Zhang Ying, Xu Huacheng, Fang Shuwei, Li Deping, Xue Weizhen, Chen Bing, Zhao Ling
China-UK Low Carbon College, Shanghai Jiao Tong University, Shanghai, 201306, China.
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China.
Environ Sci Pollut Res Int. 2023 Jan;30(2):4137-4150. doi: 10.1007/s11356-022-22355-8. Epub 2022 Aug 13.
The sustainable disposal of large volumes of contaminated dredged river sediment has become a challenge for municipal management. In this study, a cutting-edge biochar application method was innovated, which converted the polluted dredged sediment into a low-carbon and environmentally friendly building material through an autoclave-free method. As the amount of biochar addition increased from 0 to 2% (w/w), the compressive strength of the dredged sediment-based lightweight concrete (DS-LC) increased from 3.92 to 4.61 MPa. Accordingly, the thermal conductivity decreased from 0.237 to 0.222 W/(m K), the water absorption decreased by 6%, and the water resistance coefficient increased by 33%. Results of X-ray diffraction (XRD) and thermogravimetric (TG) analysis showed that biochar promoted the hydration reaction and the carbonation process. Scanning electron microscopy (SEM) attached with energy-dispersive X-ray spectroscopy (EDX) showed that biochar addition changed the microstructure of the DS-LCs, which made the pore distribution more uniform and densified. Biochar addition also strengthened the immobilization of heavy metals (Cu, Zn, Cr, and As) by approximately 18-27% and combination of biochar and silica fume could increase the heavy metal immobilization by 28-44%. Compared with the traditional concrete material, the DS-LC with biochar addition could not only reduce the carbon emission but also has potential economic benefit for the treatment and utilization of dredged sediment.
大量受污染的疏浚河道沉积物的可持续处置已成为市政管理面临的一项挑战。在本研究中，创新了一种前沿的生物炭应用方法，该方法通过无压蒸养法将受污染的疏浚沉积物转化为低碳环保的建筑材料。随着生物炭添加量从0增加到2%（w/w），疏浚沉积物基轻质混凝土（DS-LC）的抗压强度从3.92 MPa提高到4.61 MPa。相应地，热导率从0.237 W/（m·K）降至0.222 W/（m·K），吸水率降低了6%，抗水系数提高了33%。X射线衍射（XRD）和热重（TG）分析结果表明，生物炭促进了水化反应和碳酸化过程。附有能量色散X射线光谱（EDX）的扫描电子显微镜（SEM）表明，添加生物炭改变了DS-LC的微观结构，使孔隙分布更加均匀和致密。生物炭的添加还使重金属（铜、锌、铬和砷）的固定化增强了约18-27%，生物炭与硅灰的组合可使重金属固定化提高28-44%。与传统混凝土材料相比，添加生物炭的DS-LC不仅可以减少碳排放，而且在疏浚沉积物的处理和利用方面具有潜在的经济效益。
