Pyrolysis for biochar production from FS generated in UDTs and VIPs (South Africa)

Pyrolysis of faecal sludge can be a treatment and resource recovery alternative where biochar can be produced as a by-product. The objective of this research was to understand the effect of the operational parameters and the thermal and chemical phenomena during the slow pyrolysis of faecal sludge for biochar production. The methodology comprised the feedstock and device characterisation followed by two experiments. Samples of faecal sludge from Urine Diverting Dry Toilets (UUDT) and Ventilated Improved Pits (VIP) were used, characterised and submitted to slow pyrolysis at a lab scale in a Thermogravimetric Analyser (TGA). Sets of experiments were carried out in a muffle furnace at different heating rates, up to 500°C, three different temperature ranges and three different residence time ranges. The characteristic time analysis of the pyrolysis of faecal sludge was obtained. The TGA experiments occurred under chemical regime while the thermal conversion in the furnace was limited by heat transfers. The research demonstrated that UDDT and VIP sludge feedstocks had relatively low potentials for biochar production when compared to other faecal matter. Their heterogeneity was evident since both samples presented different kinetics of mass loss during thermal treatment.