1. [As] – a global problem http://www.bgs.ac.uk/arsenic/Bangladesh/
BGS and DPHE (2001)

2. As drinking water standards
World Health Organization (WHO) guideline: 10 mg/L
US standard mg/L
Bangladesh standard for drinking water: 50 mg/L
Range in Bangladesh: <1 to over 1000 mg/L

3. * * Q ~ 1000 km3/y Araihazar Dhaka
Source: M. Steckler, LDEO, based on GTOPO30 digital elevation model (USGS EROS Data Center).

6. Araihazar
Bangladesh Arsenic Mitigation and Water Supply Program

10. Sampling and interviews
at 6000 wells: 2000/2001

11. Satellite image: Araihazar, one of 464 thanas in Bangladesh Population 300,000; 170 km2 (density 1800/km2)
Sources: C. Small, LDEO, Landsat 7 image from USGS EROS Data Center, Sioux Falls, SD, 1991 National Census.

13. Depth distribution of arsenic in Araihazar tube wells44 43
164 87 52 27 11 8

14. Existing wells Alternative sources
Remediation options
Existing wells Alternative sources
New wells Surface water
As removal Well switching Shallow wells Deep wells Pond water Rain collection
Safi
3-kolshi
Tube well sand filter
Maintenance
Monitoring
Bacterial growth
Spatial variability
Social resistance
Dug wells
Seasonality
Pathogens
$50 for 150 ft
Installation
Distribution
Pond sand filter
50 ea.
Bacteria 1/100
Aquaculture
Boiling
Rainwater harverster
1 $160/$40 ea.
Storage-seasonality

16. Results of 5000 well study: well switching?
Histogram of number of wells as a function of distance from each well to the nearest safe well, shown in increments of 50 m. The proportion of wells shown as green dots in Fig. 1 is shown at a distance of <0 m. Also shown is the cumulative proportion of tubes wells within each distance interval
The proliferation of tube wells in Araihazar. Only a fraction of the wells installed in the year 2000 were surveyed.
A. van Geen et al., 2001

17. Xiaoguang Meng – Stevens Tech.
Filters?
20 L-bucket sand filter
Xiaoguang Meng – Stevens Tech.
As co-precipitation with ~ 20 mg/L Fe
Competition of phosphate and silicate
FeCl3 and NaClO addition
3” sand layer for filtration
Gravity flow 1.5 to 0.5 L/hour
Cleaning of sand twice a week
Initial cost $7/family
Reagents $4/year

19. Deep wells? t
years
kyears

20. Urinary creatinine-adjusted arsenic (μg/g creatinine)
Some success!
Urinary creatinine-adjusted arsenic (μg/g creatinine)
Baseline well [As] N
1579
1477
1413
1503
1590

21. Domestic
use As As

22. Domestic
use As As

23. irrigation
Domestic
use As As

24. irrigation
Domestic
use As As

25. irrigation
Domestic
use As As As As

26. irrigation
Domestic
use As As As As As

27. Leakage along well casing
irrigation
Domestic
use As As As As

28. Leakage through broken casing
irrigation
Domestic
use As As As As