ABSTRACT
Model studies of groundwater quality and formation characteristics in phreatic aquifer were carried out in Rivers State the study area. The research was to find a better solution of pollution transport in groundwater, considering the effect of geologic parameters such as heavy metals, micronutrients, porosity, permeability, and void ratio. The source of pollution was through indiscriminate dumping of biological wastes and wastes from soakaway, regenerating the wastes in most parts of the study area. This research was carried out through an experiment performed for E.coli transport, including some other parameters that influence microbial growth, inhibition and variation for fast migration within a short period of time. These parameters are heavy metals, micronutrients, permeability, porosity, and void ratio. Velocity of solute transport (E.coli) was determined through column experiment in each soil sample for all the locations. Empirical model was applied through experimental results plotted, generating a polynomial equation. The expressions from polynomial were applied to verify the results for E.coli, micronutrients, heavy metals, degree of porosity, permeability and void ratio. The physiochemical parameter from the study carried out found that the growth of E.coli under environmental conditions favoured it. The research was able to produce the level of physiochemical parameter influencing E.coli concentration in groundwater. The presence of E.coli depends on the availability of nutrients as well as favourable conditions in terms of physiochemical parameter. More so, the concentration increased with depth in micronutrient. The study confirmed that the higher the depth of water, the lower the population of E.coli in some locations based on the decrease in substrate utilization; while in some areas, it varies. The study explained that the rapid growth on the population of E.coli is experienced when the pH value is acidic than alkaline. The study carried out was able to express the stabilization of groundwater quality by inhibiting the presence of metallic element in some locations; while in few locations in the study area, it was discovered that the presence of E.coli in different aquifers have lower percentage and become less harmful to the quality of groundwater for human utilization. The level of porosity were investigated on the migration of E.coli influenced by porosity from one aquifer to the other, the results were calibrated and verified generating a model that can be applied to predict the rate at which E.coli transport within a short period of time. The variation of micropores i.e. void ratio from different soil depositions were determined, calibrated and verified. The results can be applied to predict the variations in the micropores and hydraulic conductivity within the soil structure, as it influences the variation in the migration of E.coli in phreatic aquifers. The rate of liquid flow within the soil profile (stratum) i.e. through the rate of permeability, is imperative because it has contributed to the rate of distribution of E.coli, as well as effectiveness in terms of stability in the region by reducing the migration and transport at different strata, this was investigated in the study. The results on the level of flow and the influence on the permeability were determined in the study areas. The permeability results were verified to predict the rate of velocity of water like that of solute at different soil formations, this results verified can be applied to predict the velocity of ground water influencing the rate of transport at different strata, the verified model result can be applied to predict the time at which the microbes can transport to groundwater aquifers in all the study areas. The soil compositions influenced by E.coli concentration as well as the rates of migration were investigated, the soil profile that contains high concentration known to be gravel and coarse were determined. Finally, the developed model from experimental results should be applied by thorough assessment of the area, to determine the type of concept to be applied in assessment of ground water quality in the study location through design of boreholes.
TABLE OF CONTENTS
CHAPTER 1: INTRODUCTION
1.1 Background of the study
1.2 Transport influence and Geologic History of Rivers State
1.3 Statement of Problem
1.4 Objectives of the Study
1.5 Scope of the Study
CHAPTER 2: LITERATURE REVIEW
2.1 Darcy’s Law
2.1.2 Transport Processes
2.1.3 Molecular Diffusion
2.1.4 Mechanical Dispersion
2.1.5 Advective Dispersive Equation (ADE)
2.1.6 Degradation
2.2 Determining Straining of Escherichia coli from Breakthrough Curve
2.2.1 Pore size Density Function
2.2.2 Bacteria Transport Model
2.2.3 Determining the Van Genuehten Parameters
2.2.4 Tracer Breakthrough
2.2.5 E.coli Breakthrough
2.2.6 Volume available for Straining
2.2.7 Indicator Organisms
2.2.8 Morphology and Surface Characteristics of E.coli Taxonomy
2.3 E.coli in Water
2.3.1 Hydrophilic Bacterial Cell Wall
2.3.2 The Surface Charge of E.coli
2.3.3 Non-uniform Surface charge Distribution
2.3.4 General Bacteria Transport Model
2.3.5 Simplifying the rate expression for fractional surface coverage (Eqn. 2.36) for E.coli Transport
2.3.6 Blocking
2.3.7 The Attachment Rate Coefficient
2.3.8 The Single Collector Contact Efficiency (0)
2.3.9 The Straining Rate Coefficient
2.4 Relative Importance of the Bacteria Transport Mechanisms
2.4.1 The Filter Coefficient (β)
2.4.2 Factors Affecting the Contact Efficiencies
2.3.3 Effect of Grain Size Uniformity of Sediment
2.4.4 Factors Affecting the Collision Efficiency
2.4.5 Effect of Ionic Strength
2.4.6 Effect of Lipopolysaccharides Composition in the outer Membrane
2.4.7 Effect of Geochemical Heterogeneity
2.4.8 Effect of Grain Surface Roughness
2.4.9 Evidence of Bimodal Efficiencies
2.4.10 Filter Coefficients and Collision Efficiencies from Field and Laboratory Experiments
2.5 Kinetic Desorption or Detachment
2.5.1 Factors Affecting Inactivation
2.5.2 Effect of protozoa and antagonists
2.5.3 Other effects on the die-off rate coefficient
2.6 Measuring and Modeling Straining of Escherichia coli in Saturated Porous Media
2.6.1 Theory
2.6.3 Model Fitting and Numerical Modeling Tools
2.6.4 Electrokinetic Characterization of E.coli, Cell Size and Stability of the E.coli Suspension
2.6.5 Nature and Occurrence of Straining, Attachment and Detachment
2.6.6 Model Fitting
2.7 Sensitivity of the Model Results to Parameter Values
2.7.1 Comparing Modelled and Measured Values
2.7.2 Effect of Transport Distance
2.7.3 The fitting parameter B and the mass balance of strained bacteria
2.8 Transport of E. coli in Columns of Geochemically Heterogeneous Sediment
2.8.1 Porosity of the column sediments
2.8.2 Column experiment method
2.8.3 The result conditions during the experiments
2.8.4 The breakthrough curves
2.8.5 Sticking efficiency
2.8.6 Effects of Lag and Maximum Growth in Contaminant Transport and Biodegradation Modeling
2.8.7 Description of kinetics
2.9 Modeling Solute Transport in Porous Media
2.10 Virus Transport from Septic Tank Systems near Seasonally Inundated Areas through Shallow Aquifers
2.11 Factors Affecting Microbial Survival in Groundwater
2.12 Studies on Viruses
2.12.1 Studies on Viruses and Bacteria
2.12.2 Studies on Bacteria and Cryptosporidium
2.13 Comparison of Escherichia coli and Campylobacter Jejuni Transport in Saturated Porous Media
2.14 Survival of Water Quality Indicator Microorganisms in the Groundwater Environment Temperature and Total Dissolved Solids Effects
2.14.1 Biomass Structures in Porous Media
2.14.2 Microbial Attachment/Detachment Processes in Porous Media
2.14.3 Modeling Biological Reactions in Porous Media
2.14.4 Heterogeneity, Transport, and Scaling Issues
2.15 Solute Transport Models
2.15.1 Deterministic-functional models
2.15.2 Stochastic-mechanistic models
2.15.3 Stochastic-functional models
2.15.4 Deterministic-mechanistic models
2.15.5 Solute Transport Models for Multi-Layered Porous Media
2.15.6 Solution of Governing Equations for Transport Models
2.15.7 Parameter Estimation
2.15.8 Modeling of Solute Dispersion
2.15.9 Models for Solute Dispersion at various Scales
2.15.10 Deficiency of Previous Researchers
CHAPTER 3: METHODOLOGY
3.0 Theoretical Background
3.1 Experimental Method
3.2 Permeability Test
3.3 Physiochemical Analysis of Heavy Metals and Micro Elements
3.4 Column Experiments
3.4. 1 Experiment set up
3.5 Bacteriological Testing of Water
3.5.1 Choice of Technique
CHAPTER 4: RESULTS AND DISCUSSION
4.0 Data Analysis
4.1 Concentration of Micronutrients versus Depths at Different Locations
4.2 Concentration of Heavy Metals versus Depth at different Locations
4.3 Concentration Result of Micronutrients at Upland Location
4.4 Concentration of Column Experiment at Different Depths
4.5 Concentrations of Heavy Metal, and Micronutrients at Different depths in Coastal Locations
4.6 Concentration Micronutrients at different Depths and Locations
4.7 Concentrations of E.coli at different Depths and Locations
4.8 Model Verification for Permeability, Porosity and Void Ratio Experimental Result
4.9 Calculated and Measured Values of Porosity at Different Depths and locations
4.10 Calculated and measured Model Values for Void ratio at
Different Depths and Locations
4.11 Determined Coefficient of Permeability Result and Discussion
4.12 Verified model result for E.coli, micronutrient and heavy metals
4.12.1 Model Result from Column Experiment (E. coli)
4.12.2 Calculated and Measured Values of E. coli transport
4.12.3 Calculated and Measured Values for Heavy at Different depths
4.13 Calculated and Measured values Micronutrients at different depths and Locations
4.14 Velocity of Micro organism (E.coli) transport from Column Experiment at Different Locations
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion
5.2 Recommendations
5.3 Further study
References
Appendices
CHAPTER 1
INTRODUCTION
1.1 Background of the Study
Throughout history, the quality and quantity of drinking water has been the major concern and the most vital issue in human welfare on earth today. The quality and quantity of water valuable to human have disappeared because of water shortage resulting from changes in climate. Even temperature, fluctuation, and limited precipitation caused problems. Devastating drought in Africa in 1980 resulted in catastrophic crop failure and more so; water is the most abundant liquid on earth. It covers three quarters of the earth, and settlement hinges on the availability of water. In man, three quarters of the fluid in him are made up of water. A man can live about a month without food, but he will die in a week without water, hence experts claim that declining supplies of fresh water will be a source of increasing tension in coming years. Worldwide, more than one billion people do not have access to clean water. About thirty percent of groundwater consist of fresh water, most of which are inaccessible, unusable or may be obtainable at great expense of energy. Only three-tenth of one percent of total fresh water can be truly considered as renewable. The water from rainfall seeping into the soil to nourish plant and tree growth and lakes, flow into the ocean and evaporating into the atmosphere in a natural hydrological cycle that will produce more rain. In 2004, there were still at least one billion people across the world, which do not have access to safe drinking water. Many of these people live in rural areas and are among the poorest and more vulnerable to be found anywhere in the world.
The international community has set up ambitious millennium development goals, to reduce by half the number of people without clean water by 2015. In this context the need for sustainable development and management of groundwater cannot be overstated. Across large swathes of Africa, South America, and Asia, groundwater provides the realistic water supply option for meeting dispersed rural demand. Alternative water resources can be unreliable and expensive to develop, surface water (if available) is prone to contamination and often seasonal, and rainwater harvesting can be expensive and requires good rainfall throughout the year. Groundwater, however, can be found in most environments, if you look hard enough with the appropriate expertise. Groundwater is the portion of the earth water cycle that flows underground. Groundwater originates from the precipitation that percolates into the ground. Percolation is the flow of water through soil and porous/fracture rock. The water table separates the saturated, or aquifer zone from the unsaturated or vadose zone, where the water does not fill all the voids or space in the soil or rock. The general trend is for water in the unsaturated zone to move down water until it reaches the water table. On the other hand, water in the saturated zone moves primarily along horizontal hydraulic gradients, from high to lower elevation, the ocean is the natural sink for groundwater flows.
Groundwater does not recycle readily. Rate of groundwater turnover vary from days to years, and from centuries to millennia, depending on aquifer location, type, depth, properties, and connectivity. The average time for the renewal of groundwater is 1,400years. Shorter renewal times tend to be associated with shallow groundwater, while longer renewal times are associated with deep groundwater.
Groundwater flow occurs under conditions that are usually classified as being either confined or unconfined. Confined groundwater flow is vertically constructed by the local geology and characterized by having positive fluid pressure throughout the domain. Conversely, unconfined flow occurs where there is a transition flow, positive fluid pressures in the saturated part of the domain, across an interface called the phreatic surface where the fluid pressure is atmospheric, into the unsaturated zone where fluid pressures are negative due to capillary forces. Because there is an open continuum, between surface processes, both natural (e.g. recharge) and artificial (e.g. waste disposal), and subsurface flow processes under unconfined conditions, then it is imperative that unconfined flow processes can be quantified to aid in the understanding and management of stresses upon the resource
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