填埋污泥的化学调理、热和真空联合作用固结机理研究及应用

Landfilling is the main disposal method of the dewatered sewage sludge from wastewater plants in China, accounting for 60%. There are many sludge lagoons around cities in need of treatment because they brought a lot of environmental problems, such as waste mass instability, odor diffusion influencing the citizen's life, seepage of leachate polluting the groundwater, and occupying landfill capacity to restrict the land reuse. According to high organic content, high bound water content and very low permeability(10-10cm/s~10-7cm/s) of disposed sludge, chemical conditioning and heating can be combined to increase the permeability of sludge, and thermal vacuum preloading method was proposed to treat the sludge lagoons. In order to achieve the breakthrough of the method, based on the key scientific problem "the consolidation mechanism of landfilled sludge under the combined effect of chemical conditioning, heating and vacuum preloading", the following researches would be carried out: (1)The effect of sludge biodegradation on its water form and geotechnical properties; (2) The influence of chemical conditioning and temperature on the permeability and deformation of the disposed sludge; (3)Thermal consolidation theory of vacuum preloading with PVD and model tests; (4) technique research of thermal vacuum preloading on sludge. This project provides theoretical basis and technical support for thermal vacuum preloading on the sludge lagoon. Two-thirds of the sludge volume will be reduced, and the undrained shear strength will increase from 0.1kPa to 10kPa, achieving the requirements of co-landfilling and land reuse.

填埋是我国脱水污泥处置的最主要方式(占60%)，导致我国大中型城市存在数量众多的污泥库，易引起堆体滑坡、恶臭扩散、渗沥液渗漏等环境灾害，占据填埋场库容制约土地利用，亟需处理。针对污泥有机质和结合水含量高、渗透系数极低(约10-10cm/s~10-7cm/s)的特点，结合化学调理及热作用联合提高污泥渗透系数，提出了污泥库的化学调理+热真空预压技术。为实现该技术突破，本项目围绕其关键科学问题"填埋污泥的化学调理、热和真空联合作用固结机理"，开展以下四方面研究：(1)污泥降解对水分存在形式及土工特性的影响;(2)化学调理与热联合作用对污泥渗透系数及变形的影响;(3)污泥热真空预压模型试验及竖井热真空固结理论;(4)污泥热真空预压技术的研发及中试试验。本项目将为污泥库热真空预压处理提供理论依据和技术支撑，实现污泥体积减少三分之二、强度由0.1kPa增长至10kPa，达到混合填埋泥质或土地再利用的要求。

该项目在深入研究填埋污泥的化学调理、热和真空联合作用固结机理的基础上，建立了污泥的温度场-渗流场-应力场多场耦合作用模型，并应用于多场耦合软件进行分析。该模型的特点在于利用试验分析污泥热化学联合真空预压过程中的污泥渗透性变化，将变化数据用于指导污泥热固结环境条件的控制当中。在深入分析和认识污泥多场耦合作用的机理后，抓住污泥多场耦合作用实现减量的几大影响因素，对后续的污泥特性试验检测对象做到有的放矢，完善污泥温度场-渗流场-应力场的初始条件输入。本项目研究成果共发表学术论文4篇，其中SCI收录1篇，EI收录2篇，实用新型专利2项。该项目研究成果将为我国目前的填埋场污泥消纳措施提供科学依据。