An investigation into human biowaste management using microwave hydrothermal carbonization for sustainable sanitation

The prolonged challenges and dire consequences of poor sanitation, especially in developing economies, call for the exploration of new sustainable technologies. These need to be: capable of effectively treating human faecal wastes without any health or environmental impacts; scalable to address rapid increases in population and urbanization; capable of meeting environmental regulations and standards for faecal management; and competitive with existing strategies. Further and importantly, despite its noxiousness and pathogenic load, the chemical composition of human biowaste (HBW) indicates that it may be considered to be a potentially valuable, nutrient-rich renewable resource, rather than a problematic waste product. This doctoral study therefore investigated microwave hydrothermal carbonization (M-HTC) as a sanitation technology for processing HBW – to convert it into a safe, pathogen-free material, while also recovering inherent value and providing an economic base to sustain the technology. To this end, the products of M-HTC treatment of sewage sludge, human faecal sludge, synthetic faecal simulant and human faeces were characterized with a suite of techniques and tests to demonstrate pathogenic deactivation, and the intrinsic value of the resultant solid char and liquor. [Continues.]