以垃圾焚烧底灰为掺合料的污泥固化/稳定化机理的试验研究

This research is to utilize the aggregate, water absorbability and pozzolanic activity of manicipal solid waste (MSW) incineration bottom ashes to solidify and stabilize the soft sewage sludge. The method, using strong waste to treat soft waste, will improve the mechanical properties of the sludge, reduce the activity of contaminants and the treatment expense, and solve the technical difficulty associated with the landfilling of sludge. In this research, the physical and chemical properties of the sludge and waste incineration bottom ashes are firstly measured. Solidification tests are carried out for the mixture of sludge and waste incineration bottom ashes by selecting suitable cementitious materials. Microscopic and meso-structure analyses and chemical analyses are performed on the solidified mixtures by using the CT, SEM and XRD techniques. It is to discover the solidification/stabilization mechanism of the sludge and waste incineration bottom ash mixture, especially the favorable role of waste incineration bottom ashes in the development of solid skeleton, transfer of water form and solidification reaction. The effects of the amount of waste incineration bottom ash admixture, type and amount of cementitious materials on the mechanical and leaching properties of the solidified sludge will be measured and evaluated. On the basis of the research, suitable proportion of sludge, waste incineration bottom ash and cementitious materials will be proposed, and an cost-effective solidification/stabilization method will developed to treat the sewage sludge to meet the requirement of safe and sanitary landfilling. The research will provide a theoretical basis and technical guide for the safe disposal of a large quantity of sewage sludge and the reuse of waste bottom incineration ashes in China.

本项目是利用垃圾焚烧底灰的骨料性能、吸水性能及火山灰活性，对城市污水污泥进行固化/稳定化处理，以废治废，以改善污泥的力学性能，降低污染物的活性，降低污泥的固化处理费用，有效解决低强度污泥填埋作业难、无法堆高及占地面积大等难题。本项目首先测试垃圾焚烧底灰和污泥的物理化学性质，优选石灰、水泥等固化材料，进行污泥、焚烧底灰和固化材料配方固化试验，利用先进的CT、扫描电镜、X-射线衍射等技术对固化物进行微、细观结构和化学成分分析，揭示焚烧底灰在污泥固化中的骨架构建作用、水分转化作用和对固化反应的促进作用机理，测试和评价焚烧底灰掺量、固化材料类型及掺量对污泥力学性能的改善效果，及其对主要污染物的物理封闭和化学稳定化效果，对污泥、焚烧底灰、固化材料三者之间的配合比进行优化设计，研究经济、环保的污泥固化处理方法，为我国污泥的安全、卫生填埋处置及垃圾焚烧灰的资源化利用提供理论依据和技术参考。

本项目是利用垃圾焚烧底灰的骨料性能、吸水性能及火山灰活性，对城市污水污泥进行固化/稳定化处理，以废治废，以改善污泥的力学性能，降低污染物的活性，降低污泥的固化处理费用，有效解决低强度污泥填埋作业难、无法堆高及占地面积大等难题。本项目首先测试了垃圾焚烧底灰和污泥的物理化学性质，开展了污泥、焚烧底灰和固化材料配方固化试验，测试分析了固化配方对污泥力学性能的改善效果，及其对重金属等浸出毒性控制效果，筛选了较优固化剂种类为石膏和水泥,确定了最优污泥固化配方，即焚烧底灰、水泥和石膏的掺量分别为污泥干重的100 %、25 %和25 %。利用扫描电镜、X-射线衍射等技术对固化物进行微、细观结构和化学成分分析，揭示了焚烧底灰在污泥固化中的骨架构建作用、吸水作用和火山灰作用机理。测试研究了干湿循环和有机质降解对固化物长期力学强度的影响规律，开展了固化污泥堆填体稳定性分析，评价了堆填过程、未封场阶段受干湿循环和降雨入渗作用，及封场后长期渗流对填埋体稳定性的影响。在此基础上研发了经济、环保的污泥固化处理方法及填埋堆高工艺，为我国污泥的安全、卫生填埋处置及垃圾焚烧灰的资源化利用提供了理论依据和技术参考。