Hydrothermal carbonization (HTC) is increasingly considered as a promising method to deal with animal manure. Inevitably, using this method for treatment of animal manure led to large amount of hydrothermal liquid. However, the effect of temperature on the characteristics of liquid product that derived from hydrothermal carbonization of animal manure was still incompletely clear. In this study, three types of animal (chicken, dairy, and swine) manures were selected for hydrothermal carbonization at three different temperatures (200, 250, and 300 °C), and the liquid was collected for further analysis, aiming to investigate the effect of temperature on the liquid properties and its potential function as a soil-leaching agent. Results show that high temperature led to high pH, volatile phenol, organic-N and Cr³⁺ concentration of liquid, but low chroma, COD, inorganic-N and Cr⁶⁺ concentration of liquid. Moreover, the manure types, temperature, and their interaction significantly (P<0.001) influenced the selected liquid properties except for BOD based on the two-way analysis of variance, indicating the liquid properties depended on the manure types and temperature. In addition, the extraction of Cu from contaminated soil using the liquid (hydrothermal carbonization of dairy manure, swine manure, and chicken manure at 200 °C) increased by 125%, 178%, and 424%, respectively, compared to distilled water, indicating that liquid can be applied as a promising soil-leaching agent for heavy metal remediation.

Graphical abstract

中文翻译：

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温度对动物粪便水热碳化液体产物性质的影响及其在土壤中的重金属浸出作用

水热碳化（HTC）越来越被认为是一种处理动物粪便的有前途的方法。不可避免地，使用这种方法处理动物粪便会导致大量的水热液体。然而，温度对源自动物粪便热液碳化的液体产品特性的影响仍然不完全清楚。在这项研究中，选择了三种类型的动物（鸡，奶和猪）粪肥在三种不同温度（200、250和300°C）下进行水热碳化，并收集了液体进行进一步分析，目的是研究温度对液体性质的影响及其作为污泥浸出剂的潜在功能。结果表明，高温导致高pH，挥发性酚，有机氮和Cr ³⁺液体浓度，但色度，COD，无机氮和Cr ⁶⁺浓度较低。此外，基于方差的双向分析，除BOD以外，粪肥类型，温度及其相互作用显着影响（P <0.001），表明液体性质取决于粪肥类型和温度。此外，与蒸馏水相比，使用液体（200°C的奶牛粪，猪粪和鸡粪的水热碳化）从污染土壤中提取Cu分别增加了125％，178％和424％，表明液体可以用作重金属修复的有前途的土壤浸出剂。

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