Abstract

Animal manures usually contain high contents of heavy metals (HMs) and thus pose a considerable threat to human health and environment when applied to soil. In this study, the effect of pyrolysis temperature (300 °C, 400 °C, 500 °C, 600 °C, and 700 °C) on the properties of biochar produced from chicken manure was studied. In addition, the response of speciation, bioavailability, leachability, and environmental risk of HMs in biochar to different pyrolysis temperature was investigated. The results showed that biochars pyrolyzed at high temperatures generally had high pH, ash content, surface area, and stability. As the pyrolysis temperature increased, the total concentrations of Cu, Zn, Cr, and Ni continually increased, whereas those of Pb and Cd initially increased and then decreased. Moreover, the transformation of the bioavailable fractions of HMs into stable fractions obviously increased with increasing pyrolysis temperature. Thus, pyrolysis at high temperature led to a further decrease in the bioavailability, leachability, and environmental risk of six HMs, as shown by DTPA, TCLP, and the potential ecological risk index. Overall, it is convincing that that 700 °C is the optimal temperature when considering the quality and environmental safety of biochar derived from chicken manure.

摘要

动物粪肥通常含有高含量的重金属（HMs），因此将其施于土壤上会对人类健康和环境构成相当大的威胁。在这项研究中，研究了热解温度（300°C，400°C，500°C，600°C和700°C）对鸡粪产生的生物炭特性的影响。此外，研究了生物炭中HMs的形态，生物利用度，可浸出性和环境风险对不同热解温度的响应。结果表明，高温下热解的生物炭通常具有较高的pH值，灰分，表面积和稳定性。随着热解温度的升高，Cu，Zn，Cr和Ni的总浓度持续增加，而Pb和Cd的浓度先升高后降低。此外，随着热解温度的升高，HMs的生物利用级分向稳定级分的转化明显增加。因此，如DTPA，TCLP和潜在的生态风险指数所示，高温下的热解导致六个HM的生物利用度，浸出性和环境风险进一步降低。总体而言，考虑到鸡粪衍生的生物炭的质量和环境安全性，令人信服的是700°C是最佳温度。