Abstract Biochar, produced from biosolids using microwave pyrolysis technology, is energetically a more efficient alternative to that produced with conventional convective heating. However the potential of microwave generated biochar as a growing media amendment has not been sufficiently explored. Here we produced biochar from biosolids using microwave energy. The pyrolysis expeiments were conducted in two stages, initially using a custom built single mode chamber to explore the energetics and product distribution of the pyrolysis process at different temperatures and secondly in a 1 m3 6 kW multi-mode chamber, to explore potential scale-up of the process. The second phase of the pyrolysis experiments was focused on biochar generation for use in the remainder of this research. Microwave pyrolyzed biochar (MB) was characterised for its chemcal and physical properties. Then, we conducted a greenhouse experiment, where we compared the ability of four growing media mixes that combined pine bark with (i) sphagnum peat and fertilizers; (ii) 20% MB and fertilizers; (iii) 60% MB and fertilizers; and (iv) 60% MB and no fertilizers, to promote plant growth and nutrient uptake and to minimise leaching losses. MB had high mesoporosity (average pore width of 4.46 nm), moderate surface area (75 m2 g−1), elevated nutrient content and low heavy metal concentrations as compared to other biosolids biochars reprted in literatures. Substitution of peat with 60% MB on volume basis reduced leaching loss of nitrate and phosphate from the media but increased leaching loss of ammonium. Addition of MB in conjunction with fertilizer increased plant growth and plant nitrogen and phosphorus use efficiency. Our study has shown microwave pyrolysis as a promising technology for pyrolyzing biosolids and also has demonstrated the synergistic interaction of MB and fertilizer which results in greater plant growth and nutrient uptake and use efficiency.

中文翻译：

---

来自生物固体微波热解的生物炭：特性和用作生长培养基改良剂的潜力

摘要 Biochar 是使用微波热解技术由生物固体生产的，是一种比传统对流加热生产的生物炭更有效的替代品。然而，微波产生的生物炭作为一种不断增长的介质改良剂的潜力尚未得到充分探索。在这里，我们使用微波能量从生物固体中生产生物炭。热解实验分两个阶段进行，首先使用定制的单模式室来探索不同温度下热解过程的能量和产物分布，然后在 1 m3 6 kW 多模式室中探索潜在的放大的过程。热解实验的第二阶段侧重于生物炭的产生，以用于本研究的其余部分。微波热解生物炭 (MB) 的特点是其化学和物理特性。然后，我们进行了一项温室试验，比较了将松树皮与 (i) 泥炭和肥料相结合的四种生长培养基混合物的能力；(ii) 20% 甲基溴和肥料；(iii) 60% 甲基溴和肥料；(iv) 60% MB 且不施肥，以促进植物生长和养分吸收，并将浸出损失降至最低。与文献中报道的其他生物固体生物炭相比，MB 具有高介孔率（平均孔径为 4.46 nm）、中等表面积（75 m2 g-1）、高营养成分和低重金属浓度。以体积为基础用 60% MB 替代泥炭减少了硝酸盐和磷酸盐从介质中的浸出损失，但增加了铵的浸出损失。MB 与肥料一起添加可提高植物生长和植物氮和磷的利用效率。我们的研究表明，微波热解是一种有前途的生物固体热解技术，并且还证明了 MB 和肥料的协同相互作用，可促进植物生长以及养分吸收和利用效率。