Biochar from human waste
Schönborn, Andreas; (2015). Biochar from human waste: Steps towards a new sanitation approach. In: ABSTRACTS 15 th Annual Meeting of the American Ecological Engineering Society. (4). Stillwater: AEES.
Human waste is the source of 80-90% of the nutrients found in domestic wastewater, and can be a major path of pathogen transmission if the wastewater is not treated adequately. Mixing human waste with other wastewater streams also increases the difficulty to reclaim the nutrients. It is therefore a main go al of ecological sanitation approaches to catch and treat human waste as close to the source as possible, and convert it into a safely reusable form. One possible solution is the direct conversion of human feces into biochar by using a pyrolytical process. An experimental pyrolysis batch reactor was developed and built in fall 2014, to pyrolyse human fecal matter from a composting toilet. Ten test runs were performed, five with wood chips and five with fecal matter from a composting toilet. The resulting biochar was analyzed on elemental composition by using X - Ray Fluorescent Spectroscopy. Water content was a major factor influencing energy demand of this process, and must be < 46% to complete the pyrolysis in a reasonable time. This can be reached either by drying or by mixing the fecal matter with dry organic material (such as sawdust). Biochar from pyrolysis contained potassium, phosphorus and copper in the expected amounts (nitrogen content was not measured). Biochar from feces may be an interesting way to reclaim
a maximum of nutrients from human excreta and convert them to a hygienically safe product. We will present ideas how this can be part of an ecological engineering concept.