Plant-based potties protect lakes from poo

Chuck Bednar for – Your Universe Online
Nearly 100,000 people reside on floating lake houses in Cambodia’s Tonle Sap Lake, and it certainly is an idyllic place to live – that is, until it comes time to use the restroom.
A person’s gut reaction is to simply relieve themselves in the water. Need to pee, standing next to a large body of water: It’s ingrained in us from a young age to do this. (Thanks family vacations to the beach!)
But 100,000 people consistently relieving themselves in a lake causes a pretty large problem, as fecal microbes contaminate the water. This can cause it to become septic and result in outbreaks of life-threatening diseases such as cholera, particularly during the low water dry season.
However, engineers from the Phnom Penh-based company Wetlands Work! are developing Handy Pods, a plant-based purifier that NPR describes as little kayaks filled with vegetation that float underneath a river house’s latrine and decontaminates the water that flows out.
Keeping the lake’s water clean is important, because more than one million people live on or around it, and exposure to wastewater leads to diarrhea outbreaks on an annual basis. In fact, 20 percent of all deaths in Cambodian children under the age of five are due to diarrheal diseases.
Handy Pods work as such: when a person goes to relieve themselves, the wastewater flows into an expandable bag known as a digester. The digester is filled with a microbial soap of bacteria and fungi that breaks down the material into gases such as CO2, ammonia and hydrogen.
Any microbes surviving the first decontamination step are then carried into a pod filled with water hyacinth, the roots of which are large enough to collect the remaining bacteria, NPR said. The water that runs off the hyacinth roots into the lake is clean enough for people to swim in, but Wetlands Work! founder Taber Hand noted it is not safe enough for consumption.
During a pilot program, the company tested the pod at a floating research house for a 13-month period. The trial, which involved up to 10 residents for a 10-week period, successfully isolated and treated wastewater “with no aesthetic problems in terms of smell,” said Wetlands Work!
“We intend to demonstrate… that a floating household’s wastewater can be contained and treated to a high grey water standard, allowing ambient water outside the Pod to be more healthful,” they added. “By significantly improving local ambient water quality as well as providing cleaner, safer water for household use, we hope to foster better health among families with children and a cleaner surrounding natural environment.”
The success of the pilot program paled in comparison to laboratory tests, where the pods were found to reduce E. coli levels by more than 99 percent, according to NPR. The difference, Hand said, is likely due to the fact that actual lakes have other sources of contamination besides bathrooms. In particular, pigsties around Tonle Sap lake produce a tremendous amount of waste, he noted.
“The floating communities of Tonle Sap Lake are one of the most challenging contexts for sanitation in the world. Handy Pods are potentially a useful way for processing human excrement in this context,” Joe Brown, an environmental engineer at Georgia Tech who is not involved with the Wetlands Work! project, told NPR.
He noted that the floating toilets would be widely distributed anytime soon, partially because it was not clear if they could filter out viruses and disease-causing parasites. Cost could also be an issue, he said, as the Handy Pods cost about $30 each and most villagers living in the region earned less than $1,000 each year.
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