More: Dugwell chlorination how?
- Hello All
We have also installed a number of dugwells in Meherpur district in the west of Bangladesh which have operated without any contamination for up to 9 years.
Maintenance is necessary such as fixing pumps, deepening etc, however in response to an inquiry to this network a few years ago, a number of people pointed out the relatively hazardous nature of chlorination if people are not careful with it.
People in Meherpur have traditionally used lime ('choon') in the dugwells, this raises the acidity and kills bacteria (thus also effective) but is safer than worrying about correct chlorine/bleach doses, and locals are familiar with it (and can do on their own without monitoring needed). It is also very cheap.
Villagers are used to dugwells in Meherpur and seem to prefer them to deep tubewells the other main option in this relatively dry district.
James S. Pender
Development & Natural Resource Management Advisor
(with Church of Bangladesh Social Development Programme)
C/o The Director
Christian Mission Hospital
GPO Box # 25
Download my report on Bangladesh & Climate Change at: http://www.kirkensnodhjelp.no/en/About-NCA/Publications/Reports/ OR http://www.churchofscotland.org.uk/councils/worldmission/wmresources.htm OR http://www.eldis.org/go/display&id=41967&type=Document&emnotif100209
From: Meera M Hira-Smith <indicalmeera@...: mjahangir298@...
Cc: Pradip Sengupta <sengupta_pradip@...>; Vinay Chand <vinaychand@...>; arsenic-crisis <email@example.com>
Sent: Tuesday, 13 October, 2009 2:14:39
Subject: [arsenic-crisis] Reply to: Dugwell chlorination how?
Shallow dugwells tap water from the unconfined aquifer that is from the surrounding water bodies that generally does not contain arsenic. With the help of experienced geologists one needs to assess the depth up to which the dugwells should be dug. We follow the rule of not to go below 30 feet. Please see the picture of arsenic test of a dugwell that was constructed in June 2009 and its result here
http://peerwater. org/projects/ 180-Arsenic- free-dugwell- PW11-SU21- funded-by- Blue-Planet- Run-Foundation
The published papers are available on the website here>
http://projectwellu sa.org/publicati ons/publications .htm
[Non-text portions of this message have been removed]
- Hello James,
Great to know that dugwells are used in Meherpur for 9 years now. I have a few queries:
1. What is the design of the dugwells? Is rope and bucket used or hand pump? (please send me pictures directly if you have some)
2. How many dugwells have you implemented? What is the average depth of the dugwells?
3. Do you have co-ordinates of Meherpur to see the location on Google Map and the surrounding area?
4. Have you tested water for bacterial counts? If so what method was used?
5. I do understand that nobody contracted diarheal illness from the dugwell water that is so unbelievable for those who have the privilege to drink chlorinated or bottled water. I see questionnaires for our study in Bangladesh and many instances I have found people drinking water from the river without boiling. I mean a child was fed river water in 2003 that was born in 2000. May be very little bit and is still alive. Well we should not take such risks at early age.
I don't know why we worry about coliform bacteria level in drinking water to be zero (to follow the WHO standard) for those who are born and exposed to all kinds bacteria and their body learn to fight these bacteria since childhood. What we need to teach everybody is 'WASHING HANDS' is the magic word to prevent diseases that are caused by contaminated water and food.
Thanks for sharing your program here.
- Adding lime to the water also changes the general water chemistry considerably. If Fe-oxide-As bearing particulates are in the water it may well lead to release of the As into the water so even if bacterial activity is reduced there may be a spike in arsenic. Dependent on the amount of lime added, arsenic could be precipitated as a Ca-salt, although this is generally unlikely due to the high solubility of Ca-arsenates it is still possible. Has anyone tested water chemistry pre- and post- addition of the "Choon". Is it a pure lime or crushed limestone or coral?
Eur.Geol. Robert Bowell PhD C.Chem C.Geol
Principal Geochemist SRK Consulting
17 Churchill House
Cardiff CF10 2HH
email: rbowell at srk.co.uk
web site www.srk.co.uk