Arsenic Removal From Well Water in Underdeveloped Countries

Trygve Hoff Dr. Harold Walker, Advisor

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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

[As] Construction Cost: Renewable:

Yes

As Contamination:

Yes

Shallow Aquifer

$100

Clay Layer 3m clay 100m aquifer of gray sand 40m aquitard marine clay Deep Aquifer Southern Bangladesh 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 – FeCl 3 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 Water Sand Filter

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] 350 300 250 200 150 100 50 0 0 126 10 200 202

Arsenic Concentration GFH Method

GFH Arsenic WHO Guideline 163 174 400 600 800

Volume Treated (ml)

267 299 1000 1200 269 291 10 1400

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Results

STAR and 3-Kalshi methods both successfully removed the arsenic 3-Kalshi

Arsenic Concentration 3-Kalshi and STAR methods

STAR Detection Limit WHO Guideline 20 15 10 10 8 5 0 0 5 2 0.5

100 0.1

9 6 4 200 0.0

300 0.0

400

Volume Treated (ml)

0.0

500 3 10 600 2

Economic Analysis

• • • Average income is $450 – Bangladesh is ranked 176 th 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