Mar
25
TBWOH Updates – March 2009
Filed Under TBOWH Updates
WORLD HUNGER OFFERING PROVIDES CLEAN WATER FOR ASIAN VILLAGES
Gravel, sand, and charcoal…That’s it. That’s all it takes to give people clean water.
OK, well, you have to have water tanks, rebar, and concrete to create stands for the water tanks, and piping to transfer the water from tank to tank, but, at any rate. . . gravel, sand, and charcoal. These are the materials used in the filters to give people clean water.
Sounds simple enough, right? Well, it actually is, and that is a good thing since villages need to be able to sustain this technology on their own.
The basis of this filtering system is slow-sand filtration because it does not require electricity or special chemicals. It only requires periodic maintenance and can produce a 90-99% bacterial reduction when maintained properly. Slow-sand filters perform this work by harnessing natural processes.
As water flows down through the sand in a filter, a biological layer forms in the top couple inches of the sand. This biological layer absorbs—or eats, if you will—organic and bacterial matter present in the water. This is good, because much of the organic and bacterial matter present in surface water (or river water in this case) is what makes people sick. By removing this bacteria, there is a much greater chance of keeping people well.
Unfortunately, a sand filter is not enough. The river water is terribly dirty and would clog up the sand filter too quickly. Therefore, the water must be pre-filtered using gravel. The water is piped to the bottom of a water tank filled with gravel and then allowed to rise up through the gravel. The gravel, with its rough sides, acts as a gathering place for the dirt and suspended materials in the water. Once these clumps become large enough, they fall to the bottom of the gravel filter. The cleaner water is then piped from the top of the tank and sent through two other gravel tanks making the water clear enough for the sand filter to be effective. Each gravel tank is fitted with a large back flush valve at the bottom so that the dirt that has settled can be flushed out.
So, this is the process. The water is pumped from the river to the top holding tank—this is the only time electricity is used; the rest of the time gravity does the work. Next, the water flows through three gravel tanks and our slow-sand filter as described above. Then, before entering the final holding tank, the water passes through charcoal, absorbing any poisons or chemicals present in the water. Once through the charcoal, the water is ready to picked up and used by villagers.
This water filtration system works amazingly well and becomes a solid way to give people clean water.
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