Xia Yi, Zhang Hua, Phoungthong Khamphe, Shi Dong-Xiao, Shen Wen-Hui, Shao Li-Ming, He Pin-Jing
State Key Laboratory of Pollution Control & Resource Reuse, Tongji University, Shanghai 200092, PR China; Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092, PR China.
State Key Laboratory of Pollution Control & Resource Reuse, Tongji University, Shanghai 200092, PR China.
Waste Manag. 2015 Aug;42:93-100. doi: 10.1016/j.wasman.2015.04.017. Epub 2015 Apr 28.
Leachate collection system (LCS) clogging caused by calcium precipitation would be disadvantageous to landfill stability and operation. Meanwhile, calcium-based compounds are the main constituents in both municipal solid waste incineration bottom ash (MSWIBA) and stabilized air pollution control residues (SAPCR), which would increase the risk of LCS clogging once these calcium-rich residues were disposed in landfills. The leaching behaviors of calcium from the four compounds and municipal solid waste incineration (MSWI) residues were studied, and the influencing factors on leaching were discussed. The results showed that pH was the crucial factor in the calcium leaching process. CaCO3 and CaSiO3 began leaching when the leachate pH decreased to less than 7 and 10, respectively, while Ca3(PO4)2 leached at pH<12. CaSO4 could hardly dissolve in the experimental conditions. Moreover, the sequence of the leaching rate for the different calcium-based compounds is as follows: CaSiO3>Ca3(PO4)2>CaCO3. The calcium leaching from the MSWIBA and SAPCR separately started from pH<7 and pH<12, resulting from CaCO3 and Ca3(PO4)2 leaching respectively, which was proven by the X-ray diffraction results. Based on the leaching characteristics of the different calcium compounds and the mineral phase of calcium in the incineration residues, simulated computation of their clogging potential was conducted, providing the theoretical basis for the risk assessment pertaining to LCS clogging in landfills.
由钙沉淀导致的渗滤液收集系统（LCS）堵塞不利于垃圾填埋场的稳定性和运营。同时，钙基化合物是城市固体废弃物焚烧底灰（MSWIBA）和稳定化空气污染控制残渣（SAPCR）中的主要成分，一旦这些富含钙的残渣被处置于垃圾填埋场，会增加LCS堵塞的风险。研究了四种化合物及城市固体废弃物焚烧（MSWI）残渣中钙的浸出行为，并讨论了影响浸出的因素。结果表明，pH是钙浸出过程中的关键因素。当渗滤液pH分别降至小于7和10时，CaCO3和CaSiO3开始浸出，而Ca3(PO4)2在pH<12时浸出。CaSO4在实验条件下几乎不溶解。此外，不同钙基化合物的浸出率顺序如下：CaSiO3>Ca3(PO4)2>CaCO3。MSWIBA和SAPCR中的钙浸出分别从pH<7和pH<12开始，分别是由CaCO3和Ca3(PO4)2浸出导致的，这通过X射线衍射结果得到了证实。基于不同钙化合物的浸出特性及焚烧残渣中钙的矿物相，对其堵塞潜力进行了模拟计算，为垃圾填埋场LCS堵塞的风险评估提供了理论依据。
