Solid Waste Disposal Engineering Laboratory, Graduate School of Engineering, Hokkaido University, N13, W8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
J Hazard Mater. 2010 Mar 15;175(1-3):747-53. doi: 10.1016/j.jhazmat.2009.10.072. Epub 2009 Oct 30.
With insufficient source separation, construction and demolition (C&D) waste becomes a mixed material that is difficult to recycle. Treatment of mixed C&D waste generates residue that contains gypsum and organic matter and poses a risk of H(2)S formation in landfills. Therefore, removing gypsum and organic matter from the residue is vital. This study investigated the distribution of gypsum and organic matter in a sorting process. Heavy liquid separation was used to determine the density ranges in which gypsum and organic matter were most concentrated. The fine residue that was separated before shredding accounted for 27.9% of the waste mass and contained the greatest quantity of gypsum; therefore, most of the gypsum (52.4%) was distributed in this fraction. When this fine fraction was subjected to heavy liquid separation, 93% of the gypsum was concentrated in the density range of 1.59-2.28, which contained 24% of the total waste mass. Therefore, removing this density range after segregating fine particles should reduce the amount of gypsum sent to landfills. Organic matter tends to float as density increases; nevertheless, separation at 1.0 density could be more efficient.
如果废物分类不充分，建筑和拆除（C&D）废物就会变成混合物料，难以回收利用。混合 C&D 废物的处理会产生含有石膏和有机物的残渣，并且在垃圾填埋场中存在形成 H（2）S 的风险。因此，从残渣中去除石膏和有机物至关重要。本研究调查了分拣过程中石膏和有机物的分布情况。使用重液分离来确定石膏和有机物最集中的密度范围。在切碎之前分离的细残渣占废物质量的 27.9%，并且含有最多的石膏；因此，大部分石膏（52.4%）分布在该部分中。当将该细部分进行重液分离时，93%的石膏集中在密度为 1.59-2.28 的范围内，该范围内包含了总废物质量的 24%。因此，在分离细颗粒后去除此密度范围应该可以减少送往垃圾填埋场的石膏量。随着密度的增加，有机物往往会浮起；然而，在 1.0 的密度下进行分离可能会更有效。
