Abstract

Food waste management by anaerobic digestion is proved to be a potential alternative than composting, landfilling or incineration. It can lead to renewable energy production coupled with the minimization of waste volume and greenhouse gas emissions. Low C/N ratio of food waste inhibit the process stability and decreases the methanogenesis rate, so enhancement of biogas yield and degradability is often required to optimize by codigesting it with another substrate. Co-digestion balances the carbon and nitrogen and increases digester performance and operations more efficiently. The addition of rice straw as co-substrate avoided the ammonia inhibition and volatile acid accumulation during the process and increases the process stability. Mixing food waste and rice straw balances the C/N ratio to 25, which is required for the maximum biogas production, whereas in case of food waste C/N ratio was 14.5. The study was performed in batch reactor under mesophilic (35+2oC) condition. The result showed that balancing C/N ratio increases the biomethane yield and 75 % of the methane was produced during initial 15 days. Methane yield and VS removal efficiency were higher significantly in comparison to mono-digestion of food waste. The biochemical methane potentials (BMP) of food waste and rice straw was calculated in a 1 L anaerobic reactor in mesophilic condition. The optimum methane yield of 0.295 m3/kg- VS was obtained which was 41.7% higher compared to the individual digestion food waste. The methane content and biogas production was obtained to be 62.37 % and 0.438 m3/kg- VS which was much higher than the mono-digestion value.