González-Corrochano Beatriz, Alonso-Azcárate Jacinto, Rodríguez Luis, Pérez Lorenzo Agripino, Fernández Torío María, Tejado Ramos Juan José, Corvinos María Dolores, Muro Carlos
a Department of Physical Chemistry, Faculty of Environmental Sciences and Biochemistry , University of Castilla-La Mancha , Toledo , Spain.
b Department of Chemical Engineering, School of Civil Engineering , University of Castilla-La Mancha , Ciudad Real , Spain.
Environ Technol. 2018 Oct;39(19):2511-2523. doi: 10.1080/09593330.2017.1358768. Epub 2017 Aug 10.
The main objective of this paper was to study how effective thermal treatment is in the retention of different heavy metals (HMs) within the structure of artificial lightweight aggregates (LWAs). These LWAs were manufactured by washing aggregate sludge and sewage sludge. The consequence of increasing the heating dwell time whilst manufacturing these LWAs was also determined. Partitioning of the HMs (Cr, Ni, Cu, Zn, Cd and Pb) was studied by means of the optimized BCR sequential extraction procedure. Then, the leaching ratio (LRx,y) was calculated. Thermal treatment was totally effective for immobilizing most of the elements studied except for a part of the non-residual Zn and Cd fraction which could volatilize, and the fractions of Pb which were water- and acid-soluble, weakly adsorbed, exchangeable, and oxidable. These were more highly concentrated in the LWAs than in the initial waste mixture. The effect of increasing heating dwell time on the retention of heavy metals in the LWAs depended on both the chemical element studied and the heating dwell time. This study is very important since certain rises in the heating dwell time caused a decrease in retention of some specific heavy metals in the LWAs.
BCR-SEP: optimized BCR sequential extraction procedure; b.d.l: below the detection limit; F1: weakly adsorbed, exchangeable and water- and acid- soluble fraction; F2: reducible fraction; F3: oxidable fraction; F4: residual fraction; HM: heavy metal; ICP-MS: inductively coupled plasma-mass spectroscopy; LOI: loss on ignition; LWA: lightweight aggregate; LWA-5: lightweight aggregate sintered for 5 min; LWA-10: lightweight aggregate sintered for 10 min; LWA-20: lightweight aggregate sintered for 20 min; LWA-30: lightweight aggregate sintered for 30 min; LR: leaching ratio of the element x in the fraction y; n.e: not established; S: compressive strength; SS: sewage sludge; WA: water absorption after 24 hours; WAS: washing aggregate sludge; W75S25: mixture of 75% (wt) of the dried washing aggregate sludge and 25% (wt) of the dried sewage sludge; ρ: loose bulk density; ρ: dry particle density; ∑1 + 2 + 3: non-residual fraction; ∑1 + 2 + 3 + 4: total concentration; ∑2 + 3: reducible and oxidable fractions.
本文的主要目的是研究热处理在人工轻集料（LWA）结构中保留不同重金属（HM）方面的效果如何。这些轻集料是通过洗涤骨料污泥和污水污泥制成的。还确定了在制造这些轻集料时增加加热停留时间的影响。通过优化的BCR顺序萃取程序研究了重金属（铬、镍、铜、锌、镉和铅）的分配情况。然后，计算了浸出率（LRx,y）。热处理对于固定所研究的大多数元素是完全有效的，但部分非残留的锌和镉部分可能会挥发，以及铅的水溶、酸溶、弱吸附、可交换和可氧化部分除外。这些在轻集料中的浓度比在初始废物混合物中更高。加热停留时间增加对轻集料中重金属保留的影响取决于所研究的化学元素和加热停留时间。这项研究非常重要，因为加热停留时间的某些增加会导致轻集料中某些特定重金属的保留率降低。
BCR-SEP：优化的BCR顺序萃取程序；b.d.l：低于检测限；F1：弱吸附、可交换以及水溶和酸溶部分；F2：可还原部分；F3：可氧化部分；F4：残留部分；HM：重金属；ICP-MS：电感耦合等离子体质谱；LOI：烧失量；LWA：轻集料；LWA-5：烧结5分钟的轻集料；LWA-10：烧结10分钟的轻集料；LWA-20：烧结20分钟的轻集料；LWA-30：烧结30分钟的轻集料；LR：元素x在部分y中的浸出率；n.e：未确定；S：抗压强度；SS：污水污泥；WA：24小时后的吸水率；WAS：洗涤骨料污泥；W75S25：75%（重量）干燥洗涤骨料污泥与25%（重量）干燥污水污泥的混合物；ρ：松散堆积密度；ρ：干颗粒密度；∑1 + 2 + 3：非残留部分；∑1 + 2 + 3 + 4：总浓度；∑2 + 3：可还原和可氧化部分。
