Department of Environment and Energy & Soil Environment Research Center, Jeonbuk National University, 567 Baekje-daero, Deokjin, Jeonju, Jeollabukdo 54896, Republic of Korea; Department of Science and Environmental Studies, State Key Laboratory in Marine Pollution, The Education University of Hong Kong, Tai Po, New Territories 999077, Hong Kong.
Department of Environment and Energy & Soil Environment Research Center, Jeonbuk National University, 567 Baekje-daero, Deokjin, Jeonju, Jeollabukdo 54896, Republic of Korea.
Sci Total Environ. 2024 Oct 20;948:174801. doi: 10.1016/j.scitotenv.2024.174801. Epub 2024 Jul 14.
Pyrolysis has been proposed to stabilize heavy metals present in livestock manure. However, many studies have not considered the applicability of manure-derived biochar containing endogenous heavy metals as an agricultural fertilizer. This study investigated the mechanisms through which pyrolysis stabilizes endogenous heavy metals in swine manure and the long-term stability of endogenous heavy metals in the biochar. As pyrolysis temperature increased from 300 °C to 700 °C, the potential ecological risk index decreased from 46.3 to 4.8 because the unstable fraction converted to organic-sulfide bonds and residues. Biochar prepared at 600 °C was the most stable and met the World Health Organization's phyto-availability standards (Cu 10 mg/kg, Zn 0.6 mg/kg). Fourier transform infrared spectroscopy and X-ray diffraction analyses indicated that endogenous heavy metals were stabilized by complexation with organic matter and precipitated as metal-phosphate forms. After 40 cycles of wet-dry aging, the leachability of heavy metals (Cu 6.0 mg/kg, Zn 460.6 mg/kg) from biochar was still lower than that of swine manure (Cu 102.5 mg/kg and Zn 704.9 mg/kg), indicating the long-term stability of the heavy metals in the biochar. Pyrolysis dramatically lowered the environmental threat posed by endogenous heavy metals, demonstrating the applicability of swine manure-derived biochar compared to manure.
热解被提议用于稳定存在于牲畜粪便中的重金属。然而，许多研究并没有考虑到含有内源性重金属的粪便衍生生物炭作为农业肥料的适用性。本研究调查了热解稳定猪粪中内源性重金属的机制以及生物炭中内源性重金属的长期稳定性。随着热解温度从 300°C 升高到 700°C，由于不稳定部分转化为有机-硫化物键和残留物，潜在生态风险指数从 46.3 降低到 4.8。在 600°C 下制备的生物炭最稳定，符合世界卫生组织的植物可利用性标准（Cu 10mg/kg，Zn 0.6mg/kg）。傅里叶变换红外光谱和 X 射线衍射分析表明，内源性重金属通过与有机物的络合而稳定，并沉淀为金属磷酸盐形式。经过 40 次干湿老化循环后，生物炭中重金属（Cu 6.0mg/kg，Zn 460.6mg/kg）的浸出率仍低于猪粪（Cu 102.5mg/kg 和 Zn 704.9mg/kg），表明生物炭中重金属具有长期稳定性。热解显著降低了内源性重金属带来的环境威胁，表明与粪便相比，猪粪衍生生物炭具有适用性。
