Effects of H2O2-modified Rice Husk-Derived Biochar on Nitrification and N2O Emission from Water by an Isolated Heterotrophic Nitrifying Bacterium

摘要

In order to explore the effect of biochar on nitrification and N2O emission from water, the indoor incubation experiment was carried out after incorporating the pristine biochar (BC) or H2O2-modified rice husk-derived biochar (20% H2O2-BC and 30% H2O2-BC) combined with the screened heterotrophic nitrifying bacterium into the simulated wastewater. The dynamic changes of inorganic nitrogen contents, pH, bacterial amount, and N2O emission of the incubation system were analyzed. Results showed that compared with BC, the amount of acidic oxygen-containing functional group of H2O2-modified biochars increased by 24.24%similar to 26.98%, while the amount of alkaline oxygen-containing functional group, pH, and the specific capacitance significantly decreased by 22.16%-27.29%, 2.54-2.68, and 15.90%-30.94%, respectively. H2O2-modified biochars significantly inhibited nitrification driven by heterotrophic nitrifying bacterium compared with BC. Moreover, the 16-h cumulative N2O emission of the treatments with 20% H2O2-BC or 30% H2O2-BC addition (0.0516 and 0.0525 mu g N2O/100 mL solution, respectively) were significantly higher than that with BC addition (0.0355 mu g N2O/100 mL solution). Correlation analysis showed that the cumulative N2O emission of the treatments with 20% H2O2-BC or 30% H2O2-BC addition was significantly positively correlated with NH2OH concentration in incubation system (r = 0.455 and 0.497, respectively), and showed no significant correlation relationship with NO2-N (p<0.05).