Appliance of Science at the Model Agriculture Centre, Phana

The appliance of science was the tag-line on a series of advertisements in the UK some years back. I think it was used by a company producing fridges and freezers. The phrase came back to me when I visited the Model Agriculture Centre in Tambon Phra Lao, Phana. It seems that this piece of equipment is proving of interest to lots of local farmers. It is only of use to them if they are keeping pigs, however. That is because it relies on a good quantity of pig dung to be produced and collected as often as possible. Here are Pensri and  the young man in charge explaining to each other how it works. He explained the day-to-day running and Pensri explained a bit of the practical chemistry behind it. The dog found it all very interesting but made no comment.

The first step is to collect as much pig dung as possible. That is not a problem here as my next post updating the post about livestock will show. The dung is washed into the strong plastic storage tank through this aperture:

The tank is filled to about half its capacity with the slurry of pig dung mixed with water. Methane gas is given off and rises to fill the tank. A pipe connects the tank with a gas cooker through this pipe arching over the water containers. An offshoot of the pipe leads into the inverted plastic bottle which has water in the bottom and a hole cut into the top. The short piece of pipe going into the bottle has a valve which allows gas into the bottle if the pressure is too great. The gas then bubbles through the water and escapes into the air through the hole in the bottle. The purpose of the water is so that if bubbles are seen then it is apparent that the gas pressure is too high. Ingeneous, eh?

Here you see the gas ring, actually a double ring, hence the divided pipe and the two taps. Depending on how much heat you require, you open one or both of the taps. Of course, the gas supply could be attached to a more sophisticated cooker if required.

 

 

About 10 kgs of pig dung is collected here each day and fed into the tank. Enough methane gas is produced to provide all the fuel the half dozen or so workers need in order to cook their food and heat water for tea.

 

The tank is emptied every few days by running off liquid from the end of the tank. Bacterial action inside the tank destroys the fecal matter and there is no smell from the run-off. However, the tank that collects the run-off is normally covered.

Comments

[Larry Hickey]

very good, Is the run off still good for firtalizer? Two uses for one product.

[Lawrence]

Hi, Larry. I think you are right about the two uses, but there is very little left (and no faeces) after the enzyme action breaks it down and the methane is produced. So I think what is left does have fertilizer properties, but there is very little of it. They're growing a line of chilli bushes nearby so there is probably enough to keep those going.