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?