1. Richard Wilson Disinfection of Dugwells
US Geological Society
Wednesday October 31st 2007
Richard Wilson
Mallinckrodt Research Professor of Physics
Harvard University
Disinfection of Dugwells
in arsenic regions
on behalf of scientists at
Dhaka Community Hospital
Jabed Yousef and Md. Golam Mostofa
Project Dugwell, WestBengal
Meera Smith et al
and UNICEF, Bangladesh
Rich Johnston
arsenic_project_introduction.html

2. DYSPIGMENTATION
KERATOSIS
GANGRENE
BOWEN”S CARCINOMA

3. 1982: R.C Saha observed keratoses and dyspigmentation in West Bengal -IGNORED DCH physicians saw lesions in Bangladesh. 30,000 drinking water with >50 ppb arsenic ACTION BEGAN in (1) Use uncontaminated deep aquifer (2) Treat the water at household level (3) return to surface waters ALL WILL WORK I will address only the last Rebuilt dug wells

4. WHO guidelines for construction No bucket to get water Animals cannot fall in Far from latrines Flood water cannot enter But not enough in a tropical climate developing countries slow to chlorinate organic matter + chlorine -> chlorinated hydrocarbons ANIMAL CARCINOGENS! Many people distrusted chlorination WHO and other reports chemical danger pale in comparison with bacterial risks Faecal coliform as indicator. Recommendation is 0 /ml; 10/ml not bad In West Bengal Chakriborti chlorinated. Cleaning every 3 months inadequate (DCH) every month inadequate (Project well) Detaied study (Yousef and Mostafa ) Data:July and August 2006 looked good Worse in 2007

5. Sanitary well: no animals fall in
no buckets! (L)
Electrically pumped to tank (R)
Lady has running water for first time in history

6. Piped water system very popular among women who carry the water Enables more families to be served by one well. Large (INDIRA) wells can serve 50 families Maintenance cost spread Large size ensures oxidization and inhibits arsenic release

7. No. of days after chlorination
Faecal coliform coun/ 100 ml
>10 after 23 days and reached from 35 to 180+ in the water samples of all dugwells at the end of the month Fig 1: Faecal coliforms count in water samples of 10 dugwells (DW2, DW3, DW6, DW7, DW8, DW10, DW21, DW29, DW34, and DW66) of Pabna district in the month of July.

8. Remarkable consistency Faecal coliform below 10 /100ml between 1-20 days after chlorination, then rising (chlorinate every 2 weeks or less) This was monsoon- worst period when ground is sodden and will not filter

9. Basic data on Sanitation
(figures in %, 2003
Progotir Pathey, BBS and UNICEF)
Diarrhoea prevalence within last 15 days boys/girls /24 25/23
Improved drinking water sources* (2002)
Access to sanitary latrines* (2002)
Insanitary hanging latrines
Open defecation
Disposal of faeces of children (under 5) in no fixed place
Washing hands after defecation with water and soap
Washing hands after defecation with water and soil/ash

10. To compare different health outcomes Murray (HSPH) recommended (1991) Disability Adjusted Life Years lost (DALYs) Quality Adjusted Life Years lost (QALYs) Faecal coliform is an indicator of problems. Bacterial disease depend on conditioning Few people in Bangaldesh looked for it, DCH was better, but not frequent enough and after, nor before cleaning Ahmed and Howard in 2005 took a selection of wells from various technologies dugwells seemed bad MEDIAN Faecal coliform was 3500/100ml DCH was at or below 5th percentile (but stll too high till 2006)

11. DALYs calculated byAhmed and Howard for a sample of Bangladesh technologies DCH (Pabna) wells are at or below lower (5%) bound of dugwells

12. Chlorination method of DCH: Using Cloteck (5
Chlorination method of DCH: Using Cloteck (5.25% Chlorine) doses based on water volume. Start summer 2006 with 20 DW in Pabna Continued 2007 in Pabna and Laksham Chlorination method by Aqua Welfare Society, “Project Well” of West Bengal has started using theoline of 1/3 of half dose every week based on water volume of water - measured every 21 days. Early tests avaialble on my site also UNICEF chlorination started August 2007 not available. Early indications that needed chlorine changes with time

13. 2007 mean of 20 Pabna wells Before 24h 7d 15 d July : : 43: 49 Aug : : 17: 59 Sept : 3: 27: 33 Oct : : 29: 56 LARGE “INDIRA” Pabna well 20 before 1 to 10 after

14. Experience of “Project Well” in West Bengal is similar but less consistent measurements. No data for 2007 yet (Smith visits wells Nov 6th-9th) Siridjikan (UNICEF) measurements started August 2007

15. 2007 Large (Indira) well in Laksham (Comilla) Before 24h 7d 15 d July : : 1 : 35 Aug : 25 :10: 35 Sept : 40: 35: 40 Oct : : 13: 8 Not as good as PABNA wells but still 100 times lower than Ahmed and Howard’s median

16. MY recommendation for Bangladesh Use deep aquifer when easy (80% of time) BUT ONLY FOR HOUSEHOLD: NEVER FOR IRRIGATION Use surface waters: for irrigation or for household with chlorination immediate application: household arsenic filters SONO or similar Use piped water system; it leads to the long term

17. In other tropical countries without a deep separable aquifer (Eastern Argentine) Equador Burkino Faso; this experience may be vital

18. ALL DCH tests are on the web at: http://DCHTests. arsenic
ALL DCH tests are on the web at: arsenic/remediation/dugwells/DCHtests Some project well tests also: