Co-Digestion of Water Hyacinth with Human Faecal Matter for Optimal Biogas Production in Kisumu, Kenya

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Abstract

The invasion of water hyacinths in Lake Victoria and poor waste management in Kisumu City have worsened pollution, threatened ecosystems and public health. This study explores the anaerobic co-digestion of water hyacinth (WH) and human fecal matter (FM) for biogas production. The methodology involved conducting experiments at the Kenya Industrial Research and Training Institute (KIRDI), where different substrate ratios and chemical pretreatments are tested to optimize biogas yield. Monte Carlo simulations are applied to evaluate the most effective substrate combination for maximizing biogas production. Gas production is measured, and methane output was analyzed to determine the effects of substrate composition and pretreatment on biogas yield. Results show that pure FM produced the highest gas yields (177.1 ml), while co-digestion with WH improved methane production efficiency, with the 0.25 WH: 0.75 FM ratio yielding 123.1 ml. Chemical pretreatment of WH with 1% NaOH enhanced biodegradability, increasing methane output by 15% compared to untreated WH. Statistical analysis confirm that the 0.25 WH: 0.75 FM mix maximized yield (mean of 71.11 ml), while the 1g FM ratio shows high variability (standard deviation of 66.03 ml). These findings present a sustainable waste-to-energy model, contributing to renewable energy solutions and environmental conservation. The study underscores the potential of co-digestion to address sanitation and ecological challenges in the Lake Victoria region.

Keywords: Water hyacinth; Co-digestion; Methane output; Waste management; Anaerobic digestion