掺加垃圾焚烧飞灰的水泥土重金属浸出毒性及力学特性分析

HEAVY METAL LEACHING TOXICITY AND MECHANICAL PROPERTIES OF CEMENT SOILS WITH MUNICIPAL SOLID WASTE INCINERATION FLY ASH ADDED

以广州某垃圾焚烧场的焚烧飞灰为研究对象,通过浸出试验研究了不同预处理方法处理飞灰以及掺预处理飞灰的水泥土重金属浸出毒性,并通过无侧限抗压强度(UCS)试验探讨了垃圾焚烧飞灰对水泥土力学特性的影响。结果表明:焚烧飞灰在固液比1∶8条件下,水洗40 min后仅出现铬浸出浓度超标的现象;除硫酸亚铁外,EDTA二钠、磷酸钠和硫化钠均未能同时有效减少飞灰中铬和铅的含量;掺预处理飞灰的水泥土试样强度随着飞灰掺量、水泥含量及龄期的增加而提高; 10%预处理飞灰替代5%水泥后两者水泥土强度相近,说明掺入飞灰可以有效减少水泥用量。掺入飞灰的水泥土重金属浸出浓度远低于预处理飞灰的重金属浸出浓度,符合GB 5085. 3—2007《危险废物鉴别标准浸出毒性鉴别》排放标准限值。

In this paper,solidification path for the municipal solid waste incineration fly ash( MSWIFA) from a municipal solid waste incineration plant in Guangzhou was studied. The heavy metal leaching toxicity of fly ash with different pretreatments and cement-soil containing the pretreated fly ash was researched through leaching test. The unconfined compressive strength( UCS) was used to explore the impact of waste incineration fly ash on the mechanical proporty of cement soil. Results showed that only the leaching concentration of chromium in the MSWIFA after water washing for 40 minutes at a solid-liquid ratio of 1 ∶ 8 exceeded the standards. Except ferrous sulfate,disodium EDTA,sodium phosphate,or sodium sulfide did not reduce the content of chromium and lead effectively. The strength of the cement soil sample mixed with fly ash increased with the increase of fly ash content,cement content,and the curing age. The strength of cement soil was similar when 10% pretreated fly ash replaced 5% cement,which meant that the addition of fly ash could effectively reduce the consumption of cement. The leaching concentrations of heavy metals in cement soil mixed with MSWIFA were much lower than those in treated MSWIFA,and they met the standard values of Identification Standards for Hazardous Wastes-Identification for Extraction Toxicity( GB 5085. 3-2007).