Abstract
Pyrolysis of latrine fecal waste could produce valuable products for minimizing environmental contamination with heavy metals. The objective of this study was to determine yields, characteristics and cadmium (Cd) sorption of biochar from latrine fecal waste and sewage sludge, as affected by pyrolysis temperature. Slow pyrolysis at 350, 550 and 650°C, was used to produce the biochar. In addition to proximate and ultimate analysis, surface area, porosity and functional groups were analyzed. A batch sorption study was conducted to determine the cadmium sorption capacity of the biochar. Biochar from latrine waste had higher yield, ash content, surface area and pore volume and lower total and fixed carbon (C) and volatile matter than from sewage sludge. Yield, volatile matter, total C, nitrogen (N) and hydrogen (H) decreased with pyrolysis temperature, while ash content, surface area and porosity increased. Surface functional groups of the biochar also varied with feedstock and pyrolysis temperature. The Cd sorption capacities were higher for biochar from latrine waste than from sewage sludge. The findings indicated that characteristics of biochar from latrine waste differ from that of sewage sludge origin and has greater potential as an adsorbent for removal of Cd from wastewater.
Highlights
The global generation of human fecal waste has increased over the past decades exacerbating the challenges of waste disposal (Seo et al, 2004; Al-Khatib et al, 2010)
Zuma et al (2015) reported that 31.3% of households in South Africa depend on pit latrines and 12.5% use the Ventilated Improved Pit latrines (VIP), for their sanitation needs
Latrine fecal wastes and domestic sewage sludge were used for production biocharin this study
Summary
The global generation of human fecal waste has increased over the past decades exacerbating the challenges of waste disposal (Seo et al, 2004; Al-Khatib et al, 2010). Cities in Southern Africa produce large quantities of human fecal wastes from wastewater treatment plants (sewage sludge) and pit latrines. Communities in the cities largely depend on the sewer systems, which treat wastewater and produce sewage sludge, through the anaerobic digestion and separation of the solid from the liquid (Snyman and Herselman, 2009). Exploitation of these organic wastes, for production of resources like biochar, is essential for minimizing environmental pollution with heavy metals and other benefits (Gerente et al, 2007)
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