Runjie Liu,Shiwei Liu,Shichang Sun,Xing Cao,Junhao Lin,Juan Peng,Fei Ji,Rui Ma
The traditional solidification/stabilization (S/S) technology, Ordinary Portland Cement (OPC), has been widely criticized due to its poor resistance to chloride and significant carbon emissions. Herein, a S/S strategy based on magnesium potassium phosphate cement (MKPC) was developed for the medical waste incineration fly ash (MFA) disposal, which harmonized the chlorine stabilization rate and potential carbon emissions. The in-situ XRD results indicated that the Cl − was efficiently immobilized in the MKPC system with coexisting Ca 2+ by the formation of stable Ca 5 (PO 4 ) 3 Cl through direct precipitation or intermediate transformation (the Cl − immobilization rate was up to 77.29%). Additionally, the MFA-based MKPC also demonstrated a compressive strength of up to 39.6 MPa, along with an immobilization rate exceeding 90% for heavy metals. Notably, despite the deterioration of the aforementioned S/S performances with increasing MFA incorporation, the potential carbon emissions associated with the entire S/S process were significantly reduced. According to the Life Cycle Assessment, the potential carbon emissions decreased to 8.35 × 10 2 kg CO 2 -eq when the MFA reached the blending equilibrium point (17.68 wt.%), while the Cl − immobilization rate still remained above 65%, achieving an acceptable equilibrium. This work proposes a low-carbon preparation strategy for MKPC that realizes chlorine stabilization, which is instructive for the design of S/S materials.
Pollution of municipal sewage sludge with heavy metals (HMs) inevitably causes secondary contamination, threatening ecosystems and human health. Dissolved organic matters (DOM) would serve as HMs carriers or ligands, directly influencing the transport and distribution. So it is of essential importance to simultaneously evaluate the release characteristics of HMs and DOM from MSS. In this paper, we investigated leaching characteristics of HMs (Cd, Cr, Cu, Zn, Ni, and Mn) and DOM from raw sewage sludge (RSS) and lime-conditioned sewage sludge (LCSS) under simulated rain with different acidities (pH 6.5 and 2.9) via column leaching experiments. The results showed the release of HMs could be divided into two distinct stages, a rapid decreasing changes in the early stage and a slow and steady change in the later stages with a slight increase in the middle of time. At the early stage, DOM was dominated by protein-like components (tryptophan-like, tyrosine-like). As time passed, protein-like components decreased while humic-like components (fulvic acid and humic acid) increased gradually. Protein-like components showed significant positive correlations with HMs, while humic acid-like components showed strong negative correlations with them. Moreover, the leaching efficiencies of Cd, Zn and Mn at pH 2.9 was about 1.5 times higher than that at 6.5, and the fluorescence intensity of humic-like components at pH 2.9 was higher than that at pH 6.5, suggesting that acid rain accelerated the release of HMs and the humification of DOM. Compared with the RSS, the DOM of LCSS showed noticeable differences, especially an obvious increase of the fulvic acid component. And the leaching efficiencies of Cd, Cr, Cu, Ni, and Mn in LCSS were much lower than that in RSS, indicating lime treatment retarded the release of HMs. Thus, our findings will be a guide to the treatment of HMs contaminants in MSS.
危险品化学品经营许可证（带存储）