Ahead of World Toilet Day on November 19, comes news that researchers from Ben-Gurion University of the Negev (BGU) demonstrated a process for converting raw human excrement into nutrient-rich fertilizer and safe, reusable fuel.

According to the study, researchers managed to refine a process for heating raw solid waste in a pressure cooker using a hydrothermal carbonization (HTC) technique, converting the excreta to hydrochar, which is a reusable and safe biomass fuel that is similar to charcoal. This could have implications for the world’s ever-growing energy needs and sanitation issues, according to the team.

To demonstrate the process, researchers exposed the raw waste by way of the HTC technique to three temperatures (180, 210 and 240° C) and three reaction times (30, 60 and 120 minutes). Consequently, the solids became dehydrated, transforming into the combustible solid substance called hydrochar, as well as a nutrient-rich aqueous phase liquid.

The researchers concluded that the reaction that forms the hydrochar also sterilizes the waste material, making it safe to handle, potentially for household heating and cooking applications, while the liquid byproduct might be suitable as fertilizer.

Despite worldwide improvements that have made waste treatment more accessible, an estimated 2.3 billion people are still without access to adequate sanitation services, according to the World Health Organization.

"Human excreta are considered hazardous due to their potential to transmit disease," said Professor Amit Gross, who is the new director of the Zuckerberg Institute. "While it is rich in organic matter nutrients such as nitrogen, phosphorus and potassium, human waste also contains micro pollutants from pharmaceuticals, which can lead to environmental problems if not disposed or reused properly."

Also problematic in those regions is energy scarcity. Roughly two billion people around the world use solid biomass, particularly wood, which is converted into charcoal and used for cooking and heating. However, this process leaves footprints on the environment by way of air pollution, greenhouse gas emissions, deforestation and soil erosion.

The findings are published in the Journal of Cleaner Production.