School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China; Shanghai Key Laboratory of Heat Transfer and Multiphase Flow in Power Engineering, Shanghai, 200093, China.
School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China.
Chemosphere. 2022 Dec;308(Pt 2):136391. doi: 10.1016/j.chemosphere.2022.136391. Epub 2022 Sep 9.
Dewatering of sewage sludge (SS) was the prerequisite for saving its drying energy and sustaining its stable combustion. Hydrothermal treatment (HT) has been a promising technology for improving SS dewaterability with high energy efficiency. However, the knowledge of phosphorus (P) transformation and heavy metals (HMs) behaviors in the combined HT and incineration process was still lack. P fractions, P-bioavailability, HMs speciation, and their environmental risk in the ash samples from this combination process were evaluated and compared with those from the co-incineration of SS and CaO. The combination process was superior to the latter one in the light of P and HMs. CaO preferred to enhance the transformation of non-apatite inorganic phosphorus (NAIP) to apatite phosphorus (AP) initially with enriched P and increased P-bioavailability in the resultant ash samples. The combination process further reduced the values of risk assessment code and individual contamination factor with the increment of the stable F4 fraction in HMs. Significant reduction of potential ecological risk was observed with the lowest global risk index of 43.76 in the combination process. Optimum CaO addition of 6% was proposed in terms of P and HMs. The work here can provide theoretical references for the potential utilization of P from SS to mitigate the foreseeable shortage of P rocks.
污水污泥（SS）的脱水是节省其干燥能源和维持其稳定燃烧的前提条件。水热处理（HT）是提高 SS 脱水性能和高能源效率的有前途的技术。然而，对于磷（P）在联合 HT 和焚烧过程中的转化和重金属（HM）行为的知识仍然缺乏。评估了来自该联合过程的灰分样品中的 P 分数、P 生物可利用性、HM 形态及其环境风险，并将其与 SS 和 CaO 共焚烧的灰分样品进行了比较。与后者相比，该联合工艺在 P 和 HMs 方面具有优势。CaO 最初优先将非磷灰石无机磷（NAIP）转化为磷灰石磷（AP），从而使灰分中 P 富集，P 生物可利用性增加。随着 HMs 中稳定的 F4 分数的增加，该联合工艺进一步降低了风险评估代码和个体污染因子的值。观察到潜在生态风险显著降低，在联合工艺中，全球风险指数最低为 43.76。提出了最佳的 CaO 添加量为 6%，以考虑 P 和 HMs。这项工作可以为从 SS 中提取 P 以减轻可预见的磷矿石短缺提供理论参考。
