Heterogeneity of biochar amendment to improve the carbon and nitrogen sequestration through reduce the greenhouse gases emissions during sewage sludge composting

Abstract

This study was performed to investigate the effects of biochar as an amendment to a gaseous emissions and sewage sludge (SS) composting dynamics. Six dosage of biochar [low dosage of biochar (LDB) - 2%, 4% and 6%; and higher dosage of biochar (HDB) - 8%, 12% and 18%] were amended to a mixture of SS and wheat straw (4:1 ratio on dry weight basis) and compared to control or without additive. The HDB significantly reduced CH₄, N₂O and NH₃ emission by 92.85-95.34%, 95.14-97.30% and 58.03-65.17%, but not the CO₂ emission. Meanwhile, humification results indicated that humic and fulvic acid 35-42% and 24-28% higher in the HDB amended treatments than those in the LDB and control treatments. The HDB significantly decreased total nitrogen losses and greenhouse gas emission, while LDB had significantly (p<0.001) higher CH₄ and N₂O emissions. Due to effective performance of HDB, the 12% biochar was recommended to be used in SS composting practice.

Keywords: Biochar; Greenhouse gas; Nitrogen losses; Sewage sludge; Wheat straw.