Chen Zhen, Li Jiang-Shan, Poon Chi-Sun, Jiang Wen-Hao, Ma Zi-Han, Chen Xin, Lu Jian-Xin, Dong Hao-Xin
State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China; IRSM-CAS/HK PolyU Joint Laboratory on Solid Waste Science, Wuhan 430071, China.
State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China; IRSM-CAS/HK PolyU Joint Laboratory on Solid Waste Science, Wuhan 430071, China.
Waste Manag. 2023 Apr 1;160:146-155. doi: 10.1016/j.wasman.2023.02.016. Epub 2023 Feb 22.
Swelling caused by gas generated from municipal solid waste incineration fly ash (MSWIFA) when it is mixed with alkali limits its uses. Besides, the leaching of anion salts and heavy metals contained in MSWIFA poses a high risk to environment. This study presents the feasibility of a one-step alkaline washing, one-step thermal quenching and two-step combination of alkaline washing and thermal quenching pretreatment methods in altering the key properties of MSWIFA for promoting its reusability. It was found that apart from H(gas), NH(gas) was also generated during the alkaline washing of the MSWIFA. Besides, pretreatments led to the reduction in particle size, the increase in pore volume and specific surface area of the MSWIFA, as well as the removal of chloride and sulfate anions. All the pretreatment methods were effective in reducing leaching of heavy metals to below levels of nonhazardous waste except Cd and Pb with alkaline washing. Furthermore, both the chemical Frattini test and the mechanical activity index test showed improvement in pozzolanic activities of the MSWIFA after the pretreatments. Overall, the combined pretreatment method was most effective in eliminating gas emission, and reducing leaching of metal ions and anions from the ash, while enhancing the pozzolanic activity of the ash.
城市固体废弃物焚烧飞灰（MSWIFA）与碱混合时产生的气体所导致的膨胀限制了其用途。此外，MSWIFA中所含阴离子盐和重金属的浸出对环境构成了高风险。本研究提出了一步碱洗、一步热淬火以及碱洗和热淬火两步联合预处理方法在改变MSWIFA关键性质以促进其再利用方面的可行性。研究发现，除了H（气体）之外，在MSWIFA碱洗过程中还会产生NH（气体）。此外，预处理导致MSWIFA粒径减小、孔体积和比表面积增加，以及氯离子和硫酸根阴离子的去除。除了碱洗时的Cd和Pb之外，所有预处理方法均能有效将重金属浸出降低至非危险废物水平以下。此外，化学弗拉蒂尼试验和机械活性指数试验均表明，预处理后MSWIFA的火山灰活性有所提高。总体而言，联合预处理方法在消除气体排放、减少灰中金属离子和阴离子的浸出以及提高灰的火山灰活性方面最为有效。
