Biochar and pyroligneous acid contributed to the sustainable reduction of ammonia emissions: From compost process to...

Aerobic composting is vital for resource recycling but struggles with high ammonia (NH₃) emissions. Biochar (BC) and pyroligneous acid (PA), products of waste pyrolysis, have great potential for reducing NH₃ emissions. However, the effective utilization of BC and PA to reduce NH₃ emissions in both compost process and product application remains unclear. In this study, different amounts of BC and PA were incorporated into the composting process. The evaluation indexes of compost products were systematically assessed and compared through the cultivation of amaranth. Results demonstrated that rational use of BC and PA could enhance compost quality and effectively reduce NH₃ emissions. The addition of 15 %BC+ 3 %PA resulted in a 92.31 % increase in NH₄⁺-N content while reducing NH₃ emission by 39.94 % during composting. The synergistic effect achieved by maintaining NH₄⁺-N, enhancing NO₃^--N, and regulating pH. The compost products in 15 %BC+ 3 %PA complied with the requirements of China's National organic fertilizer standard. Moreover, these compost products demonstrated soil sustained fertility effects, reducing NH₃ emission by 41.05 %-69.66 % and increasing total weight of amaranth by 4.62 % by a dosage of 4 %. This study is highly significant for addressing the issue of NH₃ emission in both the compost process and soil application.