SRC offers solution to Pedro Cays toilet needs

BY PETRE WILLIAMS-RAYNOR Environment editor williamsp@jamaicaobserver.com

Wednesday, October 31, 2012    

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THE Scientific Research Council (SRC) has offered the sanitary biogas unit, also known as a bio-latrine, as a solution to the lack of adequate toilet facilities on the Pedro Cays.

“It is really an upgraded energy-efficient method of treating human faecal waste in a non-flush system. It is [also] odour-free, and being a nonflush system, it is suitable for places where you have challenges with running water or a lack of running water,” Roslyn Fisher, general manager for Marketech, a subsidiary of the SRC, told the Jamaica Observer.

The Observer, in September, broke the news of the awful conditions under which people live on the Pedro Cays, some of them for up to six months each year.

In addition to a lack of toilet facilities, which has forced some fishers and other residents to designate an area of Middle Cay — one of the two islands occupied by humans — for passing faeces, there are also challenges with the buildup of solid waste on the island. Further, the islands have no running water.

According to Fisher, the biolatrine is built similar to a flush toilet, except that it does not require water and is connected to a biodigester that captures the faeces. The digester is an oxygen-free tank, which treats human waste on site, eliminating pathogens and malignant bacteria.

“The faeces would go directly into an inlet chamber and is transported by gravity to the digester in which the organic matter is broken down by bacteria in the absence of air. After a period of, say, 120 days, the bacteria degrades most of the human excrement. When it is being broken down, you will not get the smell above ground,” Fisher explained, noting that the bottom of the biodigester is sealed so as to prevent the contamination of groundwater.

“So it is environmentally friendly,” she noted.

At the same time, Fisher said that the bio-latrine has the added benefit of converting human waste into a fertiliser as well as biogas, which can be used for lighting and cooking.

“Human waste is organic, so if you put in the air-tight biodigester, what will happen is that the normally occurring organisms, such as the worms and so on, would act on the waste and break it down. When that happens, you get what we call the digested slurry, which is the effluent after it is broken down, which can be used as manure for trees. So it would be like an organic fertiliser.”

On the production of biogas, she said: “It is during the breakdown of the waste that biogas is produced and is stored in the gas-tight area enclosed by the dome [biodigester].

“Depending on the volume of [waste] produced, they can generate biogas, which could be used to provide security lighting for the same bathroom or for something else [such as cooking or heating],” Fisher told Environment Watch.

However, she cautioned that it would have to be cleaned, as one would a regular toilet.

“It has no odour and you don’t have any flies and so on, though you have to clean it like you would clean your normal bathroom,” she said.

Meanwhile, Fisher said that already they have made the suggestion to the Fisheries Division of the Ministry of Agriculture, which has indicated an interest in looking at the option.

Should they decide to explore it, Fisher said her team would visit the cays to undertake the requisite due diligence.

“What we do is, we do the site visits and we design the system to suit the specifications. You have to take the topography of the land into consideration and also the size, depending on the number of persons who we project will be using the system,” she said.

As to the cost, she said that would depend on the size of the units.

“One of the things that pushes the cost is the size of the structure you are putting above it and whether it is made of wood or block and steel,” she said. “Though for places such as that [the Pedro Cays] which will have the wear and tear with the salt, I would recommend concrete.”

To ensure the successful application of the technology, she said an excellent complement to their efforts would be public education.

“What we recommend for it to be sustainable is social intervention to teach persons to use the system correctly and to maintain sanitary conditions.”





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