BOOK
Stochastic Modelling of Drinking Water Treatment in Quantitative Microbial Risk Assessment
(2010)
Additional Information
Book Details
Abstract
Special Offer: KWR Drinking Water Treatment Set - Buy all five books together and save a total £119!Â
Safe drinking water is a basic need for all human beings. Preventing microbial contamination of drinking water is of primary concern since endemic illness and outbreaks of infectious diseases can have significant social and economic consequences. Confirming absence of indicators of faecal contamination by water analysis only provides a limited verification of safety. By measuring pathogenic organisms in source water and modelling their reduction by treatment, a higher level of drinking water safety can be verified.Â
This book provides stochastic methods to determine reduction of pathogenic microorganisms by drinking water treatment. These can be used to assess the level and variability of drinking water safety while taking uncertainty into account. The results can support decisions by risk managers about treatment design, operation, monitoring, and adaptation. Examples illustrate how the methods can be used in water safety plans to improve and secure production of safe drinking water.Â
More information about the book can be found on the Water Wiki in an article written by the author here: http://www.iwawaterwiki.org/xwiki/bin/view/Articles/Quantifyingmicro-organismremovalforsafedrinkingwatersuppliesÂ
Table of Contents
| Section Title | Page | Action | Price |
|---|---|---|---|
| Half Title | 1 | ||
| Title | 3 | ||
| Copyright | 4 | ||
| Contents | 5 | ||
| Acknowledgements | 11 | ||
| Summary | 13 | ||
| STOCHASTIC MODELLING OF DRINKING WATER TREATMENT IN QUANTITATIVE MICROBIAL RISK ASSESSMENT | 13 | ||
| Chapter 1: Introduction | 17 | ||
| HISTORY OF MICROBIALLY SAFE DRINKING WATER | 17 | ||
| STATE OF THE ART OF QMRA IN 2002 | 19 | ||
| Treatment assessment for QMRA | 19 | ||
| Distribution of pathogens in water | 20 | ||
| Treatment variation and rare events | 20 | ||
| Correlation between treatment steps | 21 | ||
| Direct assessment of pathogens in drinking water | 21 | ||
| QMRA in drinking water guidelines and legislation | 22 | ||
| QMRA: ITS VALUE FOR RISK MANAGEMENT | 22 | ||
| Complying with health targets | 23 | ||
| Quantifying normal events and special events | 24 | ||
| Setting critical limits | 24 | ||
| Designing monitoring programs | 24 | ||
| Preparing corrective actions | 25 | ||
| Treatment design: comparing alternatives | 25 | ||
| FOCUS OF THIS BOOK | 25 | ||
| APPROACH OF THE PRESENTED STUDY | 26 | ||
| Catchment to Tap System (CTS) | 26 | ||
| The treatment assessment framework | 27 | ||
| REFERENCES | 28 | ||
| Chapter 2: A stochastic pathogen reduction model for full-scale treatment | 31 | ||
| ABSTRACT | 31 | ||
| INTRODUCTION | 32 | ||
| MATERIALS AND METHODS | 32 | ||
| Case study system | 32 | ||
| Microbial monitoring | 33 | ||
| Pathogen reduction model | 33 | ||
| Process model for ozonation | 34 | ||
| Point estimate assessment | 34 | ||
| Stochastic assessment | 35 | ||
| Approaches | 35 | ||
| RESULTS | 36 | ||
| Microbial monitoring results | 36 | ||
| Approach 1: Point estimate | 36 | ||
| Approach 2: Pathogen data | 37 | ||
| Approach 3: Indicator organism data | 39 | ||
| Approach 4: Treatment modelling | 40 | ||
| DISCUSSION | 41 | ||
| Point estimate versus stochastic assessment | 41 | ||
| Pathogen versus indicator organism | 43 | ||
| Use of process models | 43 | ||
| Uncertainty of the assessment | 44 | ||
| CONCLUSIONS | 44 | ||
| REFERENCES | 44 | ||
| Chapter 3: How can the UK statutory Cryptosporidium monitoring be used for quantitative risk assessment of Cryptosporidium in drinking water? | 47 | ||
| ABSTRACT | 47 | ||
| INTRODUCTION | 48 | ||
| METHODS | 49 | ||
| RESULTS AND DISCUSSION | 51 | ||
| Overview of monitoring results | 51 | ||
| QMRA based on treated water monitoring | 54 | ||
| Cryptosporidium removal | 57 | ||
| Design and operation | 58 | ||
| Accumulation | 58 | ||
| Peaks in source water | 59 | ||
| Short treatment failure | 59 | ||
| Reduction related to microbial density | 59 | ||
| Modelling treatment in QMRA | 59 | ||
| CONCLUSIONS | 60 | ||
| ACKNOWLEDGEMENTS | 61 | ||
| REFERENCES | 61 | ||
| Chapter 4: Inactivation of Escherichia coli by ozone under bench-scale plug flow and full-scale hydraulic conditions | 63 | ||
| ABSTRACT | 63 | ||
| INTRODUCTION | 64 | ||
| MATERIALS AND METHODS | 64 | ||
| Bench-scale dissolved ozone plug flow reactor | 64 | ||
| Full-scale installation | 65 | ||
| Microbial methods | 66 | ||
| Ozone analysis | 66 | ||
| Experimental procedures | 66 | ||
| Hydraulic model of the DOPFR | 67 | ||
| Ozone profile calculations | 67 | ||
| Disinfection calculations | 69 | ||
| RESULTS | 70 | ||
| Hydraulic model of the DOPFR | 70 | ||
| Hydraulic model of the full-scale installation | 70 | ||
| Ozone decay | 70 | ||
| E. coli inactivation in the DOPFR | 71 | ||
| E. coli inactivation at full-scale | 71 | ||
| DISCUSSION | 71 | ||
| E. coli inactivation in literature | 71 | ||
| Comparing DOPFR and full-scale inactivation | 73 | ||
| T10 and CSTR calculations for E. coli inactivation in full-scale plant | 73 | ||
| Signifi cance for water treatment | 73 | ||
| CONCLUSIONS | 75 | ||
| REFERENCES | 75 | ||
| Chapter 5: Improved methods for modelling drinking water treatment in quantitative microbial risk assessment; a case study of Campylobacter reduction by filtration and ozonation | 77 | ||
| ABSTRACT | 77 | ||
| INTRODUCTION | 78 | ||
| METHODS | 79 | ||
| Case description | 79 | ||
| Microbial analysis | 80 | ||
| Non-parametric MPN bootstrapping | 81 | ||
| Non-parametric validation of treatment efficacy | 81 | ||
| Parametric extrapolation of bootstrap samples | 82 | ||
| Non parametric treatment model | 82 | ||
| Parametric treatment model | 83 | ||
| Risk calculation | 83 | ||
| RESULTS | 83 | ||
| Microbial monitoring | 83 | ||
| Methods to present distribution of concentrations | 84 | ||
| Non-parametric treatment model | 86 | ||
| Parametric treatment model | 87 | ||
| Parametric model of total chain | 89 | ||
| Modelled risk of infection | 90 | ||
| DISCUSSION | 92 | ||
| CONCLUSIONS | 93 | ||
| REFERENCES | 94 | ||
| Chapter 6: On the variability and uncertainty in quantitative microbial risk assessment of drinking water | 97 | ||
| ABSTRACT | 97 | ||
| INTRODUCTION | 97 | ||
| METHODS | 99 | ||
| Statistical methods | 99 | ||
| Monitoring data | 100 | ||
| RESULTS | 100 | ||
| Treatment performance assessment | 100 | ||
| Optimised method | 103 | ||
| Currently applied date method | 104 | ||
| Mean in/out method | 104 | ||
| Yearly variability of treatment performance | 106 | ||
| Validity of the calibrated stochastic treatment model | 107 | ||
| Use of surrogate organisms | 107 | ||
| DISCUSSION | 109 | ||
| Treatment assessment | 109 | ||
| Stochastic model calibration | 110 | ||
| Stochastic model applications | 110 | ||
| CONCLUSIONS | 111 | ||
| REFERENCES | 111 | ||
| Chapter 7: Practical applications of quantitative microbial risk assessment for water safety plans | 113 | ||
| ABSTRACT | 113 | ||
| INTRODUCTION | 113 | ||
| METHODS | 115 | ||
| RESULTS | 116 | ||
| Compliance with health-based targets | 116 | ||
| Including uncertainty of log credits | 116 | ||
| Reducing uncertainty of log credits with site specific information | 117 | ||
| Including uncertainty of disinfection modelling | 118 | ||
| Including site specific variability in disinfection modelling | 121 | ||
| Modelling improvements of disinfection processes | 121 | ||
| Verification of treatment efficacy | 122 | ||
| Design of microbial monitoring | 123 | ||
| Design of process monitoring | 125 | ||
| Operation of treatment | 128 | ||
| Setting critical limits | 128 | ||
| Preparing corrective actions | 131 | ||
| CONCLUSIONS | 132 | ||
| REFERENCES | 132 | ||
| Chapter 8: General discussion | 135 | ||
| INTRODUCTION | 135 | ||
| COMBINING INFORMATION IN THE TREATMENT FRAMEWORK | 135 | ||
| INCLUDING VARIABILITY AND UNCERTAINTY BY STOCHASTIC MODELLING | 136 | ||
| MICROBIAL MONITORING OF DRINKING WATER | 137 | ||
| PROCESS MODELLING FOR QMRA | 138 | ||
| QUANTIFYING TREATMENT EFFICACY USING MICROBIAL MONITORING | 139 | ||
| ACCURACY OF STOCHASTIC TREATMENT MODELLING | 140 | ||
| APPLICATIONS OF QMRA IN THE WSP | 141 | ||
| System assessment | 141 | ||
| Risk prioritisation | 141 | ||
| Design monitoring | 141 | ||
| Setting critical limits | 142 | ||
| Corrective actions | 142 | ||
| IMPLICATIONS FOR THE DRINKING WATER INDUSTRY | 143 | ||
| CONSIDERATIONS FOR THE REGULATORS | 144 | ||
| Choice of QMRA method | 145 | ||
| Selecting pathogens | 145 | ||
| Dose-response | 145 | ||
| Health effect and severity weight | 146 | ||
| Guidance by the legislator | 146 | ||
| FUTURE RESEARCH | 146 | ||
| Process models | 146 | ||
| Indexing new pathogens | 147 | ||
| Interaction between processes | 147 | ||
| REFERENCES | 147 |