Showing posts with label filtration. Show all posts
Showing posts with label filtration. Show all posts

Tuesday, October 20, 2009

Question from a reader: Fixing water filtration in India



A simple sand and activated charcoal filter ($10-15) can filter hundreds of gallons of water simply and cheaply. But will this solve India's (bottled) water issues?? Read on... (photosource: bethechangeinc)


I got the following question in my inbox recently. Its becoming a question of increasing frequency, and I want to address it properly. Here's the "question" the reader wrote:

Last year, after a research expedition [on the effect of plastics on the environment]...we were giving talks and meeting with legislators along the way [in North America].

At one of our talks, a woman who had just returned from a long trip in India approached me, and said, "this is all great what you guys are doing to educate people, BUT there are much larger problems with plastic bottles and waste overseas". She told me that due to poor sanitation, in some areas she'd been in, people had no choice but to drink out of plastic bottles, and lacked the infrastructure to deal with them.

Which made me wonder if bringing water filtration systems to India might make a difference, albeit small.... for peanuts here ($500-$1000), an entire school can have clean water.

I've never been to India, but would be interested to hear your thoughts. Perhaps we might try to raise money for a few filters, to start with...

Here was my response:

I agree with the bottled water issue. As much as I detest bottled water, I find that when I'm in the developing world for very short bursts (where I don't have the time to purge my system and adapt) and need reliable, safe water quickly, I rely on bottled water (note: I try to drink tea, boiled water, other boiled beverages or soups for the most part, and only eat fresh, cooked food. Bottled water is a substitute when I can't find these or its simply too hot!). Amongst poor communities, plastic bottles are a huge commodity. Recycling goes on in full, plus the thicker, better bottles are used as water bottles or to store other liquids. They use these for several reasons -- convenience, cost (free to find, recyclable when they are done, easy to replace), how light it is, how sturdy it is, its lack of brittleness, etc. And yes...often they have no other choice.

Water filters are available in abundance in most of the developing world, particularly in non-disaster zones. India has a lot of indigenous water filters that do a very good job...most selling for around $50-$100. Most middle, upper, even poorer class Indians have them installed in their houses, though the best and most effective need access to electricity (they are RO systems). If you really want, you can build one using sand and a large bucket (or see diagram above). This is how most wastewater is treated in the US, though on a much larger scale. Clear water combined with some bleach dosing (aka chlorine disinfection), should render perfectly safe and drinkable water, and all for less than $10.

Probably best of all, there is always the option of boiling...the problem with this is that its very energy intensive and if you use wood/charcoal/kerosene, its simply too expensive. (I tend to boil my water usually in the developing world, except when i've run out of my supply and then use the water i find either at a tea shop or i buy bottled water).

Sometimes its not the filtration that's the problem....its the sourcing of clean water, the collection, the transportation, and the storage of water that are the biggest issues. Outside of the sourcing issues, plastic generally fills these voids.

Of course, for problems like arsenic, fluoride, salinity, etc, where you need more advanced cleaning, or where the water is extremely turbid (cloudy or visibly dirty), it becomes a different issue. These are very regional issues, and generally you can figure out what the biggest water problems in that area are by visiting the NGOs, doctors or govt public health agencies in that area. If its pathogen-related (which is the majority of water quality issues), then generally some proper boiling or filtration/disinfection will quell the problem. But other issues need more specialized solutions.

Finally, I'm not a huge fan of transplanted filters or other mechanisms. Filters from here are not made to withstand water or field conditions there. Expensive systems have a short shelflife, then like every other good transplant, they wither and die. This is partially because there is no one to do regular operation and maintenance, or who has been trained properly to fix even the smallest problems. A COMMON problem is letting untrained hands take over the operation of a technology. Their curiosity gets the better of them, and the technology is quickly rendered useless. Replacement parts are hard to find and buy, and the issue of untrained hands repeats itself. Always look for indigenous units, you are much more likely to have success in terms of adoption, operation/maintenance, and replacement if necessary.

These are my immediate thoughts on the subject. I'm always happy to discuss this further with you...

Thoughts anyone??

Friday, May 2, 2008

An Update on the Aquaduct

A few weeks ago, I blogged about/reviewed a technology called The Aquaduct. As stated in that post, I had emailed the team a few questions that I couldn't find answers to. It took them three weeks to respond, and they sent me a generic answer after all of that. But apparently, they've started a blog with the first post answering a lot of my questions, including how they came up with their design, the type of filter they used, the cost of their product, and where they were heading with it.

Frankly I'm a bit disappointed with the vagueness of their answers. Still it atleast scratches the surface...


Monday, April 14, 2008

Water Technology: The Aquaduct


The IDEO team pose with their winning technology (photo: examiner)

Technology Name: AQUADUCT


Description:
In a nutshell, the Aquaduct a pedal powered water transportation and filtration system.

Aquaduct was designed by a team of IDEO folks in response to the Innovate or Die competition 2007, sponsored by Google and Specialized Bicycles. It placed first. The rules were simple:
  • Invent an unheard of, unprecedented pedal-powered machine, build it and film it. Just make sure that your innovation has human pedal power as its original source.
  • You may either ride solo or build with a team of up to five people.
  • Individual entrants (or the team contact) must be registered members of YouTube at the time of entry, be at least 18 or older and be residents of the U.S., Canada, France, Ireland, Italy, Japan, The Netherlands, Poland, Spain or the U.K.
Here's the basic layout and design of it:



My review:
The Aquaduct basically helps with transportation, filtration, and storage, (and disinfection?? need to check on this).

The good: It uses bicycles (with parts that can be found in even the remote parts of any developing country) and human power (probably the only thing they can count on in poor areas); it looks cute, and combines several different water processes into one unit. The filter is just representative of other more locally available filtering systems that we can find. I love the fact that the water is covered at all times, which keeps it from being contaminated further. And I love the pedal-powered pump.

The what: Ummm...bicycles being used to transport water or anything else in developing countries are not new. Infact bicycles are the first transportation vehicles that a poor person will invest in. And they've been using bicycles to transport water and everything else for centuries. So why would anyone invest in this tricked out tricycle that carries only water??

And cost-wise, bicycles are luxury items to being with, in many of these parts. So you have to make it functional. Essentially, think about the cost and then double the amenities that come with it or it will fail.


Bicycles are crucial transportation for the poor, and a luxury. On the left, Ugandan boys carry jerry cans of water back home [1]; on the right, an Indian boy carries cans of water, petrol and a friend on a tricycle [2]. If Aquaduct wants to succeed, it must expand its functionality.

Variations I would suggest:

1. Most poor people I've gone water hunting with, carry plastic or clay pots (the clay keeps the water cold), or large 20 gallon plastic jugs (aka jerry cans). The Aquaduct should actually include areas to load existing water jugs and filter into existing water jugs, not new ones that you sell with the tricycle.

2. Make the rear storage unit a "clip-on" so that they can take that thing out and carry other things when they need to.

3. I love the peristatic pump. Is there any way you can design it so that the pedal-power can be used to pump water directly from the ground? or transfer to power other things?? Poor people WON'T invest in this unless it can serve multiple purposes.

[1]: Source: Staffordshire Learning Network
[2]:
Source: People's Daily Online

Other reviews/information:
http://www.ohgizmo.com/2008/03/12/aquaduct-is-a-pedal-powered-water-purifier/
http://urlgreyhot.com/personal/weblog/innovate_or_die_winner_aquaduct
http://www.dezeen.com/2008/03/11/aquaduct-by-ideo/
http://mellowvelo.blogspot.com/2008/01/aquaduct-mobile-filtration-vehicle.html
The very uninformative Innovate or Die website
The inspiration behind Innovate or Die:

Friday, April 4, 2008

Water 101: Decontamination, the basics


Clean drinking water - the goal of decontamination [1]

In my last post of the 101 series, we discussed how water contamination happens. In this post we'll talk about how to decontaminate water.

Decontamination really involves two main steps:

1. Figuring out what the contaminants are, and their levels of concentration:


As we talked about before, most contaminants cannot be seen by the human eye. You need to do a series of lab tests on the water to determine the types of contaminants and their concentrations. The concentration of the various contaminants is particularly important because you need to know how dangerous the water really is, and how powerful a cleaning process you need. The United States Environmental Protection Agency (US EPA), the European Union (EU), and the World Health Organization (WHO) (each country has their own such organization as well) all outline safe levels of contaminants for the human body. The thing is, many contaminants are naturally occurring in water, and they are not harmful upto a certain levels. It is beyond that level that the contaminant is dangerous for human consumption, and that's the point that a cleaning process needs to be used.


Water samples need to be lab tested to determine contaminants [2]


2. Using a series of cleaning steps or processes to remove the contaminants:

Once you have determined the nature of the contaminants and their concentrations, you need to find the right processes for each contaminant.

Decontamination generally involves the following overarching processes or a combination of processes (this is an oversimplified version, we can get into the details later):


A series of cleaning processes can get the water on the left to be clean like on the right [3]

a. Sedimentation:
This is the best process for separating liquid and solids. Essentially you take the dirty water and let it sit for a while. Gravity kicks in, and all the heavier stuff will settle at the bottom (flotation, where lighter stuff floats on the top of the water and is skimmed off, is a subset of sedimentation).


Water sedimentation: notice how the heavier contaminants have settled to the bottom [4]

b. Decantation: Decantation is the process following sedimentation, where you pour the cleaner liquid (or let the liquid overflow) out, leaving behind the heavier stuff (sediments).


A Cambodian woman decants sedimented water [5]

c. Filtration: Filtration is the process where the most bad stuff gets taken out. Usually you pass the liquid through some sort of porous membrane (like cloth or other things). The bad stuff gets held back or stuck on one side of the membrane, while the cleaner water flows through to the other side. The efficacy of filtration depends on the quality of the filter, like how small the pores in the membrane are and how well it keeps the bad stuff on the other side.


Schematic diagram of a simple water filter. Water first flows through the sand, then the gravel, and finally a cloth filter. The sand and gravel take out the coarser contaminants; the cloth takes out the fine contaminants. [6]


d. Distillation: Distillation is the most effective water treatment process, but it is also the most expensive because of how much energy it uses. Essentially, you boil the water, collect the steam and cool it down. Its effective in removing metals (like arsenic, calcium and magnesium...which is why its good for your iron as it leaves no residue) and killing germs. However the removal of organic chemicals (derived from petroleum or such) have a variable removal rate. Chemicals that have boiling points lower than that of water, for example, will also vaporize with the water and contaminate it even in steamed form. For chemicals like these, advanced water cleaning processes are used.


Schematic diagram of distillation (in a lab). This can be done without the use of lab instruments as well, en masse. [7]


e. Disinfection
: Disinfection is the process of killing germs. Sometimes the water is free of metals and the other grunge, and just has a bunch of germs which need to be killed. Or often, even the cleanest water that is exposed to air quickly gets contaminated by germs in the air or area surrounding the water. Disinfection is generally the last step of water treatment.


A woman disinfects her bucket of drinking water with chlorine. [8]


Photo Sources:
[1]: Tim Norris

[2]: Juvertson
[3]: http://muriellascorneronmoringa.googlepages.com/
[4]: http://www.easttennesseewildflowers.com/Teacher_Resource.php
[5]: Tom Sprague photo
[6]: http://www.blithfieldeducationcentre.co.uk/kp/waterpages/make_a_water_filter.htm
[7]: www.chemistrydaily.com
[8]: http://www.usaid.gov/press/speeches/2005/ty050915.html