Water Quality

1
Water Quality
2
Water Quality

• 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 (1822-1895)
• Proved that microorganisms cause fermentation and
  disease
• Lister (1827-1912)
• Founder of antiseptic medicine and a pioneer in
  preventive medicine
• Koch (1843-1910)
• One of the founders of the science of
  bacteriology
• Discovered the tubercle bacillus (1882) and the
  cholera bacillus (1883)

4
The Flush Toilets 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
Hamburg
Altona's water intake and filter beds
Altona
Hamburg's sewer outfalls
Hamburg's water intake
Elbe River

• 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!

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

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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
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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
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Pathogens Protozoa

• Organism Disease Information
• Giardia lamblia Giardiasis FDA
• Entamoeba histolytica Amebiasis FDA
• Cryptosporidium parvum cryptosporidiosis FDA
• Cyclospora cayetanensis FDA

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Pathogens Bacteria

• Organism Disease Information
• Vibrio cholerae Cholera FDA
• Shigella spp. Shigellosis FDA
• Salmonella typhi Typhoid FDA
• Enterotoxigenic Escherichia coli Gastroenteritis F
  DA

15
Pathogens Viruses

• Organism Disease Information
• Hepatitis A virus Hepatitis FDA
• Hepatitis E virus Hepatitis E FDA
• Norwalk virus viral gastroenteritis FDA

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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
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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
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Optimal Pathogen Dose?
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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
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Primary Standards (Health)Inorganic chemicals
(units of mg/L)

• Contaminant U.S. EPA
• Antimony 0.006
• Arsenic 0.01
• Asbestos (fiber gt10 micrometers) 7 MFL
• Barium 2
• Beryllium 0.004
• Cadmium 0.005
• Chromium (total) 0.1
• Copper Action Level1.3 TT8
• Cyanide (as free cyanide) 0.2
• Fluoride 4.0
• Lead Action Level0.015 TT8
• Inorganic Mercury 0.002
• Nitrate (measured as Nitrogen) 10
• Nitrite (measured as Nitrogen) 1
• Selenium 0.05
• Thallium 0.002

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A Few Organic Chemicals (units of mg/L) see the
complete list!

• Contaminant MCLG MCL
• Acrylamide zero TT7
• Alachlor zero 0.002
• Atrazine 0.003 0.003
• Benzene zero 0.005
• 1-1-Dichloroethylene 0.007 0.007
• Dioxin (2,3,7,8-TCDD) zero 0.00000003
• Epichlorohydrin zero TT7
• Ethylbenzene 0.7 0.7
• Ethelyne dibromide zero 0.00005
• Lindane 0.0002 0.0002
• Polychlorinated biphenyls (PCBs) zero 0.0005
• Tetrachloroethylene zero 0.005
• Toluene 1 1
• Total Trihalomethanes (TTHMs) none5 0.10
• Trichloroethylene zero 0.005
• Vinyl chloride zero 0.002
• Xylenes (total) 10 10

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Secondary StandardsAesthetics

• Contaminant U.S. EPA, 1993 WHO, 1984
• Aluminum 0.5-0.2 mg/L 0.2 mg/L
• Chloride 250 mg/L 250 mg/L
• Color 15 color units 15 color units
• Copper 1.0 mg/L 1.0 mg/L
• Corrosivity Noncorrosive
• Fluoride 2.0 mg/L
• Foaming agents 0.5 mg/L
• Iron 0.3 mg/L 0.3 mg/L
• Manganese 0.05 mg/L 0.1 mg/L
• Odor (Threshold Odor Number) 3 TON
• pH 6.5-8.5 6.5-8.5
• Silver 0.1 mg/L
• Sulfate 250 mg/L 400 mg/L
• Total dissolved solids 500 mg/L 1000 mg/L
• Zinc 5.0 mg/L 5.0 mg/L

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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

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

• 50 mg/lifetime (exposure over 70 years)
• RFD ________
• Estimate the MCLG

30x10-6
MCLG______
0.0002
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Primary Standards (Health) Related to
Microorganisms

• Contaminant MCLG MCL
• Cryptosporidium zero TT3
• Giardia lamblia zero TT3
• Legionella zero TT3
• Viruses (enteric) zero TT3
• Heterotrophic plate count N/A TT3
• Total Coliforms zero 5.04
• Turbidity N/A TT3

Cause disease
Indicators
Interferes with disinfection
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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.

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Treatment Technique (TT)

• When there isnt 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).

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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

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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

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Fecal Contamination IndicatorColiform 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 BacteriaPresence/Absence
Tests

• Colisure allows testing for coliform bacteria
  and/or E. coli in 24 - 28 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.

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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

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

• Incubate for 24 hours at 35C
• Coliform bacteria grow into colonies with a green
  metallic sheen
• Non-coliform bacteria may grow into red colonies
• Coliform concentration is __________________

2
1
4
3
6
5
8
7
8 coliform/100 mL
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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
lens
90 detector
lamp
180 detector
sample cell
Turbidity Sensors (approximate turbidity
measurement)
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90 Detector Output?
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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