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I forgot to mention

• Alkalinity- measure of water’s abilityto neutralize acids. Usually becauseof bicarbonate, carbonate andhydroxyl content

• Highly alkaline water tastes bad butisn’t bad for you

I forgot to mention•• HardnessHardness is a measure of ions that

carry a charge of 2+ or greater•• Ca, MgCa, Mg, Fe, Sr, Mn are primary

Dissolved Oxygen (DO) and

Biological Oxygen Demand (BOD)

This is all about eating

We need O2 to eat andBOD is a measure of how much food there is to eat

Dissolved Oxygen (DO)

• DO is a function of a range ofvariables

• We can predict whether DO will behigh or low based on these variables

• We (you) can also measure DO

Some reasons why we careabout DO

Carphuntersabroad.comDO>3 mg L, DO >5

Dissolved Oxygen• The same way that

there is dissolved CO2in the water, there willalso be dissolved O2 inthe water

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Factors• Henry’s law- equilibrium concentrations will

vary with temperature• Ability of O2 to dissolve in water

decreases with increasing temperature• At 20° C the solubility of O2 is about 9 mg

L or 0.3 millimolar or 0.3 x 10-3 M

Temperature

• Temperature (C˚)• 0• 20• 40

• DO (mg/L)• 14.6• 9.07• 6.41

DO in Boulder over a 24 hr periodin February

How O2 gets into water:Fast running versus Still

• Moving water, wind, waterfalls, waves willall incorporate air into water

• Still waters are much more likely not besaturated with O2

Plants• Photosynthesis creates oxygen• 6CO2+ 6H2O → C6H12O6 +6O6O22

www.cdatribe-nsn.gov

Ionic strength• Waters with high concentrations of

dissolved ions can hold less gas thanwaters with low concentrations ofdissolved ions and dissolved orsuspended solids

• ‘Salting out effect’- just like highblood pressure

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Salting Out• ln(Sw/Se)=KsCe• Or the natural log of the ratio of the

solubility of O2 in pure water to thatin salty water is equal to theelectrolyte concentration (ionicstrength) times the saltingcoefficient

Variations in a river

Biological Oxygen Demand(a measure of how much there is to eat)

• Is one of the major variables thatcan impact DO

• It is also the one that is oftenaltered by anthropogenic activities

Eating- aerobic eaters

CH2O + O2= CO2+H2O+energy

www.co.dane.wi.us

Where food comes fromWWTP effluent, domestic wastes

Agricultural wastes… • Domestic sewage• All manufacturing• Chemicals and

allied products• Paper• Food• Metals

• 165• 200• 314

• 372• 747• 13

•BOD for different types of wastes(mg O2 per liter of wastewater)

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Example

• Given:– Above a wwtp outfall, DO = 7 ppm– Below the outfall, DO = 4 ppm

• Find: the amount of CH2O degraded

• Assume: no O2 from atm, photosynthesis

Answer

• 7-4 = 3 mg/L O2 consumed– One mole of CH2O per mole O2

– Total demand * FW CH2O/FWO2

(3 mg/L)*(12+2+16)/(2*16) = 2.8mg/L CH2O

In different units, to eat 30 g carbsyou need 32 g oxygen

CH2O + O2= CO2+H2O+energy

• If you have 50 g of food (CH2O),how much oxygen (in g) will you needto eat it?

Lake in the summer

DO at surface?DO at depth?

DO Variations in a riverCity of Boulder-Boulder Creek

• September• 3.4 - 17 mg L

• February• 8.2-12.6 mg L

What accounts for the widerswings in summer?

Would you expect anydifference in a 24 hour period?

Yakima RiverUSGS study on water quality

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Water borne disease

• Great illnesses of history were veryoften caused by waterbornepathogenic organisms

• Cholera (Vibrio cholerae)• Dysentery (Entamoeba histolytica)• Typhoid fever (Salmonella typhi)

Term-Waterborne

• Water is not where thesewant to live or evengenerally survive well

• They like a human oranimal host

• Water is a means to find anew home

Cholera

Remf.dartmouth.edu

Crystalinks.com

King Cholera

• The bacteria makes a toxin that prevents peoplefrom absorbing liquids

• Dehydration can kill within hours• Disease has killed millions over time• Can be treated with antibiotics and oral

rehydration solution• In US 1832-1873 was ‘our time of cholera’• In 1854 Dr. John Snow in England related

incidences of the disease to contaminated water

King Cholera

• Potentially begun in India along the Ganges river Firstpandemic 1816-1826, spread to China and Caspian Sea

• 1829-1851 Second pandemic reached London (3000 dead),Russia and the US where it killed President James Polk

• 1852-1860 Russian outbreak 1 000 000 dead• 1961-1970s Indonesian pandemic called ElTor after specific

strain• 1991-1994 South American outbreak from ballast water

0139 Bengal responsible strain 10 000 dead- signs ofantibiotic resistance

Cholera

•

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Disease causing micro organisms• Bacteria 2 x 0.7 µm• 1 µm = 0.001 mm=0.000000 m

– Bacilli– Cocci– Spirilla

• Largest group, smallest organismsvery difficult to identify and classify

Bacteria• Are able to live outside of a host

organism• Single celled organisms with no

specific nucleus• Some can move, some group together

Capsule

Bacteria• Different abilities to culture and

classify• Different abilities to culture

Gram positive Gram negative

Bacterial all stars• Salmonella typhi• Salmonella paratphyi-A• Shigella• Escherichia coli• Leptospira

• Fecal coliforms

One isn’t enough

• Infectious dose of bacteria is notspecifically known, howeverestimates range from 103-109

• With exposure 1-95% of people willbe infected

Methods

• We can’t identify, we can’t culture allpathogenic bacteria. We also don’tknow survival times outside of hostorganism

• Fecal coliform are ubiquitous in fecesand we know how they grow

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Fecal coliform

• Used as an indicator organism• Generally more hardy than other

disease causing organisms• Culture for F. coliform• If present in high enough numbers

seen as potential for disease

Fecal coliform

Disease causing organismsViruses

• Are not alive per se• Parasitic particles that contain

genetic material. Invade host cellsand take over their operations

• Examples include hepatitis,adenovirus, polio, coxsackie…

• Here 1 can be enough

100 types of virus in humanfeces

• 1 g of feces can have 106 infectiousparticles in it

• Very few that come in contact will beinfected and not all will get sick

• 1% infection, 2% illness= 1 in 5000get sick as a result of exposure

Disease causing organismsProtozoa

• Are different from bacteria as theyhave a real nucleus in their cells (justlike us)

• Self sufficient, independent, singlecelled organisms that fall into theanimal kingdom

• Different protozoa are oftenexceedingly different

ProtozoaTwo life stages

• Active trophozoites- when they arealive and feeding

• Dormant cysts- can remain in stasisfor extended periods but still beviable

USC school of medicine

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Waterborne and problematic

• Entamoeba histolytica– Amebic dysentery and amebic hepatitis

• Giardia lamblia– Giardiasis

• Cryptosporidium– Cryptosporidiosis

UC SF school of medicine

Giardia lamblia

• Make a home in your intestines• And they live it up

Giardia lamblia

Day 1 - 1 cyst which comes alive with stomach acidsAnd begins to multiply

Day 10- 1 millionDay 15- 1 billion

Giardia- symptoms and progression

• Nausea, cramps, bloating, severediarrhea, flatulence, fatigue

• Generally will last about 1 week• (realize with the high rate of

reproduction, when you are infected,your feces carry a high dose ofinfectious agents)

Giardia- not host specific So how to we make sure water issafe to drink?

• Least sophisticated and very powerful isto keep toilet water away from drinkingwater

• Boiling water is also very efficient meansto kill pathogenic organisms

X

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World wide• 5 x 106 deaths (WHO)

Trisana.com

On a municipal level

• Chlorination, ozonation, flocculation, UVradiation and filtration

ci.mesa.az.us

Chlorination• 1870s- scientists figured out that microbes in

water were making people sick• 1890s chlorine first added to water to disinfect• 1908 Jersey City and Chicago- set the trend• 1915- first bacterial drinking water standard• 1918- over 1000 cities in US use chlorine

disinfection

How it is done• Can add chlorine in four forms

– Elemental Chlorine (gas)– Sodium hypochlorite– Calcium hypochlorite– Chloramines

• When it is added to water, two species ‘freechlorine’ will be formed

• Hypochlorite (OCl-) and HOCL Hypochlorous acid

How it is done•

How it is done• HOCL Hypochlorous acid is better disinfectant and is

more effective at low pH• The bacteria has a charged surface and so can repell

the OCl-• Factors that will effect efficacy include contact time,

temperature and particulate matter in the water• Standards for minimum chlorine concentration in water• Water will still contain chlorine when it comes out of

your tap

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UV disinfection

• Type of light (ultra violet radiation)• Enters cells and damages genetic

material and so stops reproduction• Effective against ocysts.

Causes for concern in the US• Contamination of domestic water by

animal wastes• Virulent strain of E. Coli (O157:H7)

– Walkerton, ON 2000 6 deaths,2300 cases

– Runoff from farm fields enteringtown water

– Washington Co, NY 2 deaths 116cases

– Runoff at fairgrounds– Cabool, MO 4 deaths, 243 cases– Water line breaks in farm community

Chuck Gerba: Dr. Germs

• DO YOUR WORLDWIDE STUDIES CONFIRM THATAMERICA HAS THE SAFEST DRINKING WATER?

• Yes it does. However, we are seeing more and moreinstances of water-born illnesses. Every year, we discoveranother microorganism that can be transmitted by water,and I don't see that trend decreasing. Almost all watersupplies are at risk. The microorganisms originate fromfecal material, so any time you have an animal in awatershed or water supply, you have risk. Forty percent ofgroundwater drinking wells contain viruses like Hepatitis,Rotavirus and Eterovirus.