Sino-Dutch R&D Centre for Future Wastewater Treatment Technologies/Beijing Advanced Innovation Centre of Future Urban Design, Beijing University of Civil Engineering & Architecture, Beijing 100044, PR China.
Sino-Dutch R&D Centre for Future Wastewater Treatment Technologies/Beijing Advanced Innovation Centre of Future Urban Design, Beijing University of Civil Engineering & Architecture, Beijing 100044, PR China.
Sci Total Environ. 2023 Aug 25;888:164200. doi: 10.1016/j.scitotenv.2023.164200. Epub 2023 May 17.
A high moisture content of waste activated sludge (WAS) associated with a low calorific value needs to be deeply dried towards self-supporting incineration. On the other hand, thermal energy with low temperature exchanged from treated effluent has great potential for drying sludge. Unfortunately, low-temperature drying of sludge seems to be low in efficiency and long in drying time. For this reason, some agricultural biomass was added into WAS to improve the drying efficiency. The drying performance and sludge properties were analyzed and evaluated with this study. Experimental results demonstrated that wheat straw was the best in enhancing the drying performance. With only 20 % (DS/DS) of crushed wheat straw added, the average drying rate achieved up to 0.20 g water/g DS·min, much higher than 0.13 g water/g DS·min of the raw WAS. The drying time to the targeted moisture content (63 %) (for self-supporting incineration) was shortened to only 12 min, much lower than 21 min of the raw WAS. The analysis revealed that wheat straw could reduce the specific resistance of filtration (SRF) and increase the sludge filterability (X). Also, the sludge rheology, particle size distribution and SEM images could conclude that agricultural biomass played a positive role in skeleton builders, forming a mesh-like structure in sludge flocs. These special channels could obviously improve the transfer capacities of heat and water inside the sludge matrix and thus greatly increase the drying performance of WAS.
高含水率、低热值的废活性污泥（WAS）需要深度干燥以实现自持焚烧。另一方面，处理后废水中交换出的低温热能具有很大的污泥干燥潜力。然而，污泥低温干燥似乎效率较低，干燥时间较长。为此，本研究中向 WAS 中添加了一些农业生物质以提高干燥效率。通过该研究分析和评估了干燥性能和污泥特性。实验结果表明，小麦秸秆在提高干燥性能方面效果最佳。仅添加 20%（DS/DS）的粉碎小麦秸秆，平均干燥速率即可达到 0.20 g 水/g DS·min，远高于原 WAS 的 0.13 g 水/g DS·min。干燥至目标水分含量（63%）（自持焚烧）的时间缩短至仅 12 min，远低于原 WAS 的 21 min。分析表明，小麦秸秆可降低过滤比阻（SRF）并提高污泥过滤性（X）。此外，污泥流变性、粒径分布和 SEM 图像表明，农业生物质在骨架构建者中发挥了积极作用，在污泥絮体中形成了网状结构。这些特殊通道明显提高了污泥基质内部的传热和传水能力，从而大大提高了 WAS 的干燥性能。
