College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China.
Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing, 100871, China.
Environ Sci Pollut Res Int. 2020 May;27(14):17109-17122. doi: 10.1007/s11356-020-08098-4. Epub 2020 Mar 7.
This study investigated the distribution and transformation behaviors of heavy metals (HMs) and phosphorus (P) during hydrothermal carbonization (HTC) of sewage sludge. In addition to a large reduction in sludge volume, HTC significantly decreased the exchangeable fraction of HMs (Zn, Cu, Cr, Ni, and Mn) and increased their residual fraction, which resulted in immobilization of HMs accumulated in hydrochar. The ecological toxicity of HMs was greatly reduced, and all HMs exhibited their lowest risk levels after HTC at 220 °C for 1 h in 2% HSO solution. Most of the P (~ 97%) in the input sludge remained in the hydrochar after HTC. HTC facilitated transformation of organic P to inorganic P and promoted conversion of apatite P to non-apatite inorganic P under acidic conditions. The feasibility of recovering P from sludge by HTC was verified by an acid extraction experiment utilizing hydrochar, which recovered more than 90% P. Graphical abstract.
本研究考察了水热碳化（HTC）过程中污水污泥中重金属（HM）和磷（P）的分布和转化行为。除了大幅减少污泥体积外，HTC 还显著降低了 HM（Zn、Cu、Cr、Ni 和 Mn）的可交换部分，并增加了其残留部分，从而使积累在水热炭中的 HM 得到固定。HM 的生态毒性大大降低，所有 HM 在 2% HSO 溶液中 220°C 下 HTC1 小时后均表现出最低的风险水平。输入污泥中的大部分 P（~97%）在 HTC 后仍留在水热炭中。HTC 促进了有机 P 向无机 P 的转化，并在酸性条件下促进了磷灰石 P 向非磷灰石无机 P 的转化。通过利用水热炭进行酸浸实验验证了从污泥中回收 P 的可行性，该实验回收了超过 90%的 P。
