Study of Different Parameters of Mixing on Biogas Production from Food Waste

Abstract

Food waste generation is an increasing issue, and the disposal of it is controversial. It raises food prices, and the municipal solid waste contains 8.4% food waste by weight. The current study generates a pilot plant for converting food waste to biogas production as an energy source for tremendous paths. The present work deals with the study of the effect of mixing on biogas production from food waste in the pilot-scale digesters. A propeller agitator was employed for mixing in an anaerobic digester. Multiple experimental trials were addressed to optimize the parameters participating in the process of biogas production in semi-continuous operation at mesophilic conditions. Different mixing duration and mixing frequency was studied at the mixing speed of 5 rpm and a comparison was carried out with reference to the digester without a mixing facility. The highest biogas production of 0.12 m3/(kg dry mass) was observed at the mixing time of 5 min compared with the duration of 10 min and 15 min and without mixing conditions. Mixing once in a day obtained biogas production in the range 0.048 to 0.071 m3/(kg dry mass) while mixing at two times in a day obtained biogas production in the range of 0.019 to 0.0357 m3/(kg dry mass). Hence, mixing frequency once a day provided almost double biogas production. Effect of temperature and pH was also studied with different mixing duration and found that mixing duration of 5 min was the best for biogas production from food waste. Minimum mixing of 5 min is required once a day in semi-continuous digestion for stable biogas production. The study concluded to a point that mixing is important for stable processes and maximum biogas production.

Keywords

• biogas production
• mixing effect
• mesophilic digestion
• pilot scale
• food waste