Transcript Toxins removal in Water Treatmentx

Using Chlorination and UV treatment for the
removal of toxins in Water Treatment
Hernesto Tellez
Outline
• Introduction
– Waste Water History
– Clean Water Act
– Widespread use of Chlorination
• Chlorine used as a water treatment disinfectant
– Chlorine used to kill microbes
– Disinfection by-products production
– Reactions of DBPs
• UV light used as a water Disinfectant
– UV used as disinfectant microorganisms
– DNA damage
Waste Water History
Water supply systems during the Roman
Empire
• Network of Aqua ducts to supply..
• Large cities with fresh water
• Elaborate Public Baths
• Fountains, Latrines
• Irrigation and Industry
Waste Water Systems
• Waste water collection from numerous sources
• Sewer Channels
• Cloaca Maxima, Rome’s sewer system
http://www.romanaqueducts.info/picturedictionary/framepicturedicti
onary.htm
Waste Water History
http://www.romanaqueducts.info/picturedictionary/framepicturedictionary.htm
Clean Water Act
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Industrial Revolution, population explosion
Large Cities across US
Waterborne outbreaks in early 1900s
1908 Chlorine used in New Jersey
EPA Clean Water Act 1974
EPA, History of Drinking Water Treatment
History of Chlorination
• 1908 Chlorine used to treat drinking water
• By 1995 EPA survey, 64% of community ground water disinfected by use of
Chlorine
• Widely used because effectiveness and cost
• Used to kill Typhoid, Cholera, Dysentery, and…
• Bacteria: Salmonella genus (Typhoid) and Escherichia Coli. Outbreak in
Walkerton, Ontario in 2000
• Viruses: Polio virus, hepatitus-A
• Protozoans: Cryptosporidium and Giardia lamblia.
Chlorine used to kill Microbes
• Most widely used is Hypochlorous Acid (HOCl)
made on site
• Easily passes through cell membranes to kill
bacteria, viruses, and protozoans
• Cl2(g) +H2O(aq)  HOCl(aq) + HCl
• HCl  H+ and Cl• Cl gas dangerous to store and handle
Disinfection By-products (DBPs)
• Chlorine can react with numerous chemicals
in water and in micro pollutants
• Rxns with Fe, As, pesticides, pharmaceuticals,
phenols, …
• Cyclohexane, Benzene and Phenols
• Chlorine Rxns
• Phenol reactions
• Chloroform production
Phenol Reactions
Other DBPs, Steroids
UV light as a disinfectant
• UV light uses high energy to directly damage
the DNA of any microbe involved
• Creates the formation of Thymine-Thymine
dimers
• Also creates Oxygen radicals that react quickly
with cellular components
Nucleotides
DNA Base Pairing
DNA Double Helix
Thymine Dimers
DNA Replication and Mutations
http://www.web-books.com/MoBio/Free/Ch7F5.htm
DNA Repair
References
Bougeard, C. M., Goslan, E. H., Jefferson, B., & Parsons, S. A. (2010). Comparison of the
disinfection by-product formation potential of treated waters exposed to chlorine and
monochloramine . Water Research , 729-740.
Hader, R. P.-P. (2002). UV-induced DNA damage and repair: a review. Photochemical &
Photobiological Sciences , 225-236.
S.J. De Mora, S. D. (2000). environment, The effects of UV radiation in the marine.
Cambridge University Press .
Tan, Y., Kilduff, J., & Karanfil, T. (2007). Disinfection by-product (DBP) formation and
speciation in chlorinated waters after anion exchange treatment. American Chemical
Society, (pp. 574-574).
US EPA. (2000). The History of Drinking Water Treatment. US EPA, Office of Water.
V, B. (2006, June). Technical Briefs. Journal of Environmental Health , 61-63.
Zimmer JL, S. R. (2002). Potential Repair of Escherichia coli DNA following exposure to UV
radiation from both medium and low-pressure UV sources used in drinking water
treatment. Applied and Environmental Microbiology , 3293-3299.