School of Civil Engineering, Southeast University, Nanjing, 210096, China.
School of Civil Engineering, Southeast University, Nanjing, 210096, China.
Chemosphere. 2022 Nov;307(Pt 4):135994. doi: 10.1016/j.chemosphere.2022.135994. Epub 2022 Aug 13.
High water content in sludge will affect the transportation and subsequent disposal of sludge. Bioleaching is a biological sludge conditioning technology, which can effectively improve the dewatering performance of sludge and reduce the content of heavy metals in sludge. Coal fly ash, as a skeleton builder, can also improve the dewatering performance of sludge. In this study, bioleaching combined with coal fly ash (BL-CFA) process was employed to improve sludge dewatering performance. Based on the results of response surface methodology (RSM), the capillary suction time (CST) and water content (WC) of sludge decreased by 52.27% and 38.92%, respectively. The dewatering effect of BL-CFA is superior compared with single process. For extracellular polymeric substances (EPS), the content of protein and polysaccharide in tightly and loosely EPS (TB-EPS and LB-EPS) of sludge decreased after BL-CFA process, while that in soluble EPS (S-EPS) increased. Three-dimensional fluorescence indicated that the weakened fluorescent areas of proteinoid and soluble microbial by-product-like (SMP) organic in LB-EPS and TB-EPS, which is beneficial to the improvement of sludge dewatering performance. Fourier transform infrared (FTIR) spectroscopy showed that the polysaccharides and proteins in the sludge were cleaved and released into the supernatant after BL-CFA process. The variation of particle size revealed that flocculation occurred after adding CFA into acidified sludge, and a supporting structure was formed in the sludge with the assist of CFA through the analysis of the scanning electron microscopy (SEM). Based on the above results, a triple dehydration mechanism was proposed for BL-CFA process, namely, cracking-flocculation-skeleton construction, which endows the combined process with superior sludge dewatering effect and application potential.
高含水率的污泥会影响污泥的运输和后续处置。生物沥滤是一种生物污泥调理技术，可有效改善污泥的脱水性能，降低污泥中重金属的含量。粉煤灰作为骨架构建剂，也可以改善污泥的脱水性能。本研究采用生物沥滤与粉煤灰（BL-CFA）联合工艺来提高污泥的脱水性能。基于响应面法（RSM）的结果，污泥的毛细吸水时间（CST）和含水率（WC）分别降低了 52.27%和 38.92%。与单一工艺相比，BL-CFA 联合工艺的脱水效果更优。对于胞外聚合物（EPS），经过 BL-CFA 工艺后，污泥中紧密结合型 EPS（TB-EPS）和松散结合型 EPS（LB-EPS）中的蛋白质和多糖含量降低，而可溶性 EPS（S-EPS）中的含量增加。三维荧光表明，LB-EPS 和 TB-EPS 中蛋白质和可溶性微生物副产物（SMP）有机物质的荧光减弱区域，有利于改善污泥的脱水性能。傅里叶变换红外（FTIR）光谱表明，BL-CFA 工艺后，污泥中的多糖和蛋白质被裂解并释放到上清液中。粒径的变化表明，在向酸化污泥中添加 CFA 后会发生絮凝，并且通过扫描电子显微镜（SEM）的分析，在 CFA 的协助下，污泥中形成了支撑结构。基于上述结果，提出了 BL-CFA 联合工艺的三重脱水机制，即裂解-絮凝-骨架构建，赋予了联合工艺优越的污泥脱水效果和应用潜力。
