Public Health Implications of Water Supply Improvements
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Transcript of Public Health Implications of Water Supply Improvements
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Monroe L. Weber-Shirk School of Civil and
Environmental Engineering
Public Health Implications of Water Supply Improvements
Did Environmental Engineers save the world?
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Public Health
Environmental Engineers help protect communities from waterborne disease
Water related Public Health is complexHygiene, education, Chlorine may be overratedHousehold infrastructure matters
Reflections on skepticism, engineering, and love
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The role of Water Supply, Sanitation, and Hygiene (WASH)
Contribute significantly to mortality and morbidity on the global level
Have an enormous influence on U5MR (under 5 mortality rate)
What is the effect of safe drinking water?
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Mills-Reincke Phenomenon
‘…. the purification of polluted public water-supplies reduces the general death-rate much more than it would be reduced by the saving of deaths from the commonly recognized water-borne disease, typhoid fever and Asiatic cholera alone.’Sedgwick WT, MacNutt JS. On the Mills-Reincke phenomenon and Hazen's theorem concerning the decrease in mortality from diseases other than typhoid fever following the purification of public water-supplies. J.Infect.Dis. 1910; 7 : 489-564.
This is the “Environmental Engineers Saved the World” Hypothesis.
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U.S. Typhoid Fever Mortality
Chlorination was begun in Jersey City, N.J., in 1908. Adoption by other cities and towns across the US soon followed and resulted in the virtual elimination of waterborne diseases such as cholera, typhoid, dysentery and hepatitis A
Chlorine saved the day
Chlorination begins in Jersey City
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1900 1910 1920 1930 1940 1950
year
deat
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Salmonella typhi
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Chlorine Cause and Effect:What else would you like to know…
What was the mortality rate before the introduction of chlorine?
When did other cities adopt chlorination?How did the mortality rate change for cities
when they began chlorinating?What other changes were occurring during
the 1900s that may have influenced mortality?
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Disease rates as measures of efficiency
“The final criterion of the efficiency of a purification plant is the absence or prevalence in the community of water-borne diseases. Typhoid fever being the most typical and widespread of such diseases, statistics of its prevalence are of much significance. Prior to the general introduction of purification works, the typhoid death rate was invariably high in many of our large cities drawing their supply from polluted rivers and lakes. Most of these cities are now supplied with satisfactory water, and many records could be given showing the marked effect of water treatment on the typhoid rate. The following data for the cities of New Orleans, Pittsburgh and Cincinnati will suffice.”
Public Water-Supplies by Turneaure, Russell, Mead, Baker. John Wiley & Sons (1924) pages 430-431.
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Evidence for a Causal Link:New Orleans, Pittsburgh, Cincinnati
Pittsburgh, Cincinnati and New Orleans were used as evidence of the efficacy of filtrationPublic Water-Supplies by Turneaure, Russell, Mead, Baker. John Wiley & Sons (1924)
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Typh
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TyphoidFiltrationChlorination
New Orleans, LA
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Typh
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TyphoidFiltrationChlorination
Cincinatti, OH
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100120140160
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Typh
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TyphoidFiltrationChlorination
Pittsburg, PA
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Let’s look at all the data using log scale (showing improvement ratio)
0.1
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Typh
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TyphoidFiltrationChlorination
Baltimore, MD
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TyphoidFiltrationChlorination
Chicago, IL
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Typh
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TyphoidFiltrationChlorination
Cincinatti, OH
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Typh
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talit
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TyphoidFiltrationChlorination
Cleveland, OH
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Typh
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talit
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TyphoidFiltrationChlorination
Detroit, MI
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Typh
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talit
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TyphoidFiltrationChlorination
Jersey City, NJ
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Typh
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TyphoidFiltrationChlorination
Louisville, KY
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Memphis, TN
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TyphoidFiltrationChlorination
Milwaukee, WI
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Typh
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TyphoidFiltrationChlorination
New Orleans, LA
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Typh
oid
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talit
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TyphoidFiltrationChlorination
Philadelphia, PA
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Typh
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talit
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TyphoidFiltrationChlorination
Pittsburg, PA
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Typh
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TyphoidFiltrationChlorination
St. Louis, MO
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Correlation between Water Supply Improvements and Public Health?
A causal link?FiltrationChlorination
Delayed response?No link?US 1900 – 1940
interpretation?
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Chorine isn’t always required
The European Union does not require disinfection. Of the 15 original European Union member states, only Spain and Portugal require disinfection in distribution systems.1
1) http://www.epa.gov/ogwdw/disinfection/tcr/pdfs/issuepaper_effectiveness.pdf
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Trying to Understand the Data
“The steady reduction… is probably due in part to improved operation and in part to the gradual elimination of the disease from the community and so removing sources of contamination.”
“It should be noted that typhoid fever is frequently traced to other causes than the water-supply,…”
What do you think?
Public Water-Supplies by Turneaure, Russell, Mead, Baker. John Wiley & Sons (1924)
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Causes of diarrhoea according to ‘Diseases of children’
1889 1899
Sour milkUnripe fruitInhalation of sewer gasEmanations from the soil
‘no doubt that the immediate cause is an infection of the alimentary canal, by …bacteria contained in milk or other forms of food’
EmpowermentPowerlessness!
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Changes recommended: public health campaign
Breast feedBoil cow’s milk, sterilize bottlesProtect infants from persons known to be illControl fliesWash hands
You can improve your health!
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Reading the Typhoid Data
How long did it take for typhoid incidence to decrease? _____________
If typhoid was waterborne how long should it have taken for filtration and chlorination to eliminate typhoid? _____________
How does milk get typhoid?
30 to 40 years
A few weeks
Human excrement (milker’s hands?) or bovine excrement
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My Typhoid Conclusions
The reduction was not due to a one time centralized changeNot due to filtrationNot due to chlorination
Was due to changes that occurred at different times throughout the population Improved hygiene
Installation of toilets in bathrooms with sinks to wash hands and toilet paper
Education encouraging hand washingBetter food handling practices
Milk pasteurizationRefrigeration
Public Health Education and medical care
Typhoid was likely not waterborne
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Southwark Water Source
Courtesy of the National Library of Medicine
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The Grand Cholera Experiment
Those houses served by the Lambeth Company had a low incidence of cholera, lower than the average population of London as a whole
Those served by the Southwark Company had a very high incidence
The socioeconomic conditions, climate, soil, and all other factors were identical for the populations served by the two companies
Snow concluded that the water supply was transmitting the cholera agent
Snow's study is impressive since the germ theory of disease had not yet been established
Proof that cholera was waterborne
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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
HamburgAltona
Elbe RiverHamburg's water intake
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Altona vs. Hamburg: Cholera Cases
Hamburg
Altona
Cases in Altona acquired in HamburgCholera cases
Received water from Altona
Cholera was waterborne
Slow sand filtration may have protected Altona
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Maybe we are helping to save the world from stunted growth
Of the 555 million preschool children in developing countries, 32% are stunted and 20% are underweight.1
A key cause of child undernutrition is a subclinical disorder of the small intestine known as tropical enteropathy
Caused by faecal bacteria ingested in large quantities
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Fecal-Oral Pathways
Human excreta
Animal excreta
Dry sanitation involving reuse
Waterborne sewage
Non recycling latrines
Soil
Surface water
Ground water
Food
Drinking water
Oral
Pathogen source
Sanitation method
Land application
Environment Transport
Hands
Crops
Flies
Water
HygieneWater treatmentSanitation
washing
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Improved or Safe?Improved
Came out of a pipe that was near the town.
Meets the Millennium Development Goal!!!!!!!!!!!
SafeWas treated to remove contamination and won’t make you sick
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ImprovedSafeConvenient
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ImprovedSafeConvenient
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The customer wanted…Safe water on tap
What do people want?Reliable, easy access to plenty of safe, aesthetically
pleasing water Judge based on __________________________
Will they be willing to pay for and maintain more expensive infrastructure to have aesthetically pleasing water? ________________________We are competing with expensive bottled water and
cheap unsafe, inconvenient, unreliable water sourcesCan we make tap water as reliable as bottled water and
almost as cheap as dirty water?
looks and taste/smell
YES! (at least in many cases)
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Course Reflections?
What is one thing that you learned in this course that you want to always remember?
Form groups of 3 and share your ideas.One minute to reflect3 minutes to share your ideas
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Skepticism and Group Think
My default setting when reading a textbook or peer reviewed paper about drinking water treatment is to not believe the claims of the authors (remember typhoid)
Drinking water treatment is NOT a mature field
Every one of the core unit processes is poorly understood
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Emerging Field of Sustainable Hydraulic Water Treatment
Conventional mechanical
Computer controlled peristaltic pumps
Sustainable hydraulic
Automated chemical dose controller
Chemical dosing
Rapid Mix• Velocity Gradient
various mixersNot sure how to scale
• Energy dissipation rateOrifice and jetKolmogorov length scale vs. clay separation distance
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Emerging Field of Sustainable Hydraulic Water Treatment
Conventional mechanical
Velocity gradientResidence timeMechanical paddles
Sustainable hydraulic
Energy dissipation rateCollision potentialBaffles
Flocculator
Sedimentation• 4 m deep
Mechanical sludge removalusually no floc blankettube or plate settlers
• 2 m deephydraulic sludge removalfloc blanketplate settlersawesome hydraulic controls
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Emerging Field of Sustainable Hydraulic Water Treatment
Conventional mechanical
Rapid Sand FilterBackwash pumps
Sustainable hydraulic
Stacked Rapid Sand FilterNo change in flow for backwash
Widely applicable: less costly and operate without electricity
We need to solve the clogging slot problem
Filter
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Engineering for Love
Love is about helping others to thriveWe design water treatment plants so that
communities can thriveWe intend to make a world of difference!