Aisha Khan
Independent Researcher
India
Abstract
The global challenge of organic waste management has driven significant interest in decentralized, household-scale anaerobic digestion systems, commonly known as bio-digesters. This manuscript presents a comprehensive study on the design and implementation of bio-digesters tailored for household organic waste streams, using only technologies and engineering practices available up to 2018. An initial survey of existing small-scale digesters worldwide guided the selection of two prototype configurations: a fixed-dome system and a tubular polyethylene reactor. Key process parameters—temperature, hydraulic retention time, and organic loading rate—were optimized through bench‐scale trials. Performance metrics included biogas yield, methane content, and digestate quality. Two field installations in semi-urban Indian homes were instrumented for continuous monitoring over six months. Results demonstrated average biogas production of 0.25 m³ per kilogram of volatile solids added, with methane concentrations ranging from 55 % to 60 % under mesophilic conditions (35 °C). Digestate nutrient analysis confirmed reduction in chemical oxygen demand by 65 % and total solids by 40 %, yielding a nutrient-rich slurry suitable for horticultural use. The study concludes with recommendations for reactor sizing, operational protocols, and safety safeguards, highlighting the potential of household bio-digesters to mitigate organic waste disposal challenges and contribute to renewable energy portfolios at the domestic level.
Keywords
Anaerobic digestion, mesophilic reactor, biogas yield, household waste, fixed-dome, tubular reactor
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