• 1-4-041-4-04

• At least 11 million people in the U.S. currently At least 11 million people in the U.S. currently drink water contaminated with arsenic at levels drink water contaminated with arsenic at levels above 10 ppb, according to the U.S. above 10 ppb, according to the U.S. Environmental Protection Agency (EPA). From: Environmental Protection Agency (EPA). From: Drinking Water Standard for Arsenic.Drinking Water Standard for Arsenic. U.S. U.S. Environmental Protection Agency, Office of Water, Environmental Protection Agency, Office of Water, January 2001. January 2001.

• Arsenic has been found in at least 1,014 of the Arsenic has been found in at least 1,014 of the 1,598 current or former sites on the National 1,598 current or former sites on the National Priorities List (NPL), the most serious hazardous Priorities List (NPL), the most serious hazardous waste sites in the nation identified by the U.S. waste sites in the nation identified by the U.S. Environmental Protection Agency.Environmental Protection Agency.

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(är´senik)(är´senik)

• semimetallic chemical element semimetallic chemical element

• stable form: silver-gray, brittle stable form: silver-gray, brittle crystalline solid, tarnishes rapidly in crystalline solid, tarnishes rapidly in air.air.

• high temperatures burns white cloud high temperatures burns white cloud of arsenic trioxideof arsenic trioxide

• A yellow crystalline form and a black A yellow crystalline form and a black amorphous form are also known amorphous form are also known

Rule #2: Use style checker; be consistent

There’s an extra space before the A.

HISTORYHISTORY

• Used since 3000 B.C.Used since 3000 B.C.

• Arsenic mined by the early Chinese, Arsenic mined by the early Chinese, Greek and EgyptianGreek and Egyptian

• Albertus Magnus obtained the Albertus Magnus obtained the element in 1250 A.D. by heating soap element in 1250 A.D. by heating soap and orpiment (arsenic trisulphide, and orpiment (arsenic trisulphide, As2S3)As2S3)

• Element has an alchemical symbolElement has an alchemical symbol

Rule #3: Don’t overwhelm the audience

• naturally occurring elementnaturally occurring element• considered a heavy metalconsidered a heavy metal• pure form not commonly found in the pure form not commonly found in the

environmentenvironment• However, arsenic is found in natural However, arsenic is found in natural

and man-made compounds.and man-made compounds.

Rule #4: Use Spelling/Grammar Checker

• About 90% of all arsenic produced is used About 90% of all arsenic produced is used as a preservative in wood (e.g., pressure-as a preservative in wood (e.g., pressure-treated lumber).treated lumber).

• which contains chromated copper which contains chromated copper arsenate (CCA).arsenate (CCA).

• Used in insecticides, Used in insecticides, • weed killers, weed killers, • fungicides, fungicides, • glass production, glass production, • semiconductors, semiconductors, • to make metal alloysto make metal alloys• some medications (mostly veterinary). some medications (mostly veterinary).

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• Various industries release arsenic into the Various industries release arsenic into the air and groundwaterair and groundwater

• mines mines • SmeltersSmelters• cotton ginscotton gins• glass manufacturing operationsglass manufacturing operations• coal burning facilitiescoal burning facilities• municipal incinerators municipal incinerators • leach from landfills leach from landfills

Rule #2: Be consistent, revisited

• Once a treatment for SyphilisOnce a treatment for Syphilis

• Experimental for leukemiaExperimental for leukemia

• Taken in medicationTaken in medication

• A brownfield,A brownfield, by definition, is a by definition, is a poten-poten-tially polluted and abandoned tially polluted and abandoned commer-commer-cial and industrial site. cial and industrial site.

Brownfield Assessment of the Brownfield Assessment of the Benton Auto Wreckers Site,Benton Auto Wreckers Site,Corvallis, OregonCorvallis, Oregon

4-acre Benton Auto Wreckers site, located several miles southwest of the City of Corvallis on

State Highway 20 in Benton County, Oregon

What is arsenic?What is arsenic?•Arsenic is a natural element in the Arsenic is a natural element in the earth’s crust.earth’s crust.•In the environment, arsenic In the environment, arsenic combines with oxygen, chlorine, and combines with oxygen, chlorine, and sulfur to form inorganic arsenic sulfur to form inorganic arsenic compounds.compounds.•In animals and plants, arsenic In animals and plants, arsenic combines with carbon and hydrogen combines with carbon and hydrogen to form organic arsenic compounds.to form organic arsenic compounds.•IARC has reviewed the available IARC has reviewed the available data and considers arsenic to be a data and considers arsenic to be a Group 1 carcinogen.Group 1 carcinogen.

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Basic InformationBasic Information

• Chemical Formula = CChemical Formula = C66HH88AsNoAsNo33

• CAS No = 98-50-0CAS No = 98-50-0

• Solubility = very soluble in hot water; Solubility = very soluble in hot water; slightly soluble in cold water, alcohol, slightly soluble in cold water, alcohol, and acetic acid; insoluble in acetone, and acetic acid; insoluble in acetone, benzene, ether, and chloroform.benzene, ether, and chloroform.

• Reactivity= condition contributing to Reactivity= condition contributing to instability varies depending on the instability varies depending on the specific organic arsenic compound. specific organic arsenic compound.

Health EffectsHealth Effects

• Arsenic compounds are irritants, systemic Arsenic compounds are irritants, systemic toxins, and carcinogens in humans.toxins, and carcinogens in humans.

• Acute poisoning initial responses include; Acute poisoning initial responses include; burning of the lips, constriction of the burning of the lips, constriction of the throat, and dysphasia.throat, and dysphasia.

• Initial response is followed by excruciating Initial response is followed by excruciating pain in the abdominal region, severe pain in the abdominal region, severe nausea, vomiting, and diarrhea.nausea, vomiting, and diarrhea.

Health EffectsHealth Effects

• Toxic effects on the liver, blood-Toxic effects on the liver, blood-forming organs, both central and forming organs, both central and peripheral nervous systems, and the peripheral nervous systems, and the cardiovascular system may also occur.cardiovascular system may also occur.

• Convulsions, coma, and death may Convulsions, coma, and death may follow within 24 hours of severe follow within 24 hours of severe poisonings.poisonings.

Health EffectsHealth Effects

• Inhalation may damage the mucous Inhalation may damage the mucous membranes of the respiratory system.membranes of the respiratory system.

• Severe irritation of the nasal mucosa, Severe irritation of the nasal mucosa, larynx, and bronchi have been observed larynx, and bronchi have been observed following exposure.following exposure.

• Exposed skin may become irritated; Exposed skin may become irritated; cases of visual disturbances, hyper cases of visual disturbances, hyper pigmentation of the skin, and perforation pigmentation of the skin, and perforation of the nasal septum have been noted.of the nasal septum have been noted.

Health EffectsHealth Effects• Chronic exposure causes damage to Chronic exposure causes damage to

the nervous and cardiovascular the nervous and cardiovascular systems, also to the liver.systems, also to the liver.

• Anemia and leukocytopenia have Anemia and leukocytopenia have been reported to occur following been reported to occur following chronic exposures to arsenic chronic exposures to arsenic compounds.compounds.

• Cancers of the skin, lungs, larynx, Cancers of the skin, lungs, larynx, lymphoid system, and viscera have lymphoid system, and viscera have been identified as potential been identified as potential responses to arsenic poisoning.responses to arsenic poisoning.

Measurement of Arsenic in Measurement of Arsenic in WaterWater• Accurate measurement of arsenic in Accurate measurement of arsenic in

drinking-water at levels relevant to drinking-water at levels relevant to health requires laboratory analysis, health requires laboratory analysis, using sophisticated and expensive using sophisticated and expensive techniques, facilities as well as techniques, facilities as well as trained staff not easily available or trained staff not easily available or affordable in many parts of the affordable in many parts of the world.world.

• Field test kits can detect high levels Field test kits can detect high levels of arsenic bur are typically unreliable of arsenic bur are typically unreliable at lower concentration of concern for at lower concentration of concern for human health.human health.

There are currently 9 general processes

I. Oxidation

II. Coagulation/Co-precipitation

III. Sedimentation

IV. Filtration

V. Adsorption

VI. Ion Exchange

VII. Membrane/ Reverse Osmosis

VIII. Biological

IX. Other  

Arsenic RemediationArsenic RemediationArsenic RemediationArsenic Remediation

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Of the two predominant forms of arsenic in water,

arsenate and arsenite, most treatment processes are effective at removing arsenate, but not arsenite, since arsenite is typically non-charged below pH 9.2. Therefore, treatment for the removal of arsenic often includes an oxidation step to convert arsenite to arsenate.

        Oxidation can be simply the addition of oxygen to a compound, or more generally, any reaction involving the loss of electrons from an atom. Aeration, the supplying of air, oxidizes arsenic, converting arsenite to arsenate, and the iron that co-occurs. This is precipitated as FeAsO4. Arsenic can also be oxidized by a number of other chemicals including chlorine, hypochlorite, ozone, permanganate, hydrogen peroxide and Fenton’s reagent (H2O2/Fe2+). Photochemical oxidization proceeds from the reaction of radiant energy and a chemical system.

Oxidation alone does not remove arsenic from solution but must be combined with an arsenic removal process.

1. Oxidation

2. Coagulation/Co-Precipitation

Coagulation involves the removal of colloidal (0.001 - 100 microns) and settleable (> 100 microns) particles.

Co—precipitation: incorporation of soluble arsenic species into the metal hydroxide floc.

Coagulation encompasses all reactions, mechanisms and results in the overall process of particle growth (floc formation) and particle aggregation within a water being treated.

 converts soluble arsenic into insoluble reaction products, allowing separation by sedimentation and/or filtration.

*  Precipitation: the formation of insoluble compounds Al(AsO4) or Fe(AsO4)

*   Co—precipitation: incorporation of soluble arsenic species into the metal hydroxide floc

*  Adsorption: the electrostatic binding of soluble arsenic to the external surfaces of the insoluble metal hydroxides

Coagulation

1.             Inclusion: mechanical entrapment of a portion of the solution surrounding the growing particle.

 

2.              Adsorption: the attachment of an impurity onto the surface of a particle or precipitate.

3.             Occlusion: A contaminant is trapped in the interior of a particle of precipitate.

4.             Solid-solution formation: another type of occlusion where a particle of precipitate becomes contaminated with a different type of particle that precipitates under similar conditions and is formed from ions whose sizes are nearly equal to those of the original precipitate.

There are 4 types of co-precipitation:

Sedimentation is the gravity separation of solids from

liquid by settling. It is generally used in conjunction

with coagulation/precipitation

3. Sedimentation

            Conventional filtration is the separation of solid

particles from water by passing the solution through a medium.

Particles are removed during filtration as a result of any one or

combination of mechanisms: mechanical straining, sedimentation,

flocculation,adsorption and/or biological metabolism (AWWA, 1999).

4. Filtration

Adsorption is the accumulation of materials at an interface, the liquid/solid boundary layer.

* oxides (e.g. hydrated ferric oxide, titanium oxide, silicon oxide);

* iron oxide-coated or MnO2-coated sand;

* bauxite, hematite, feldspar; * clay minerals (e.g. kaolinite, bentonite, Bijoypur

clay); * synthetic anion exchange resins; * chitin and chitosan; * bone char; * cellulose materials (sawdust, newspaper pulp).

5. Adsorption

            Ion exchange is the reversible interchange of ions between the solid and the liquid phase where there is no permanent change in

the structure of the solid. Developed for large-scale applications, ion

exchange is probably not appropriate for small hand‑pumped wells,

but could potentially be used on a village scale in Bangladesh

Charged functional groups are attached to the matrix through covalent bonding and fall into four groups (Clifford, 1999)  

•Strongly acidic •Weakly acidic •Strongly basic •Weakly basic

6. Ion Exchange

Membrane separation uses semi-permeable membranes that are

selectively permeable to water and certain solutes to separate

impurities from waterMembranes are able to remove many different kinds of dissolved solids, including arsenic, from water. However, they are usually expensive and therefore are typically considered in applications such as desalination, brackish water conversion and for removal of specific ions, such as arsenic, that are difficult to remove by other means

7. Membrane/Reverse Osmosis

Biological treatment transforms, stabilizes and/or removes

arsenic by means of microorganisms. Microorganisms, primarily

certain specific bacteria, accomplish this by oxidation/reduction,

mineralization,detoxification or methylation. Critical factors

include energy and carbon source; aerobic, anoxic or anaerobic

conditions; temperature; pH

8. Biological

Dug Wells Deeper Tube Wells Ponds Solar Distillation

Solar distillation uses the sun's energy to evaporate water, which then recondenses. The process of evaporation and recondensation

separates all chemicals, including arsenic, from the water. In

Bangladesh,where solar energy is plentiful, this approach may be

especially suited for application in crisis areas, and, if cost-

effective approaches can be developed, in rural are as generally.  

9. Other

1.Oxidation2.Precipitation3.Filtration and Removal

Point Of Use- POU-Point Of Use- POU-Home FilterHome Filter SystemsSystems

Arsenicfilters.comdisplay

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Contaminants: Chromated Copper Arsenate (CCA)

Cost: Full Scale plant capable of treating 100 tons/day of CCA

contaminated waste wood will cost around $1,000,000Other Applications: Remediation of Metal contaminated soil, sludge and other debris

Secondary Waste: None

Operating Cost: It will cost between $120 to $150 /ton for remediation of of CCA contaminated wood in a 100 ton/day plant

West Central Environmental Consultants, Inc Can Provide A Complete Cleanup Plant for Arsenic Treated Wood facilities.

Tech Know New Remediation Technologies www.techknow.org

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State Average Arsenic Concentrations for Systems Finding Arsenic

                                                                                                           

 Based on best estimate of average arsenic levels for systems that found arsenic.

USGS

Rules to Remember1. 6x6 Rule2. Proofread and use

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audience4. Use

Spelling/Grammar Checker

5. No punctuation in a presentation

6. Let PowerPoint work for you

7. Use features to enhance the show, not be the show

8. Show them, don’t tell them

9. KIS Rule