College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, China.
College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, Shaanxi, 712100, China.
J Environ Manage. 2024 Feb 14;352:120048. doi: 10.1016/j.jenvman.2024.120048. Epub 2024 Jan 20.
Understanding the porosity of biochar (BC) that promotes the heavy metal (HM) passivation during composting can contribute to the sustainable management of pig manure (PM). The current work aimed to explore the influence of BC with varying pore sizes on the physicochemical properties and morphological changes of HMs (including Zn, Cu, Cr, As, and Hg), and microbiota development during PM composting. The various pore sizes of BC were generated by pyrolyzing pine wood at 400 (T1), 500 (T2), 600 (T3) and 700 (T4) °C, respectively. The results revealed a positive correlation between specific surface area of BC and pyrolysis temperature. BC addition contributed to a significantly extended compost warming rate and duration of high-temperature period, as well as HM passivation, reflected in the decrease in Exc-Zn (63-34%) and Red-Cu (28-13%) content, and the conversion of Oxi-Cr (29-21%) and Red-Hg (16-5%) to more stable forms. Moreover, BC at T4 exhibited the best effect on Zn and Cu passivation due to the highest specific surface area (380.03 m/g). In addition to its impact on HM passivation, BC addition improved the microbial environment during PM composting, leading to enhanced microbial diversity and richness. Notably, Chloroflexi and Bacteroidota played key roles in promoting the transformation of Exc-Cu and Red-Hg into stable forms. This phenomenon further stimulated the enhanced decomposition of organic matter (OM) when BC prepared at 600-700 °C was added. Therefore, it can be concluded that the regulation of BC porosity is an effective strategy to improve HM passivation and the overall effectiveness of PM composting.
了解生物炭（BC）的孔隙率如何促进堆肥过程中重金属（HM）的钝化，可以有助于实现猪粪（PM）的可持续管理。本研究旨在探索不同孔径大小的 BC 对 HM（包括 Zn、Cu、Cr、As 和 Hg）理化性质和形态变化以及 PM 堆肥过程中微生物区系发育的影响。分别在 400°C（T1）、500°C（T2）、600°C（T3）和 700°C（T4）下热解松木来产生不同孔径大小的 BC。结果表明，BC 的比表面积与热解温度呈正相关。BC 的添加促进了堆肥升温速率的显著延长和高温期的持续时间，以及 HM 的钝化，表现为 ExC-Zn（63-34%）和 Red-Cu（28-13%）含量的降低，以及 Oxi-Cr（29-21%）和 Red-Hg（16-5%）向更稳定形式的转化。此外，由于 T4 的比表面积（380.03 m/g）最高，T4 的 BC 对 Zn 和 Cu 的钝化效果最好。除了对 HM 钝化的影响外，BC 的添加还改善了 PM 堆肥过程中的微生物环境，提高了微生物的多样性和丰富度。值得注意的是，Chloroflexi 和 Bacteroidota 在促进 ExC-Cu 和 Red-Hg 转化为稳定形式方面发挥了关键作用。这种现象进一步刺激了添加 600-700°C 下制备的 BC 时有机物质（OM）的增强分解。因此，可以得出结论，调节 BC 的孔隙率是提高 HM 钝化和 PM 堆肥整体效果的有效策略。
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