Jiangsu Key Laboratory for Eco-Agricultural Biotechnology around Hongze Lake/ Collaborative Innovation Center of Regional Modern Agriculture & Environmental Protection, Huaiyin Normal University, Huai'an 223300, China.
Nanjing Institute of Soil Science, Chinese Academy of Sciences, 71 Beijing East Road, Nanjing, Jiangsu Province 210008, China; Global Centre for Environmental Research, Advanced Technology Center (ATC) Building, Faculty of Science, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia.
Waste Manag. 2023 Sep 1;169:52-61. doi: 10.1016/j.wasman.2023.06.023. Epub 2023 Jul 3.
Poor properties and high concentrations of heavy metals are still major concerns of successful application of animal manure-derived biochar into the environment. This work thus proposed to add chlorine-based additives (Cl-additives, i.e., CaCl, MgCl, KCl, NaCl, and PVC, 50 g Cl/ kg) to improve biochar properties and enhance heavy metal volatilization during swine manure pyrolysis. The results showed that the addition of CaCl could improve the retention of carbon (C) by up to 13.1% during pyrolysis, whereas other Cl-additives had little effect on it. Moreover, CaCl could enhance the aromaticity of biochar, as indicated by lower H/C ratio than raw biochar. Pretreatment with CaCl, MgCl and PVC reduced phosphorus (P) solubility but increased its bioavailability via the formation of chlorapatite (Ca(PO)Cl). The CaCl was more effective for enhancing the volatilization efficiency of heavy metals than other Cl-additives, except for Pb that tended to react with the generated Ca(PO)Cl to form more stable and less volatile Pb(PO)Cl. However, high pyrolysis temperature (900℃) was essential for CaCl to simultaneously decrease the bioavailability of heavy metals. Our results indicated that co-pyrolysis of swine manure with CaCl is a promising strategy to increase C retention, P bioavailability, and volatilization of heavy metals, and, at higher temperature, reduce the bioavailability of biochar-born heavy metals.
动物粪便生物炭在环境中成功应用仍存在性质差和重金属浓度高的问题。本研究提出添加含氯添加剂（Cl-添加剂，即 CaCl、MgCl、KCl、NaCl 和 PVC，50g Cl/kg）来改善生物炭性质并促进猪粪热解过程中重金属的挥发。结果表明，添加 CaCl 可在热解过程中使碳（C）保留提高 13.1%，而其他 Cl-添加剂对此几乎没有影响。此外，CaCl 可以提高生物炭的芳香度，表现为 H/C 比 raw biochar 更低。预处理用 CaCl、MgCl 和 PVC 降低了磷（P）的溶解度，但通过形成氯磷灰石（Ca(PO)Cl）提高了其生物利用度。与其他 Cl-添加剂相比，CaCl 更有利于提高重金属的挥发效率，但 Pb 除外，Pb 更倾向于与生成的 Ca(PO)Cl 反应，形成更稳定、更不易挥发的 Pb(PO)Cl。然而，高温（900℃）是 CaCl 同时降低重金属生物利用度的必要条件。本研究结果表明，猪粪与 CaCl 的共热解是提高 C 保留、P 生物利用度和重金属挥发的有前景的策略，且在较高温度下可降低生物炭源性重金属的生物利用度。
