New technology turns human crap into clean biofuel

Millions of people living in developing countries face a double challenge: sanitation and energy production. Researchers at the Ben Gurion University of the Negev (BGU) in Israel have killed two birds with one stone by developing a solution to turn human waste into hydrochar, a readily available fuel.

Dirty waste to clean the fuel

According to the World Health Organization (WHO), 2.3 billion people still do not have access to basic sanitation services. Among them, about 892 million people defecate in the open air. Open defecation poses a significant risk of contamination of the freshwater supply and is badociated with the deaths of 700,000 children each year who are affected by diseases such as diarrhea.

Exposure to germs not only exposes children to the development of disease, but can also, in the long run, cause changes in intestinal tissue that impede the absorption and utilization of nutrients in foods, even when the child does not seem sick. A report by the World Bank linked open defecation with poor knowledge of children. As such, open defecation threatens the human capital of developing countries.

"Human excreta is considered dangerous because of its potential for transmission of the disease," said lead professor Amit Gross, lead author. This can lead to environmental problems if it is not removed or reused properly. "

BGU researchers have sought to address this major global health problem using a process called Hydrothermal Carbonization (HTC). In a system that resembles a pressure cooker, the team heated raw solid human waste at three temperatures (180, 210 and 240 ° C) and at reaction times (30, 60 and 120 minutes) that dehydrated the excrement , thus producing a solid. known as hydrochar and a nutrient rich liquid. Previously, the BGU research team had been working on poultry excrement.

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Hydrochar produced from wood sample (Euc Amplifolia). Credit: Fang et al, Journal of Industrial Chemistry and Engineering.

Hydrochar is very similar to biochar, with some notable differences. Although both are solid and carbon-rich solid byproducts, both characters have different physicochemical properties that affect their potential applications. These include, but are not limited to, carbon sequestration, soil improvement, bioenergy production and wastewater remediation. While the biochar is the result of a slow pyrolysis (burning essentially without a flame), the hydrochar is produced with hot compressed water instead of drying. Another advantage is that HTC produces larger amounts of coal and uses less energy than pyrolysis.

Hydrochar can be used as coal, for domestic heating and cooking, replacing wood. Used in this way, hydrochar reduces the carbon footprint of communities by preventing deforestation, soil erosion and greenhouse gas pollution. Due to the high temperatures involved in the HTC process, the resulting hydrochar is sterilized and can be handled safely. The aqueous by-product can be used as a fertilizer, according to the authors. Journal of own production.

It remains to be seen how this technology can be adapted to those who need it most. In the meantime, as we approach World Toilet Day (November 19), it's good to take a moment to appreciate the invention that saved the most lives in history: 'water.

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