Arsenic Removal From Well Arsenic Removal From Well Water in Underdeveloped Water in Underdeveloped

CountriesCountries

Trygve HoffTrygve Hoff

Dr. Harold Walker, AdvisorDr. Harold Walker, Advisor

IntroductionIntroduction• Arsenic contamination is a growing Arsenic contamination is a growing

problem throughout the worldproblem throughout the world

•Argentina, Chile, Argentina, Chile, China, India, Mexico, China, India, Mexico, United States, Vietnam, United States, Vietnam, Thailand and Thailand and BangladeshBangladesh

•Worst cases in Worst cases in Bangladesh and West Bangladesh and West Bengal regionsBengal regions

Bangladesh EpidemicBangladesh Epidemic

• Problem originated in the 1970sProblem originated in the 1970s– UNICEF program to provide “safe” waterUNICEF program to provide “safe” water– Arsenic wasn’t a known pollutant at the Arsenic wasn’t a known pollutant at the

timetime– Saved thousands of lives from microbial Saved thousands of lives from microbial

pathogens, but …pathogens, but …

• 35-77 Million citizens at risk of arsenic 35-77 Million citizens at risk of arsenic poisoning (Out of a pop. of 125 Million)poisoning (Out of a pop. of 125 Million)

Bangladesh EpidemicBangladesh Epidemic• Tube well Tube well

options:options:– Shallow WellShallow Well– Deep WellDeep Well

• Deep ConcernsDeep Concerns– RenewabilityRenewability– Contamination Contamination

from drilling? from drilling?

Deep Aquifer

Shallow Aquifer

Construction Cost: $100Renewable: Yes

As Contamination: Yes

Construction Cost: $1000Renewable: ??

As Contamination: No

Southern Bangladesh

Clay Layer

[As]

3m clay

100m aquifer of gray sand

40m aquitard marine clay

Deep Sandy Aquifer

Bangladesh EpidemicBangladesh Epidemic

• Arsenic Source: GeologicalArsenic Source: Geological– Rock, Clay, Peat and Sand potential Rock, Clay, Peat and Sand potential

sourcessources– Increased [As] due to desorption from Increased [As] due to desorption from

iron oxidesiron oxides•Change in pH, oxidation/reductions, and Change in pH, oxidation/reductions, and

competing anionscompeting anions

•Excessive irrigation pumping in dry season Excessive irrigation pumping in dry season with carbon-caused mobilizationwith carbon-caused mobilization

Bangladesh EpidemicBangladesh Epidemic

• The World Health Organization has The World Health Organization has set a guideline value of 0.01mg/l or set a guideline value of 0.01mg/l or 10 ppb10 ppb– Bangladesh wells range from 0 to 1660 Bangladesh wells range from 0 to 1660

ppbppb

Bangladesh Well Arsenic Contamination

Safe (0-10ppb)58%

Questionable (10-50ppb)

17%

Dangerous (50+ppb)

25%

Health RisksHealth Risks

• Arsenic poisoning appears after 10 Arsenic poisoning appears after 10 years of consumption as arsenicosisyears of consumption as arsenicosis– Can lead to:Can lead to:

•KeratosisKeratosis•GangreneGangrene•Skin CancerSkin Cancer•Kidney CancerKidney Cancer•Bladder CancerBladder Cancer•Lung CancerLung Cancer

Health RisksHealth Risks

• 10 year old 10 year old children are children are developing the developing the arsenicosisarsenicosis

• Cancers appear Cancers appear after 20 yearsafter 20 years– Huge epidemic Huge epidemic

expected in the expected in the near futurenear future

Health RisksHealth Risks

• Treatments are limitedTreatments are limited– Consumption of only arsenic free waterConsumption of only arsenic free water– Zinc, Selenium, and Vitamin A for repair Zinc, Selenium, and Vitamin A for repair

of the skinof the skin– Chelation therapyChelation therapy

•Not proven to help patientsNot proven to help patients

Research GoalResearch Goal

• To find a temporary process that To find a temporary process that satisfies these objectives:satisfies these objectives:

1.1. Effectively removes [As] to a potable levelEffectively removes [As] to a potable level– Less than 10 ppbLess than 10 ppb

2.2. Is economically feasible in undeveloped Is economically feasible in undeveloped situationssituations– Bangladesh Average Per Capita Income is $450Bangladesh Average Per Capita Income is $450

3.3. Requires minimal technological Requires minimal technological understandingunderstanding

Experimental DetailsExperimental Details

• Three methods were used to treat the Three methods were used to treat the samples:samples:

1.1. The STAR methodThe STAR method– FeClFeCl33 mixed into sample, poured through sand mixed into sample, poured through sand

filterfilter

2.2. The 3-Kalshi methodThe 3-Kalshi method– Sample poured through sand, iron filings, and Sample poured through sand, iron filings, and

sandsand

3.3. Granular Ferric Hydroxide ColumnGranular Ferric Hydroxide Column

STAR SetupSTAR Setup

Ferric Chloride

Packet

WaterSand Filter

3-Kalshi Setup3-Kalshi Setup

Contaminated Water

Coarse Sand

Coarse Sand

Iron Shavings

Fine Sand

Fine Sand

Wood Charcoal—Not Used

Collected

Water

GFH Column(s)GFH Column(s)

Contaminated Water

Treated Water

ResultsResults

• The GFH column performed sub parThe GFH column performed sub par– Possibly due to:Possibly due to:

•Channeling of the mediaChanneling of the media

• Inadequate contact timeInadequate contact time

•Media grains too large—Insufficient surface Media grains too large—Insufficient surface area and sorption sitesarea and sorption sites

ResultsResults• The GFH removed just over 80% [As]The GFH removed just over 80% [As]

Arsenic ConcentrationGFH Method

126

202163 174

267299

269291

10 100

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400

Volume Treated (ml)

Ars

enic

Rem

ain

ing

(p

pb

)

GFH Arsenic WHO Guideline

ResultsResults• STAR and 3-Kalshi methods both STAR and 3-Kalshi methods both

successfully removed the arsenicsuccessfully removed the arsenic

Arsenic Concentration3-Kalshi and STAR methods

5

8 9

64 3

0.5 0.1 0.0 0.0 0.02 2

10 10

0

5

10

15

20

0 100 200 300 400 500 600

Volume Treated (ml)

Ars

en

ic C

on

cen

trati

on

(p

pb

)

3-Kalshi STAR Detection Limit WHO Guideline

Economic AnalysisEconomic Analysis

• Average income is $450Average income is $450– Bangladesh is ranked 176Bangladesh is ranked 176thth of 271 countries of 271 countries

• Average Family size of 6 peopleAverage Family size of 6 people

• Consumption assumed to be 50 Consumption assumed to be 50 liters/day/personliters/day/person– Arsenic poisoning only through Arsenic poisoning only through

consumptionconsumption– Only treat drinking and cooking waterOnly treat drinking and cooking water

Economic AnalysisEconomic Analysis

• STAR: Packets available for $4/family/yearSTAR: Packets available for $4/family/year

• 3-Kalshi: Iron available for$4.50/family/year3-Kalshi: Iron available for$4.50/family/year– Iron fines available at $30/tonIron fines available at $30/ton– 3 kg shavings for ~240 liters3 kg shavings for ~240 liters

• GFH: Initial cost of $7.00 for two columns, GFH: Initial cost of $7.00 for two columns, materials $2.00/family/year afterwardmaterials $2.00/family/year afterward

Ease of UseEase of Use• STAR: SimpleSTAR: Simple

– Drop packet in, pour through sand filterDrop packet in, pour through sand filter– Collect clean waterCollect clean water

• 3-Kalshi: Simple3-Kalshi: Simple– Pour water into top bucketPour water into top bucket– Collect clean waterCollect clean water

• GFH: Very difficultGFH: Very difficult– Requires technical training for a family memberRequires technical training for a family member– Pump necessary for correct flow rate and Pump necessary for correct flow rate and

pressurepressure– Need a field test kit to determine when Need a field test kit to determine when

breakthrough has been reachedbreakthrough has been reached

ConclusionConclusion

• The STAR method is most efficient The STAR method is most efficient and cheapest, and is easiest to useand cheapest, and is easiest to use

• 3-Kalshi method is plausible, though 3-Kalshi method is plausible, though doesn’t remove as much [As]doesn’t remove as much [As]

• GFH is a good method, but best used GFH is a good method, but best used in neighborhoods that have a in neighborhoods that have a treatment plant and technicianstreatment plant and technicians

• Education of the population is KEYEducation of the population is KEY