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Best Practice Guide on the Management of Metals in Small Water Supplies

Best Practice Guide on the Management of Metals in Small Water Supplies

Matthew Bower | Colin Hayes

(2016)

Additional Information

Book Details

Abstract

The management of small water supplies presents a unique challenge globally, in countries at all stages of development. A combination of lack of resources, limited understanding of the risks and poor expertise means that individuals and communities may face serious health risks from these supplies. This is not only due to microbiological contamination, but also from contamination by metals, either due to natural or man-made contamination of the source water or through leaching from plumbing materials due to inadequate conditioning and corrosion inhibition and use of inappropriate materials. 
This Best Practice Guide aims to share best practice and experience from around the world on a practical level. It looks at general issues relating to small supplies and ways of managing these, adopting a Water Safety Plan approach to deliver sound and lasting improvements to quality. Management techniques and treatment relating to specific metals will be covered, from a theoretical and practical perspective, to deliver a publication that will act as an authoritative guide for all those faced with the problem of ensuring the quality of a small water supply. Varied case-studies will help to illustrate issues and ways in which they have been resolved.  

Table of contents

The Difficulties of Managing Water Quality in Small Water Supplies; What are Small Supplies?; The Management and Regulation of Small Water Supplies; The Vulnerability of Small Water Supplies to Contamination by Metals; Water Safety Plans for Small Water Supplies; Making WSPs Work for Small Supplies; Teamwork- The Value of a WSP Team;     A Practical Guide to Developing a WSP for a Small Supply;   Practical Guidance for Risk Assessments; Establishing the Metals Problem: Risk Assessment, Sampling and Analysis; The Range of Possible Problems; Metal Solubility and Influencing Factors; Risk Assessment of Small Water Supply Systems; Sampling and Analysis; Consumer Awareness; Sources of Metals in Small Water Supplies; Origin of Contaminants; Contamination of Surface Waters; Contamination of Ground Water; Contamination from Treatment Processes; Contamination in Distribution Pipework; Contamination from Plumbing Fittings; Water Treatment Processes Available for Use on Small Water Systems; Process Selection; Types of Treatment; Practical Considerations of Treatment for Metals in Small Water Supplies; Iron; Manganese; Conditioning of Water to Prevent Dissolution of Plumbing Materials or Post-treatment Contamination; Treatment is Only Part of the Story; Indications and Effects of Post-treatment Metal               Contamination in Small Water Supplies; Establishing the Source of the Problem; Factors Controlling the Corrosion of Metals into Small Water Supplies; The Conditioning of Water to Minimise Corrosion; Manual of Individual Metals in Small Water Supplies, Aluminium, Antimony, Arsenic, Barium, Beryllium, Boron, Cadmium, Chromium, Cobalt, Copper, Iron, Lead, Manganese, Mercury, Nickel, Selenium, Tin, Tungsten, Uranium, Vanadium, Zinc; Case Studies; Arsenic removal in Small Supplies in Italy; A New Borehole Supply with Iron Removal for a Single Property in England, UK; Metals in Small Water Supplies in Areas of Water Scarcity in African Regions; Unexplained Lead Contamination of a Small Water Supply in Northern Scotland

EDITORS

Matt Bower, Drinking Water Quality Regulator for Scotland, UK

Colin Hayes, Swansea University, UK

Table of Contents

Section Title Page Action Price
Cover Cover
Contents v
Authors ix
Editors ix
Authors and Contributors ix
Acknowledgements xi
Review Panel xi
Abbreviations and Acronyms xiii
About this Best Practice Guide xv
Foreword xvii
Executive Summary xix
Chapter 1: The difficulties of managing water quality in small water supplies 1
1.1 WHAT ARE SMALL WATER SUPPLIES? 1
1.1.1 Definitions 1
1.1.2 What does a small water supply look like? 2
Individual responsibility supplies 2
Community supplies 3
1.2 THE MANAGEMENT AND REGULATION OF SMALL WATER SUPPLIES 4
1.3 THE VULNERABILITY OF SMALL WATER SUPPLIES TO CONTAMINATION BY METALS 4
Raw water sources 6
Treatment 7
Delivery to point of consumption 7
REFERENCES 7
Chapter 2: Water safety plans for small water supplies 9
2.1 INTRODUCTION 9
2.2 MAKING DWSPS WORK FOR SMALL WATER SUPPLIES 10
2.3 TEAMWORK – THE VALUE OF A WSP TEAM 11
2.4 A PRACTICAL GUIDE TO DEVELOPING A WSP FOR A SMALL SUPPLY 11
2.4.1 Section 1 – Overview of the supply 12
2.4.2 Section 2 – Risk assessment and identification of controls for risk 12
2.4.3 Section 3 – Verification 15
2.4.4 Section 4 – Action plan 16
2.4.5 Section 5 – Review of the WSP 17
2.5 PRACTICAL GUIDANCE FOR RISK ASSESSMENTS 17
2.5.1 The catchment and the source 17
2.5.2 Water treatment 18
2.5.3 Networks and storage tanks 19
2.5.4 Domestic distribution systems 20
REFERENCES 21
Chapter 3: Establishing the metals problem: Risk assessment, sampling and analysis 23
3.1 INTRODUCTION 23
3.2 THE RANGE OF POSSIBLE PROBLEMS 23
Impact on human health 23
Aesthetic effects and nuisance 23
3.3 METAL SOLUBILITY AND INFLUENCING FACTORS 24
Oxidative states of various metals 24
pH, alkalinity and temperature 24
Organic complexion 25
Interaction between corrosion scales and water 25
Corrosion inhibitors 25
3.4 RISK ASSESSMENT OF SMALL WATER SUPPLY SYSTEMS 25
Introduction 25
Approaches to risk assessment 26
Source water pollution by metals 27
General water quality considerations 27
Inventory of metal components and potential sources 27
Visual evidence 28
3.5 SAMPLING AND ANALYSIS 28
Introduction 28
Spot sampling 28
Split-flow composite sampling 28
Sequential profile sampling 28
Differentiation between particulate and dissolved metals 29
Analysing for metals and pH 30
3.6 CONSUMER AWARENESS 30
REFERENCES 30
Chapter 4: Sources of metals in small water supplies 33
4.1 ORIGIN OF CONTAMINANTS 33
4.2 CONTAMINATION OF SURFACE WATERS 34
4.3 CONTAMINATION OF GROUND WATER 36
4.4 CONTAMINATION FROM TREATMENT PROCESSES 41
4.4.1 Ion exchange processes 41
4.4.2 Filter media 41
4.4.3 Oxidation 42
4.4.4 Coagulated treatment processes 42
4.4.5 Corrosion of metals within the treatment process 43
4.4.6 Metal contamination from treatment chemicals 43
4.5 CONTAMINATION IN DISTRIBUTION PIPEWORK 43
4.6 CONTAMINATION FROM PLUMBING FITTINGS 45
REFERENCES 45
Chapter 5: Water treatment processes available for use on small water supplies 47
5.1 PROCESS SELECTION 47
5.1.1 System installation and maintenance 47
5.1.2 Point of use versus point of entry 48
5.2 TYPES OF TREATMENT 49
5.2.1 Physical filtration 49
Loose media filters 49
Cartridge filters 51
5.2.2 Chemical or adsorptive filters 53
Granular Activated Carbon (GAC) 53
Manganese dioxide 53
Activated alumina 54
Granular ferric oxide/hydroxide 54
Other media 55
Cartridge filters 55
5.2.3 Ion exchange 55
5.2.4 Reverse osmosis membrane 56
Design of RO systems 56
Monitoring and maintenance 57
5.2.5 Distillation 57
5.2.6 Treatment options and specifications 58
REFERENCES 60
Chapter 6: Practical considerations of treatment for iron and manganese in small water supplies 61
6.1 IRON 61
6.1.1 Principles of process design 61
6.1.2 Iron removal – treatment methods 62
Settlement 62
Oxidation & filtration systems 62
Filter washing 64
Process refinements 64
Problem waters 65
Other oxidation regimes 66
Regenerating filter systems 67
Regenerating ion exchange systems 67
6.2 MANGANESE 68
REFERENCE 70
Chapter 7: Conditioning water to prevent dissolution of plumbing materials or post-treatment contamination 71
7.1 TREATMENT IS ONLY PART OF THE STORY 71
7.2 INDICATIONS AND EFFECTS OF POST-TREATMENT METAL CONTAMINATION IN SMALL WATER SUPPLIES 72
Lead 72
Copper 73
7.3 ESTABLISHING THE SOURCE OF THE PROBLEM 74
7.3.1 Investigative sampling 74
7.3.2 Indices 75
7.4 FACTORS CONTROLLING THE CORROSION OF METALS INTO SMALL WATER SUPPLIES 75
Contact time 75
Temperature 75
Galvanic effects 76
Age of system 76
pH and alkalinity 76
Oxidising chemicals 76
Natural organic matter (NOM) 76
Chloride and sulphate 77
7.5 THE CONDITIONING OF WATER TO MINIMISE CORROSION 77
FURTHER READING 78
Chapter 8: Manual of individual metals – occurrence, implications and management 79
ABOUT THIS CHAPTER 79
ALUMINIUM 80
ANTIMONY 81
ARSENIC 82
BARIUM 84
BERYLLIUM 85
BORON 86
CADMIUM 87
CHROMIUM 88
COBALT 89
COPPER 90
IRON 92
LEAD 94
MANGANESE 95
MERCURY 97
NICKEL 98
SELENIUM 99
TIN 101
TUNGSTEN 102
URANIUM 103
VANADIUM 104
ZINC 105
REFERENCES 106
Aluminium 106
Arsenic 106
Beryllium 106
Cobalt 106
Copper 106
Lead 106
Mercury 106
Selenium 107
Tungsten 107
Uranium 107
Zinc 107
Chapter 9: Case studies 109
9.1 ARSENIC REMOVAL IN SMALL WATER SUPPLIES IN ITALY 109
9.1.1 Plant A: Adsorption with granular ferric hydroxide 109
9.1.2 Plant B: Resins functionalized with ferric hydroxide 111
9.1.3 Plant C: Chemical precipitation and adsorption with granular ferric hydroxide 112
REFERENCES 114
9.2 A NEW BOREHOLE SUPPLY WITH IRON REMOVAL FOR A SINGLE PROPERTY IN ENGLAND, UK 114
9.2.1 Background 114
9.2.2 Network requirements 115
9.2.3 Drilling the borehole 116
9.2.4 Time line 117
9.2.5 Analysis 118
9.2.6 Equipment data 121
Borehole pump 121
Iron reduction filter 121
Tank 122
Booster pump 122
Sediment filter 122
Ultra violet unit 122
9.2.7 System flow tests 122
9.2.8 Risk assessment 122
9.2.9 Review 122
ACKNOWLEDGEMENTS 123
9.3 METALS IN SMALL WATER SUPPLIES IN AREAS OF WATER SCARCITY IN AFRICAN REGIONS 124
REFERENCES 125
9.4 UNEXPLAINED LEAD CONTAMINATION OF A SMALL WATER SUPPLY IN NORTHERN SCOTLAND 126
9.4.1 Background 126
9.4.2 Identifying the source of the problem 126