Sunday, September 28, 2008

Getting a gov't grant and the first trial of the filter

Now we can get to the stages involving hard research and analysis. Before the
spring 2007 semester started, I approached Dr. Durham about this concept. He
was skeptical but gave me some literature from the concrete industry regarding
pervious concrete. The literature basically pointed out what I have already
posted: pervious concrete was already being used in some simple structures to
improve drainage and the quality of that drainage by trapping large diameter

Dr. Durham also directed me to Dr. Anu Ramaswami, who at the time was taking over the environmental engineering side of the university's civil engineering department. After a brief description of my concept, she suggested I apply to the EPA's P3 (People, Places, Prosperity) research grant competition.

This is a two stage competition, the first stage is a $10,000 grant and the second
stage is a $75,000 grant, with the goal being to initially develop
sustainable/green technologies or educational programs that can be used to
assist developing communities around the world and be profitable as well.
In addition to information about this competition, I was also informed that I had
only 4 days to develop, type and submit an abstract. I turned down
snowboarding in great conditions to hunker down on the couch and hammer
out whatever came to mind. Without much of an environmental or science
background beyond my BS, which I received 9 years prior and did not use in the
work force and relying on the business development skills I honed to a razor's
edge in Shanghai, I managed to bang out what I will honestly call "something"
and send it off to the EPA.

The copy that I turned over the Civil Engineering Dept got less than stellar
reviews, but in the end I did receive the money and managed to turn a few heads
in the process.

So now Dr. Durham and I get down to work. We also enlist the aid of Dr. David
Mays, who has hands on research experience in fluid flow. The two of us
basically got a crash course in filtration through a granular medium (which is
what the filter basically is). What came next was a barage of variables that had
to be determined so that I could get another variable in order to allow me to
calculate the needed filter length for a list of biological, organic and inorganic
pollutants. The process of coming up with a spreadsheet also took another 4
days, over a weekend of course. Once I came up with that, Dr. Durham
determined how much concrete we would need and we set about making a mold
and getting the materials for the experiment.

The chemicals were easy to buy, and I wanted to see what desalinization
potential this filter might have, so in addition to copper and iron (typical
pollutants in water) I added 35,000 ppm of sea salt. Thank goodness I had a big
container of the stuff at home (great for seasoning veggies and noodles).
I also had to reproduce biological contamination, but without the hazard of
handling E. coli. So I used another species found on human skin and in our
mouths, Micrococcus luteus. This bactria thrives on our skin and is similar in
diameter to E. coli except that M. luteus is spherical rather than conical and has
no large flagella, so in effect it is a smaller particle.

Instead of trying to grow a specific number of bacteria, I went with the idea that polluted waters would typically have concentrations of microorganism that are "too high to count".
So I approached the university Biology department and enlisted their aid (I'll
mention the lab manager's name once I look it up in my P3 paper, which is not in
front of me right now). He basically cultured a thick soup of bacteria in broth
overnight. After asking some questions, I decided that I could approach the large bacteria
concentration as a "total suspended solids" value. I then measured the original
TTS value and diluted it by a factor of 10, 5 times and tested the filter separately
against the bacteria contaminated water and the salts contaminated water.

In my next post I'll show graphs of the results as well as some of the write up.
Unfortunately I did not win the second round of funding at the April
demonstration, but I did attract considerable of attention from many very
experienced scientists ( I counted about 20). To add to the heat I was
completely mentally exhausted being bombarded with questions I had yet to
consider at that time.

BTW, if you are really into the whole global environmental/water thing, you need to see this film.

Monday, September 22, 2008

Raw Innovation

Before I go on to discuss the actual design process, lab tests, results,
applications and such, you must be wondering to yourself "why concrete for a
water filter"? Well, this is what I was wondering myself when I first began thinking about how
such a filter would work, but also what the advantages and disadvantages of
using such a filter would be. And after reading the previous post, you can all come to the conclusion that I made it a "mission" of sorts to come up with a cheap water filter made of a
universal material available to everyone.

Think about this. Concrete has been used in one form or another since the
Sphinx and the Pyramids were built. The Great Wall, elements of ancient
western hemisphere civilizations as well. Portland cement as we know it today
was developed by the Romans who mixed quick lime into their mix to allow the
concrete for their roads, aquaducts and other structures to cure and become
usable in a shorter amount of time and even in wet conditions.

And over time, concrete became and has remained the global standard for
building materials. This means that around the world, there are skilled people
who know how to engineer and work concrete for their local needs, even in the
poorest countries. I've met people who have traveled to small villages where the
locals mix concrete on prepared dirt surfaces and place it for basic structures.
So this is not so much a case of re-inventing the wheel as it is teaching an old
dog a new trick.

I brought this idea to Dr. Stephan Durham, a faculty member at CU Denver who
specializes in concrete. It should be of no surprise he was a bit skeptical at first,
but he did give me some literature on something called "pervious concrete".
Pervious concrete has been around for about 30 years, but recently it has
become more "vogue" for lack of a better term as local and state governments
become increasingly aware of the need to improve surface water quality and
take a look at non-traditional sources of pollution like construction sites,
parking lots, building runoff, gas station surfaces and sidewalks.
Pervious concrete, which is basically standard concrete with most or all of the
fine grains not included in the mix, resembles a grey rice krispie treat in appearance.

The mechanism for improved water quality begins with surface water containing
a variety of organic and inorganic pollutants. The water runs over the surface
of pervious concrete and trickles through the pores. During this process larger
diameter pollutants such as drops of autmobile fluid, brake material, dust, etc are
removed (though not completely). When the water meets the much less
pervious bed of small diamater gravel or prepared soil on which the concrete
sits, the water velocity slows and the pollutants settle onto the surface of the
bed while the water slowly percolates though the bed thanks to hydraulic

The pervious concrete filter relies on filter length to remove pollutants via a
variety of mechanisms (I'll go into that in later posts). The big difference
between this filter and the use of pervious concrete for a parking lot is that the
parking lot design revolves around strutural integrity while the filter has no
structural requirement and yet is much longer vertically than a section of
parking lot pervious concrete.

So with that in mind, here is a list of potential uses for a pervious concrete filter
(including the Moon and Mars since they have many of the same materials used
for concrete manufacturing).

I. Acid Mine Drainage Remediation
a. Acid Mine Drainage (AMD) contributes to surface water pollution.
b. Global demand from large developing countries has increased mining
activities as well as the use of alternative sources such as scrap metal.
c. AMD waters may be another potential source of metals.
d. This is highlighted by a Pennsylvania Department of Environmental
Protection study stating [Rathbun, 2004]:
e. “the annual cost to state taxpayers for AMD remediation to be $23
million dollars a year and the estimated state wide value of sludge from these
systems to contain millions of dollars in metals, yet it is handled as waste.”
f. Experimental results have shown that:
1. The filter increased the pH by an average factor of 3.3.
2. The average percent concentration of iron in the filtrate was 15% of
the original concentration.
3. The average percent concentration of sodium in the filtrate was 39%
of the original concentration.
4. The average percent concentration of zinc in the filtrate was 26% of
the original concentration.
5. The average percent concentration of sulfate in the filtrate was 37%
of the original concentration.
g. From a Sustainability perspective:
1. The per unit cost and lifespan of the filter may be attractive for
developing countries for both AMD and improved drinking water quality
2. Any country with existing ready mixed concrete infrastructure can
produce the filter.
3. Filters may have a long storage life and can be easily transported for
use in remote areas and disaster relief.
4. The filter is not designed to be load bearing.
5. Recycled concrete to be used as a source of aggregate, requiring the
fines to be removed by sieve.
6. The filter can be easily produced by manual or automated processes.

II. Poverty Relief
a. local, low tech concrete plants or factories can make filters from
separately pre-packaged ultra fine particles, gravel and Portland cement.
Concrete companies at the regional or national level can prepare, package and
sell these supplies at local prices.
b. Containers can be assembled on site from other local/regional
suppliers or bought by the concrete companies, and given to subcontractors for
final assembly before shipment, or all components can be collected and taken to
the local area for final, on-site assembly.
c. Concrete materials are available almost everywhere, and ultra fine
material should be easy to process and fairly readily available.
d. “Expired” cartridges can be swapped out by trained local people and
sent back to the local concrete factory for recycling. The same local people can
be trained to test the water using simple testing kits to determine when the
cartridge is no longer effective.

II. Military applications
a. Field hospitals can assemble these filters and swap out “expired”
cartridges as needed. They will also be able to test the water as needed for
specific needs and add additional treatment as needed.
b. All of these filters can be recycled by military construction units or
contractors using prepared ultra fine particles, portland cement and pebbles.

III. Underserved Communities
a. Communities in underserved areas of developed countries can utilize
these filters in the same manner as impoverished communities, so those who do
not choose or are unable to live in areas with formal water treatment plants can
use the pervious concrete water filter to process surface and subsurface water
for consumption.
b. These pervious concrete filters are also recycled by sending them
back to concrete plants.
c. The filters can be sold as individual units for individual households
or as larger units for small, multi-family communities.

IV. Other commercial applications
a. Water treatment kits for outdoors enthusiasts, national guard or civil
protection units and as emergency treatment kits for ranchers and farmers.
b. The final stage of gray water systems, to remove all impurities from
gray water after the water has been used for irrigation and before it is consumed.
c. Pretreatment for industrial or laboratory use.
d. Treating brackish water in tailings ponds where oil sand or oil shale
mining is taking place (not yet experimentally proven).
e. Pre-treatment of salt water. This filter will not desalinate water to the
point of making the water consumable, but it could remove significant amounts
of salt (and chemical pollutants) which could prolong the life of filtration
membranes and potentially reduce the amount of energy needed to desalinate

V. Lunar exploration
a. (soil composition)
b. Portland cement composition: calcium silicate cement made with a
combination of calcium, silicon, aluminum, and iron.
c. Similar soil composition means concrete could be produced on the
moon, which means concrete filters can be produced.
d. A gray water system mixing human waste with artificially produced
water would utilize the concrete filter as the last step to filter water for reuse in
irrigation and other non-potable uses..

VI. Martian exploration
a. Iron ore mining
b. Rock composition
c. Portland cement composition: calcium silicate cement made with a
combination of calcium, silicon, aluminum, and iron.
d. Similar soil composition means concrete could be produced on the
Mars, which means concrete filters can be produced.
e. A gray water system mixing human waste with artificially produced
water would utilize the concrete filter as the last step to filter water for reuse for
irrigation and other non-potable uses.

Saturday, September 20, 2008


I ended up in China after Comcast bought ATT Broadband in 2002 and took my severance over to China. I had thought about Europe but decided "everyone does Europe" and I was looking for a challenge ( go ahead and laugh other China vets and old hands). And for those of you who are familiar with Shanghai past the inner ring road and namely the Min Hang district, there are alot of canals in the area and they are all used as public trash cans and toilets (as are most of the bodies of water I saw in China).

While always unsightly, in the sultry air of August you'll know when you are approaching a canal long before you see it. So I am walking over a bridge over the canal on the way to pick up a minibus on Hu Min road to go into the city (I felt robbed when line 5 was completed long after I left that area, taxi fares from downtown are pricey even on an empty road early in the morning or late at night).
I see one of the many cargo barges that ply the canal system to transport stuff and one of the guys who drive them standing on the edge of the boat. Before he sees me he bends down and scoops out a handfull of this inky black and putrid smelling water and drinks it. He then sees me, smiles and waves. His teeth look like a brown train wreck. I'm shocked and a bit disgusted by this but realize this guy was obviously too poor and possibly didn't know any better. And even if he did he may have not had enough money to buy bottled water. I also thought that if pushed into severe enough circumstances, I would do the same and so would anyone else.

That is the unique property of water as a commodity.

Fast forward to 2006 at the University of Colorado Denver and I am sitting in Physics I, the instructor (Dr. Randall Tagg) is lecturing us on fluid flow theory and flow through porous spaces. He also happened to be a specialist in fluid properties. I also am working as a materials tester at the time, meaning I do various tests on concrete, soils, asphalt, rebar and welds at construction sites. I noticed that in the curing tanks for our concrete cylinders that even after the concrete cured, when removed it would take some time for the water to drain from the pores of the cylinders.

So the light bulb comes on and I ask myself if concrete pores could trap organisms in water. I then posed the idea to Dr. Tagg and with his assistance wrote two papers reinforcing the idea that pore space only had to be small enough to inhibit E. coli from being able to swim. An accumulation of less mobile/immobile bacteria would then create a physical barrier at each pore space and inhibit the flow of additional bacteria through the pore space.

I was encouraged to pursue the idea further with some newer faculty members in the Civil Engineering Dept and that is where the research really took off.