Evaluation of solid fuel char briquettes from human waste

Area of Science:

• Environmental Science
• Energy Engineering
• Waste Management

Background:

• Developing nations face escalating energy demands and inadequate sanitation infrastructure, creating environmental burdens.
• Human feces present a significant waste stream with potential for resource recovery.

Purpose of the Study:

• To evaluate the feasibility of using human feces-derived char as a solid fuel.
• To assess the energy content and elemental composition of chars produced at different pyrolysis temperatures.
• To determine the potential of fecal char briquettes as a sustainable energy source and sanitation solution.

Main Methods:

• Chars were produced from human feces via pyrolysis at 300, 450, and 750 °C.
• Higher heating values (HHV) were measured and compared with predicted values using elemental composition.
• Fecal chars were briquetted using molasses/lime and starch binders, and their impact resistance and HHV were assessed.

Main Results:

• Fecal chars produced at 300 °C exhibited a high heating value (25.6 MJ/kg), comparable to wood chars and coal.
• Chars produced at 750 °C had a lower heating value (13.8 MJ/kg).
• Briquettes made with 10% starch binder showed good impact resistance (79) and a heating value of 25 MJ/kg, similar to commercial briquettes.

Conclusions:

• Human feces-derived char is a feasible solid fuel, particularly when produced at lower temperatures (300 °C).
• Fecal char briquettes offer a sustainable and environmentally friendly alternative to conventional fuels.
• This approach addresses both energy poverty and sanitation challenges in developing regions.