Physico-chemical properties of waste derived biochar from community scale faecal sludge treatment plants

Gates Open Res. 2022 Dec 13:6:96. doi: 10.12688/gatesopenres.13727.2. eCollection 2022.

Abstract

Background: The dumping of untreated faecal sludge from non-sewered onsite sanitation facilities causes environmental pollution and exacerbates poor public health outcomes across developing nations. Long-term mechanisms to treat faecal sludge generated from these facilities are needed to resolve the global sanitation crisis and realize the Sustainable Development Goal (SDG) 6 "ensure availability and sustainable management of water and sanitation for all" by 2030. Pyrolysis of faecal sludge removes pathogens and generates biochar, which can be used as a soil enhancer. Methods: The properties of faecal sludge biochars from three full-scale treatment plants in India were determined via Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy dispersive x-ray (EDX) spectroscopy, crystal x-ray diffraction (XRD), proximate analyses, and BET surface area porosimetry. Results: Results showed that all three biochars had low specific surface area, high alkaline pH values, high ash content, and negative surface charge. Fourier transform infrared spectra showed the same surface functional groups present in each biochar. X-ray diffraction analysis showed the mineral composition of each biochar differed slightly. Scanning electron microscopy analysis indicated a porous structure of each biochar with ash particles evident. Conclusions: Slight differences in the ash content, surface area, pH and mineral content was observed between the three biochars.

Keywords: Biochar; Characterization; Faecal Sludge; Fecal; Properties; Pyrolysis; Sanitation.

Grants and funding

This work was supported by the Bill & Melinda Gates Foundation [OPP1149054], and under the grant conditions of the Foundation, a Creative Commons Attribution 4.0 Generic License has already been assigned to the Author Accepted Manuscript version that might arise from this submission. The work was also supported by Swansea University’s ‘SUNRISE’ project funded through GCRF via EPSRC [EP/P032591/1].