Prediction of Bio-methane Potential of Fresh Human Feces for the Development of Sustainable Urban Sanitation Technology in Jimma Town, Southwest Ethiopia

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