POU Arsenic Removal Team DHMO Justin Ferrentino Barry Schnorr Haixian Huang David Harrison

Arsenic in Bangladesh

Background Historically, drinking water was primarily taken from surface water Historically, drinking water was primarily taken from surface water –Open dug wells –Ponds –Rivers High population density  disease High population density  disease –diarrhea, dysentery, typhoid, cholera and hepatitis

Arsenic Concentrations in Water Districts of Bangladesh/India

Wells In the past 30 years, programs have provided safer drinking water with wells In the past 30 years, programs have provided safer drinking water with wells 8-12 million shallow tube-wells 8-12 million shallow tube-wells Reduction in waterborne disease Reduction in waterborne disease Well water was the preferred water source Well water was the preferred water source Approximately 90% of Bangladesh’s 130 Million served by wells Approximately 90% of Bangladesh’s 130 Million served by wells

Arsenic 1993, Arsenic discovered in Bangladesh groundwater 1993, Arsenic discovered in Bangladesh groundwater Arsenic is naturally occurring in geological formations under Bangladesh Arsenic is naturally occurring in geological formations under Bangladesh British Geological Survey in 1998 British Geological Survey in 1998 –>70% of shallow tube wells (in 61 of 64 districts) had [As] > 10 ppb –27% had [As] > 50 ppb –estimated that million exposed to [As] above 50 ppb and million exposed to [As] above 10 ppb Well marked with red X due to Arsenic contamination

Effects Most common disease result is skin lesions Most common disease result is skin lesions Skin and internal cancer rates are expected to rise over the next decade Skin and internal cancer rates are expected to rise over the next decade

Options Providing low arsenic groundwater Providing low arsenic groundwater –Safe shallow groundwater –Deep (>200 m) aquifers Rain water harvesting Rain water harvesting Pond sand-filtration Pond sand-filtration Household chemical treatment Household chemical treatment Piped water from safe/treated sources Piped water from safe/treated sources

Chemical Treatment Technologies Common methods Common methods –Oxidation & co-precipitation Alum addition Alum addition –Adsorption to media Activated carbon, iron & manganese coated sand Activated carbon, iron & manganese coated sand –Ion exchange and membrane techniques Membrane filters (Reverse Osmosis) Membrane filters (Reverse Osmosis)

Bucket Treatment Unit Oxidize in one bucket, filter in another Oxidize in one bucket, filter in another Red / Green buckets (Bangladesh well code) Red / Green buckets (Bangladesh well code) Collect As(V) on alum, FeCl 3, other Fe compounds Collect As(V) on alum, FeCl 3, Fe 2 (SO 4 ) 3, other Fe compounds

Red Bucket: Oxidation Oxidizing agent: 2 mg/L KMnO 4 Oxidizing agent: 2 mg/L KMnO 4 –Color and safety issues –Color removed in filter? –Alternative oxidants: CaCl 2 O 2, aeration Adsorption of As(V) Adsorption of As(V) –Naturally occurring Fe removal Can also disinfect Can also disinfect

Red Bucket: Co-precipitation Add packet, mix with stick Add packet, mix with stick DHPE-Danida unit: s mixing and 90 s gentle stirring recommended DHPE-Danida unit: s mixing and 90 s gentle stirring recommended Settling for 1-2 hours Settling for 1-2 hours Stevens Institute Unit: Settling in filter bucket Stevens Institute Unit: Settling in filter bucket

Green Bucket: Filtration Green Bucket: Filtration Sand filter bed Sand filter bed –Sometimes inside cloth filter Needs washing 1-8 times/month Needs washing 1-8 times/month –Where does As go? Bacterial growth in filter bed Bacterial growth in filter bed

Oxidation Oxidation of arsenite [As (III)] to arsenate [As (V)] with potassium permanganate (KMnO 4 ) Oxidation of arsenite [As (III)] to arsenate [As (V)] with potassium permanganate (KMnO 4 ) As (V) is 60 times less toxic than As (III) As (V) is 60 times less toxic than As (III) As (III) occurs in non-ionized form As (III) occurs in non-ionized form Use 2 mg/L of KMnO 4 for aluminum coagulation and 1.4 mg/L for iron Use 2 mg/L of KMnO 4 for aluminum coagulation and 1.4 mg/L for iron

Coagulation and Co-precipitation Aluminum coagulation Aluminum coagulation -use 200 mg/L of aluminum sulfate -use 200 mg/L of aluminum sulfate [Al 2 (SO 4 ) 3 ] to form Al-As complex [Al 2 (SO 4 ) 3 ] to form Al-As complex Iron coagulation Iron coagulation -use 100 mg/L of ferric chloride -use 100 mg/L of ferric chloride (FeCl 3 ) or ferric sulfate (FeCl 3 ) or ferric sulfate [Fe 2 (SO 4 ) 3 7H 2 O] to form Fe-As complex [Fe 2 (SO 4 ) 3 7H 2 O] to form Fe-As complex

Aluminum vs. Iron For arsenic concentration < 1000 ppb both For arsenic concentration < 1000 ppb both resulted in > 90% removal resulted in > 90% removal For arsenic concentration > 1000 ppb, ferric salts were found to be better than aluminum sulfate For arsenic concentration > 1000 ppb, ferric salts were found to be better than aluminum sulfate Ferric salts are effective over a wider pH range Ferric salts are effective over a wider pH range Iron: pH of Iron: pH of Aluminum: pH of Aluminum: pH of

A Temporary Solution Bucket treatment must be a temporary solution, not a permanent one. Bucket treatment must be a temporary solution, not a permanent one. It creates toxic sludge that needs to be disposed of It creates toxic sludge that needs to be disposed of The ultimate goal should be to connect people to a safe and sustainable water source The ultimate goal should be to connect people to a safe and sustainable water source

Alternative Solutions Stop relying on groundwater. Use surface water. Stop relying on groundwater. Use surface water. –Problem: Surface water is contaminated with fecal matter. –It is easier to treat water for fecal matter than for arsenic. Invest in treatment plants. Use rainwater. Set up rainwater catchments. This is only a partial solution, because there is a 3-month dry season. Use rainwater. Set up rainwater catchments. This is only a partial solution, because there is a 3-month dry season. Dig surface wells, or drill deep aquifer wells - both are less likely than tubewells to become contaminated with Arsenic. Dig surface wells, or drill deep aquifer wells - both are less likely than tubewells to become contaminated with Arsenic.

Current Developments in BTU BTU’s are in demand and available all over Bangladesh and West Bengal. They cost $US There are NGO programs that subsidize the cost for the very poor. BTU’s are in demand and available all over Bangladesh and West Bengal. They cost $US There are NGO programs that subsidize the cost for the very poor. The WHO wants NGO’s, not foreign companies, to manufacture and install the BTU’s. The WHO wants NGO’s, not foreign companies, to manufacture and install the BTU’s. There are over BTU’s in Bangladesh and West Bengal, as of Dec 2000 [can’t find a more recent number] There are over BTU’s in Bangladesh and West Bengal, as of Dec 2000 [can’t find a more recent number]

References: Alliance for Global Sustainability: WHO: “Rapid Assessment of Technologies for Arsenic Removal at the Household Level”, Sutherland et al. 2001, “An Overview of Arsenic Removal Technologies in Bangladesh and India”, M. Ahmed 2001 “Development of Low-cost Technologies for Removal of Arsenic from Groundwater”, Ali et al All from: BUET-UNU International Workshop on Technologies for Arsenic Removal from Drinking Water full.html Groundwater Arsenic Contamination in Bangladesh and West Bengal, India: full.html full.html full.html BBC Coverage: BBC Coverage: Supply Chain Initiative: Supply Chain Initiative: