Yesiller Nazli, Hanson James L, Cox Jason T, Noce Danielle E
Global Waste Research Institute, California Polytechnic State University, San Luis Obispo, CA 93407, USA.
Civil and Environmental Engineering Department, California Polytechnic State University, San Luis Obispo, CA 93407, USA.
Waste Manag. 2014 May;34(5):848-58. doi: 10.1016/j.wasman.2014.02.002. Epub 2014 Mar 7.
This investigation was conducted to evaluate experimental determination of specific gravity (Gs) of municipal solid waste (MSW). Water pycnometry, typically used for testing soils was adapted for testing MSW using a large flask with 2000 mL capacity and specimens with 100-350 g masses. Tests were conducted on manufactured waste samples prepared using US waste constituent components; fresh wastes obtained prior and subsequent to compaction at an MSW landfill; and wastes obtained from various depths at the same landfill. Factors that influence specific gravity were investigated including waste particle size, compaction, and combined decomposition and stress history. The measured average specific gravities were 1.377 and 1.530 for as-prepared/uncompacted and compacted manufactured wastes, respectively; 1.072 and 1.258 for uncompacted and compacted fresh wastes, respectively; and 2.201 for old wastes. The average organic content and degree of decomposition were 77.2% and 0%, respectively for fresh wastes and 22.8% and 88.3%, respectively for old wastes. The Gs increased with decreasing particle size, compaction, and increasing waste age. For fresh wastes, reductions in particle size and compaction caused occluded intraparticle pores to be exposed and waste particles to be deformed resulting in increases in specific gravity. For old wastes, the high Gs resulted from loss of biodegradable components that have low Gs as well as potential access to previously occluded pores and deformation of particles due to both degradation processes and applied mechanical stresses. The Gs was correlated to the degree of decomposition with a linear relationship. Unlike soils, the Gs for MSW was not unique, but varied in a landfill environment due both to physical/mechanical processes and biochemical processes. Specific gravity testing is recommended to be conducted not only using representative waste composition, but also using representative compaction, stress, and degradation states.
本研究旨在评估城市固体废物（MSW）比重（Gs）的实验测定方法。通常用于测试土壤的水比重瓶法被调整用于测试MSW，使用一个容量为2000 mL的大烧瓶和质量为100 - 350 g的试样。对使用美国废物成分制备的人造废物样本、在MSW填埋场压实前后获得的新鲜废物以及从同一填埋场不同深度获得的废物进行了测试。研究了影响比重的因素，包括废物颗粒大小、压实以及分解和应力历史的综合影响。制备好的/未压实的和压实的人造废物的实测平均比重分别为1.377和1.530；未压实和压实的新鲜废物的平均比重分别为1.072和1.258；旧废物的平均比重为2.201。新鲜废物的平均有机含量和分解程度分别为77.2%和0%，旧废物分别为22.8%和88.3%。Gs随颗粒尺寸减小、压实程度增加和废物年龄增长而增加。对于新鲜废物，颗粒尺寸减小和压实导致颗粒内封闭孔隙暴露以及废物颗粒变形，从而使比重增加。对于旧废物，高Gs是由于低Gs的可生物降解成分损失以及由于降解过程和施加的机械应力导致可能进入先前封闭的孔隙和颗粒变形。Gs与分解程度呈线性相关。与土壤不同，MSW的Gs不是唯一的，而是在填埋环境中由于物理/机械过程和生化过程而变化。建议不仅使用具有代表性的废物成分，还使用具有代表性的压实、应力和降解状态来进行比重测试。
