Arsenic Removal From Well Water
in Underdeveloped Countries
Trygve Hoff
Dr. Harold Walker, Advisor
Introduction
• Arsenic contamination is a growing
problem throughout the world
•Argentina, Chile, China,
India, Mexico, United
States, Vietnam, Thailand
and Bangladesh
•Worst cases in Bangladesh
and West Bengal regions
Bangladesh Epidemic
• Problem originated in the 1970s
– UNICEF program to provide “safe” water
– Arsenic wasn’t a known pollutant at the time
– Saved thousands of lives from microbial
pathogens, but …
• 35-77 Million citizens at risk of arsenic
poisoning (Out of a pop. of 125 Million)
Bangladesh Epidemic
• Tube well
options:
– Shallow Well
– Deep Well
• Deep Concerns
– Renewability
– Contamination
from drilling?
Construction Cost: $1000
Renewable: ??
As Contamination: No
Construction Cost: $100
Renewable: Yes
As Contamination: Yes
3m clay
[As]
100m
aquifer of
gray sand
Shallow Aquifer
Clay Layer
Deep Aquifer
Southern Bangladesh
40m
aquitard
marine clay
Deep Sandy
Aquifer
Bangladesh Epidemic
• Arsenic Source: Geological
– Rock, Clay, Peat and Sand potential sources
– Increased [As] due to desorption from iron
oxides
• Change in pH, oxidation/reductions, and
competing anions
• Excessive irrigation pumping in dry season with
carbon-caused mobilization
Bangladesh Epidemic
• The World Health Organization has set a
guideline value of 0.01mg/l or 10 ppb
– Bangladesh wells range from 0 to 1660 ppb
Bangladesh Well Arsenic Contamination
Dangerous
(50+ppb)
25%
Safe (0-10ppb)
58%
Questionable
(10-50ppb)
17%
Health Risks
• Arsenic poisoning appears after 10 years of
consumption as arsenicosis
– Can lead to:
• Keratosis
• Gangrene
• Skin Cancer
• Kidney Cancer
• Bladder Cancer
• Lung Cancer
Health Risks
• 10 year old children
•
are developing the
arsenicosis
Cancers appear after
20 years
– Huge epidemic
expected in the near
future
Health Risks
• Treatments are limited
– Consumption of only arsenic free water
– Zinc, Selenium, and Vitamin A for repair of the
skin
– Chelation therapy
• Not proven to help patients
Research Goal
• To find a temporary process that satisfies
these objectives:
1. Effectively removes [As] to a potable level
– Less than 10 ppb
2. Is economically feasible in undeveloped
situations
– Bangladesh Average Per Capita Income is $450
3. Requires minimal technological
understanding
Experimental Details
• Three methods were used to treat the
samples:
1. The STAR method
– FeCl3 mixed into sample, poured through sand filter
2. The 3-Kalshi method
– Sample poured through sand, iron filings, and sand
3. Granular Ferric Hydroxide Column
STAR Setup
Ferric Chloride
Packet
Sand Filter
Water
3-Kalshi Setup
Contaminated Water
Coarse Sand
Iron Shavings
Coarse Sand
Fine Sand
Wood Charcoal—Not Used
Fine Sand
Collected
Water
GFH Column(s)
Contaminated Water
Treated Water
Results
• The GFH column performed sub par
– Possibly due to:
• Channeling of the media
• Inadequate contact time
• Media grains too large—Insufficient surface area
and sorption sites
Results
• The GFH removed just over 80% [As]
Arsenic Concentration
GFH Method
Arsenic Remaining
(ppb)
GFH Arsenic
WHO Guideline
350
300
267
250
202
200
163
150
299
269
291
174
126
100
50
10
0
0
10
200
400
600
800
Volume Treated (ml)
1000
1200
1400
Results
• STAR and 3-Kalshi methods both
successfully removed the arsenic
Arsenic Concentration
3-Kalshi and STAR methods
3-Kalshi
STAR
Detection Limit
WHO Guideline
Arsenic Concentration
(ppb)
20
15
10
10
8
5
5
0
2
0.5
0
10
9
6
4
0.1
100
0.0
200
0.0
300
0.0
400
Volume Treated (ml)
3
500
2
600
Economic Analysis
• Average income is $450
– Bangladesh is ranked 176th of 271 countries
• Average Family size of 6 people
• Consumption assumed to be 50
liters/day/person
– Arsenic poisoning only through consumption
– Only treat drinking and cooking water
Economic Analysis
• STAR: Packets available for $4/family/year
• 3-Kalshi: Iron available for$4.50/family/year
– Iron fines available at $30/ton
– 3 kg shavings for ~240 liters
• GFH: Initial cost of $7.00 for two columns,
materials $2.00/family/year afterward
Ease of Use
• STAR: Simple
– Drop packet in, pour through sand filter
– Collect clean water
• 3-Kalshi: Simple
– Pour water into top bucket
– Collect clean water
• GFH: Very difficult
– Requires technical training for a family member
– Pump necessary for correct flow rate and pressure
– Need a field test kit to determine when breakthrough
has been reached
Conclusion
• The STAR method is most efficient and
cheapest, and is easiest to use
• 3-Kalshi method is plausible, though
doesn’t remove as much [As]
• GFH is a good method, but best used in
neighborhoods that have a treatment
plant and technicians
• Education of the population is KEY