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Water treatment for human consumption

Water treatment for human consumption. Irina Cech, Ph.D. Safe Drinking Water Act. Background; Purpose; Amendments. http://www.epa.gov/safewater/mcl.html. Typical water treatment plant. Credit: Irina Cech. Pretreatment Chemical mix and flocculation Sedimentation basin

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Water treatment for human consumption

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  1. Water treatment for human consumption Irina Cech, Ph.D.

  2. Safe Drinking Water Act • Background; • Purpose; • Amendments http://www.epa.gov/safewater/mcl.html

  3. Typical water treatment plant Credit: Irina Cech

  4. Pretreatment Chemical mix and flocculation Sedimentation basin Rapid sand filtration Clear well Typical steps in water treatment:

  5. @Irina Cech

  6. @Irina Cech

  7. Reverse osmosis Distillation Desalinization Ion exchange Aeration Carbon filtration The type of treatment is dictated by the desired use of the water product. Other treatment methods:

  8. Agents: Chlorine Chlorine Dioxide Ozone UV Irradiation Hydrogen Peroxide Peracetic Acid Bromine Iodine Thermal Disinfection of water and wastewater:

  9. Reverse Osmosis Water Filters

  10. How to disinfect the contaminated well • To disinfect the rest of the system, chlorine is allowed to circulate, by adding some water down the well with a garden hose. • The nearest faucet in the house is opened, until the smell of chlorine bleach is detected and then turned off. This is repeated through the system at each faucet, until the smell of chlorine is detected in the farthest faucet of the house.. • After the bleach circulates through the system, an access plug is placed back. Well is shut down and chlorine is allowed to remain in the system overnight, or for 24 hours where possible.

  11. How to disinfect the contaminated well After that, the chlorine is flushed out of the system until the bleach is no longer smelled. The opening of faucets is done in the reverse order, starting with the farthest one. This water is not suitable for use without boiling, until a sample free of bacteria is obtained. Retesting of water is required one month later to confirm safe performance.

  12. How to disinfect your water • If possible, boil the water for 10 minutes • Do not use suspicious containers, i.e. those previously used to store petroleum or paint. • If boiling the water is not possible, add 2 drops of chlorine (bleach) per 1 liter of water, or 40 drops per 20 liter container. • In Spanish language this is called “chloro patito,” “chloralex,” “chlorax.”

  13. http://www.epa.gov/safewater/contaminants/index.html#mcls Drinking Water Contaminants List of Contaminants & their MCLs Microorganisms Disinfectants Disinfection Byproducts Inorganic Chemicals Organic Chemicals Radionuclides

  14. Microorganisms Coliform bacteria are common in the environment and are generally not harmful. However, the presence of these bacteria in drinking water is usually a result of a problem with the treatment system or the pipes which distribute water, and indicates that the water may be contaminated with germs that can cause disease.

  15. Fecal coliform and e-coli are bacteria whose presence indicates that the water may be contaminated with human or animal wastes. Microbes in these wastes can cause effects, such as diarrhea, cramps, nausea, headaches, or other symptoms.

  16. This is a parasite that enters lakes and rivers through sewage and animal waste. It causes cryptosporidiosis, a mild gastrointestinal disease. However, the disease can be severe or fatal for people with severely weakened immune systems. EPA and CDC have prepared advice for those with severely compromised immune systems who are concerned about Cryptosporidium.  Cryptosporidium

  17. Turbidity • Turbidity has no health effects. However, turbidity can interfere with disinfection and provide a medium for microbial growth. • Turbidity may indicate the presence of disease causing organisms. These organisms include bacteria, viruses, and parasites that can cause symptoms such as nausea, cramps, diarrhea, and associated headaches.

  18. @Irina Cech, 2005

  19. @Irina Cech, 2005

  20. pH • This is a measure of the acidity or alkalinity of the water. The optimal pH for most organisms in waters is pH 6.5 to pH 8.2. • Changes in pH outside this normal range will cause a reduction in species diversity. • pH will vary depending on the geology of the area. Water flowing through limestone will be alkaline and water flowing through sandstone or basaltic soils will be slightly acidic.

  21. Antimony Barium Beryllium Cadmium Chromium Copper Lead Mercury Thallium Arsenic Asbestos Cyanide Nitrate Nitrite Selenium Inorganic Contaminants

  22. Lead typically leaches into water from plumbing in older buildings. Lead pipes and plumbing fittings have been banned since August 1998. ` Children and pregnant women are most susceptible to lead health risks. Lead http://www.epa.gov/seahome/leaddw.html

  23. Percentage of children aged 1-6 years with blood lead levels > 10 ug/dl

  24. Arsenic and Human Health Effects

  25. Water and soil arsenic

  26. A typical tubewell in S. E. Asia

  27. The Effect of Aluminum in Formation of Neurofibrillary Tangles • Studies associated ALUMINUM in tap water with neuro-skeletal developmental disorders and cognitive impairments in the elderly. • Whether or not aluminum in drinking water is, indeed, a risk factor for Alzheimer’s disease has not been resolved.

  28. Benzene Carbon Tetrachloride Chlorobenzene  o-Dichlorobenzene p-Dichlorobenzene  1,1-Dichloroethylene cis-1,2-Dichloroethylene trans-1,2 Dicholoroethylene Dichloromethane 1,2-Dichloroethane 1,2 Dichloropropane Ethylbenzene Styrene Tetrachloroethylene 1,2,4-Trichlorobenzene 1,1,1,-Trichloroethane  1,1,2-Trichloroethane Trichloroethylene  Toluene Vinyl Chloride Xylenes Volatile Organic Contaminants

  29. China's toxic river poisons water in Russian Far East 11/24/2005 19:18 Harbin, the second largest city in China, has been virtually under siege for a few days. The Chinese authorities confirmed that the Sungari River had been polluted with benzene and other dangerous chemicals. Poisonous substances got into the river due to powerful explosions at a chemical plant that took place on November 13th, 2005. The Sungari flows into the Amur River. Pravda, Ru, Headlines, 11/24/2005 19:18

  30. Cloud of chemical smoke covers China Pravda, Ru, Headlines, 11/24/2005 19:18

  31. Benzene is Linked to Leukemia • It has been known for a long time that Benzene has caused cancer. This dates back to the early 1900's when the first strong connections were made. • In the US, the maximum contaminant level for benzene in public drinking water supplies was set at 5 ppb and this standard was promulgated by the Environmental Protection Agency in 1989

  32. Benzene • Benzene is an aromatic hydrocarbon that is produced by the burning of natural products. It is a component of products derived from coal and petroleum and is found in gasoline and other fuels. • Benzene is used in the manufacture of plastics, detergents, pesticides, and other chemicals.

  33. @Irina Cech

  34. Credit: Irina Cech

  35. @Irina Cech, 2006 Northwest Harris County, Texas. Until recently, the major activity here was the extraction of gas and oil.

  36. Benzene concentrations in the soil, Ug/Kg, within 1.5 mile radius of the contaminated well • Scale: 1:24,000 @Irina Cech Harris-Montgomery County border, Texas, July 1996

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