生活垃圾焚烧飞灰生物脱氯机制研究

Dechlorination mechanism of municipal solid wastes incineration fly ash by biological process

垃圾焚烧飞灰中的高氯含量是限制其在水泥工业中资源化利用的重要因素,如何实现垃圾焚烧飞灰的有效脱氯是飞灰应用于水泥工业亟需解决的关键技术问题.在对我国7个典型垃圾焚烧厂飞灰组成及特征分析的基础上,开发了飞灰与污泥共处置脱氯工艺,结果表明,我国典型生活垃圾焚烧厂飞灰氯含量达4.6%～12.7%;不同地区焚烧飞灰中氯含量差异性比较明显,主要原因是不同地区垃圾组成不同,其中工业垃圾是飞灰中不可溶氯的主要来源之一;对比水洗前后飞灰同步辐射X射线衍射分析结果,飞灰中可溶氯主要以KCl、Na Cl、Ca Cl OH形态存在,不可溶氯主要以Al OCl形态存在;飞灰与污泥按质量比8：2混合,并共处置150d后,飞灰氯含量由14%降低至0.03%,满足我国《通用硅酸盐水泥》（GB175-2007）标准所规定的水泥氯含量不高于0.06%的要求;飞灰与污泥共处置发酵产酸使得混合体系p H值降低,促进飞灰中不可溶氯盐向可溶性氯盐转化是飞灰生物脱氯的主要机制。

The high content of chlorine limits the reuse of municipal solid waste （MSW） fly ash in cement industry and dechlorination is the major technical problem to be solved. Based on the analysis of content and chemical properties of chlorine in the fly ash from 7representative MSW incineration plants in China, the co-disposal process of fly ash and excess sludge was developed to provide theoretical and technical support for the utilization of fly ash. The content of chlorine in the fly ash from representative incineration plants was 4.6%-12.7% （wt）; the contents of chlorine in fly ash from different regions were different due to various waste compositions; industrial waste is the main source of insoluble chlorine in fly ash; by comparing the synchrotron XRD analysis of washed and unwashed fly ash, it was found that the speciation of soluble chlorine includes KC1, NaC1 and CaC1OH and the speciation of insoluble chlorine is AIOCI; the content of chlorine in fly ash decreased to 0.03% （wt） and met Chinese national standard, GB175-2007, after 150d co-disposal of fly ash and excess sludge with the mixing ratio of 8：2; volatile fatty acids produced by fermentation of excess sludge decreased the pH of co-disposal system and converted insoluble chlorine into soluble chlorine to accelerate the dechlorination of fly ash.