Bioaugmentation strategy for mitigating pollutant gas emissions in food waste composting using fermented mixtures

Abstract

The fermented mixtures at different composting stages exhibit varying physicochemical and microbiological properties, adding them to compost, which may show different biological enhancement abilities. This study analyzed the efficiency of fermented mixtures in mitigating pollutant gas emissions during composting, through the co-composting of food waste and sawdust, supplemented with 20 % fermented mixtures from different composting stages: thermophilic (TS), cooling (CS), and mature (MS). Results revealed that fermented mixtures affected the composting process and pollutant gas emissions by regulating bacterial communities. The TS treatment increased the abundance of high-temperature resistant organic matter degrading bacteria, thereby effectively promoting temperature and reaching the highest peak temperature (> 70 °C) in just 2 days. Among all the treatments, TS exhibited the most pronounced reduction in N₂O emissions, inhibiting the proliferation of bacteria engaged in nitrite respiration, which resulted in reducing overall N₂O emissions by 20.7 %. Furthermore, TS outperformed both CK and MS treatments regarding CO₂ reduction, achieving declines of 11.2 % and 20.2 %, respectively. The MS treatment diminished the abundance of acidogens and methanogens bacteria, such as Lactobacillus, Weissella, and Leuconostoc, resulting in a 24.2 % reduction in methane emissions compared to CK. In contrast, the CS treatment had minimal effect, reducing methane emissions by 4.2 %. In conclusion, thermophilic compost demonstrated superior effectiveness in reducing pollutant gas emissions compared to other fermented mixtures. Additionally, owing to its economic advantages, thermophilic compost can be produced significantly faster than the others. Therefore, thermophilic compost is recommended as a bioaugmentation technology that synergistically offers environmental benefits and cost-effectiveness.