ABSTRACT
In this research work, the effect of environmental pollution on the dissolved oxygen resources of a receiving stream, Amadi creek, was investigated .Amadi creek, located in Port- Harcourt metropolis is a unique creek that is of high economic importance to the residents of Rumuobiakani, Mini-Ewa, Oginigba, Woji and Okujagu communities as it hosts the activities of the majority of the companies around the Trans- Amadi Industrial area and also provides water for fishing and water transportation The study was carried out to evaluate the water quality changes resulting from increasing human and industrial activities in and around the creek. For this purpose the physic o -chemical characteristics of the water in the creek at different seasons were measured and the results compared against W.H.O standards. Statistical methods were used at some point to calculate the mean, variance and the standard deviations in all stations and the results were then presented using computer based excel spreadsheet. The results show that the creek has relatively low concentrations of heavy metals ranging from (0.26-0.30mg\l), (0.00-0.01mg\l), (0.01-0.02mg\l), and (0.85-1.17mg\l for chromium, copper, aluminum and iron respectively. Mean values of other physic o- chemical parameters like temperature, salinity, suspended solids, pH, DO, BOD, range from (22.1-29.5oC), (0.1-2.7mg\l), (7.0-59.5mg\l), (6.3-8.4), (2.3-5.11mg\)],(0.8-5.7mg\l) respectively. Dissolved oxygen water quality standards for creeks and rivers require the maintenance of DO level of 5mg\l or more at any time. However, practical analysis of the water samples for dry and wet seasons showed that the conditions in the creek fall below this standard. .Measured DO concentrations were found to be as low as 2.3mg\l. Hence this research attempted to solve this problem of DO depletion by optimizing the locations of waste discharge locations into the creek. The DO deficit equations are solved by the methods of simple calculus (classical optimization), which simplifies the mathematical solution of the model equations by avoiding difficult to evaluate integrals. Two scenarios were identified and used to investigate the effect of BOD on the DO level in the stream, using mathematical simulation techniques. Simulation results of the two scenarios suggest that the dissolved oxygen deficit is dependent on the distance between waste discharge points .Hence to ensure minimum impact on water quality, waste discharge locations should be placed at the optimal locations of 10015m and 6992m upstream and downstream waste discharge points respectively, at an optimum DO deficit of 4.14 mg/l for the first scenario, and at 41233m, 40995m, 33605m upstream and downstream waste discharge points respectively for the second scenario at an optimum DO deficit of 4.57mg/l. This means that if a new waste input ( e.g., a new sewage treatment plant) is proposed for a stream or river, both its BOD input and the proposed location with respect to the other inputs are important in order to determine the effects of pollution on the stream DO level. Comparing the Dt values predicted by the new models with Ugbebor, the new models are in good agreement with the values of observed Dt with a standard error of 1.05%. It is recommended that Industrial establishments planning to site their treatment facilities along rivers or streams should be compelled to discharge their waste stream in compliance with the optimal locations (with respect to any existing plant) ,and the existing effluent standards, so as to avoid undue dissolved oxygen (DO ) depletion .
TABLE OF CONTENTS
Title page
Abstract
Table of Contents
List of Figures
List of Tables
CHAPTER ONE
1.0 Introduction
1.1 Background
1.2 Work Justification
1.3 Definition of the Problem
1.4 Research Objectives
1.5 Scope of Research
1.6 Significance of research
CHAPTER TWO
2.0 Literature Review
2.1 Sources of Pollution in Rivers
2.2 Effect of Pollution in Aquatic Environment
2.3 Assimilatory Capacity of Stream
2.4 Factor Affecting Self-Purification of Streams
2.4.1 Hydrodynamic Factors
2.4.2 Environmental Factors
2.4.3 Climate Factors
2.5 Water Quality
2.5.1 Water Quality Assessment
2.5.2 Assessment Approaches
2.5.3 Assessment Operations
2.6 Effect of Point and Non-Point Discharge on Water Quality
2.7 Water Quality Models
2.7.1 Re aeration
2.7.2 Transport
2.7.3 Empirical Models
2.7.4 Deterministic Models
2.7.5 Stochastic Models
CHAPTER 3:
RESEARCH METHODOLOGY
3.1 Site Description
3.2 Sources of Data
3.3 Parameters of Interest
3.3.1 Biochemical Oxygen Demand (BOD)
3.3.2 Dissolved Oxygen (DO)
3.3.3 Temperature
3.3.4 pH
3.3.5 Heavy Metals
3.4 Experimental Set-up
3.5 Sampling Locations
3.6 Method of Sampling
3.7 Laboratory Analyses of Samples
3.7.1 Temperature Analysis
3.7.2 pH analysis
3.7.3 Biochemical Oxygen Demand Analysis
3.7.4 Dissolved Oxygen Analysis
3.7.5 Metal Analysis
3.8 Statistical Analysis
CHAPTER 4
THEORETICAL FORMULATION
4.1 Mechanism of Pollution Fate in the Environment
4.2 Derivation of the deficit equation
4.2.1 Formulation of Equations for Multiple Waste Discharge Location into Rivers
4.2.2 Case 1 – One Source of Waste Water Discharge
4.2.3 Case 2- Two Sources of Waste Water Discharge
4.3 Mathematical Model
CHAPTER 5
RESULTS AND DISCUSSION
5.1 Sensitivity Analysis
5.1.2 Effect of Velocity on the Optimal DO deficit
5.1.3 Effect of ultimate BOD on Optimum DO deficit
5.1.4 Effect of initial DO deficit on optimum DO deficit
5.1.5 Variation of optimum DO (Lo) deficit with distance
5.1.6 Effect of ultimate BOD (Lo) on Optimal Locations
5.1.7 Effect of Initial DO deficit on Optimal Location
5.1.8 Effect of velocity on Optimal Locations
5.2 Case studies
5.2.1 Effect of Flow conditions on Single Point Source Discharge
5.2.2 Effect of Flow Conditions on Two Sequential Point Source Discharge
CHAPTER 6
CONCLUSION AND RECOMMENDATION
Recommendation
Contribution of Knowledge
REFERENCES
CHAPTER 1
INTRODUCTION
Pollution is the befouling of the environment by the disposal of solid, gaseous, and liquid waste products resulting from human activities (Agunwamba, 2001).
Agunwamba(2001) further submits that pollution of the marine environment is the introduction by man directly or indirectly of pollutants which result in such deleterious effect as:
ñ Harm to living organisms
ñ Hazards to public health
ñ Hindrance to marine activities (e.g., fishing)
ñ Impairment of water quality with respect to use, and
ñ Reduction of amenities.
The deterioration of water quality in rivers, estuaries and coastal regions has been an alarming outcome of ever increasing discharge of industrial and municipal wastes. Wastes are discharged at selected points along rivers or oceans which create local high levels of pollution. However, the natural mixing and dispersion processes facilitate the reduction of the local pollution level by distributing the dissolved substances gradually over time. Dispersion is the action by which water flowing in a river or ocean water body spreads out and dilutes a mass of pollutant .Rather than moving downstream as a slug, such a mass is distributed along the length of the river, some parts moving faster and some slower than the mean flow velocity. The distribution of the average cross-sectional concentration is highly skewed at first, characterized by high concentration values within a short zone and a tapering tail in the upstream direction. The distribution becomes Gaussian after some large flow time (Fischer,1968;Smith,1986).The Federal Environmental Protection Agency FEPA (1991) defined pollution as “Generally the presence of matter of energy whose nature, location or quantity produces undesired environmental effect”. Under the Clean Water Act, for example, pollution is defined as the man-made or man-induced alteration of the physical, biological and radiological integrity of water. Water pollution therefore is concerned with the effect of contaminated water on the environment. Contaminated waste is treated to ensure the end products of treated processes are compatible with existing environmental resources and not overtake the assimilatory powers of the water body (Howard et al, 1985). Improperly treated or untreated liquid waste from industries, shops, and residencies discharged into receiving water bodies will lead to pollution on vegetation existing fauna/flora, etc (Bowman et al, 1974), as untreated waste water can enter soil, and mix with rivers and streams causing upset to creatures within the ecosystem. When untreated and treated domestic and industrial waste is discharged into natural bodies of water, the situation becomes even more complex. The discharge of domestic and municipal waste water, industrial and agricultural waste (organic, inorganic pollutants and heat), solid and semi-solid refuse to the streams and creeks result in the accumulation of sediments in watersheds. This reduces the rate of self -purification due to the depletion of dissolved oxygen level in the water, which in turn initiates the anaerobic conditions at watersheds. Therefore, precautions should be taken to restrict the discharge of such wastes into creeks, rivers and other marine environments. The quality of municipal, industrial and agricultural wastes should be controlled at the point of generation. This means the water should be treated before being discharged into any marine environment. The human waste, drinking water and communicable diseases are directly related. Water contamination is measured by the level of pollutants present in a sample. All successful Rivers Basin Management must be based on data obtained for that creek or river in question (Brown et al,1971).This information includes the knowledge of water quality profiles, criteria, impacts and control strategies upon which value judgments can be made. Criteria here refers to the scientific requirements upon which decisions are based on concerning the suitability of the water quality to support a designated use(Gordon et al,1971), while standard refers to legally statutory authority like the World Health Organization (WHO) and the Federal Ministry of Environment ( formerly known as the Federal Environmental Protection Agency .FEPA),based on scientific parameters .It is therefore in the interest of the populace to restore and maintain the chemical, physical and biological integrity of natural water and in addition to making the water safe to drink to provide for the projection and propagation of fish, shell fish etc and provide for recreation on water (Davis et al, 1988). Most of the towns and villages in the Niger delta area of Nigeria have suffered severely from water pollution resulting from oil spillages and effluents discharged into water bodies according to Atorudibo (2007). The Amadi creek is a typical example of a water body in the Niger delta region of Nigeria that has been highly polluted. Almost all industries in Nigeria, continues Atorudibo (2007) generate wastes which in most cases are disposed off without due regard to sound environmental management practices. These industries include petroleum and petrochemicals, steel, plastics, paints chemicals, fertilizers, battery and textile. Industrial activities have gradually led to.....
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