Abstract:
Background: Recycling human excreta has become one of the alternatives for the prevention of
communicable diseases related from lack of safe sanitation while generating revenue. In urban
areas, sanitation-related health risks extend far beyond basic access to household sanitation. The
problem is more serious in low-income countries, including Ethiopia, and particularly in urban
slums where the majority of people live together. Biogas toilets are among the most resource efficient sanitation technologies, generating energy and stabilizing waste-producing biofertilizers
for agricultural input. In Ethiopia, knowledge of the energy potential of human excrement is
limited to optimizing the development of biogas toilet facility Therefore, the prediction of the bio methane potential of human excreta for the development of sustainable sanitation technology is
one alternative way of reducing the environmental pollution.
Objective: This study aimed to evaluate the biogas and biofertilizer potential of human excreta in
Jimma City, Ethiopia, which may contribute to the development of sustainable sanitation
technologies.
Methods and materials: In this study, experimental and theoretical prediction methods were used.
The lab-scale batch experiment was conducted by taking composite samples of fresh human feces
using Eco-San technology. Using both ultimate and proximate laboratory analysis, the theoretical
yield of biogas was predicted. Then a series of anaerobic digestion batch experiments were
conducted to determine the practical energy yield. The biofertilizer potential of human feces was
determined by analyzing the nutrient constituents of human feces.
Results: The findings of this study showed that the biogas yield from the experimental results of
Experiment 1,2,&3 was, on average, 0.393 m3
/kg. Based on the energy conversion of methane to
MJ by multiplying the values, the mean was 14.16 MJ/kg. The biogas meter cubes per capita per
head per year were 28.71 (28.03–29.27) in the experimental result and 45.26 for the theoretical
yield of methane & C/N ratio was 20.11%. In our study, the biofertilizer potential of human feces
was evaluated using nutrient analysis, specifically the NPK. Accordingly, human feces contain
potassium (2.29 mg/kg), phosphorus (1.12 mg/kg), and nitrogen (4.29 g/kg). This finding suggests
the bio-methane potential of human feces can satisfy energy recovery and alternative sanitation
options, providing a positive remedy for the sanitation crisis in urban settings
