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Monroe L. Weber-Shirk S chool of Civil and Environmental Engineering Water Quality.

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Presentation on theme: "Monroe L. Weber-Shirk S chool of Civil and Environmental Engineering Water Quality."— Presentation transcript:

1 Monroe L. Weber-Shirk S chool of Civil and Environmental Engineering Water Quality

2  History of our understanding of waterborne disease  Brief history of water treatment  Drinking Water Standards: how do we decide what is allowed in the water we drink?

3 Germ theory  Pasteur ( )  Proved that microorganisms cause fermentation and disease  Lister ( )  Founder of antiseptic medicine and a pioneer in preventive medicine  Koch ( )  One of the founders of the science of bacteriology  Discovered the tubercle bacillus (1882) and the cholera bacillus (1883)

4 The Flush Toilet’s Connection to Disease  In the early 1800s new flush toilets and sewers carried the waste directly into rivers and streams  London drained its raw sewage into and withdrew its drinking water from the Thames River, both without any treatment.  Several of the drinking water intakes were below sewage outfalls!

5 Southwark and Vauxhall Water Company  In 1850, the microbiologist Arthur Hassall wrote of the River Thames water they were using,"...a portion of the inhabitants of the metropolis are made to consume, in some form or another, a portion of their own excrement, and moreover, to pay for the privilege."  Next Cartoon presents John Edwards, owner of the Southwark Water Company, posing as Neptune ("Sovereign of the Scented Streams"). He is seen crowned with a chamber-pot, seated on a stool on top of a cesspool which doubles as the water-intake for the Southwark Water Company customers in south London.

6 Southwark and Vauxhall Water Company Courtesy of the National Library of Medicine

7 Drinking Water Treatment and Germ Theory  1829: First sand filter used to treat some of London's drinking water  1850: John Snow established the link between drinking water (from a contaminated well) and Cholera  1872: Poughkeepsie, NY installs first filter in US  1885: Sand filters are shown to remove bacteria  1892: Cholera outbreak in Hamburg, Germany

8 1892 Cholera outbreak in Hamburg Germany  Large outbreak of Cholera in Hamburg  17,000 cases; 8,600 deaths  Very few cases in neighborhoods served by Altona's filtered water supply  Hamburg's sewers were upstream from Altona's intake! Altona's water intake and filter beds Hamburg's sewer outfalls Hamburg Altona Elbe River Hamburg's water intake

9 Altona vs. Hamburg: Cholera Cases Hamburg Altona Cases in Altona acquired in Hamburg Cholera cases Received water from Altona Cholera was waterborne Slow sand filtration may have protected Altona Conclusions

10 Disease Definitions  Pathogen: an agent that causes infection in a living host. It acts as a parasite within the host or host cells and disrupts normal physiological activities  Infection: growth of a disease-producing organism within the host  Virulence: ability of the pathogen to inflict damage on the host

11 Epidemic  An occurrence of disease that is temporarily of high prevalence  An epidemic occurring over a wide geographical area is called a pandemic  Epidemics require  _________________________  __________________________ an infected host a number of non-infected potential hosts a mechanism of pathogen transfer

12 Waterborne Threats to Human Health  Infectious diseases  caused by viruses, bacteria, protozoa (pathogens)  Noninfectious diseases  _____: caused by short term exposure to harmful chemicals  _______: caused by long term exposure to harmful chemicals  low levels of exposure to certain chemicals over a long period of time may cause cancer, liver and kidney damage, or central nervous system damage acute chronic

13 Pathogens: Protozoa OrganismDiseaseInformation Giardia lambliaGiardiasis FDAFDA Entamoeba histolyticaAmebiasis FDAFDA Cryptosporidium parvum cryptosporidiosis FDAFDA Cyclospora cayetanensis FDAFDA

14 Pathogens: Bacteria OrganismDiseaseInformation Vibrio choleraeCholeraFDAFDA Shigella spp.Shigellosis FDAFDA Salmonella typhiTyphoidFDAFDA Enterotoxigenic Escherichia coli GastroenteritisFDAFDA

15 Pathogens: Viruses OrganismDiseaseInformation Hepatitis A virusHepatitisFDAFDA Hepatitis E virus Hepatitis EFDAFDA Norwalk virus viral gastroenteritis FDAFDA

16 Propose a Drinking Water Standard  You have been granted the authority to regulate drinking water quality. Create a standard for the concentrations of disease-causing organisms in drinking water.  In the absence of technological/economic constraints,  Which pathogens would you regulate?  What concentration would you choose?  Given technological and economic constraints how might you change your regulation? Setting the standards

17 Optimal Pathogen Exposure  Should we be exposed to small doses of pathogens so we build up our resistance?  How could we build pathogen exposure into our daily lives?  Potential application  Common cold (continues to mutate)  Norwalk virus (Immunity, however, is not permanent and reinfection can occur after 2 years)  HIV (no immunity)

18 Philadelphia Typhoid

19 Optimal Pathogen Dose?

20 Safe Drinking Water Act (1974)  Specific standards for drinking water  primary (__________)  secondary (__________ upper limits for non-health related parameters)  Applicable to all water supplies serving more than 25 people or having 15 or more service connections  Enforced by U.S. Environmental Protection Agency mandatory suggested

21 Primary Standards: (Health) Inorganic chemicals (units of mg/L) ContaminantU.S. EPA Antimony0.006 Arsenic0.01 Asbestos (fiber >10 micrometers)7 MFL Barium2 Beryllium0.004 Cadmium0.005 Chromium (total)0.1 CopperAction Level=1.3; TT 8 8 Cyanide (as free cyanide)0.2 Fluoride4.0 LeadAction Level=0.015; TT 8 8 Inorganic Mercury0.002 Nitrate (measured as Nitrogen)10 Nitrite (measured as Nitrogen)1 Selenium0.05 Thallium0.002

22 A Few Organic Chemicals (units of mg/L) see the complete list! ContaminantMCLGMCL AcrylamidezeroTT 7 7 Alachlorzero0.002 Atrazine Benzenezero Dichloroethylene Dioxin (2,3,7,8-TCDD)zero EpichlorohydrinzeroTT 7 7 Ethylbenzene Ethelyne dibromidezero Lindane Polychlorinated biphenyls (PCBs)zero Tetrachloroethylenezero0.005 Toluene11 Total Trihalomethanes (TTHMs)none Trichloroethylenezero0.005 Vinyl chloridezero0.002 Xylenes (total)1010

23 Secondary Standards: Aesthetics ContaminantU.S. EPA, 1993WHO, 1984 Aluminum mg/L0.2 mg/L Chloride250 mg/L250 mg/L Color15 color units15 color units Copper1.0 mg/L1.0 mg/L CorrosivityNoncorrosive Fluoride2.0 mg/L Foaming agents0.5 mg/L Iron0.3 mg/L0.3 mg/L Manganese0.05 mg/L0.1 mg/L Odor (Threshold Odor Number)3 TON pH Silver0.1 mg/L Sulfate250 mg/L400 mg/L Total dissolved solids500 mg/L1000 mg/L Zinc5.0 mg/L5.0 mg/L

24 ESW Social  BOWLING and PIZZA  7 PM - 9 PM today!  Helen Newman

25 How do they determine MCLGs?  Determine NOAEL (No Observed Adverse Effect Level) by experimental data on humans or animals  Divide NOAEL by uncertainty factor (UF)  UF = 10 when good data on humans available  UF = 100 when good data on animals available  UF = 1000 when no good data available  To get reference dose  Determine drinking water equivalent level

26 Setting the Standards (Non- Carcinogens)  For chemicals that can cause adverse non-cancer health effects, the MCLG is based on the reference dose.  A reference dose (RFD) is an estimate of the amount of a chemical that a person can be exposed to on a daily basis that is not anticipated to cause adverse health effects over a person's ________.  In RFD calculations, sensitive subgroups are included, and uncertainty may span an order of magnitude. lifetime

27 MCLG Calculations RFDreference dose adult body weight (70 kg) M daily water consumption (2 liters) Drinking Water Equivalent Level DWEL Q MCLG Maximum Contaminant Level Goal

28 Example MCLG: Lindane  50 mg/lifetime (exposure over 70 years)  RFD = ________  Estimate the MCLG 30x10 -6 MCLG=______0.0002

29 Primary Standards : (Health) Related to Microorganisms ContaminantMCLGMCL CryptosporidiumzeroTT 3 3 Giardia lambliazeroTT 3 3 LegionellazeroTT 3 3 Viruses (enteric)zeroTT 3 3 Heterotrophic plate countN/ATT 3 3 Total Coliformszero5.0% 4 4 TurbidityN/ATT 3 3 Cause disease Indicators Interferes with disinfection

30 Microbial Contaminants  For microbial contaminants that may present public health risk, the MCLG is set at zero because ingesting one protozoa, virus, or bacterium may cause adverse health effects.  EPA is conducting studies to determine whether there is a safe level above zero for some microbial contaminants.  The MCL is set as close to the MCLG as feasible, (the level that may be achieved with the use of the best available technology, treatment techniques, and other means which EPA finds are available), taking cost into consideration.

31 Treatment Technique (TT)  When there isn’t an economical and technically feasible method to measure a contaminant, a Treatment Technique is set rather than an MCL.  A treatment technique is an enforceable procedure or level of technological performance which public water systems must follow to ensure control of a contaminant.  Surface Water Treatment Rule (disinfection and filtration)  Lead and Copper Rule (optimized corrosion control).

32 Indicator Organisms  Impractical to detect, differentiate, or enumerate all of the pathogenic organisms that may be present in water  Pathogenic organisms share a common fecal origin  therefore limit fecal contamination of water  need a measure of fecal contamination

33 Ideal Indicator Organism  Be present when pathogens are  Not reproduce in the environment  Survive at similar rate to pathogens  Correlate quantitatively with pathogens  Be present in greater numbers than pathogens  Be easily, accurately and quickly detected

34 Fecal Contamination Indicator: Coliform Bacteria  Normally are not pathogenic  Always present in the intestinal tract of humans and excreted in very large numbers with human waste  Easier to test for the presence of coliforms rather than for specific types of pathogens  Are used as indicator organisms for measuring the biological quality of water

35 Indicator Organism Failure  Relative viability of pathogens and indicator organisms  Effect of treatment processes Some pathogens survive for a longer time in the environment (raw water concentrations are different) Some pathogens are resistant to chlorine

36 Testing for Coliform Bacteria: Presence/Absence Tests  Colisure allows testing for coliform bacteria and/or E. coli in hours.  The detection limit of ColiSure is 1 colony forming unit (CFU) of coliform bacteria or E. coli per 100 mL of medium.  If coliform bacteria are present, the medium changes color from yellow to a distinct red or magenta.  If E. coli are present, the medium will emit a bright blue fluorescence when subjected to a long wave (366 nm) ultraviolet (UV) light.

37 Testing for Coliform Bacteria: Membrane Filtration  Membrane filter  0.45 μm pores  47 mm in diameter  Filter 100 mL of water to be tested through the membrane filter

38 Membrane Filtration Petri dish with sterile absorbent nutrient pad Add 2 mL of m- endo broth (selective media) Place membrane filter in the petri dish on top of the nutrient pad

39 Membrane Filtration: Incubation and Results  Incubate for 24 hours at 35°C  Coliform bacteria grow into colonies with a green metallic sheen  Non-coliform bacteria may grow into red colonies  Coliform concentration is __________________ coliform/100 mL

40 Turbidity  A measure of the scattering of light by particles in a suspension  A turbid water sample appears cloudy or “dirty”  High turbidity is the result of lots of light scattering caused by the particles in suspension  Measured in NTU (Nephelometric Turbidity Units) cloud

41 Turbidity Measurements 90° detector lamp lens sample cell 180° detector LED sample cell 170° detector Turbidity Sensors (approximate turbidity measurement)

42 90° Detector Output? 90° detector 180° detector

43 Coagulant Dose  How will you determine coagulant dose for your water treatment plant?  What will you monitor to decide if coagulant dose should be increased or decreased?  Why is it hard to use feedback (data from a sensor) to set the coagulant dose?

44 Summary  The causes of waterborne disease have been identified  Indicator organisms are used to measure the extent of fecal contamination  Standards for microbiological and chemical contaminants have been set by US EPA  Waterborne disease continues to be a significant public health concern especially for the poorest 2 billion


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