Evaluation of biochar powder on oxygen supply efficiency and global warming potential during mainstream large-scale aerobic composting

- Pore oxygen concentration in two groups exceeded 5% during 80% of the whole time.
- The average GWP of the BC group was 19.82% lower than that of the CK group.
- Biochar has the potential for oxygen supply and reducing GWP effects.

This study investigated the effects of biochar powder on oxygen supply efficiency and global warming potential (GWP) in the large-scale aerobic composting pattern which includes cyclical forced-turning with aeration at the bottom of composting tanks in China. A 55-day large-scale aerobic composting experiment was conducted in two different groups without and with 10% biochar powder addition (by weight). The results show that biochar powder improves the holding ability of oxygen, and the duration time (O2 >5%) is around 80%. The composting process with above pattern significantly reduce CH4 and N2O emissions compared to the static or turning-only styles. Considering the average GWP of the BC group was 19.82% lower than that of the CK group, it suggests that rational addition of biochar powder has the potential to reduce the energy consumption of turning, improve effectiveness of the oxygen supply, and reduce comprehensive greenhouse effects.