Arsenic And Fluoride Presentation


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  • Instructor Notes Introduce This module looks at the incidence of water-related disease, and the types of pathogens that cause it. as the caption under the title indicates, we are going to look at the cause of diseases “bad bugs”!
  • Arsenic And Fluoride Presentation

    1. 1. Arsenic and Fluoride 2007-07
    2. 2. 2007-07 Zheng Gong, MIT department of Civil and Environmental Engineering, August 2005 Over 30 countries in the world is affected by arsenic in drinking water
    3. 3. 2007-07 <ul><li>Naturally occurring metalloid element in the earth’s crust </li></ul><ul><li>Released to the environment by natural pathways </li></ul><ul><li> volcanic emissions </li></ul><ul><li> biological activities </li></ul><ul><li> weathering reactions </li></ul>Arsenic in the Environment Source: WHO Synthesis Report on Arsenic in Drinking Water 2002
    4. 4. 2007-07 <ul><li>Released to the environment by human activities </li></ul><ul><li> burning high-arsenic coal </li></ul><ul><li> arsenic mining </li></ul><ul><li> CCA-treated wood (chromated copper arsenic) </li></ul><ul><li> arsenic-containing pesticides and herbicides </li></ul><ul><li>Arsenic is an element that CANNOT be destroyed. It can only change from one form to another </li></ul>Arsenic in the Environment Source:WHO Synthesis Report on Arsenic in Drinking Water 2002
    5. 5. 2007-07 Baseline Arsenic in the Environment Water Source Typical baseline concentrations Atmospheric precipitation (rain and snow) Usually < 0.03 ug/L River water Usually < 2 ug/L Lake water Usually < 1 ug/L Seawater Usually about 1.5 ug/L Groundwater Usually < 10 ug/L
    6. 6. 2007-07 <ul><li>Ingestion </li></ul><ul><li>Drinking water </li></ul><ul><li>Eating food containing high arsenic </li></ul><ul><li>Dermal absorption </li></ul><ul><li>Bathing in high arsenic water </li></ul><ul><li>Handling arsenic contaminated substances </li></ul><ul><li>Inhalation </li></ul><ul><li>Breathing sawdust or burning smoke from wood treated with arsenic </li></ul><ul><li>Living in areas with unusually high natural levels of arsenic in rock </li></ul>Exposure Pathways <ul><li>Sources: </li></ul><ul><li>US Agency for Toxic Substances and Diseases Registry (ATSDR) ToxFAQ for Arsenic. Accessed Sep 27, 05. </li></ul><ul><li>WHO Synthesis Report on Arsenic in Drinking Water 2002 </li></ul>Usually major Usually minor
    7. 7. Chronic Health Effects Source: Harvard University. “Harvard Arsenic Project.” Internet. Accessed Sep 27, 05. After melanosis, keratosis and other lesions may occur Keratosis is the hardening skin bulges on palms and feet
    8. 8. 2007-07 Guideline Value in Drinking Water WHO 10 ug/L(ppb) = 0.01 mg/L (ppm) Australia 7 ug/L Canada 25 ug/L EU 10 ug/L Japan 10 ug/L USA 10 ug/L Bangladesh 50 ug/L Cambodia 50 ug/L China 50 ug/L India 50 ug/L Lao 50 ug/L Myanmar 50 ug/L Nepal 50 ug/L Pakistan 50 ug/L Vietnam 10 ug/L urban, 50 ug/L rural Source: World Bank. Towards a More Effective Operational Response. Volume 1. 2005
    9. 9. 2007-07 Overview of Mitigation Options Alternative Arsenic-Free Sources Arsenic Removal Technologies <ul><li>Safe tube wells </li></ul><ul><li>Improved Dug wells </li></ul><ul><li>Deep wells </li></ul><ul><li>Rainwater harvesting </li></ul><ul><li>Surface water treatment </li></ul>Arsenic Mitigation
    10. 10. The Removal of Arsenic <ul><li>Modification to </li></ul><ul><li>The All Natural Biosand Water Filter </li></ul>
    11. 11. Diffuser Basin Brick Chips / Iron Nails Outlet Pipe Filter Lid Fine Sand Layer Standing Water Layer Separating Gravel Under drain Gravel
    12. 12. THE REMOVAL OF ARSENIC By adding 5 kg (11lbs) of small non-galvanized iron nails, covered by a layer of brick chips, the Biosand filter can remove a certain level of arsenic from water. This is accomplished by replacing the diffuser plate with a deep diffuser basin. The iron nails in the diffuser basin, after contact with water and air, will quickly rust. Iron rust (ferric hydroxide) is an excellent adsorbent for arsenic. When arsenic-containing water is poured into the filter, surface reactions with iron occurs, and arsenic is rapidly adsorbed onto the surface of ferric hydroxide particles . The arsenic loaded iron particles are then flushed down and trapped on top of fine sand. The purpose of the brick chips is to disperse the water over the nails to allow for further absorption.
    13. 13. 2007-07 Slow sand filter adapted for intermittent use for a household <ul><li>Advantages: </li></ul><ul><li>Removal of turbidity, colour, odour </li></ul><ul><li>Good microbial removal </li></ul><ul><li>High flow rate (15-30L/hr) </li></ul><ul><li>Limitations: </li></ul><ul><li>Not 100% microbial removal, may require post-disinfection </li></ul><ul><li>May not remove pesticides, fertilizers, and other chemicals </li></ul><ul><li>Cost: </li></ul><ul><li>US$30-50 initial </li></ul><ul><li>Minimal maintenance </li></ul>Surface Water Treatment Example: Biosand Filter
    14. 14. 2007-07 Diffuser Basin Lid Container Pipe Kanchan TM Arsenic Filter Components Gravel Coarse Sand Water Fine Sand Iron Nails Brick chips
    15. 15. 2007-07 <ul><li>Advantages: </li></ul><ul><li>Simple </li></ul><ul><li>Excellent microbial removal </li></ul>Pass water through a porous, colloidal silver soaked ceramic container. Small pores and silver traps and inactivates pathogens. <ul><li>Limitations: </li></ul><ul><li>Fragile </li></ul><ul><li>Low flow (1-2L/hr) </li></ul><ul><li>Requires frequent cleaning for turbid water </li></ul>Surface Water Treatment Example: Potter for Peace Filter Developed in South America <ul><li>Cost </li></ul><ul><li>US$10-15 initial </li></ul><ul><li>Minimal maintenance cost </li></ul>
    16. 16. 2007-07
    17. 17. 2007-07 Arsenic Symptoms, Diagnosis and Treatment    UPdate Summer 2002 Diagnosis of arsenic poisoning, especially from low doses of inorganic arsenic, the type found in CCA lumber, is not easy. There is no one set of symptoms. Different people respond differently, depending on how much exposure they get, and by what means. Arsenic can be inhaled, ingested (swallowed) or absorbed through contact. Arsenic poisoning is difficult to pin down because most of the arsenic leaves the body within three days of exposure.  The arsenic which remains is stored in the brain, bones, and tissue and continues to do serious damage. Some people have no immediate symptoms, but the exposure can cause many types of cancer or diabetes later on. T There is new evidence that arsenic may also lead to heart disease or strokes. It may cause long term liver, kidney, and central nervous system damage.
    18. 18. Arsenic exposure, even at low levels, can result in a range of symptoms. Swallowing or inhaling low levels of inorganic arsenic can result in stomach ache, nausea, vomiting and diarrhea.  It can also result in decreased production of red and white blood cells which may cause fatigue, abnormal heart rhythm, blood-vessel damage resulting in bruising, and impaired nerve function. One of the early warning signs of arsenic poisoning is  a &quot;pins and needles&quot; sensation in hands and feet. Long-term oral exposure to inorganic arsenic can result in skin changes including a darkening of the skin and the appearance of small &quot;corns&quot; or &quot;warts&quot; on the palms, soles, and torso.
    19. 19. 2007-07 Other signs and symptoms include skin thickening, fluid accumulation (resulting in puffiness) especially around the lower eyelids, face and ankles, diarrhea, garlic breath, perspiration, excessive salivation, generalized itching, oral inflammation, sore throat, runny nose, excessive tearing, numbness, skin inflammation, hair loss, weakness, and loss of appetite. Arsenic can also cause a range of neurological effects, including headaches and vision problems. It can cause noticeable behavioral changes, most commonly aggression or depression.
    20. 20. 2007-07 Because most arsenic leaves your body within a few days, analysis of  urine cannot detect if a person was exposed to arsenic in the past. Tests of hair or fingernails can determine exposure to high levels of arsenic over the past 6-12 months, but these tests are not very useful in detecting low-level exposures. Early treatment of arsenic poisoning is critical.  The longer arsenic remains in the body, the more damage is done. If arsenic poisoning is determined, oxygen therapy, chelation therapy, saunas and other methods used for detoxification of heavy metals is the usual treatment. There is some new information that selenium may help decrease the effects of arsenic. Naturopaths may be able to help with diagnosis and treatment with other methods.
    21. 21. Defluoridation of Drinking Water 2007-07
    22. 22. Fluoride in Water <ul><li>Naturally occurring fluorides are released from rocks and minerals as they are eroded over time. </li></ul><ul><li>They are also released into the environment through volcanic activity or marine aerosols. </li></ul><ul><li>Industrial activities such as mining, phosphate fertilizer manufacturing, and coal fired power plants can also result in release of fluoride into the environment. </li></ul><ul><li>Fluoride is usually tightly bound in the soil, but when this level is above what the soil can retain, inorganic fluorides can be leached into the groundwater or taken up by plants. </li></ul>2007-07
    23. 23. Harmful Levels <ul><li>WHO guidelines specify that fluoride levels be no higher than 1.5 mg fluoride/L drinking water </li></ul><ul><li>However, levels of 0.6 mg/L have been suggested as being a problematic in areas of hot dry climate </li></ul><ul><li>Source: ( ) </li></ul>2007-07 Source:
    24. 24. Fluoride Guidelines 2007-07 Dose Symptoms < 0.5 mg/L Susceptibility to dental caries 0.5 - 1.0 mg/L Lower dental caries 1.5 - 4 mg/L Dental fluorosis > 4 mg/L Dental and skeletal fluorosis >10 mg/L Cripping fluorosis
    25. 25. Health Effects <ul><li>Low levels of fluoride can prevent dental caries </li></ul><ul><li>Excess fluoride can cause fluorosis </li></ul><ul><ul><li>Dental fluorosis </li></ul></ul><ul><ul><li>Skeletal fluorosis </li></ul></ul><ul><ul><li>Acute fluorosis </li></ul></ul><ul><li>Note: Fluorosis is further </li></ul><ul><li>aggravated by calcium and </li></ul><ul><li>vitamin D deficiencies. </li></ul><ul><li>(Source: </li></ul>2007-07 Source:
    26. 26. Theory of Fluoride Removal <ul><li>Adsorption/Ion Exchange: Through adsorption, fluoride ions are collected on the surface of the adsorbant; in ion exchange, fluoride ions would be removed from solution onto the ion exchange resin in exchange for a less problematic ion. </li></ul><ul><li>Chemical: By chemical reaction with fluoride, the fluoride is bound in the solution, it would then require removal from solution. </li></ul><ul><li>Precipitation/Sedimentation: Employed along with chemical reaction to remove particles, such as flocculants, from solution. </li></ul><ul><li>Filtration: This method can be used in to remove particles, such as flocculants or bacteria from solution </li></ul>2007-07