EUR/03/5041122 ORIGINAL: ENGLISH UNEDITED FINAL DRAFT REGIONAL OFFICE FOR EUROPE ___________________________ STATE OF THE ART REPORT HEALTH RISKS IN AQUIFER RECHARGE USING RECLAIMED WATER R. Aertgeerts, A.Angelakis Eds. SCHERFIGSVEJ 8 DK–2100 COPENHAGEN Ø DENMARK TEL.: +45 39 17 17 17 TELEFAX: +45 39 17 18 18 TELEX: 12000 E-MAIL: [email protected] WEB SITE: HTTP://WWW.WHO.DK 2003 © World Health Organization – 2003 All rights in this document are reserved by the WHO Regional Office for Europe. The document may nevertheless be freely reviewed, abstracted, reproduced or translated into any other language (but not for sale or for use in conjunction with commercial purposes) provided that full acknowledgement is given to the source. For the use of the WHO emblem, permission must be sought from the WHO Regional Office. Any translation should include the words: The translator of this document is responsible for the accuracy of the translation. 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WHO Regional Office for Europe, Copenhagen TABLE OF CONTENTS 1 PROLEGOMENON ............................................................................................. 10 1.1 FOREWORD .................................................................................................. 10 1.2 HEALTH AND REGULATORY ISSUES – AN OVERVIEW................................... 12 1.3 CONCLUSIONS.................................................................................................. 14 2 METHODS USED FOR HEALTH RISK ASSESSMENT ............................... 17 2.1 INTRODUCTION ................................................................................................ 17 2.2 LEGISLATION CONCERNING DRINKING WATER PRODUCTION ......................... 19 2.3 ASPECTS OF DRINKING WATER STANDARDS, IMPORTANT FOR GROUNDWATER AQUIFER RECHARGE FOLLOWED BY ABSTRACTION .................................................... 20 2.4 PARAMETER APPROACH FOR HEALTH RISK ASSESSMENT ............................... 21 2.4.1 Water quality standard approach ........................................................... 22 2.4.2 Quantitative Health Risk Assessment (QRA)........................................... 23 2.4.3 Quantitative microbial risk assessment (QMRA).................................... 23 2.4.4 Quantitative chemical risk assessment (QCRA)...................................... 25 2.4.5 Quantitative risk assessment applied to household wastewater.............. 27 2.4.6 Model approach ...................................................................................... 31 2.4.6.1 Overview of the systematic approach ................................................. 32 2.4.6.2 Probabilistic approach......................................................................... 38 2.4.6.3 Strengths and advantages .................................................................... 40 2.4.6.4 Weaknesses and disadvantages ........................................................... 41 2.5 QUALITY MANAGEMENT APPROACH ............................................................... 42 2.6 BIOTESTS ON WATER ....................................................................................... 44 2.6.1 Bioassays................................................................................................. 44 2.6.2 Genotoxicity ............................................................................................ 44 2.6.3 Effect-specific tests.................................................................................. 45 2.7 CONTAMINANTS OF CONCERN ......................................................................... 45 2.7.1 Unregulated chemicals............................................................................ 46 2.7.2 Pathogenic micro organisms................................................................... 47 2.7.3 Priority pollutants................................................................................... 47 2.7.4 Pharmaceuticals...................................................................................... 48 2.7.5 Natural hormones ................................................................................... 48 2.7.6 Endocrine disrupting chemicals.............................................................. 48 2.7.7 Personal care products ........................................................................... 49 2.7.8 Surfactants .............................................................................................. 49 3 HEALTH RISK IN AQUIFER RECHARGE WITH RECYCLED WATER. 54 3.1 INTRODUCTION ................................................................................................ 54 3.1.1 Unintentional and intentional reuse (Direct and indirect reuse) ............ 55 3 3.1.2 How was the current reuse situation and its control arrived at? Contrasts that should be recognized ....................................................................................... 56 3.1.3 How can water reuse realistically reduce aquifer recharge health risks? 57 3.2 THE HEALTH IMPLICATIONS OF DIFFERENT TECHNIQUES................................ 59 3.2.1 Microbiological aspects.......................................................................... 59 3.2.1.1 Viruses ................................................................................................ 60 3.2.1.2 Bacteria ............................................................................................... 64 3.2.1.3 Parasites .............................................................................................. 69 3.2.1.4 Helminths............................................................................................ 71 3.2.2 Infectious doses....................................................................................... 72 3.2.3 Concentration of microbes in wastewater............................................... 75 3.2.4 Survival of pathogens in the environment ............................................... 75 3.2.5 Microbiological analytical techniques.................................................... 79 3.2.6 Microbiological indicators...................................................................... 80 3.2.6.1 Traditional indicators .......................................................................... 80 3.2.6.2 Non-conventional indicators ............................................................... 81 3.2.6.3 Viruses ................................................................................................ 82 3.2.6.4 Protozoan cysts and helminths ova ..................................................... 83 3.2.7 Risk studies.............................................................................................. 83 3.2.8 The establishment of quality guidelines based on microbiological aspects 85 3.2.9 Organic matter........................................................................................ 85 3.2.9.1 Interesting compounds ........................................................................ 85 3.2.9.2 Analytical techniques .......................................................................... 87 3.3 TREATMENT OF WASTEWATER FOR AQUIFER RECHARGE................................ 87 3.3.1 General considerations ........................................................................... 88 3.3.2 Pathogen removal ................................................................................... 89 3.3.3 Treatment processes................................................................................ 90 3.3.3.1 Primary and advance primary treatments (APT)................................. 90 3.3.3.2 Activated sludge.................................................................................. 91 3.3.3.3 Stabilization ponds.............................................................................. 92 3.3.3.4 Slow filtration ..................................................................................... 93 3.3.3.5 Constructed wetlands .......................................................................... 94 3.3.3.6 Tertiary coagulation-flocculation process ........................................... 96 3.3.3.7 Rapid filtration .................................................................................... 97 3.3.3.8 Activated carbon ................................................................................. 98 3.3.3.9 Membrane processes ........................................................................... 98 3.3.3.10 Disinfection..................................................................................... 99 3.3.4 Aquifer recharge ................................................................................... 106 3.3.4.1 ASR system....................................................................................... 106 3.3.4.2 Types of water for ASR .................................................................... 107 3.3.4.3 Management and operational practices ............................................. 109 3.3.4.4 Mexico city example ......................................................................... 112 3.3.4.5 Mezquital example ............................................................................ 113 4 3.3.4.6 Identification of recharge phenomenon............................................. 113 3.3.4.7 Issues on ASR systems.....................................................................