Phosphorus (P) recovery from sewage sludge (SS) have been regarded as an effective method of P recycling. The effects of incineration temperature, incineration time, and chlorine additives on the distribution of P speciation during sludge incineration were studied. Moreover, the reactions between model compounds AlPO₄ and additives (MgCl₂ and CaCl₂) were investigated by thermogravimetric differential thermal analysis and X-ray diffraction measurements. The results demonstrated that the increase in temperature and time stimulated the volatilization of non-apatite inorganic phosphorus (NAIP) instead of apatite phosphorus (AP). MgCl₂ and CaCl₂ can greatly promote the conversion of NAIP to AP. Additionally, AlPO₄ reacted with MgCl₂ are incinerated at 500–600 °C to form Mg₃(PO₄)₂, which is mainly due to the reaction of the intermediate product MgO and AlPO₄. Reactions between AlPO₄ and CaCl₂ occurred at 700–750 °C and produced Ca₂PO₄Cl, which can be directly used with high bioavailability. These findings suggested that chlorine additives in the SS incineration process can obtain phosphorus-containing minerals with higher bioavailability to realize the resource utilization of P in sludge.

Graphical abstract

中文翻译：

---

污水污泥焚烧过程中MgCl2和CaCl2对磷的转化

从污水污泥（SS）中回收磷（P）已被认为是一种有效的磷回收方法。研究了焚烧温度、焚烧时间和氯添加剂对污泥焚烧过程中磷形态分布的影响。此外，模型化合物AlPO ₄和添加剂（MgCl ₂和CaCl ₂）之间的反应通过热重差热分析和X射线衍射测量进行了研究。结果表明，温度和时间的增加刺激了非磷灰石无机磷（NAIP）而不是磷灰石磷（AP）的挥发。MgCl ₂和CaCl ₂可以极大地促进NAIP向AP的转化。此外，AlPO₄与 MgCl ₂反应在 500–600 °C 下焚烧形成 Mg ₃ (PO ₄ ) ₂，这主要是由于中间产物 MgO 和 AlPO ₄的反应。AlPO ₄和CaCl ₂之间的反应发生在700-750 °C，并产生Ca ₂ PO ₄ Cl，可直接使用，生物利用度高。这些研究结果表明，在SS焚烧过程中添加氯添加剂可以获得生物利用度更高的含磷矿物质，从而实现污泥中磷的资源化利用。

图形概要