Systematic characterization of faecal sludge from various sources for its use as a solid fuel

Area of Science:

• Environmental Science
• Energy Engineering
• Waste Management

Background:

• Faecal sludge (FS) is often dismissed as a solid fuel due to perceived variability.
• On-site sanitation systems (e.g., pit latrines, VIPs, UDDTs) generate FS with diverse properties.

Purpose of the Study:

• To systematically characterize FS from different containment systems.
• To assess FS properties relevant for combustion and its potential as a fuel source.

Main Methods:

• Collected 24 FS samples from pit latrines, VIPs, and UDDTs at two depths.
• Analyzed higher heating value (HHV), ash content, organic elements, major/minor inorganic elements, and nitrogen (N) concentration.

Main Results:

• HHV ranged from 13-22 MJ/kg dry matter (DM), with pit latrines showing higher variability.
• Ash content varied significantly (15-50% DM), while organic elements were similar across samples.
• High N concentrations (2.5-4.5% DM) and specific major inorganic elements (Si, P, Ca, K) were consistent.

Conclusions:

• FS properties, particularly ash content, vary by containment type.
• High ash and N content may pose challenges for standalone combustion.
• Co-combustion of FS with lignocellulosic biomass is a more suitable application.