超临界水无害化共处理PVC和医疗垃圾焚烧飞灰的可行性探讨  

Feasibility of supercritical water treatment on co-detoxification of PVC and medical waste incinerator fly ash

作　　者：薄达[1] 张付申[1] 

机构地区：[1]中国科学院生态环境研究中心,北京100085

出　　处：《环境工程学报》2010年第1期178-182,共5页Chinese Journal of Environmental Engineering

基　　金：国家自然科学基金资助项目(20777084);"十一五"国家科技支撑计划重点项目(2008BAC32B03)

摘　　要：采用超临界水氧化降解PVC同时无害化处理医疗垃圾焚烧飞灰,利用PVC脱氯形成的中间产物盐酸提取医疗垃圾焚烧飞灰中的重金属,达到飞灰无害化的目的。结果显示,超临界水可以将飞灰颗粒打碎,从而提高盐酸提取重金属的速率和效果,但是在超临界水中还存在重金属的固定过程,过长的反应时间和过高的反应温度都会降低重金属的提取效率。在提取过程中,Cu和Zn优先于Pb被盐酸浸出,而Pb被浸出后很容易被超临界水进一步固定。综合考虑重金属在超临界水中的变化特性,总结出超临界水处理飞灰和PVC的最佳条件为:PVC与飞灰质量比0.5:1,温度400℃,提取时间90 min。处理后的飞灰再次经过水洗后,其重金属浸出浓度低于USEPA规定的限制值。本研究为飞灰的无害化处理提供一条新的思路。This study investigated the feasibility of supercritical water（SCW） treatment on synchronous detoxification of medical waste （MW） incinerator fly ash and PVC. The main merit was that hydrocloric acid could be formed during deehlorination of PVC in supercritical water which was effective for heavy metals extraction. SCW could destroy ash particles, thus improved heavy metals extraction efficiency and velocity. However, SCW also had the effect of fixing metal ions into the ash matrix, hence over time or extremely high temperature treatment conversely lowered heavy metal extraction efficiency. During the treatment process, the extraction of Cu and Zn by HCl was prior to Ph, and Pb could be easily solidified in SCW. Considering the changing properties of heavy metals, it was concluded that the optimum SCW treatment conditions were： PVC/ash ratio = 0.5： 1 （by weight）, temperature = 400℃ and treatment time = 90 min, respectively. Heavy metals leaching from the treated ash was below the USEPA standard limits after further washing with water. This study provides a new potential approach for fly ash detoxification.

关 键 词：超临界水氧化 PVC 医疗垃圾焚烧飞灰 提取 重金属 

分 类 号：X705[环境科学与工程—环境工程]