50 / 2023-05-05 13:01:56

Bacterial Dynamics and Functions Driven by Fermentation Material Backflow to Reduce Environmental Burden During Food Waste Composting

Food waste,composting,Fermentation material backflow,Gaseous emission,Bacterial dynamics and functions

Globally, 30%-50% of food is wasted. To reduce the adverse climate impact caused by more than 1.3 billion tons of food waste, composting is receiving increasing attention from countries around the world. Control of pollutant gas emissions in food waste composting is a matter of global sustainable development. In order to clarify the effect of mature compost backflow on the pollutant gas emissions of composting process and its cyclic reinforcing effect on the structure and metabolic function of indigenous bacterial. Food waste were used as raw composting materials, rape straw and sawdust as auxiliary materials in this study, and composted under the initial conditions of C/N of 30 and moisture content of 60% with non-backflow (CK) as the control, and investigated the effect of different fermentation periods of materials such as backflow of thermophilic material (GW), cooling material (JW) and mature material (FS) on the pollutant gas emissions and bacterial community structure. High-throughput sequencing was integrated with functional Annotation of Prokaryotic Taxa (FAPROTAX) to decipher the mechanism of the above effects. Results show that the accumulative emissions of N₂O in GW was reduced by 20.7%, which could be ascribed to the higher abundance of the genus Bacillus in the phylum Firmicutes, which accelerated organic biodegradation and promoted higher temperatures. The genus Pseudoxanthomonas and Acinetobacter was a typical group of denitrifying bacteria and unfavourable to high temperature and therefore N₂O emissions were reduced. FS reduced the accumulative NH₃ and CH₄ emissions by 21.54% and 24.03%, and nitrogen losses by 56.32%, which was closely related to the decrease of pH and the enhancement of methane oxidation in composting. Results reported here show that backflow of thermophilic material has obvious effect on N₂O emission reduction. Backflow of mature material reduce the NH₃ and CH₄ emission and reduce nitrogen losses. Therefore, it is possible to shorten composting period and reduce the pollution gas emissions by changes in bacterial dynamics and functions driven by fermentation material backflow.