Arsenic removal technologies

Q: I am looking for information about arsenic removal, preferably with images and technical details. It should be as simple and user friendly (easy to use) as possible.
(Senior professional officer, IRC, The Netherlands).

Answer: please take a look at the following resources:

[1] Prof. Richard Wilson of Harvard University maintains a regularly updated page on arsenic remediation methods, focusing mainly on Bangladesh and West Bengal.

He gives some important warnings:

“According to a recent study, villagers seem to be more willing to pay for running water than for arsenic free water. Thus, any solution which leads toward running water is to be preferred. […] Many experts and groups have stopped recommending small scale purification. […]. It is unclear … whether there exist ARS [Arsenic Removal Systems] that work on all waters in Bangladesh and which they are; and if a particular ARS only works on some waters how to decide whether it will work on a particular village water and how to explain all of this to the villagers affected.

Alternative solutions mentioned include deep drilled wells (>150 m), sanitary dug wells and rainwater harvesting with safe storage.

Positive results are mentioned for the prize-winning SONO filter, of which 21,000 have been distributed in Bangladesh. This filter is one of the four technologies approved for "provisional" use by the Bangladesh government, the others are READ-F, Sidko and MAGC/ALCAN.

Technology options are mentioned in the Government of Bangladesh Implementation Plan for Arsenic Mitigation. The annexes can be found in: http://phys4.harvard.edu/~wilson/arsenic/countries/bangladesh/National%20Water%20Policy%202003/

[2] Ahsan, T. (2002). Technologies for arsenic removal from groundwater.
In: Wijk-Sijbesma, C.A. van (ed.) and Smet, J.E.M. (ed.). Small community water supplies : technology, people and partnership. (Technical paper series / IRC; no. 40). Delft, The Netherlands, IRC International Water and Sanitation Centre.
More information and how to order: http://www.irc.nl/page/1917

[3] Petrusevski, B. … [et al.] (2006). Arsenic in drinking water. (Thematic overview paper). Draft. Delft, The Netherlands, IRC International Water and Sanitation Centre
This TOP outlines the global extent of arsenic contamination and its basic chemistry, as well as associated health problems. It looks at removal technologies for centralised and household point-of-use systems, and describes two case-study trials in Bangladesh and in Hungary.
You can download the whole document as a PDF, download separate chapters, or read a summary.

[4] Johnston, R. … [et al]. (2001). Safe water technology.
In: United Nations ACC Sub-Committee on Water Resources. United Nations synthesis report on arsenic in drinking water. Geneva, Switzerland, World Health Organization (WHO)

Rainwater collection - how to calculate the volume

Q: How to calculate the volume of a storage tank based on a certain annual rainfall. For our project in Tibet I need technical information on rain water collection, including project design.
(Water and sanitation programme officer, NGO, Tibet)

Answer: In principle, rainwater harvesting is NOT cheap. So, it is either a supplementary source or means with a relatively small storage volume, or people have to be very economic and use more during rainy season and the bare minimum during dry season. If they would accept that then it is a solution. Unless there is a lot of money available. I understand that in your situation, you have a semi-arid condition, so people may be used to be very economic with water.

One option is to collect rooftop rainwater for drinking and cooking, and ground surface runoff/rainwater for other uses. For both you can use groundwater tanks (from simple to advanced, depending on soil stability etc. and availability of funds) and for rooftop rainwater storage an above-ground tank is most common; also to ease the drawing of water.

Calculations
Important is also to determine the volumes people use for drinking and cooking (say between 2-5 litres per capita day (lcd)) and that for other proposes (say between 10-20 lcd).

Using those figures and the number of people you can calculate the amount of water you need per day or month. If you have to collect those volumes all from rainwater (as the sole source) then you can calculate the required surface area and the required storage capacity. Each surface area has a specific runoff coefficient, i.e. the efficiency of collection or the rainfall minus the wasted water. For hard roofing materials the coefficient is between 05-0.9, which means that of each litre of water fallen on the roof you can collect between 0.5 -0.9 litres! For ground surface areas this coefficient is much lower, depending on soil type and condition: usually between 0.10 and 0.25!

Cumulating the volume of water in a diagram
The simplest way to calculate is cumulating the required monthly volume of water (drinking/cooking) in a diagram, and plot the volume of water required to satisfy this demand.

Demand drinking and cooking Q = number of consumers * C1 * 30 = Q [m3/month]
C1 = daily water consumption for drinking/cooking per capita (say 2-5 lcd)
Demand other purposes Q = number of consumers * C2 * 30 = Q [m3/month]
C2 = = daily water consumption for non- drinking/cooking per capita (say 10-20 lcd)

You can then calculate (from the graph, see for an example of this graph the WELL fact sheet on domestic rainwater harvesting). There is not a good indication for the cost as it depends on volume, materials used, location etc. Cost for underground tanks are usually cheaper as the soil pressure holds the tank and the water pressure. Also simple lining materials may be used if the soil is sufficiently stable.

Operation and maintenance
One more issue is the management, and operation and maintenance of the water system; this is well described in IRC’s Technical Paper 30 - Water Harvesting.
If the rainwater catchment is a privately owned system then the house-owner can control use and manage this. If it is a community owned facility the problems are many and conflicts, misuse, mismanagement, are very common and people get dissatisfied and may turn away for contributing to operation and maintenance costs.

Design
There are many manuals/handbooks and guidelines that can help you in designing a rainwater collection system. Both for surface runoff/rainwater and for rooftop harvesting. Below, some of these key references are mentioned. If you want a quick overview of points you could consult the WELL fact sheet on domestic rainwater harvesting.

The specifics of the tank design depend on many factors, including:

• The rainfall pattern; in your case it is a very short season (6-8 weeks) (sounds as a monsoon) and with only a few heavy storms
• Total annual rainfall; in your case also limited 425-500mm
• Available rooftop surface area; roofing material and slope of roof
• Available rock catchment area or ground surface area that could be used for rainwater catchment; and what is the soil type or any hard impenetrable material
• Availability of other water sources, their reliability (volume), availability (seasonality), accessibility (distance and altitude difference), quality of water at source
• Availability of streams, piped water, tankered water
• Number of people to be served
• External and own funding; level/amount of funding
• Availability and Cost of building materials
• Availability uilding skills
• Consumption of water
• People’s attitude towards water use: very economic as water is very scarce to wasting as water is in abundance
• Acceptance of different qualities for different water uses/ purposes
• Level of management and control over source
• Perceptions and beliefs on water quality influences acceptance (e.g. rainwater has flat taste; groundwater is ‘living’ water

Further reading

IRC FAQ sheet - Rainwaterharvesting.org
Web site of CSE India containing (among other topics) urban case studies

Domestic Roofwater Harvesting Programme of the University of Warwick – Development Technology Unit.
Contains much information based on two research projects, see for example Domestic Roofwater Harvesting in the Tropics: the State of the Art, by Terry Thomas, Warwick University, UK (2003).

Various specialised rainwater networks are united in the Rainwater Partnership, such as:

International Rainwater Catchment Systems Association

International Rainwater Harvesting Alliance

SearNet - Southern and Eastern Africa Rainwater Harvesting Network -

RAIN - Rainwater Harvesting Implementation Network - initiated by Bunker Roy (Barefoot College, India). He has left and launched the Global Rainwater Harvesting Collective.


IRC, January 2007
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This response has been provided by the WELL Resource Centre Network with funding from the UK Department for International Development (DFID). Since March 2007 the WELL enquiry service has stopped.

Status of the world water crisis

Q: Please send me some material on world water: what is the status of world water, how to prevent water stress, what can be done to prevent water loss, and what strategies should developing countries have to cope up with water crisis? (Professional, Social Services, Karachi, Pakistan)

Answer: A good start for information on the global water crisis is the Human Development Report 2006 which focuses on water scarcity this year. It´s title is Beyond scarcity: Power, poverty and the global water crisis. Read the article in Source Bulletin (10 Nov 2006) for information and recommendations, http://www.irc.nl/page/31625 Or download the full report at the UNDP web site: http://hdr.undp.org/hdr2006/

Secondly, in Source Weekly, 18 Sep 2006, there was an article called Water crisis: global action required, say two new studies. Read the article in Source Weekly: http://www.irc.nl/page/30900 or download the studies below.

[1] Dickie, P. (2006). Rich countries, poor water. Zeist, The Netherlands, WWF Global Freshwater Programme. PDF file [2.56 MB] http://assets.panda.org/downloads/richcountriespoorwater.pdf

[2] IWMI (2006). Insights from the Comprehensive Assessment of Water Management in Agriculture. PDF file [2.5 MB] http://www.iwmi.cgiar.org/assessment/files_new/publications/Discussion%20Paper/Insights%20Book_Stockholm2006.pdf

Transparency and public toilets in India

Q: Commercial public toilets and so called 'community toilets' have been tried in several cities in India and there is interest in using these on a larger scale. Since both involve some form of payment for use both provide opportunities for corruption and raise issues of transparency and financial accountability. Do you have information on this?
(researcher, LSHTM, UK)

Answer: Lots of public toilets, the majority in slums and peri-urban areas just don’t work right and are really horrible. As with all things where money flows and contractors are used, there can be problems. One good example of transparency in finance and good operating facilities comes from Tiruchi in Tamil Nadu where the public toilet/baths are run by federated women’s savings groups where the members check each other.

Read more on the Tiruchi model:

Ganapathy, V. “A silent revolution for healthy living in the slums of Tiruchi” in Martin J. Bunch, V. Madha Suresh and T. Vasantha Kumaran, eds., Proceedings of the Third International Conference on Environment and Health, Chennai, India, 15-17 December, 2003. Chennai: Department of Geography, University of Madras and Faculty of Environmental Studies, York University. Pages 138 – 142.

Andhra team praises Tiruchi model of pay-and-use toilets, The Hindu, 11 Jan 2005, http://www.hindu.com/2005/01/11/stories/2005011106570300.htm

Documents
In addition, you can find more about public toilets through IRC´s library database IRCDOC, using the following links:

http://www.irc.nl/docsearch/results/?subj=104453 (public toilets)
http://www.irc.nl/docsearch/results/?subj=102046 (community blocks)

One of the publications from the first list gives some interesting insights from outside India:

Ayee, J. and Crook, R. (2003). Toilet wars : urban sanitation services and the politics of public-private partnerships in Ghana. (Working paper / IDS; no. 213). Brighton, UK, University of Sussex, Institute of Development Studies.

This paper examines the impact of the new forms of partnership between the public authorities and private/citizen-based organisations on urban environmental sanitation in the two largest cities of Ghana – Accra and Kumasi. It traces the history of public toilet policies in the two cities and analyses the factors that contributed to their relative failure in poor neighbourhoods. Toilets consistently have been poorly managed and have been the site of local political conflicts – toilet wars – despite efforts at franchising them and involving communities in their management. This is attributable to the politics of patronage at the urban level, the relationship between city government patronage and community level groups, and the failure of regulation. Public-private partnerships have not worked. The provision of reasonable sanitation facilities may require: full public provision of basic infrastructure; transparent, independent and rigorous regulation of any contracts for service provision given to non-state agencies; and the enforcement of “conflict of interest” laws applying to elected local representatives.

A good overview of experiences with public toilets in India is:

Burra, S. ; Patel, S. and Kerr, T. (2003). Community-designed, built and managed toilet blocks in Indian cities. Environment and urbanization ; vol. 15, no 2 ; p.. 11-32.

This paper describes the ten-year programme of community designed, built and managed toilet blocks undertaken by urban poor federations and women’s cooperatives, with support from the Indian NGO SPARC. This programme has reached hundreds of thousands of poor urban dwellers with much improved sanitation and facilities for washing; it has also demonstrated how such provision is affordable and manageable for all Indian cities. But this programme has also demonstrated to city authorities the capacity and competence of urban poor organizations, and helped change the relationship between the residents of slums and local government agencies. The paper begins by explaining why sanitation has been neglected, and describes the inadequacies in government sanitation programmes. It then describes the first experiments with community sanitation and the difficult negotiations in many cities, including Mumbai, Kanpur and Bangalore. Then it discusses the major community toilet programmes that developed in Pune and Mumbai. It highlights the innovations that allowed these to work better than previous public toilet blocks, the reasons why the urban poor organizations took on these projects, the lessons learnt and the ways in which community toilet blocks helped address other problems faced by the urban poor.

WIN
Finally, you may also want to contact the Water Integrity Network (WIN). They are promoting anti-corruption solutions in water, sanitation and water resources management worldwide.

Pre-paid water systems

Q: Do you have information about systems to charge users for water use at source? In particular information on pre-paid card or coin operated water points.
(Manager of small waterschemes, Benin)

Answer: here is some background information on pre-paid water systems.

Pre-paid systems are strongly opposed by some NGOs. Their reasons are summarized in: 11 Reasons to Oppose Prepaid Water Meters, http://www.foodandwaterwatch.org/water/right/prepaid/11-reasons-to-oppose-prepaid-water-meters

For news on this issue see also:

Uganda: introducing a pre-paid water system and free sewer connections, Source Weekly, 25 Aug 2006, http://www.irc.nl/page/30487

Namibia: NGO slams prepaid water scheme, Source Weekly, 10 Apr 2006, http://www.irc.nl/page/28645

South Africa: cost recovery policy detrimental for HIV/AIDS-affected households, Source Weekly, 11 Oct 2006, http://www.irc.nl/page/31182

On implementation of prepaid systems see:

Nigerian parliamentarians pay by smart card, Source Bulletin, 14 Nov 2004, http://www.irc.nl/page/6077

Johannesburg Water

- Prepayment water meter, http://www.johannesburgwater.co.za/uploads/publications/Prepayment.pdf

- Presentation of the Operation Gcin’ Amanzi Project to the Pre-Payment Innovation Award Competition, http://www.spintelligent-events.com/auw2006/web-files/pdf/JHB%20Water.pdf

Rainwater harvesting in Uganda

Q: Here we receive heavy rains for almost two-three months as it is rigth now, the season has just began and it covers almost the alll country. But no way of reserving this water for the dry season.
(Teacher in secondary school, Uganda)

Answer: On our IRC website you will find information on rainwater harvesting and links to websites and documents at http://www.irc.nl/page/14666

The following organisations may have more specific information on the situation in your region.

The Uganda Rainwater Association (URWA)
Secretariat
Plot 27, Room 203
Clement Hill Road,
P o. Box 34209,
KAMPALA
Tel No: 256-41-340201
Email: urwa@infocom.co.ug, urwa@searnet.org
http://www.gharainwater.org/urwa_aboutus.html

SEARNET (Southern and Eastern Africa Rainwater Network) Global Water Partnership - Associated Programme ICRAF House, UN avenue, Gigiri P. O. Box 30677, Nairobi 00100, Kenya
Tel: (+254 20) 722 44 00 / 722 44 24
Fax: (+254 20) 722 40 01
E-mail: searnet@cgiar.org
http://www.searnet.org/home.asp

The One World Africa website: http://africa.oneworld.net/guides/water/harvesting

I hope this information will be useful.

Handwashing and diarrhoea

Q: We are currently undertaking a Cochrane systematic review of the effects of hand washing promotion on diarrhea in adults and children. We are looking for completed (1981-date) or ongoing evaluation studies. Could you help us?
Associate professor, University of Alabama at Birmingham

Answer: You may find the following review study useful input for your review:

Review of hand washing programmes
Overview of research on: the impact of handwashing with soap; handwashing behaviours; promoting handwashing behaviours; and critical issues. It is written by Kathleen Shordt of IRC for the Hygiene Improvement Project (HIP). This project is funded by USAID and supported by the Academy for Educational Development (AED). Incl. 4 p. bibliography.
http://www.irc.nl/page/31717