ABSTRACT

When solid waste is disposed of at landfills, it undergoes a combination of physical, chemical and microbial processes. These processes help to transform the waste into various water-soluble compounds termed (leachate) and transfer the pollutants from the refuse to the percolating water, leading to contamination of surrounding groundwater and surface water. Characterisations of the leachate originating from the Isale-Ijagba and Oke-Diya dumpsites (situated in Sagamu, Ogun State, Nigeria) as well as evaluation of the pollution potential on the quality of the local aquifer were carried out.

The composite sampling method was employed and samples collected over a period of five weeks, parameters such as, Electrical conductivity (EC), pH, Total Dissolved Solid (TDS), Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), NH3–N, PO4–P, SO42−, Cl−, K+, Cd, Mn, Zn, Ni, Fe and Pb were determined using standard method for water and waste water analysis. And the data gotten analysed using Microsoft excel spreadsheet.

Mean concentration values for TDS, BOD, COD, NH4+, PO4+,  SO4+ and Cl- are 493 and 534 mg/L; 1.50 and 1.08mg/L; 0.28 and 0.60 mg/L; 0.46 and 0.28 mg/L; 0.46 and 0.72 mg/L; 18.46 and 25.13 mg/L for the two monitoring wells  respectively. The highest observed BOD5 and COD values were 319 and 846 mg/L; 525mg/L and 1105mg/L for Isale-ijagba and Oke-Diya leachate samples respectively. The mean concentration values for Fe, Mn, Zn, Pb, Ni and Cr- in groundwater samples are 2.81 and 1.39mg/L; 0.02 and 0.08mg/L;  0.22 and 0.21mg/L ; 0.61 and 0.61mg/L; 0.17 and 0.14mg/L and 0.11 and 0.09mg/L for Isale-Ijagba and Oke-Diya monitoring wells respectively.

The mean concentrations of all measured parameters except, Pb, Fe and Cr conform to the stipulated World Health Organization potable water standard and the Nigerian Standard for Drinking Water Quality. It was however observed that in the absence of a properly engineered landfill system, percolation of leachates into waterbodies could be deleterious in the very near future. The study recommends an upgrade of both landfill so as to guarantee adequate protection of both the surface and the groundwater resources in the locality.

Key words: Leachate, groundwater, metal, physico-chemical, Sagamu.

TABLE OF CONTENTS

       Page

TITLE PAGE                                                                                                                        

ABSTRACT                                                                                                                                 ii

DEDICATION                                                                                                                            iv

ACKNOWLEDGEMENT                                                                                                     v                                                                                                                       

TABLE OF CONTENT                                                                                                            vi-ix

LIST OF TABLES                                                                                                                        x

LIST OF FIGURES                                                                                                                 xi-xii

CHAPTER ONE

1.0     INTRODUCTION                                                                                                                1

1.1     PROBLEM STATEMENT                                                                                                      4

1.2    SIGNIFICANCE OF THE STUDY                                                                                           5

1.3    AIMS AND OBJECTIVES                                                                                                      6

CHAPTER TWO

2.0      LITERATURE REVIEW                                                                                                       7

2.1     DEFINITION OF WASTE                                                                                                    7

2.2     LANDFILL SITING IN SAGAMU                                                                                         7

2.3     LEACHATE PRODUCTION                                                                                                9

2.4     DEGREE OF WASTE DECOMPOSITION                                                                          10

2.5     LEACHATE COMPOSITION                                                                                            11

2.5.1    POLLUTANTS IN LANDFILL LEACHATE                                                                        12

2.5.2    DISSOLVED ORGANIC MATTER                                                                                   13

2.5.3    COD AND BOD                                                                                                            13

2.5.4    INORGANIC MICRO-COMPONENTS                                                                           16

2.5.5    HEAVY METALS                                                                                                            17

2.5.6    FACTORS THAT MAY AFFECT LEACHATE COMPOSITION                                           20

2.6       MOVEMENT OF LEACHATE                                                                                         20

2.6.1    DIFFUSIVE TRANSPORT                                                                                               21

2.6.2    CONVECTIVE TRANSPORT                                                                                          22

2.6.3    DISPERSIVE TRANSPORT                                                                                             22

2.7       POSSIBLE IMPACTS OF LEACHATE                                                                              23

2.7.1   IMPACT ON THE ENVIRONMENT                                                                                 23

2.7.2    IMPACT ON HUMAN HEALTH                                                                                     24

CHAPTER THREE

3.0      MATERIALS AND METHOD                                                                                          27

3.1      GEOLOGY OF STUDY AREA                                                                                          27

3.2      SAMPLE COLLECTION                                                                                                  31

3.3     SAMPLE TREATMENT                                                                                                    31

3.4     FIXING OF DO                                                                                                               32

3.5     SAMPLE PREPARATION                                                                                                33

3.5.1   HEAVY METALS DETERMINATION USING AAS                                                           33

3.5.2   TOTAL DISSOLVED SOLID                                                                                           33

3.5.3   ACIDITY DETERMINATION USING TITRIMETRIC METHOD                                         34

3.5.4   ALKALINITY DETERMINATION USING TITRIMETRIC METHOD                                   34

3.5.5   CHLORIDE DETERMINATION BY VOLUMETRIC METHOD                                          35

3.5.6   NITRATE DETERMINATION BY COLORIMETRIC METHOD                                         36

3.5.7   BOD DETERMINATION BY THE WRINKLER METHOD                                                36

3.5.8   TURBIDIMETRIC DETERMINATION OF SULPHATE                                                     38

3.5.9   COD DETERMINATION BY TITRIMETRIC METHOD                                                    38

3.6      ASCORBIC ACID DETERMINATION OF PHOSPHATE                                                 39

3.6.1   pH DETERMINATION USING pH METER                                                                    40

3.6.2   ELECTRICAL CONDUCTIVITY DETERMINATION                                                         40

CHAPTER FOUR

4.0   RESULTS AND DISCUSSION                                                                                         41

4.1    LEACHATE CHARACTERIZATION AND BIODEGRADABILITY                                        42

4.2    HEAVY METALS CONTAMINATION OF LANDFILL LEACHATE                                     47

4.3    GROUNDWATER HYDROLOGY                                                                                    51

4.4    GROUNDWATER QUALITY                                                                                           51

4.5    HEAVY METALS CONCENTRATION IN MONITORING WELLS                                     56

CHAPTER FIVE

5.0    SUMMARY                                                                                                                    63

5.1    CONCLUSION                                                                                                               63

5.2    RECOMMENDATION                                                                                                    63

         REFERENCES                                                                                                                 64

ABBREVIATIONS

AAS:               ATOMIC ABSORPTION SPECTROSCOPY

APHA:            AMERICAN PUBLIC HEALTH ASSOCIATION

AWWA:          AMERICAN WATER WORKS ASSOCIATION

BOD:              BIOCHEMICAL OXYGEN DEMAND

B&L:               BAUSCH LOMB

COD:              CHEMICAL OXYGEN DEMAND

DO:                 DISSOLVED OXYGEN

EPA:               ENVIRONMEMTAL PROTECTION AGENCY

ISLE:              ISALE-IJAGBA LEACHATE

ISMW:            ISALE-IJAGBA MONITORING WELL

LE:                  LEACHATE

LGA:               LOCAL GOVERNMENT AREA

MW:                MONITORING WELL

NAFDAC:      NATIONAL AGENCY FOR FOOD AND DRUGS ADMINISTRATION

CONTROL

NCS:               NIGERIAN CUSTOM SERVICE

NSDQW:        NATIONAL STANDARD FOR DRINKING WATER QUALITY

OKLE:            OKEDIYA LEACHATE

OKMW:          OKEDIYA MONITORING WELL

TDS:                TOTAL DISSOLVED SOLID

TOC:               TOTAL ORGANIC CARBON

USEPA:          UNITED STATE ENVIRONMENTAL PROTECTION AGENCY

UV-VIS SPEC: ULTRAVIOLET VISSIBLE SPECTROSCOPY

WGS:                 WORLD GEODETIC SYSTEM

WHO:                WORLD HEALTH ORGANISATION

WPCF:               WATER POLLUTION CONTROL FACILITY

WW:                   WELL WATER

XOCs:                XENOBIOTIC ORGANIC COMPOUNDs

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