenzie, 1989). Such waste

export/import practices are difficult to detect, but important

for situation assessment as disposal of such wastes is likely to

pose a risk of groundwater contamination. It is, therefore, often

necessary to collect information on both formal and informal

(i.e. illegal) waste composition and loading.

Table .1: Solid-waste generation and composition from selected regions in the world

(OECD, 1993, 1997; Attahi, 1999; Onibokun and Kumuyi, 1999; Lusugga Kironde 1999).

Landfilled refuse is rich in microorganisms. Mature sites may be

compared to large bioreactors in which the organic content of the

waste is decomposed anaerobically. Most of the organisms that

23

carry out these processes are harmless saprophytes, but a small

percentage of the population may be opportunistically pathogenic

microorganisms. Waste arising from households, medical practices

and hospitals, veterinary practices, industrial sites and from

environmental sources will contain pathogenic microorganisms.

Whereas waste from industrial, medical and veterinary sources is

more likely to be controlled or to be of known composition,

domestic waste tends to be highly variable and of uncontrolled

composition. An analysis of household waste in the UK showed that

over 4 per cent of the waste comprised disposable nappies

(diapers) of which about one-third may be soiled with faeces.

Domestic waste also contains bloodstained materials, such as

sanitary pads, tampons and discarded wound dressings and animal

wastes, such as dog faeces and soiled cat litter. The potential

for pathogens within this mixture of sources is extremely high.

Pathogens may also be transported to landfill sites by vermin

(rats) and other scavengers, in particular seagulls.

The fate of pathogens in landfill sites is not understood.

Although it is generally assumed that most are rapidly

inactivated by the conditions that prevail in the landfill

24

environment, the potential of leachate and run-off from landfill

sites to transport pathogens into local water resources should be

addressed in situation assessment.

2.3.2 Leachate Production

Most waste deposited in landfills is not inert. Degradation of

many components of waste including food, paper and textiles

consumes oxygen thereby changing the redox potential of the

liquid present and potentially influencing mobility of other

constituents. Plastics, glass and metal compounds tend to be less

reactive and degrade more slowly. Under some conditions, metals

may, however, become rapidly mobilised.

Percolating rainwater provides a medium in which waste,

particularly organics, can undergo degradation into simpler

substances through a range of biochemical reactions involving

dissolution, hydrolysis, oxidation and reduction, processes

controlled to a large extent within landfills and dumps by

microorganisms, primarily bacteria. Table.1 indicates that the

largest fraction of disposed waste is organic matter (e.g. food,

paper), which has a well documented degradation path. Mechanisms

25

regulating mass transfer from wastes to leaching water, from

which leachate originates, can be divided into three groups of

processes :

Hydrolysis of solid waste and biological degradation;

Solubilisation of soluble salts contained in the waste; and

Suspension of particulate matter.

The first two groups of processes, which have the greatest

influence on the composition of leachate produced, are associated

with the stabilisation of waste.

Initially, organic matter, in the form of proteins, carbohydrates

and fats, is decomposed under aerobic conditions (i.e. oxidised),

through a series of hydrolysis reactions, to form carbon dioxide

and water together with nitrates and sulphates via a number of

intermediate products such as amino acids, fatty acids and

glycerol. Such oxidation reactions are exothermic, so

temperatures in the landfill become elevated. Carbon dioxide is

released as a gas or is dissolved in water to form carbonic acid

(H2CO3) which subsequently dissociates to yield the bicarbonate

anion (HCO3 -) at near neutral pH.

26

Aerobic decomposition of organic matter depletes the waste

deposit of oxygen (O2) as buried waste in the landfill or refuse

dump becomes compacted and circulation of air is inhibited. As

oxygen becomes depleted, it is replaced as the oxidising agent by

in succession, nitrate (NO3 -), manganese (as MnO2), iron (as

Fe(OH)3) and sulphate (SO4 2-). In general, the aerobic stage is

short, no substantial volumes of leachate are produced, and

aerobic conditions are rapidly replaced by anaerobic conditions.

The main stages of anaerobic digestion are (i) acetogenic (acid)

fermentation, (ii) intermediate anaerobiosis, and (iii)

methanogenic fermentation, all three of which can be operating

simultaneously in different parts of the landfill. Acetogenic

fermentation brings about a decrease in leachate pH, high

concentrations of volatile acids and considerable concentrations

of inorganic ions (e.g. Cl-, SO4 2-, Ca2+, Mg2+, Na+). As the redox

potential drops, sulphate is slowly reduced, generating

sulphides, which may precipitate iron, manganese and heavy metals

that are dissolved by the acid fermentation.

Decrease in pH is due to production of volatile fatty acids

(VFAs) and to high partial pressures of carbon dioxide (CO2),

27

whilst the increased concentrations of anions and cations results

from leaching (lixiviation) of easily soluble organic material

present in the waste mass.

Breakdown of organic material reduces the redox potential to <

330mV, which allows the next stage of the process to become

initiated. Leachate from this phase is characterised by high

values of biochemical oxygen demand (BOD, commonly > 10,000

mg/L), high BOD5/COD (chemical oxygen demand) ratios (commonly >

0.7), acidic pH values (typically 5-6) and ammonia (NH3) due to

hydrolysis, and fermentation in particular of proteins.

Intermediate anaerobiosis commences with a gradual increase in

the methane (CH4) concentration in the gas, coupled with a

decrease in H2, CO2 and volatile fatty acids.

Conversion of the volatile fatty acids leads to an increase in pH

values and to alkalinity, with a consequent decrease in the

solubility of calcium, iron manganese and the heavy metals, which

are probably precipitated as sulphides. Ammonia is released but

is not converted to nitrate in such an anaerobic environment.

Methanogenic fermentation, the final stage in the degradation of

organic wastes, operates within the extremely limited pH range of

28

6-8. At this stage in the degradation process, the composition of

leachate is characterised by almost neutral pH, and low

concentrations of volatile acids and total dissolved solids

(TDS), indicating that solubilisation of the majority of organic

components is almost complete, although waste stabilisation will

continue for several decades. The biogas being produced has a

methane content of generally > 50 per cent, whilst ammonia

continues to be released by the acetogenic process. Leachate

produced at this stage is characterised by relatively low BOD

values, and low ratios of BOD/COD.

Degradation processes convert nitrogen into a reduced form

(ammonium), and bring about mobilisation of manganese and iron

and also liberation of hydrogen sulphide gas. Production of

methane indicates strongly reducing conditions with a redox

potential in the order – 400 mV. Unlike carbon dioxide, methane

is poorly soluble in water.

Due to the decomposition of organic matter, leachate derived from

landfills or dumps comprises primarily dissolved organic carbon

(Table 2.), largely in the form of fulvic acids (Christensen et

al., 1998). The solubility of metals in leachate is enhanced

29

through complexation by dissolved organic matter. The solubility

of organic contaminants (e.g. solvents) in waste may also be

slightly enhanced through the presence of high levels of organic

carbon in leachate. Hydrophobic compounds may be mobilised

through leachate, as they adsorb to organic carbon in solution.

For example, benzene- and naphthalenesulphonates comprise between

1 and 30 per cent of the dissolved organic carbon in

landfillleachates recently analysed in Switzerland (Riediker et

al., 2000).

Table 2. Key characteristics of landfill leachates from England, Germany and USA (allvalues in mg/L except pH) (Robinson et al., 1982; Ehrig, 1982; Fetter, 1993).2.3.3 Leachate migration

30

In unsealed landfills above an aquifer, waters percolating

through landfills and refuse dumps often accumulate or 'mound'

within or below the landfill (Figure.1). This is due to

production of leachate by degradation processes operating within

the waste, in addition to the rainwater percolating down through

the waste. The increased hydraulic head developed promotes

downward and outward flow of leachate from the landfill or dump.

Downward flow from the landfill threatens underlying groundwater

resources whereas outward flow can result in leachate springs

yielding water of a poor, often dangerous quality at the

periphery of the waste deposit. Observation of leachate springs

or poor water quality in adjacent wells/boreholes are indicators

that leachate is being produced and is moving. Leachate springs

represent a significant risk to public health, so their detection

in situation assessment is critical in order to prevent access to

such springs.

One method used to reduce the generation of leachate and, hence,

hydraulic heads generating flow from a closed landfill is to

place a capping of low permeability material (e.g. clay or high

density polyethethylene - HDPE) over the waste deposit in order

31

to reduce infiltration of rainwater. These should be recorded in

situation assessment because if a landfill is capped to impede

rainwater ingress, reducing leachate volumes, a more concentrated

leachate will be generated. Also, microbiological and biochemical

reactions will be inhibited thereby prolonging the degradation

process and the activity of the waste possibly for decades or

even centuries. Groundwater pollution potential from older capped

landfills may therefore be higher than from younger, open

landfills.

Figure 1. Conceptual diagram of leachate migration from a landfill (from Freeze andCherry, 1979).

32

Leachate migration is also affected by the manner in which waste

is deposited. Compaction of waste prior to deposition reduces its

permeability, whereas regular application of a topsoil cover

between the loading of waste to landfills induces layering. These

characteristics inevitably give rise to preferential flow paths

through landfills. Johnson et al. (1998) found, for instance, that

residence times for rainwater entering a landfill varied from a

period of a few days to several years. This is reflected in the

frequently temporal nature of leachate "springs", which can

appear in wet seasons but subsequently disappear in dry seasons

to leave patches of discoloured soil (Jefferis, 1993).

Inspections of potential leachate production should, therefore,

focus on periods towards the end of wet seasons or following

excessive rainfall events. Further, situation assessment needs to

account for uncertainties in both the prediction and monitoring

of leachate migration from landfills and dumps, in consequence of

the complex hydrogeology of waste deposits.

CHAPTER THREE

3.0 INTRODUCTION

33

This chapter dealt with methods and procedures that was used

to carry out the procedures for data collection and analysis for

this study. Research design, description of the study area,

sampling method, procedure for chemical analysis of samples, data

collection methods' study materials, data management and analysis

were considered in this chapter.

3.1 RESEARCH DESIGN

Descriptive exploratory and cross sectional survey design

have been

adopted for this study. This study have been carried in both

field and laboratory based on limited work done in scope to all

the designated dump site in Ogun state.

3.2 DESCRIPTION OF THE STUDY AREA

Ogun state is a state in south-western Nigeria. It borders

Lagos state to the south, Oyo and Osun states to the North, Ondo

state to the east and the republic of Benin to the west Abeokuta

is the capital and largest city in the state. According to 2006

population census in Nigeria; Ogun state was estimated to have

3,658,908. Ogun has one federal university: university of

34

Agriculture, Abeokuta and two state government universities:

Olabisi Onabanjo University, Ago Iwoye(formerly known as ogun

state university)and the Tai-Solarin University Of

Education(TASUED) Ijebu ode. Ogun state has a total of nine

registered universities, the highest of any state in Nigeria.It

has five private universities, including Babcock university in

Illisan-Remo, which was the first private university in the

country. The state has two major government hospital in sagamu.

The state is characterized by large and small

industries(manufacturing and agro allied industries);house holds;

and commercial, religious as well as other various types of

institutions.

3.3 SAMPLING METHOD

Purposive sampling method was used to select all the old

designated dump sites in Ogun state for the study while

quartering method were adopted for sampling materials for

laboratory analysis in the latter case, each site were stratified

equally into 4 quadrants, grab sample of the materials and soil

samples were taken from each quadrant and pulled together to from

a heap that represent sample of the materials

35

3.4 PROCEDURES FOR CHEMICAL ANALYSIS OF SAMPLES

The following physico-chemical parameters were determined in

the laboratory: moisture content PH, total organic-carbon, total

nitrogen C:N ratio, hydrogen, total phosphorus, lead, chromium,

Nickel, zinc, and cadmium-to ascertain the quality of compost

material and energy recovery potential standard analytical

methods as described by the America Public Health Association

(APHA 2005)was used to assess each parameter. Digestion procedure

for phosphorus Determination about 0.2g of the powdered organic

material will be digested with Nitric perchloric: sulphuric acid

mixture in the ratio of 5:1:1 respectively in a 100ml conical

flask. The mixture is heated on a hot plate for about one hour

until about 1ml of clear solution is left in the flask. A lot of

brownish fume with choking smell is given off. It is allowed to

cool and 100ml of distilled water is added to the clear solution.

The solution is filtered through an ash less filter paper

(what man NO. 3)into a volumetric flask. Digestion method for

heavy metals determination of lead(pb),chromium (cr)

Nickel(Ni),Zinc (zn),and cadmium (cd) in the raw organic sample

will be done by weighing 1g of grounded sample into a conical

36

flask.5ml of digestion reagent(2:1 conc.HNO3 and conc.H2SO4)are

added and heated until brown peroxide and white perchloric acid

is evaporated. The resulting residue were totally dried. The

procedure were repeated until a white precipitate remained in the

flask. This is then filtered through a what man filter papar into

a 100ml volumetric flask. The filtrate is diluted with 0.1

NHNO3(p.a)to 100ml.The digested samples was analyzed for the

heavy metals at the institute of Tropical

Agriculture(11TA)Ibadan.

PHOSPHOROUS DETERMINATION

Determination of total phosphorus as P205 in the raw orgnic

waste will be done spectrophotometrically. Using the

MO(molybdovanadate) blue colour method of murphy and

Riley(1962),revised 2009

POTASSIUM DETERMINATION (EXPRESSED AS K20)

Potassium conent of raw sample was determined

titrimetrically using sodium tetraphenyl boron volumetric method

as described by APHA methods of analysis(2005)

3.5 DATA COLLECTION METHODS

37

The data collection methods include the following:

i.  Direct observation' which include:

ii.  Observation checklist and specified tools for physical

waste

characterization, and general on-site observation.

iii.  Baseline laboratory measurement to appraise the

chemical quality of raw wastes, using standard analytical method

as described by the American Public Health Association(APHA,2005)

3.6 STUDY MATERIALS

Materials for laboratory analysis include composite samples

of organic

and combustible materials like plastic, wood and paper materials

and equipment for physical characterization of waste include

refuse bags, rakes, spades, pickers, spring balance(with maximum

capacity oe 500kg), Sacks, boots, gloves, and nose cover.

3.7 DATA MANAGEMENT AND ANALYSIS

Appropriate simple statistical tools employed for the data

analysis include; use of frequency tables, bar-charts and pie

charts.

38

39

CHAPTER FOUR

4.0 ANALYSIS OF RESULT

4.1 PHYSICAL CHARACTERIZATION OF WASTE

Components Amount (%)

Leaves 3.02Papers 8.46Rags 3.02

Garbage 16.41Wood 1.06Metal 0.00

Polythene and other

plastics

8.91

Water contents 21.00

Total Weight (Kg) 2.1Total Volume (L) 16.00

From the table above, the amount of Leaves in the dumpsite

sample was 3.02%, the amount of papers was 8.46%, the amount of

rags was 3.02%, the amount of garbage was 16.41%, the amount of

wood was 1.06%, the amount of metal was 0.00%, the amount of

polythene and other plastics were 8.91%, while the amount of

40

water contents was 21.00%. The total weight of the dumpsite

sample was 2.1% while the total volume was 16.00%.

Leaves

Papers

Rags

Garbage

Wood

Metal

Polythene and other plastics

Water content

0

5

10

15

20

25Physical Characterization of Waste

41

Leaves5%Papers14% Rags

5%

Garbage27%

Wood2%

Polythene and other

plastics14%

Water contents34%

Physical Characterization (%)

42

4.2 CHEMICAL CHARACTERIZATION

Components Amount (%)Empirical Carbon 29.00%Total Nitrogen 2.1%

Total Phosphorus 3.3%

From the table above, the amount of Empirical carbon in the

dumpsite was 29.00%, the total Nitrogen was 2.1%, while the total

Phosphorus was 3.3%.

Empirical Carbon Total Nitrogen Total Phosphorous0

5

10

15

20

25

30

Chemical Characterization of Waste

43

Empirical Carbon84%

Total Nitrogen6% Total

Phosphorus10%

Chemical Chracterization

44

CHAPTER FIVE

5.0 SUMMARY CONCLUSION AND RECOMMENDATION

5.1 SUMMARY

Due to the fact that landfills (dumps) in Abeokuta North and

South Local Government were not subject to the regulations

governing modern landfills, and were usually sited for

convenience, such as the presence of pre-existing hole into which

the waste could be deposited, this study then assessed existing

dumpsite in Abeokuta North and South Local Government Area of

Ogun State. The study therefore critically identified physical

and chemical characterization of waste at each dumpsite in

Abeokuta North and South Local Government. Descriptive

exploratory and cross sectional survey design was adopted for

this study which was carried out in both field and laboratory

based on limited work done in scope to all the designated dump

site in Ogun state. Physico-chemical parameters were determined

in the laboratory: moisture content PH, total organic-carbon,

total nitrogen C:N ratio, hydrogen, total phosphorus, lead,

chromium, Nickel, zinc, and cadmium-to ascertain the quality of

45

compost material and energy recovery potential standard

analytical methods as described by the America Public Health

Association(APHA 2005)was used to assess each

parameter.

5.2 CONCLUSIONS

Result for physical characterization of the waste sample

revealed that waste major content of the waste are leaves,

papers, rags, garbage, wood and metal. The amount for leaves was

3.02%, papers was 8.46%, rags was 3.02% garbage was 16.41%, wood

was 1.06%, metal was 0.00, polythene and others were 8.91%, water

content was 21.00%. It showed that major content of the waste

sample was water content (21.00%). The total weight was 1.26

while the total volume was 16.00.

The chemical characterization revealed that the amount of

empirical carbon was 29.00%, total nitrogen was 2.20% and total

phosphorous was 2.7%. Empirical carbon was the known chemical

component which had the greatest amount in the waste sample.

5.3 RECOMMENDATIONS

46

Modern landfills must be made available, A modern landfill

which should be a carefully designed and built into or on top of

the ground in which waste is isolated from the surrounding

environment (groundwater, air, soil). The modern landfill should

offer much more protection for the environment and for local

people than traditional dumps did. Problems with odours, litter,

vermin, etc., are must be greatly reduced by the careful

management of the site.

Landfill sites must be monitored on a regular basis to make

sure they are being run efficiently and safely. The

responsibility for this monitoring rests with the government and

landfill operators themselves. 

While the government and other environmental agencies carry

out routine inspections on landfill sites and provides guidance

for landfill operators on the best practices for maintaining

their sites, the operators themselves are required to constantly

monitor various aspects of their site to ensure they remain in

compliance with their license. Different sites will be required

to monitor for different pollutants, depending on the location

and potential environmental impact of their sites. Landfill

47

gases, such as methane, carbon dioxide and sulphur dioxide are

produced by the breaking down of waste and can cause pollution

and odour problems. 

Proper compacting of waste, covering waste with a layer of

soil at the end of the day, litter control, surface water control

and general tidiness are all necessary parts of a landfill's

management plan. Poor organisation of a landfill site can lead to

problems with odours, flies, vermin and litter, which, in turn,

will lead to complaints

Many problems in dumpsites have been identified by many

researchers, so the coming researches should focus on finding

solutions for these problems. The researcher recommends that

additional studies should be done on the characteristics of

dumpsites like seasonal variations, laboratory experiments,

volume of components, etc.

48

49

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