A team of researchers from Ben-Gurion University of the Negev have demonstrated, for the first time, a technique for converting human excrement into hydrochar—a safe, renewable biomass fuel that resembles charcoal—as well as a nutrient-rich fertilizer.
According to BGU, this process could potentially address two major issues that affect many less affluent countries—poor sanitation and growing energy needs.
In a pilot study published in the Journal of Cleaner Production, BGU described how they used a technique known as “hydrothermal carbonization” to heat raw solid human waste in a special “pressure cooker” to three different temperatures (180, 210 and 240 degrees Celsius) for periods of either 30, 60 or 120 minutes.
This sterilizes the human waste and dries it out, creating a solid coal-like substance known as hydrochar, which can be used for household cooking and heating. Last year, BGU researchers carried out similar research using poultry excrement.
“While it is rich in organic matter nutrients such as nitrogen, phosphorus and potassium, human waste also contains micropollutants from pharmaceuticals, which can lead to environmental problems if not disposed or reused properly,” says Prof. Amit Gross, director of BGU’s Zuckerberg Institute for Water Research and expert in the efficient use of marginal water, remediation techniques and the environmental risks associated with contaminated water resources.
Approximately 2.3 billion people still lack basic sanitation services, according to the World Health Organization. Of those, around 892 million people—most of whom live in rural areas—defecate in the open.
Energy scarcity is also a problem in these regions. Approximately 2 billion people worldwide use solid biomass—such as wood—which is converted into charcoal and then used for cooking and heating. However, these practices have a significant impact on the environment.
“By treating human waste properly, we can address both of these issues at once,” Gross says.
This article has been republished from materials provided by Ben-Gurion University of the Negev. Note: material may have been edited for length and content. For further information, please contact the cited source.
Using hydrothermal carbonization for sustainable treatment and reuse of human excreta. Reut Yahav Spitzer, Vivian Mau, Amit Gross. Journal of Cleaner Production, Volume 205, 20 December 2018, Pages 955-963, https://doi.org/10.1016/j.jclepro.2018.09.126.