Researchers at Ben-Gurion University of the Negev (BGU) have found a new method to convert raw human excrement into a nutrient-rich fertilizer and a safe, reusable fuel, ahead of World Toilet Day on November 19.
In the groundbreaking study, featured in Journal of Cleaner Production, the researchers used hydrothermal carbonization (HTC) to refine a process of heating raw solid waste of human in a designated ‘pressure cooker’, converting excreta into ‘hydrochar’, a safe reusable biomass fuel that resembles charcoal.
Last year, a similar experiment was conducted by the researchers on poultry excrement. To demonstrate the new process, the researchers exposed the raw waste through HTC in three varying temperatures – 180, 210, and 240 degree Celsius while the reaction times were divided into 30, 60 and 120 minutes. Consequently, when the Human Excrement solid waste became dehydrated, it transformed into combustible solid matter called ‘hydrochar’ and an aqueous phase liquid rich of nutrients.
In addition to forming hydrochar, the reaction sterilizes the human waste material making it safe to handle. The researchers concluded that the hydrochar can be used as coal for cooking application and household heating, while the liquid byproduct can be utilized as a fertilizer.
This discovery may have implications for the world’s increasing energy demands and sanitation issues. According to the World Health Organization, despite expanding access to waste treatment worldwide, about 2.3 billion people are deprived of basic sanitation services. Of those, nearly 892 million individuals defecate in the open, mostly in rural areas, making sanitation a major world health issue.
Professor Amit Gross, Zuckerberg Institute’s newly appointed director said that the human excreta is considered hazardous as it is potential for transmitting diseases. While human waste is a rich source of organic substance nutrients such as nitrogen, potassium, and phosphorus, it contains significant amount of micro pollutants from medicines or pharmaceuticals. If the waste is not dumped or reused properly, it may lead to several environmental problems, Prof. Gross added.
Energy scarcity is also one of the major problems in the world today. Nearly two billion people across the globe still use biomass, mostly wood, for cooking and heating, by converting them into charcoal. Such practices have a negative impact on the environment, giving rise to greenhouse gas emissions, air pollution, deforestation, and soil erosion.
According to the Prof. Gross, these two issues can be addressed at once by using proper methods to treat human waste.