Hubei Key Laboratory of Multi-media Pollution Cooperative Control in Yangtze Basin, School of Environmental Science & Engineering, Huazhong University of Science and Technology (HUST), 1037 Luoyu Road, Wuhan, Hubei 430074, China.
Hubei Key Laboratory of Multi-media Pollution Cooperative Control in Yangtze Basin, School of Environmental Science & Engineering, Huazhong University of Science and Technology (HUST), 1037 Luoyu Road, Wuhan, Hubei 430074, China; Hubei Provincial Engineering Laboratory for Solid Waste Treatment Disposal and Recycling, Wuhan, Hubei 430074, China.
Sci Total Environ. 2024 Dec 1;954:176679. doi: 10.1016/j.scitotenv.2024.176679. Epub 2024 Oct 2.
The world's phosphorus (P) resources are gradually depleting. Sewage sludge is an important secondary P resource, and sludge-derived biochar for land use is an effective way to achieve P recovery. However, P in biochar synthesized by direct pyrolysis of sludge usually shows comparatively low bioavailability. In this study, biomass ash from different types of straw was used as an additive for co-pyrolysis with sludge. The distribution of different P fractions in the obtained co-pyrolyzed biochar was investigated. The P bioavailability of the co-pyrolyzed biochar was comprehensively evaluated by three methods, including chemical extraction, diffusive gradients in thin films (DGT) technology and pot experiments. The results indicate that the bioavailable P in co-pyrolyzed biochar is significantly positively correlated with the contents of K, Ca, and Mg elements in straw ash, which facilitate the transformation of P in sludge into forms that are more easily utilized by plants, including monetite (CaHPO), hydroxyapatite (Ca(PO)OH) and pyrocoproite (KMgPO). Moreover, pot experiments show that the P contents in ryegrass shoots and roots cultivated in co-pyrolyzed biochar-added soils increased by 11.98-114.97 % and 28.90-69.70 %, respectively, compared to the control soil. The DGT technology could better reflect the uptake of P by plants with a Pearson correlation coefficient as high as 0.94. This study provides references for P resource recovery, and the collaborative reutilization of sewage sludge and straw ash.
世界磷（P）资源正在逐渐枯竭。污水污泥是一种重要的次生 P 资源，而用于土地利用的污泥衍生生物炭是实现 P 回收的有效途径。然而，污泥直接热解合成的生物炭中 P 的生物有效性通常较低。在这项研究中，不同类型秸秆的生物质灰被用作与污泥共热解的添加剂。研究了所得共热解生物炭中不同 P 形态的分布。采用化学提取法、扩散梯度薄膜（DGT）技术和盆栽试验三种方法综合评价了共热解生物炭的 P 生物有效性。结果表明，共热解生物炭中有效 P 与秸秆灰中 K、Ca 和 Mg 元素含量呈显著正相关，这有利于将污泥中的 P 转化为更易被植物利用的形态，包括独居石（CaHPO）、羟磷灰石（Ca（PO）OH）和钾镁磷矿（KMgPO）。此外，盆栽试验表明，与对照土壤相比，添加共热解生物炭的土壤中黑麦草地上部和根部的 P 含量分别增加了 11.98-114.97%和 28.90-69.70%。DGT 技术能更好地反映植物对 P 的吸收，其皮尔逊相关系数高达 0.94。这项研究为磷资源回收和污水污泥与秸秆灰的协同再利用提供了参考。
