Published Research Confirms SOIL’s Composting Method is Effective
At SOIL, we love teaming up with scientists to explore how ecological sanitation works. And one of the main pillars of our ecological sanitation operation is transforming environment-polluting poop into nutrient-rich compost. To do this, we follow the World Health Organization (WHO) standards for human waste composting – creating piles with the ideal ratio of poop to cover material so that natural heat-tolerant bacteria will get to work and break the materials down and destroy pathogens. These piles get hot! At peak temperatures, an average pile will reach 160 degrees Fahrenheit, far surpassing the WHO’s recommended threshold.
Figure. Proportion of microbial community derived from untreated source material (buckets) samples throughout the composting process.
A few years ago, we teamed up with scientists at UC Berkeley to understand what pathogen communities live in SOIL’s compost piles, and how well they tolerate the heat. We took samples from our compost piles in Haiti at several stages of decomposition, extracted the DNA, and sent it off to California for analysis on a device called a PhyloChip. While we assumed that our compost was pathogen-free after reaching such high temperatures, the data from this work confirmed that, telling us that pathogenic bacterial families like E. coli were eliminated while the heat-tolerant “good” bacteria were increased. More details about this work can be found in the full PloS One journal article:
Piceno YM, Pecora-Black G, Kramer S, Roy M, Reid FC, Dubinsky EA, et al. (2017) Bacterial community structure transformed after thermophilically composting human waste in Haiti. PLoS ONE 12(6): e0177626. https://doi.org/ 10.1371/journal.pone.0177626
Huge thank you to our fellow researchers at the Lawrence Berkeley National Laboratory, University of California – Berkeley, and University of California – Davis, for making this paper possible!
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Chris Canaday
June 18, 2017 (1:15 pm)
This is spectacular. Would these same researchers be interested in looking at our dry toilet system here in Omaere, in which we use decomposed feces as cover material for the new feces. We have been recycling in this way since the beginning of 2011. Our experience is that this cover material is much better for controling smell and flies, compared to sawdust, wood ash, or a mix of the two. Our theory is that this recycled soils contains lots of great microbes from the previous cycle (in an inactive state, like endospores, fungal spores, etc.), ready to have a new party in the new sh*t. It would also be great for them to study the fermentation of feces and (separately) urine that Nadia Andreev does with lactic acid bacteria. Could you please mention this to these researchers in Berkeley? (Are they gearing up to apply to the Resilient By Design Bay Area Challenge http://resilientbayarea.org/ ? I would like to help one team apply EcoSan.)
Monika Roy
June 27, 2017 (8:40 pm)
Hi Chris! Great to hear about your projects. We’ve thought about using our finished compost as cover material for the decomposing waste, but it’s just selling out too fast! In theory, yes, it would probably be a good inoculant for the fresh material. At the moment, the researchers are not studying lactic acid bacteria or participating in the Resilient By Design Bay Area Challenge. Thanks for your interest!