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Abstract
Flocs in Water Treatment is the first of its kind - serving as a valuable aide-mémoire for scientists, process engineers and other professionals engaged in water treatment. The framework described in Flocs in Water Treatment can also be applied to aggregated solids found both in the natural environment, and within a broad range of industries. Flocs (aggregated solid matter) resulting from the combined influence of coagulation and flocculation play a vital role in solid-liquid separation processes. The design and operation of water treatment plants demands a proper understanding of the ways in which flocs affect treatment systems and how their properties can be manipulated to increase treatment efficiency.
Flocs in Water Treatment provides a comprehensive account of the ways in which flocs are formed, their characterization, and how they behave in practice. Flocs are complex entities, whose properties defy easy description and measurement. In spite of this, the authors provide a clear and discerning account of the current state of knowledge; this is rooted in science and draws on many disciplines. Based on their experiences in research and the workings of full scale treatment plants, the authors offer candid advice on tasks such as the measurement of floc properties and guidance on problems involving the use of chemicals for controlling floc properties within treatment systems.
Table of Contents
| Section Title | Page | Action | Price |
|---|---|---|---|
| Contents | |||
| Preface | |||
| Section 1 Background Concepts | |||
| 1.1 INTRODUCTION | |||
| 1.1.1 Water quality perspective | |||
| 1.1.2 Surface characteristics | |||
| 1.2 COLLOIDS | |||
| 1.2.1 General concepts | |||
| 1.2.2 Van der Waals interaction | |||
| 1.2.3 Electrical double layer | |||
| 1.2.4 Double layer interaction energy | |||
| 1.2.5 Combined interaction | |||
| 1.2.6 Hydration and hydrophobic interactions | |||
| 1.2.7 Steric stabilisation | |||
| 1.2.8 Polymer bridging | |||
| 1.2.9 Electrostatic bridging | |||
| 1.2.10 Stability and binding | |||
| 1.3 FLOC FORMATION | |||
| 1.3.1 Introduction | |||
| 1.3.2 Mechanisms of coagulation | |||
| 1.3.2.1 Double layer compression | |||
| 1.3.2.2 Adsorption and charge neutralisation (ACN) | |||
| 1.3.2.3 Enmeshment | |||
| 1.3.2.4 Polymers and destabilisation | |||
| 1.3.3 Principles of flocculation | |||
| 1.3.3.1 Introduction | |||
| 1.3.3.2 Perikinetic aggregation | |||
| 1.3.3.3 Orthokinetic aggregation | |||
| 1.4 MIXING FACTORS | |||
| 1.4.1 Introduction | |||
| 1.4.2 Facets of turbulence | |||
| 1.4.2.1 Energy cascade | |||
| 1.4.2.2 Smallest stable vortex | |||
| 1.4.2.3 Energy spectrum | |||
| 1.4.2.4 Decay of turbulence | |||
| 1.4.3 Characterisation of mixers | |||
| 1.4.4 Mixing timescales | |||
| 1.4.4.1 Bulk mixing | |||
| 1.4.4.2 Dispersive and diffusive mixing | |||
| 1.4.4.3 Implications | |||
| 1.5 HYDROLYSING COAGULANTS | |||
| 1.5.1 Perspective | |||
| 1.5.2 Monomeric hydrolysis products | |||
| 1.5.3 Polynuclear species | |||
| 1.5.3.1 Hydroxide bridges | |||
| 1.5.3.2 Iron polymerisation | |||
| 1.5.3.3 Aluminium polymerisation | |||
| 1.5.4 Time factors | |||
| 1.5.5 Charge factors | |||
| 1.5.6 Surface area | |||
| 1.5.7 Water binding | |||
| 1.6 SYNTHETIC ORGANIC POLYMERS | |||
| 1.7 SOLIDS PRODUCTION AND COMPOSITION | |||
| 1.8 REFERENCES | |||
| Section 2 Characterisation | |||
| 2.1 PARTICLE STRUCTURES | |||
| 2.1.1 Introduction | |||
| 2.1.2 Fractal dimensions | |||
| 2.1.2.2 Information dimension | |||
| 2.1.2.3 Correlation dimension | |||
| 2.1.2.4 Relationship between fractal dimensions | |||
| 2.1.2.5 Multifractals | |||
| 2.1.3 Clusters | |||
| 2.1.3.1 Descriptors of structure | |||
| 2.1.3.2 Packing factor | |||
| 2.1.4 Chain format | |||
| 2.1.5 Bound water | |||
| 2.2 HYDRODYNAMIC BEHAVIOUR OF SUSPENSIONS | |||
| 2.2.1 Low Reynolds number flows | |||
| 2.2.2 Permeability | |||
| 2.2.3 Settlement | |||
| 2.2.3.1 Framework | |||
| 2.2.3.2 Shape factors | |||
| 2.2.3.3 Flow-through effects | |||
| 2.2.3.4 Settling of fractal aggregates | |||
| 2.3 RHEOLOGY | |||
| 2.3.1 General concepts: patterns of deformation | |||
| 2.3.2 Viscosity: basic concepts | |||
| 2.3.3 Gels | |||
| 2.3.4 Fast elastic deformation | |||
| 2.3.5 Yield stress in shear | |||
| 2.3.5.1 ‘True’ yield stress | |||
| 2.3.5.2 Bingham yield stress | |||
| 2.3.6 Normal stresses | |||
| 2.3.6.1 Multifractal elasticity | |||
| 2.3.6.2 Normal yield stress | |||
| 2.3.7 Viscosity | |||
| 2.4 FLOC STRENGTH | |||
| 2.4.1 Perspective | |||
| 2.4.2 Viscous flows | |||
| 2.4.2.1 Surface stress | |||
| 2.4.2.2 Flow fields | |||
| 2.4.2.3 Induced stresses | |||
| 2.4.3 Turbulent flows | |||
| 2.4.3.1 Stress fields | |||
| 2.4.3.2 Fine structure: specification of turbulence energy | |||
| 2.4.3.3 Rupture criterion | |||
| 2.4.4. Structural model | |||
| 2.4.5 Strength-turbulence interaction | |||
| 2.5 DISTRIBUTIONS | |||
| 2.5.1 Overview | |||
| 2.5.2 Representation of distributions | |||
| 2.5.3 Distribution moments | |||
| 2.6 REFERENCES | |||
| Section 3 Flocs in Practice | |||
| 3.1 MEASUREMENT | |||
| 3.1.1 Perspective | |||
| 3.1.2 Size | |||
| 3.1.2.1 Some experiences | |||
| 3.1.2.2 Stress regimes in PSD | |||
| 3.1.2.3 Remote sensing | |||
| 3.1.2.4 Image analysis | |||
| 3.1.3 Fractal properties | |||
| 3.1.3.1 Perspective | |||
| 3.1.3.2 Sedimentation analysis | |||
| 3.1.3.3 Scattering | |||
| 3.1.3.4 Monitoring floc formation and breakage | |||
| 3.1.4 Strength | |||
| 3.1.5 Overview | |||
| 3.2 IMPACTS ON FLOC PROPERTIES | |||
| 3.2.1 Perspective and scope | |||
| 3.2.2 Coagulants | |||
| 3.2.2.1 Background | |||
| 3.2.2.2 Mode of Destabilisation | |||
| 3.2.2.3 Hydrolysing metal coagulants | |||
| 3.2.2.4 PACl | |||
| 3.2.2.5 Hybrid compounds | |||
| 3.2.2.6 Organic coagulants | |||
| 3.2.3 Size-density relationship | |||
| 3.2.4 Optimised coagulation conditions | |||
| 3.2.5 Temperature | |||
| 3.2.5.1 System chemistry | |||
| 3.2.5.2 Flocs and floc formation | |||
| 3.2.6 Flocculant aids | |||
| 3.2.6.1 Polymer flocculants | |||
| 3.2.6.2 Activated silica | |||
| 3.2.6.3 Ballasting | |||
| 3.2.7 Shear | |||
| 3.2.7.1 Rapid mixing | |||
| 3.2.7.2 Restructuring | |||
| 3.2.7.3 Impacts on distributions | |||
| 3.2.8 Overview | |||
| 3.3 IMPACTS ON TREATMENT PROCESSES | |||
| 3.3.1 Background | |||
| 3.3.1.1 Ease of treatment | |||
| 3.3.1.2 Processes as collectors | |||
| 3.3.1.3 Thrust of Section 3.3 | |||
| 3.3.2 Chemical application | |||
| 3.3.3 Flocculation | |||
| 3.3.4 Floc blanket clarifiers | |||
| 3.3.5 Dissolved air flotation | |||
| 3.3.6 Filtration | |||
| 3.3.6.1 Foreword | |||
| 3.3.6.2 Impacts of size | |||
| 3.3.6.3 Solids handling capacity | |||
| 3.3.6.4 Deposit stability | |||
| 3.3.6.5 Operation problems | |||
| 3.3.7 Dewatering | |||
| 3.3.7.1 Perspective | |||
| 3.3.7.2 Water state | |||
| 3.3.7.3 Impacts of coagulation | |||
| 3.3.7.4 Permeability | |||
| 3.3.7.5 Polymers | |||
| 3.2.7.6 Optima | |||
| 3.2.7.7 Shear | |||
| 3.3.7.8 Thickening | |||
| 3.3.7.9 Cake filtration | |||
| 3.3.7.10 Expression | |||
| 3.3.7.11 Key points | |||
| 3.3.8 Overview | |||
| 3.4 REFERENCES | |||
| Appendix A: SI Units and Physical Constants | |||
| SI BASE UNITS | |||
| SI DERIVED UNITS | |||
| SI PREFIXES | |||
| NON-SI UNITS | |||
| PHYSICAL CONSTANTS | |||
| Appendix B: Symbols | |||
| Acknowledgements | |||
| Index |