固体废弃物处理与资源化实验室知识库

      畜禽粪便是典型的废弃生物质 资源 ，也是我国 重要的 农业 面源 污染 源 。 若处理 不及时 或 不 恰当 ，畜禽粪便 会 导致严重的环境污染如温室气体排 放、地下水和土壤污染等。传统的畜禽粪便处理方法如堆 肥和厌氧发酵 耗 时长，效率 低 。此外， 这些 传统 方法 不能有效降低粪便中的污染物尤其是重金属和抗生素的生物有效性和潜 在 环境 风险。为 实现 畜禽粪便的 彻底 无害化 和 高效 资源化 利用本 研究 以 猪粪为代表 通过水热炭化技术 将其 转化 为水热炭 。 一方面从土壤安全利用角度出发， 利用 CaO辅助的水热 炭化 对 猪粪 进行 处理 ，研究 猪粪 基 水热炭特性及 典型 污染物包括重金属和多环芳烃（ Polycyclic aromatic hydrocarbonsPAHs）在水热 炭化 过程中的迁移转化行为，评估 猪粪基 水热炭进行土壤利用的环境风险。另一方面，从能源回收角度出发，通过 猪粪 与木质纤维素生物质共水热处理，研究水热炭 的 燃烧行为 及 水热 液体循环利用的影 响 ，为畜禽粪便进行能源回收提供理论基础。
      1、 从土壤 安全 利用角度出发，研究结果如下：
      1)、CaO辅助的水热炭化提高了猪粪基水热炭的 pH和产率。 猪粪 经水热炭化 处理 后 P富集在水热炭中 ，且 CaO添加促 进 P由不稳定态向稳定态 转变降低 了 P的流失风险 。 此外， CaO添加 改善 了 水热炭表面的孔结构 及 含氧官能团 有利于 水热炭 与 土壤之间的相互作用。
     2）猪粪 经水热 炭化 处理后 重金属 多 富集 在水热炭中。 CaO添加降低 了 水热 炭 中的 重金属浓度 。此外 提高水热温度和 CaO添加率均促 进 水热 炭中的 重金属向相对稳定态转变，降低了 重金属 的 生物有效性和环境风险。
      3）、猪粪 基 水热炭 中 的 PAHs毒性 随 着水 热 温度升高先下降后升高， 而水热液体 中 的 PAHs毒性则 呈现 逐渐上升 的趋势 。 CaO添加抑制 了 PAHs的生成，促进高分子量 PAHs转化为低分子量 PAHs 从而 降低 了 水热 产物 中的 PAHs总浓度和毒性。
      2、 从能源回收角度出发，研究结果如下：
      1）共水热过程中 猪粪与 木质纤维素 生物质 之间 发生了明显的协同作用 。共水热 处理 提高了水热炭 的能源 产率 改善了 水热炭的燃料性能 提高 了水热炭的燃烧稳定性 和 活化 能，降低了反应性 。
      2）、 将 猪粪 与木屑 共水热处理后的水热液体 进行 循环利用 促进 了 猪粪 的 脱水和脱羧反应，提高了水热炭的燃料性能和能源 产 率 提高了反应性， 增强 了水热炭化在畜禽粪便处理中的经济竞争性 。

      Animal manure is typical waste biomass resource, and also an important source of agricultural non-point source pollution in China. Without timely or proper disposal, animal manure is likely to result in serious environmental pollution including greenhouse gas emissions, groundwater and soil pollutions. The traditional disposal methods of animal manure such as composting and anaerobic digestion are time-consuming and low-efficiency. Additionally, these traditional methods are not effective to eliminate the bioavailability and potential environmental risk of the inherent contaminants in animal manure especially heavy metals and antibiotics. In order to achieve the complete detoxicity and efficient resource utilization of animal manure, swine manure (SM), as the typical manure, was converted into the hydrochar by hydrothermal carbonization (HTC) in this study. On one hand, from the perspective of safe application in soil, SM was treated by CaO assisted HTC. The hydrochar properties and transformation behavior of contaminants such as heavy metals and polycyclic aromatic hydrocarbons (PAHs) during HTC were investigated, and the environmental risk of the hydrochar application in soil was evaluated. On the other hand, from the perspective of energy recovery, SM was treated by co-HTC with lignocellulosic biomass. The combustion behavior of the hydrochar from co-HTC and effect of process water recirculation were studied to provide theoretical basis of energy recovery from animal manure.
      1. From the perspective of safe application in soil, main conclusions were as follows:
      1) CaO addition during HTC significantly increased the pH value and yield of the hydrochar derived from SM. The P originally contained in SM was enriched in the hydrochar by HTC, and CaO addition promoted the P transformation from labile fraction to stable fraction, mitigating the risk of P loss. Additionally, CaO addition improved the porosity and functional groups present on the surface of the hydrochar, benefiting the interaction between the hydrochar and soil.
      2) High fraction of heavy metals originally contained in SM was enriched in the hydrochar by HTC. CaO addition decreased the heavy metal content in the hydrochar. In addition, increasing HTC temperature and CaO addition ratio promoted the transformation of heavy metals into relatively stable fraction, reducing the bioavailability and environmental risk of heavy metals.
      3) With increasing HTC temperature, the toxicity of PAHs in the hydrochar derived from HTC of SM firstly decreased and then increased, while the toxicity of PAHs in process water showed a gradual uptrend. CaO addition suppressed the PAHs formation and promoted the conversion from higher molecular weight PAHs to lower molecular weight PAHs, resulting in the decreased PAHs content and toxicity of HTC products.
      2. From the perspective of energy recovery, main conclusions were as follows:
      1) Significant synergy occurred between SM and lignocellulosic biomass during co-HTC. For the hydrochar, co-HTC increased the energy yield, improved the fuel properties, increased the combustion stability and average activation energy, and decreased the reaction activity.
      2) The process water recirculation during co-HTC of SM and sawdust promoted the dehydration and decarboxylation reactions of SM, enhanced the fuel properties and energy yield of the hydrochar, increased the combustion reactivity, and increased the economic competitiveness of HTC among the disposal methods of animal manure.