Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and...

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Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina

Transcript of Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and...

Page 1: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Solar Water Pasteurization

Dale Andreatta,Frank Husson,Robert Metcalf

October 16, 2013Water and Health Conference

Chapel Hill, North Carolina

Page 2: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Presenters• Dale Andreatta, Ph.D. in mechanical

engineering, designer of pasteurizers, Columbus, Ohio. (Presenter)

• Frank Husson, president of Solar Solutions, designer of pasteurizers, San Diego, California. (Present today)

• Robert Metcalf, Ph.D. in microbiology, promoter of water pasteurization and solar cooking, Sacramento, California. (Currently in Africa)

Page 3: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Bob Metcalf is in Kenya at a water conference

Page 4: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Basics of Pasteurization• Pasteurization: A heat process that kills all disease-causing

microbes (pathogens) including cryptosporidium. • First discovered by Louis Pasteur 150 years ago.• Hepatitis A is the most heat resistant pathogen, but is killed

by a few minutes at 65° C. • Not necessary to boil the water, as many believe.• Process is not affected by turbidity or acidity of water. • World Health Organization now says “thermal processing”,

rather than “boiling”.• Thermal processing (boiling or pasteurization) is identified

as the most effective method of biological pathogen eradication in the 2012 Household Water Treatment handbook from WHO.

• Heat denatures the proteins, similar to cooking an egg white (which can also be done at 65° C.

Page 5: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.
Page 6: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.
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D values (90% reduction times) bacteria in water

seconds at

Bacterium 55°C 60°C 65°C

E.coli 0157:H7 223 67 3

Shigella sonnei 354 54 3

Salmonella tyhpimurium 77 4 <2

Ref: A. Spinks et.al, Water Research 401326-1332 (2006)

Page 9: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Temperatures which kill disease microbespresent in contaminated water

MICROBE KILLED RAPIDLY AT:

Worms, Giardia, Entamoeba,Cryptosporidium 131F (55C)

Escherichia coli, Shigella, cholera, 140F (60C)Typhoid, Rotaviruses, Polioviruses

Hepatitis A virus 149F (65C)

Milk Pasteurization = 160F (71.7C) for 15 secondsJust as with milk pasteurization, temperatures well below boiling will kill microbes in water.

Page 10: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Why is Boiling the Standard Treatment?

• Until 1992 there was no practical way to know whether the pasteurization temperature has been achieved.

• In 1992, the first Water Pasteurization Indicator (WAPI) or “Indicator” was designed.

• Several other indicators have since been developed.

Page 11: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Pasteurization

• This talk is primarily about solar pasteurization, but we also include fuel-based pasteurization.

• Indicators work in all sizes and shapes of water vessels.

• Typically, solar heating is very slow, so you get a 6 log reduction (99.9999%) in all pathogens by the time you reach 65° C.

Page 12: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Two Types of IndicatorsPetroleum WaxInitial positionMelts at 65 C

If found here later,65 C was reached

Page 13: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Water Pasteurization IndicatorsAlso known as WAPIs or Indicators• This is an indicator, not a thermometer. Even if

the water has cooled down, it still indicates that the water attained the required temperature.

• Only tells whether required temperature was reached.

• Indicator sits in the bottom of the water, where the coolest water is located.

• Inexpensive and reusable.

Page 14: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Pasteurization vs. Boiling

• With the necessary temperature of 65° C, about ½ the energy can be saved compared to boiling. Indicator alone saves 50% of energy.

• Solar plus indicator saves 100% of fuel.• Much easier to achieve 65° C than boiling

temperature, so simple solar devices are viable.• Solar on sunny days, fuel heat on cloudy days

(or chlorine).

Page 15: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Real Purpose of This Talk

• To provide information, yes, but……• The real purpose is to stimulate your thinking.• Where, how, under what conditions can

pasteurization be used? • What niche(s) does pasteurization fill?

Page 16: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

How to Pasteurize Water-Part 1

• Batch Pasteurizers • Indicator is required

Page 17: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

The Aqua Pak

• The Aqua Pak is a dedicated batch pasteurizer, made of inexpensive plastic.

• Can pasteurize 4-5 liters at a time.• Small glass indicator built into the cap. • Cost is about $2 if made in the developing

world. Currently available, made in San Diego.• The plan is for independent entrepreneurs to

set up a series of factories, copying the product and the process of making it.

Page 18: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Aqua Pak in Use

Page 19: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Aqua Pak is multi-function

• The Aqua Pak is intended as a pasteurizer, but also as a transport, storage, and anti-recontamination (with its small opening) vessel.

• Pasteurization can be achieved while on the move, as long as sunlight is hitting the transparent top.

• Aqua Pak comes with chlorine tablets for cloudy days, and a filter for filtering the water.

Page 20: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

SOIL

TROUGHWATER

INSULATION

CLEAR PLASTICDOUBLE PLASTIC LAYER(TOP LAYER BLACK)

AIR GAP

SPACER

The Solar Puddle, A Large Batch Pasteurizer

Basic Solar Puddle, built into the ground.Horizontal dimensions compressed for clarity.

Page 21: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

The Solar Puddle• The solar puddle has been tested and studied extensively.• Over 80° C can be achieved with thin water layers (25

mm).• Pasteurization temperatures can be achieved with up to

75 mm water depth. This is 75 liters of water for a 1 square meter puddle.

• Many variations possible.• Basic version is built into the ground, but benchtop

puddle is also possible with wooden sides.• Basic version has 4 or 5 plastic layers, but bubble wrap

can be substituted.

Page 22: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Two benchtop solar puddles: Bubble wrap top layer on left. Two-layer top layer, on right, with top layer removed.

Page 23: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Pot-based pasteurizers

Page 24: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Test Results• Limited testing to date, due to issues with

latitude and cloudy weather in Ohio.• 70° C was achieved on a mostly sunny day at 40°

North latitude. About 6.5 liters pasteurized.• Larger pots tested, 29 liters, 55° C achieved for

1 hour. • The key to performance is that the grass gets

hot quickly, transfers heat to the pot by convection and radiation.

Page 25: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Other Batch Pasteurizers

• Other batch pasteurizers can be made from things including bottles, jugs, and sheets of plastic used to form a pouch.

• Plain materials can be used, (grass, cheap polyethylene) though cheap plastic degrades in about 3 months because it does not have UV inhibitors added. The polyethylene in the Aqua Pak has 36 months of UV inhibitor added.

• Any kind of solar cooker can also be a pasteurizer.

Page 26: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Simple Solar Cooker Being Used as a Pasteurizer

Page 27: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Summary of Batch Pasteurization

• Batch pasteurization is simple, effective, and can be very low in initial cost.

• An indicator is required.• Batch pasteurization is limited to modest

amounts of water. Will always be in the “Household Water Treatment and Storage” category.

• Can be combined with filtering, and chlorine to give residual disinfection.

Page 28: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

How to Pasteurize Water-Part 2

• Flow-Through Pasteurizers• Thermostatic valve is required

Page 29: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Flow-Through Water Pasteurizer Principle

DirtyWater, 20° C

Heater,Solar orFlame Heat

Heat Exchanger

Heat transfer From hot to cold

Thermostatic valve

80 ° C

60° C

Clean waterOut, 40° C

Page 30: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Flow-through pasteurizers• Solar or flame heat can be used.• Process is automatic.• Outlet water is only warm, not hot.• You can use a heat exchanger to recycle the heat

in the outgoing water, increasing the throughput by 3 times or more, while adding 50% or less to the cost.

• Many experimental units have been built using solar, but no commercial solar units currently available.

Page 31: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

InStove Water Pasteurizer

• Institutional Stove Solutions, Cottage Grove, Oregon, builds large high quality wood-burning stoves for schools.

• A new option is a flow-through pasteurizer using the large stove and large pot as the heater.

• Much larger quantities of water can be pasteurized.

Page 32: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.
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Page 35: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.
Page 36: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

400 Liters per hour at 10 grams of wood per liter

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Page 38: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

InStove Water Pasteurizer• 100% effective against common harmful microbes in preliminary testing

• Failsafe design – unpasteurized water cannot leave the system

• Can produce over 4000L of safe water per day– One unit provides drinking water for as many as 1000 people

• Optimized for use with InStove stoves– 20+ times more energy efficient than boiling water over an open fire– Uses less than: - 10g of fuel per liter produced - 4kg of fuel per hour

• Designed for use in refugee camps, institutions (schools, hospitals, etc.), or as a small business

• Cost is about $1000 for the stove and $1000 for the pasteurizer parts.

Page 39: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Limitations of Pasteurization

• No residual disinfection, but you can add a little chlorine.

• Doesn’t improve appearance or taste, but you can add a filter.

• Somewhat energy intensive.• Doesn’t help with chemical or mineral

contamination (most places only have biological contamination).

Page 40: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Summary• Pasteurization is one way of purifying water. • Very safe, very verifiable, low cost.• Somewhat energy intensive, so appropriate only

for small to modest quantities of water. • No residual disinfection (unless coupled with

chlorine) and does not improve taste, color, cloudiness (unless coupled with a basic filter).

• Clearly, pasteurization is not the solution in all situations, but its potential has barely been touched.

Page 41: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Additional Information

• Contact information• Where to get…….• Further reading• A worldwide energy calculation

Page 42: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Contact Information

• Dale Andreatta, Ph.D., [email protected]

• Frank Husson, [email protected]

• Robert Metcalf, Ph.D., [email protected]

Page 43: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Additional contacts,Solar Cookers International

• For plastic indicators, Aqua Paks, and solar cookers.

• 1919 21st St. Sacramento, California, US 95811• (916) 455-4499• [email protected]• www.solarcookers.org

Page 44: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Additional Contacts,Solar Solutions, LLC

• For Aqua Paks, glass indicators, petroleum wax.

• Solar Solutions, LLC 10080 Willow Creek Rd. San Diego, California, US 92131

[email protected]• (858) 695-3806 extension 4703

Page 45: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

An Excellent Review of Water Purification Technologies is:

• An Overview of Water Disinfection in Developing Countries and the Potential for Solar Thermal Water Pasteurization, by Jay Burch and Karen Thomas

• Search for NREL/TP-550-23110

Page 46: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Worldwide Energy Consumption to Boil Water

• If one billion people boil 4 liters of water per day for drinking, this requires about 4.58E17 Joules of energy.

• If they boil on wood stoves with 12% efficiency (also accounting for the fuel left unburned when the water reaches boiling) the amount of fuel burned will be 2.4E8 metric tons. This produces about 3.5E8 metric tons of carbon dioxide. This is about 1.2% of the total from fossil fuels, plus carbon monoxide and black carbon.

• If they boil on propane stoves with 50% efficiency, 1.9E7 metric tons of propane will be consumed, leading to 5.7E7 metric tons of carbon dioxide. This is about 0.2% of the yearly total from fossil fuels.

• Regardless of the method, the global warming potential is significant, and could be reduced significantly with any of the techniques given here.

Page 47: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.

Papers by the Current Presenters

• “The Solar Puddle – A Low-Cost Water Pasteurizer,” Andreatta, Dale; American Solar Energy Society, 2001

• “Inexpensive Personal Solar Water Pasteurizer,” Husson, Frank; Andreatta, Dale, American Solar Energy Society, 2003

Page 48: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.
Page 49: Solar Water Pasteurization Dale Andreatta, Frank Husson, Robert Metcalf October 16, 2013 Water and Health Conference Chapel Hill, North Carolina.