城市垃圾焚烧飞灰的污染特性分析

Analysis of pollution characteristics of fly ash from municipal solid waste incineration

城市垃圾焚烧处理以其具有明显的减量化、无菌化、资源化等优点,近年来得到了较广泛的应用.然而,垃圾焚烧后产生的飞灰中含有大量的水溶性盐分和重金属,如果处理处置不慎就会对环境产生二次污染.为合理有效的处理城市垃圾焚烧飞灰,并为其资源化利用提供科学依据,需对其中污染物的特性进行分析,本文研究了城市垃圾焚烧飞灰的粒径分布,pH值,水溶性盐分含量,不同粒径上重金属的含量及不同粒径上的重金属对总量的贡献率.结果表明：飞灰的粒径分布近似正态分布,80%以上颗粒集中在54～280μm之间,粒径小于54μm和大于280μm的颗粒所占的质量分数都很少,还不足3%和15%;飞灰呈强碱性,pH值高达12以上;飞灰样品中水溶性盐分的含量较高,可达2%以上;易挥发性的重金属在飞灰不同粒径上的分布与粒径有一定的相关性,而半挥发和难挥发性重金属的分布与粒径的相关性不大;中等大小的颗粒对重金属总量的贡献率最大.

In recent years,incineration disposure of municipal solid waste has been used widely due to its obvious volume reduction,germfree treatment and resource reuse.However,the fly ash derived from municipal solid waste incinerator（MSWI） contains high level of water soluble salts and heavy metals,and if treated inadvertently,it can bring secondary pollution to the environment.In order to dispose the fly ash reasonably and effectively and provide scientific evidence for its resource reuse,characteristics of contaminants in it should be analyzed.In this study,the fly ash derived from municipal solid waste incinerator was classified by particle sizes.The content of water soluble salts and pH in the fly ash were measured.The concentrations of heavy metals in the classified fractions and their contributions to the total heavy metal in fly ash were studied.The results showed that the particle size distribution of fly ash was similar to normal distribution,and sizes of particles between 54 μm and 280 μm reached up to over 80 percent of the total,while sizes under 54 μm or over 280 μm only took made up small mass percentage,which were less than 3 percent or 15 percent,respectively.Fly ash was highly alkaline and its pH value was up to 12.The content of water soluble salts in the fly ash was very high and could be over 2%.The contents of volatile heavy metals in different particles of fly ash had relationship with the particle size,while those of semi-volatile and refractory heavy metals had no obvious relationship with the size.It indicated that the contribution of heavy metals in the middle-sized particles to the total was the highest.