Dong Yang, Yu Rongzhen, Yan Tinggui, Zhao Xiaojiao, Zhang Wei
School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China.
Research Center of Karst Ecological Civilization, Guizhou Normal University, Guiyang 550025, China.
ACS Omega. 2022 Apr 5;7(15):13057-13066. doi: 10.1021/acsomega.2c00444. eCollection 2022 Apr 19.
Phosphorus is a depletable resource, and the consumption of phosphorus fertilizer increases with the growing population size. Phosphorus recycled from incinerated sludge ash can be a complement to phosphatic fertilizers in districts suffering from phosphorus resource shortages (e.g., Germany, Japan, and Sweden). The apatite inorganic phosphorus (AP) content in incinerated sludge ash is a key factor influencing the recoverability and bioavailability. Biomass straw is rich in calcium and magnesium minerals and can be used as an additive to be blended with sludge to increase the AP content. However, most of the current studies added excessive amounts of calcium-based or biomass additives, and the bioavailability of various Ca-Mg-P minerals generated after the addition of biomass has not been systematically discussed. In this study, the changes of the phosphorus form in the mixed sludge and biomass with Ca/P in the range of 1.0-2.5 are studied, and the influence of temperature and additives on the phosphorus form and the bioavailability of phosphorus in the ash samples are discussed by combining X-ray diffraction and citric acid (CA) leaching experiments. The AP content is very low in the residue of the sludge or corn straw (CS) that has been burned individually. The sludge and the blended sludge and CS were incinerated at various temperatures. As the incineration temperature increased, the conversion of non-apatite inorganic phosphorus (NAIP) to AP was promoted, but the bioavailability did not change until 1050 °C for samples with a Ca/P of 2.5. In the range from 750 to 950 °C, higher temperature promotes the formation of CaPO and CaPO. CaPO is insoluble in CA; thus, the bioavailability changes little from 750 to 950 °C, although the AP content increases. With the increase of Ca/P, the conversion of NAIP to AP and the bioavailability of phosphorus were promoted. For the blended sludge and CS ash, CaMgPO appears at 950 and 1050 °C and the bioavailability also increases.
磷是一种可耗竭资源，且磷肥的消费量随着人口规模的增长而增加。从焚烧污泥灰中回收的磷可作为磷肥的补充，用于磷资源短缺的地区（如德国、日本和瑞典）。焚烧污泥灰中的磷灰石无机磷（AP）含量是影响其回收性和生物有效性的关键因素。生物质秸秆富含钙和镁矿物质，可作为添加剂与污泥混合以增加AP含量。然而，目前大多数研究添加了过量的钙基或生物质添加剂，且添加生物质后生成的各种钙镁磷矿物的生物有效性尚未得到系统讨论。本研究考察了钙磷比在1.0 - 2.5范围内混合污泥和生物质中磷形态的变化，并结合X射线衍射和柠檬酸（CA）浸出实验，探讨了温度和添加剂对灰分样品中磷形态及磷生物有效性的影响。单独焚烧的污泥或玉米秸秆（CS）残渣中的AP含量很低。污泥以及混合的污泥和CS在不同温度下进行焚烧。随着焚烧温度升高，促进了非磷灰石无机磷（NAIP）向AP的转化，但对于钙磷比为2.5的样品，在1050℃之前生物有效性并未改变。在750至950℃范围内，较高温度促进了CaPO和CaPO的形成。CaPO不溶于CA；因此，尽管AP含量增加，但在750至950℃范围内生物有效性变化不大。随着钙磷比的增加，NAIP向AP的转化以及磷的生物有效性得到促进。对于混合的污泥和CS灰分，在950℃和1050℃出现了CaMgPO，生物有效性也有所增加。
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