Microbial driven reduction of N2O and NH3 emissions during composting: Effects of bamboo charcoal and bamboo vinegar

Abstract

In this study, we systematically analyzed the microbial-driven effects of bamboo charcoal (BC) and bamboo vinegar (BV) on reducing NH3 and N2O emissions during aerobic composting. The results showed that BC and BV improved the nitrogen conversion and compost quality, but the combined BC + BV treatment obtained the best improvements. The BC, BV, and BC + BV treatments reduced the NH3 emissions by 14.35%, 17.90%, and 29.83%, respectively, and the N2O emissions by 44.83%, 55.96%, and 74.53%. BC and BV reduced the NH3 and N2O emissions during composting by controlling ammonia oxidation, where napA, nirK, and nosZ served as useful indicators of the N2O emissions from compost, especially the nirK gene. The dominant nitrifying and denitrifying bacteria belonged to Proteobacteria, and the changes in environmental factors during composting significantly affected the succession of the nitrifying and denitrifying bacterial communities. Nitrosomonas was a key nitrifying bacterial genus in the mesophilic composting period, and BC and BV may have reduced the NH3 emissions by enhancing its conversion to NH4+-N by Nitrosomonas. In addition, norank_p__environmental_samples, unclassified_k__norank_d__Bacteria, and unclassified_p__Proteobacteria were jointly responsible for driving the production of N2O during the compost maturity stage.