典型危废填埋场导排层淤堵形成机理及时空演化特征

Research on mechanism of clogging in drainage system is conducive to leachate level control, ensuring stable operation and risks control of hazardous waste landfill (HWL), which will be helpful for resolving the conflict between the increasing demand on HWL construction and the difficulty of HWL site selection. Previous study mainly focus on the clogging of drainage layer (DL) in municipal solid waste landfill (MSWL) with leachate high in content of organic matter and low in pH, while little information is known about clogging behavior and mechanism in HWL environment with leachate low in organic matter and high in pH. Our preliminary study shows that there is a common clogging in the domestic HWL site, but the specific formation mechanism and key influencing factors of clogging under such circumstance need to be further studied. This research, based on the HWL characteristics of landfill leachate, use the Column device to simulate the clogging process in HWL, aiming to: ①expounds the formation mechanism and key influencing factors of the DL clogging under HWL environment, in order to provides a theoretical basis for the DL design, and its prevention and control of clogging; ②explicit the quantitative relationship between clogging rate and the leachate rate and its concentrations, and in conjunction with the information on clogging material, morphology, structure and spatial distribution to clarify the temporal and spatial change of drainage capacity, in order to provide methodology for the prediction of service life of DL. The achievement are helpful to the optimal design of HWL guided drainage system and the prevention and control of clogging, which has practical significance and scientific significance for the control of leachate water level and the environmental risk control for the HWL operation.

导排系统淤堵研究有利于危险废物填埋场(HWL)渗滤液水位控制,保障其稳定运行和环境风险控制，对化解日趋增加的HWL建设需求以及选址困难这一激烈社会矛盾具有重要意义。已有研究主要针对生活垃圾填埋场（渗滤液有机质含量高、pH低），对HWL环境下（有机质含量低、pH高）的淤堵行为和机理还知之甚少。前期调查已证实了国内HWL导排层潜在淤堵问题严重，并初步探索了该环境下淤堵物的时空分布规律，但对该环境下淤堵的具体形成机理和关键影响因素还有待进一步研究。本研究以典型HWL的选择和代表性渗滤液的确定为基础，开展室内模拟实验研究HWL导排层淤堵的形成机理和关键影响因素，为其导排系统设计、淤堵防控提供理论依据；探索淤堵速率与渗滤液流速和组分浓度间定量关系，结合淤堵物形貌、结构和空间分布特征分析，阐明淤堵条件下导排性能的时空演化规律，为HWL导排层导排性能及其服役寿命的评估提供方法学。

填埋场是危险废物无害化处置的主要场所，也是危险废物不利环境影响集中的场所。渗滤液导排系统（LCDS）是危险废物填埋场（HWL）渗滤液产生和污染风险控制的重要单元。淤堵导致的LCDS导排性能劣化和渗滤液水位壅高将加剧渗滤液渗漏引起的环境风险，因此亟需深入研究其形成机理、控制机制和演化规律，以指导LCDS长期稳定服役。本项目对填埋场导排淤堵机理及其影响因素，以及淤堵物结构、形貌和空间分布，及其对渗流参数的影响进行了试验研究和理论分析。通过淤堵模拟试验，确定了导排层淤堵机理主要分为化学淤堵和生物淤堵两类，还有少量物理淤堵，且化学淤堵占主导地位；对主要影响因素的研究表明，渗滤液的浓度和渗透速率都对淤堵物形成存在促进作用；在此基础上，发现淤堵物主要为白色固体颗粒、深红色颗粒与絮凝毛绒状三类，确定其主要组成成分是CaCO3，而且从表层开始形成，逐渐向下迁移；在确定淤堵机理的基础上，选择HCl为清淤试剂，经过短期的清淤试验，渗透系数有明显回升，清淤效果明显，证明HCl可以作为清淤试剂；最后通过数据分析和拟合，构建了淤堵速率与污染物质量负荷和流速的量化模型。依托本研究，项目团队共发表学术论文10篇，其中SCI收录5篇，EI收录3篇；获国家实用新型专利1项；出版著作1部。