Bangladeshi arsenic- and salt-mitigation sourcebook and decision-support tool

220 Pages·2015·4.81 MB·English

by  Dr.ir. Gábor Szántó

Bangladeshi arsenic- and salt-mitigation
sourcebook and decision-support tool
Final report

In partial fulfilment of the ASTRA-Bangladesh project (BRAC WASH II program)
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COLOPHON
This document was prepared in the project ‘Aiding Sustainable Water Technology Realization in
Arsenic contaminated Areas of Bangladesh’ or for short ‘ASTRA-Bangladesh’ in the framework of the
BRAC WASH II program (http://www.irc.nl/brac). This program is managed by BRAC and IRC
International Water and Sanitation Centre and funded by the Embassy of the Kingdom of the
Netherlands (Bangladesh).

Written by
Dr.ir. Gábor SZÁNTÓ PRACTICA Foundation
Dr.ir. Doris van HALEM Delft University of Technology
Samuele OLIVERO, MSc Delft University of Technology
Prof.dr.ir. Louis C. RIETVELD Delft University of Technology
Alida PELGRIM-ADAMS, MSc PRACTICA Foundation
Dipok Chandra ROY, MSc PRACTICAL ACTION Bangladesh
Jacqueline BARENDSE, MBA WASTE Foundation
Valentin POST, MSc WASTE Foundation

Software (at ASTRAdst.info) is by Menno BISCHOPS, BSc [VRConcepting]
Color drawings by Susanna Horn Jardemark, MSc

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ACKNOWLEDGMENTS
This book lists eight names as authors, but that’s only accurate if it is to cover those responsible for its
content. There are several more who contributed with information regarding the approach,
structuring and content of the described mitigation strategy and also the related technology
information sheets.
For this reason, the authors gratefully acknowledge the information and cooperation provided by Ms.
Ingeborg Krukkert and Mr. Jan Willem Dogger (IRC) and for the expert guidance of Dr. Mofazzal
Hoque (BRAC). The authors are also thankful for the final comments of Mr. Arif Waliullah Bhuiyan
(BRAC).
The authors are indebted to Dr. Kurian Baby (IRC) whose views and guidance were essential in the
development of the ASTRA tool.
The authors also want to express their gratitude to numerous Bangladeshi and international water
supply experts. A wealth of information from arsenic mitigation practice could be gathered thanks to
their selfless sharing of knowledge. Some of their experience is now available in this document for the
advancement of water provision in Bangladesh.
This publication and the related research was realized with the financial support of the BRAC WASH II
programme.

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SUMMARY
This publication contains the detailed description of the ASTRA arsenic- and salt-mitigation tool
developed in the framework of the BRAC WASH II programme. In essence, this work is a supporting
compendium and tool for decision-makers, practictioners and education institutes. It’s main
objective is to aim understanding and identification of potentially appropriate technological solutions
to tackle the widespread arsenic and salinitiy problems in the water sources of Bangladesh. Confirm
the currently available solutions, the work leans towards the removing or mitigating of arsenic and –
where treatments are included – solutions that mainly concern disinfection and (in)filtration. The
contained information draws on both Bangladeshi and international research and practical
experience.
The general mitigation strategy is explained as the identification of potentially appropriate water
supply methods for implementation in Bangladesh. The identification process is based on a
multidisciplinary assessment and matching of method functionality with the intended local context.
This book contains both the critical reviews and practical information of all potentially applicable
technical mitigation methods to aid decision-makers and engineers.
In the first chapter of the publication, the growing water stress and its key drivers in Bangladesh are
listed and detailed. This sourcebook section enables the proper understanding of mitigation methods
through a range of critical reviews that can either treat or circumvent arsenic- or salt-contaminated
sources. Three mitigation routes are outlined that include water supply or treatment methods. These
mitigation options are to (i) target arsenic- or salt-free groundwater, (ii) treat arsenic- or salt-
contaminated groundwater or (iii) disinfection of alternative, non-groundwater sources.
Utilizing one or more of the identified mechanisms, 26 specific technological methods are identified
as eligible for the Bangladeshi water sector context. Their in-depth descriptions are given in chapter 6
of this book. The descriptions of technical, institutional, ecological and socio-economic features are
completed by eligibility matrices. The matrices demonstrate quality of functioning according to local-
or project-specific criteria and allow users to assess performance of the method in the context of
application.
The description of the content of the decision-suport tool are coupled to the manual on how to use it
and the related online version. Finally, a discussion is offered that tackles indirect considerations that
Bangladeshi water experts could apply to further improve the sustainability of the local water sector.
The chosen structure of this publication allows two distinctively different utilizations. Decision-
makers and engineers may view potential approaches first before formulating specific strategies to
mitigate the arsenic-related problems. As the compendium section is also possible to use without the
more theoretical initial parts, especially field experts are hoped to benefit from the technology
information sheets and matrices during multistakeholder processes of water projects.

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Table of Contents
1 Introduction ................................................................................................................................... 15
1.1 Rationale of arsenic- and salt-mitigation in Bangladesh ....................................................... 15
1.1.1 Challenges in Bangladeshi water supply ....................................................................... 15
1.1.2 Overview of the arsenic- and salt-mitigation challenge ................................................ 15
1.2 Development of the ASTRA arsenic- and salt-mitigation strategy ........................................ 17
1.2.1 The BRAC WASH II programme ..................................................................................... 17
1.2.2 The ASTRA project ......................................................................................................... 17
1.2.3 Methodology ................................................................................................................. 18
1.3 Structure of the book ............................................................................................................ 19
2 Description of the general mitigation strategy ............................................................................. 21
2.1 The ASTRA approach ............................................................................................................. 21
2.1.1 Brief historical overview of sourcebooks and decision-support tools .......................... 21
2.1.2 Description of the mitigation approach ........................................................................ 23
2.2 Context analysis ..................................................................................................................... 25
2.2.1 Introduction ................................................................................................................... 25
2.2.2 Natural context .............................................................................................................. 25
2.2.3 Human context .............................................................................................................. 26
2.2.4 Technical context ........................................................................................................... 26
2.3 Technical mitigation approaches........................................................................................... 27
2.3.1 Assessment of potential approach ................................................................................ 27
2.3.2 Targeting arsenic- and salt-free groundwater............................................................... 28
2.3.3 Treatment of arsenic- and salt-containing groundwater .............................................. 30
2.3.4 Appropriate non-groundwater alternatives .................................................................. 32
2.4 Matching context and eligibility – the ASTRA tool ................................................................ 33
2.4.1 Classification of the knowledge base ............................................................................ 33
2.4.2 The eligibility screening ................................................................................................. 36
2.4.3 Determining the pool of potential methods ................................................................. 37
2.4.4 Method selection and post-implementation assessment ............................................. 38
2.5 Intended users and use of the ASTRA approach ................................................................... 38
2.5.1 Decision-makers and practicioners ............................................................................... 38
2.5.2 Multistakeholder processes .......................................................................................... 39
2.5.3 Education and research institutes ................................................................................. 39
2.6 Quality of the approach ......................................................................................................... 39
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3 Targeting arsenic-free groundwater ............................................................................................. 41
3.1 Deep and intermediate tube wells ........................................................................................ 42
3.2 Dug well ................................................................................................................................. 43
3.3 Shallow and shrouded tube wells ......................................................................................... 44
3.4 Well switching ....................................................................................................................... 45
3.5 Piped water supply schemes ................................................................................................. 46
4 Treatment of arsenic- or salt-contaminated groundwater ........................................................... 49
4.1 Oxidation of Arsenite ............................................................................................................ 50
4.1.1 Chemical Oxidation........................................................................................................ 50
4.1.2 Oxidation via Ultraviolet Radiation ............................................................................... 51
4.1.3 New Developments: Advanced Oxidation Technologies .............................................. 51
4.2 Precipitation, Coagulation, and Filtration Technologies ....................................................... 52
4.2.1 Conventional coagulation and filtration ........................................................................ 52
4.2.2 Lime Softening ............................................................................................................... 54
4.2.3 Household Water Treatment and Safe Storage Solutions based on Precipitation,
Coagulation, and Filtration Technologies ...................................................................................... 54
4.2.4 New Developments: Electrocoagulation ....................................................................... 57
4.3 Adsorption and Ion Exchange Technologies ......................................................................... 58
4.3.1 Iron Oxides-Based Adsorbents ...................................................................................... 59
4.3.2 Aluminum Oxides-Based Adsorbents ............................................................................ 60
4.3.3 Zerovalent Iron (ZVI) ...................................................................................................... 61
4.3.4 Ion Exchange (IX) Resins ................................................................................................ 62
4.3.5 Household Water Treatment and Safe Storage Solutions ............................................ 63
4.3.6 New Developments: Geological and Organic Adsorbents ............................................ 67
4.4 Membrane-based technologies ............................................................................................ 68
4.4.1 NF and Low-Pressure RO ............................................................................................... 69
4.4.2 Energy Recovery Systems and Renewable Energy Powered Reverse Osmosis ............ 70
4.4.3 New Developments: Forward Osmosis, Membrane Distillation, Capacitive
Deionization, and Electrodialysis Reversal .................................................................................... 71
4.5 Biological Processes ............................................................................................................... 75
4.5.1 Microbial-assisted arsenic removal technologies ......................................................... 76
4.5.2 Phytofiltration ............................................................................................................... 77
4.6 In-Situ Remediation ............................................................................................................... 78
4.6.1 Permeable Reactive Barriers ......................................................................................... 78
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