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
11 Background information - - - - 1
12 General Description of River Illo - - - - 2
      121 Identified Sources of pollution - - - 2
      122 Water Uses and Conflict - - - - - 3
13 Statement of the problem - - - - -   4
14 Justification of the Study - - - - 5          
15 Objectives of the Study - - - - - -   5
16 Expected Contributions to Knowledge - - - - - 6
17 Scope of the Study - - - - 6
 
CHAPTER TWO: LITERATURE REVIEW
21 Surface Water Quality and Anthropogenic Activities - - 7
22 Slaughterhouses - - - - 7
221 Characterization of slaughterhouse wastes - - 8
222 The Nigerian Experience - - - 8
223 Abattoir Waste Management - - - 9
2 231 Waste Treatment Methods - - - 10
2232 Pollution Prevention - - - 11
23 Parameters Frequently Examined in the Determination of Water Quality - 12
231 Physico-ChemicaParameters - - - 12
232 Microbiological Parameters - - - 15
24 Water Pollution and Control in Nigeria - - - 16
25 Water Laws and Standards - - - - 18
26 Water Quality Measurements and Quantitative Hydrology - - 19
261 Assimilative Capacity Studies - - - 20
27 Field Survey and Sampling - - - - 21
28 Quality Control and Assurance - - - 21
29 Data Interpretation - - - - 23
 
CHAPTER THREE: METHODOLOGY
31 Field Survey and Sampling Exercise - - - 25
32 Sampling Locations - - - - 26
33 Conditions of Sampling - - - - 28
34 Quality Control and Assurance - - - - 29
35 Laboratory Analysis - - - - - 29
36 Data Analysis - - - - - 30
37 Solid Waste Management - - - - 30
 
CHAPTER FOUR: RESULTS AND DISCUSSIONS
41 The Abattoir - - - - - 34
42 Solid Waste Characterization and Management practice at the abattoir - 34
43 Hydraulic Data - - - - - 36
44 Water Quality Parameters - - - - 36
441 Physical Parameters - - - 36
442 Chemical Parameters - - - 37
443 Microbiological Parameters - - - 37
45 Correlation and Regression Analysis - - - 37
46 Percentage Compliance with Standards - - - 40
47 Descriptive Statistics - - - - 41
48 Self purification capacity of stream - - - 42
49 Dispersion Modeling - - - -    44
491    Determination of Coefficient of Dispersion - - 45
      492    Dissolved Oxygen modeling - - - 48
493  Assumptions of the model - - - 52
 
CHAPTER FIVE: CONCLUSION AND RECOMMENDATION
51 Conclusion - - - - 53
52 Recommendation - - - - 54
 
REFERENCES - - - - 56
 
APPENDIX - - - - - 60


LIST OF TABLE
 
Table                               Title                                                             Page
 
21              Physico-Chemical Parameters of Water Quality Importance - 13
22              Nigerian States, key Industries and Waste Characterization - 17
23  Water Quality Parameters and Storage Conditions for Samples - 22
31              Hydraulic properties of the sampling points - - 27
41  Hydraulic Data from the River - - - 36  
42  Physical Parameters of the Water Samples from River Illo - 36
43              Chemical Parameters of the Water Samples from the River - 37
44              Microbiological Parameters for the river - - 37
45              WHO Guideline Values and Percentage Compliance of samples41
46  Descriptive Statistics - - - - 42
47  Self purification factor for receiving water at 200C - 48

LIST OF FIGURES
Figure                                               Figure Caption                          Page
     11                 Map of Ota District Showing Important Settlements and Rivers - 2b
     31                 River cross section and Dimensions obtained - - 28
     32                 Distances along the river where samples and hydraulic  
                          measurements were obtained - - - 29  
     33                Sketch of the site plan of the abattoir and sampling  
                          points along the river - - - 31
     41  Graph of discharge against velocity - - 38
     42  Graph of conductivity against Total Solids - - 39
    43                  Graph of discharge against conductivity - - 39
    44                 Graph of Velocity against Dissolved Oxygen - - 39
    45                 Graph of Velocity against Phosphate - - - 40
    46                 Graph of Ammonia against Alkalinity - - 40
    47                 Plot of Total Solids against the Sampling Points - - 42
    48                 Plot of phosphate against the Sampling Points - - 43
    49                 Plot of COD against the Sampling Points - - 43
    410               Plot of Ammonia against the Sampling Points - - 43
    411               Plot of Dissolved Oxygen against the Sampling Points - 44
    412               Ideal Dissolved Oxygen Curve - - - 48
    413              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
DAF – Dissolved Air Floatation
DO – Dissolved Oxygen
EC – European Communities
FEPA – Federal Environmental Protection Agency
GEM – 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 DO 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