ABSTRACT 
This report presents results obtained from the investigation and water sampling exercise carried out on the segment of River Illo that passes through Sango in Ado Odo-Ota Local Government Area, Ogun State, Nigeria. The report reveals that while some people used water from the river for domestic, food production and recreation purposes, others discharge their wastes without any form of pre-treatment into it. The multipurpose usage of water from River Illo by local residents thus hinges public health on the self purification capacity of the river alone.
Information on water use and waste disposal practices of the local residents were obtained through direct observation and oral interview of members of randomly chosen households built along the river within a distance of 2km. Single grab samples of water were obtained from the river at the site of an abattoir effluent discharge at distances 0m, 10m, 20m, 30m, 50m and 100m from the point of discharge. A seventh sample was also obtained 10m upstream of the point of effluent discharge to furnish information on ambient conditions of the river prior to pollution while an eighth sample which was prepared by diluting the water obtained at 0m with distilled water (i.e. 25%  stream water, 75% distilled water) was included to serve as control sample. All water samples were transported (within 3 hours of isolating them from the river body) to the laboratory for analysis and the results were subjected to graphical, statistical and mathematical analysis. Pollution from the abattoir caused a drop in dissolved oxygen level of the river from an ambient value of 4.6mg/l to 0.01mg/l at the point of discharge. The pollution also caused an increase of 447.5mg/l to 1071.5mg/l in T.S., 0.04mg/l to 4.4mg/l in ammonia, 170mg/l to 670mg/l in BOD, 0.05mg/l to 3.05mg/l in phosphorus, 50mg/l to 1066.7mg/l in alkalinity and 18mg/l to 820mg/l in Acidity. It was also found out that between 30m ” 80m downstream of the pollution point, a threat of eutrophication is caused by plants growing in the river path. Despite this obstruction, the river recovered considerably to a D.O. level of 3.9mg/l at 100m downstream. Results from the dispersion modeling shows the self-purification capacity of the river, f, to be 1.1 within 30m distance from the point of discharge and 0.8 between 30m and 100m from the point of discharge. The results from the application of the Streeter-Phelps model showed that the eutrophication occurring between 30m ” 80m is interfering adversely
with the self purification processes of the river.   The percentage compliance of each of the eight water samples with Guideline Values (GLV) of WHO and FEPA was performed. None of the samples met the minimum requirements for BOD, COD and TSS, which are indicators of pollution. It was concluded that River Illo is being polluted by abattoir effluents discharge thereby exposing the health of local residents who use the water from the river for domestic, recreation and food production purposes to avoidable risks. Suggested actions that could further complement the self-purification capacity of the river were offered.

TABLE OF CONTENTS             Page 
Title Page ……………………….i
Certification……………………… ..ii
Acknowledgement……………………..iii
Dedication…………………………iv
Table of Contents………………………..v
List of Tables………………………..xiii
List of Figures………………………ix
List of Plates…………………………x
Abbreviations and Symbols……………… …..xi
Abstract…………………………..xii

CHAPTER ONE: INTRODUCTION 
1.1 Background information…………………….. 1
1.2 General Description of River Illo………………… 2
1.2.1 Identified Sources of pollution………………. 2
1.2.2 Water Uses and Conflict………………………….. 3
1.3 Statement of the problem……………………….  4
1.4 Justification of the Study……………………. 5
1.5 Objectives of the Study…………………………….  5
1.6 Expected Contributions to Knowledge………………………. 6
1.7 Scope of the Study…………………….. 6

CHAPTER TWO: LITERATURE REVIEW 
2.1 Surface Water Quality and Anthropogenic Activities…………7
2.2 Slaughterhouses…………………….7
2.2.1 Characterization of slaughterhouse wastes………..8
2.2.2 The Nigerian Experience………………..8
2.2.3 Abattoir Waste Management……………..9
2.2.3.1 Waste Treatment Methods……………..10
2.2.3.2 Pollution Prevention………………11
2.3 Parameters Frequently Examined in the Determination of Water Quality….12
2.3.1 Physico-ChemicaParameters……………..12
2.3.2 Microbiological Parameters……………15
2.4 Water Pollution and Control in Nigeria………………16
2.5 Water Laws and Standards…………………..18
2.6 Water Quality Measurements and Quantitative Hydrology………19
2.6.1 Assimilative Capacity Studies………………20
2.7 Field Survey and Sampling………………….21
2.8 Quality Control and Assurance……………….21
2.9 Data Interpretation……………………..23

CHAPTER THREE: METHODOLOGY 
3.1 Field Survey and Sampling Exercise……………….25
3.2 Sampling Locations……………………26
3.3 Conditions of Sampling……………………28
3.4 Quality Control and Assurance………………….29
3.5 Laboratory Analysis………………………29
3.6 Data Analysis……………………….30
3.7 Solid Waste Management……………………30

CHAPTER FOUR: RESULTS AND DISCUSSIONS 
4.1 The Abattoir………………………34
4.2 Solid Waste Characterization and Management practice at the abattoir……34
4.3 Hydraulic Data……………………….36
4.4 Water Quality Parameters…………………..36
4.4.1 Physical Parameters………………..36
4.4.2 Chemical Parameters……………….37
4.4.3 Microbiological Parameters……………..37
4.5 Correlation and Regression Analysis………………37
4.6 Percentage Compliance with Standards……………..40
4.7 Descriptive Statistics…………………….41
4.8 Self purification capacity of stream……………..42
4.9 Dispersion Modeling………………….   44
4.9.1    Determination of Coefficient of Dispersion………..45
4.9.2    Dissolved Oxygen modeling……………….48
4.9.3  Assumptions of the model……………..52

CHAPTER FIVE: CONCLUSION AND RECOMMENDATION 
5.1 Conclusion……………………..53
5.2 Recommendation…………………….54

REFERENCES……………………..56

APPENDIX…………………………60

LIST OF TABLE

Table                               Title                                                             Page 

2.1              Physico-Chemical Parameters of Water Quality Importance…..13
2.2              Nigerian States, key Industries and Waste Characterization……17
2.3  Water Quality Parameters and Storage Conditions for Samples…22
3.1              Hydraulic properties of the sampling points…………27
4.1  Hydraulic Data from the River……………..36
4.2  Physical Parameters of the Water Samples from River Illo……36
4.3              Chemical Parameters of the Water Samples from the River…..37
4.4              Microbiological Parameters for the river…………..37
4.5              WHO Guideline Values and Percentage Compliance of samples..41
4.6  Descriptive Statistics………………….42
4.7  Self purification factor for receiving water at 200C……..48

LIST OF FIGURES
Figure                                               Figure Caption                          Page 
1.1                 Map of Ota District Showing Important Settlements and Rivers…2b
3.1                 River cross section and Dimensions obtained………..28
3.2                 Distances along the river where samples and hydraulic
measurements were obtained…………….29
3.3                Sketch of the site plan of the abattoir and sampling
points along the river………………..31
4.1  Graph of discharge against velocity…………..38
4.2  Graph of conductivity against Total Solids…………39
4.3                  Graph of discharge against conductivity………….39
4.4                 Graph of Velocity against Dissolved Oxygen………..39
4.5                 Graph of Velocity against Phosphate……………40
4.6                 Graph of Ammonia against Alkalinity…………..40
4.7                 Plot of Total Solids against the Sampling Points……….42
4.8                 Plot of phosphate against the Sampling Points ………43
4.9                 Plot of COD against the Sampling Points ……….43
4.10               Plot of Ammonia against the Sampling Points ………43
4.11               Plot of Dissolved Oxygen against the Sampling Points…..44
4.12               Ideal Dissolved Oxygen Curve…………….48
4.13              Dissolved Oxygen Curve for Case Study………..49

LIST OF PLATES

Plate                                    Plate Caption                                          Page 
1.  Dug well supplying process water…………….32
2.  The Slaughtering Slab………………..32
3.  A section of the receiving river………………32
4.  Accumulated sludge in contact with the water body………33
5.  Animal bones being sun dried……………..33
6.  Land and water pollution from rendering activities……….33
ABBREVIATIONS AND SYMBOLS
ACS ” Assimilative Capacity Studies
ASP ” Activated Sludge Pond
BOD ” Biochemical Oxygen Demand
COD ” Chemical Oxygen Demand
D.A.F. ” Dissolved Air Floatation
D.O. ” Dissolved Oxygen
E.C. ” European Communities
F.E.P.A. ” Federal Environmental Protection Agency
G.E.M. ” Global Environmental Monitoring Systems
mg/l ” milligram per liter
NPC ” National Population Commission
POC ” Pollutants of Concern
TDS ” Total Dissolved Solids
TSS ” Total Suspended Solids
TS ” Total Solids
µs/cm ” microsiemen per centimeter
WHO ” World Health Organization
-DL =  m2
/s, where the negative sign is to show the flow of molecules from area of
higher        concentration to lower concentration
Da = initial DO deficit
La = initial BOD
q = kg/m2
s, where q is flux
Cs = concentration of D.O. at saturation
C1 = mg/l, where subscript 1 stands for point 1
r d  = mg/m3
d, is the rate of deoxygenation
Di,  ti = dissolved oxygen, time, at point of inflexion
Dc,  tc = dissolved oxygen, time, at critical point
Xc, Xi  = distance at which Dc, Di occurs
K1,1 = deoxygenation rate in segment 1