c lean w ater 4 a ll revolutionizing the way you view dirt
TRANSCRIPT
CLEAN WATER 4 ALLRevolutionizing the way you view dirt.
MOTIVATIONS FOR PROJECT
More than 1 billion people lack access to safe water for drinking, personal hygiene, domestic use
3.6 million people die each yearof water-related diseases; 98% ofdeaths occur in developing world
Diatomaceous earth filters are low cost, locally producible solution
http://www.firstbaptistclinton.org/clientimages/33351/child-with-dirty-water.jpg
TARGET POPULATION AND FILTER USAGE
Majority of those without proper sanitation live in Southern Asia and Sub-Saharan Africa
Over 2/3 live on less than $2/day Target 3 liters daily per person for household
filters serving 5-7 people
UNICEF / WHO Progress on Drinking Water and Sanitation Report, 2008
GOALS
Development and production of a filter that balances
DIATOMS
Common name for over 200 genera of often unicellular organisms encased within cell walls made of silica
Own the ability to create exact replicas of themselves with micro or nano-scale definition.
Often diatomaceous earth, the fossilized remains of diatoms, is mined for many uses.
University of Washington: Emily Marshall
DIATOMACEOUS EARTH
Soft, chalk-like sedimentary rock, which is often ground into an off-white powder (if no other minerals are present).
The powder is abrasive and porous.
Common uses:- Organic pesticide- Pool filters- De-wormer of livestock- Thermal Insulator
www.safesolutionsinc.com
www.prsa.com.au/watercare.html
DIATOMACEOUS EARTH FILTERS
Used for filtration of:- Pool water- Drinking Water- Beer and wine- Syrups and Sugar
Size of the pores range from .5 to 2 microns.
www.associatedcontent.com
DIATOMACEOUS EARTH FILTERS
Bacteria can range in diameter from 0.2 to 2 microns. But, diatomaceous earth is still effective at filtering even small pathogens.
EXISTING FILTER TECHNOLOGY
Filter Candles-The ceramic of a filter candle is cast in such a way that it has one domed closed end. The other end of the ceramic is open. This open end is closed off with a food grade plastic mount, which enables the candle to fit into a filter housing. Water passes from the outside of the candle to the inside, leaving particles of dirt, bacteria, etc. on the outside of the ceramic. The filtered water then passes out of the candle through the mount. - Cost: $30-50
DARCY’S LAW
Flow through a porous media is governed by:
Q (volume/time) = Total Discharge
k (area) = Permeability of Media
A (area) = Cross Sectional Area
Pb – Pa (Pressure) = Pressure Drop
u (Pressure second) = Dynamic Viscosity
L (Length) = Length the Pressure Drop is Taken Over
Only valid for slow viscous flow
DEVELOPING OPTIMAL FILTER DESIGN
SPECIFIC TESTING DETAILS
Both Filters Flow Rate
Gravity driven Pressurized
Filtering Ability Check filtering of
microorganisms Fouling Rate
Liters filtered before clogging
Improve to minimize cost
Sintered Filter Abrasion Test
Ability to withstand cleanings
Yield Strength Must be robust
Elastic Modulus
SINTERING AT A GLANCE
2
D
1
3
Driven by Surface Energy and Capillary Pressure
Material Moves by Boundary diffusion
(1) Lattice diffusion (3) Surface diffusion and
vapor transport (2) Densification occurs
when material moves from between centers, reducing D.
SINTERING CONCERNS
Densification is the enemyWe want to maximize surface and vapor
transport and minimize boundary and lattice diffusion
SiO2 has high Tm!Sintering can occur far below Tm and our
“sharp” material should have a large driving force to sinter
Reactivity?Luckily SiO2 is already oxidized so air is OK
Plan: Short, low temperature sinter in air
POTENTIAL STUMBLING BLOCKS
Sintering Technology/Ability Inconsistent structure leading to poor filtering and
reproducibility Poor durability
Cost If DE was the solution, why hasn’t it been done?
Balancing Flow Rate and Filtering Ability May find we can filter effectively or filter fast, but
not both Inability to filter solutes
Filter only effective against biological threats Feared Scenarios:
Slurry too slow and sintered too expensive Inability to produce consistent well-sintered filters Produce filters that work almost as well as existing
tech at 5x the cost
PROJECT GOAL TIMELINE
THANK YOU!
QUESTIONS?