Post-treatment of landfill leachate using rice husk ash as adsorbent medium

Abstract Sanitary landfill is the most disposal method for urban solid waste. However, in the process of organic matter degradation, a dark-colored liquid with high potential for polluting is produced, necessitating an efficient treatment before its discharge into watercourses. Several technologies can be used in the treatment, such as biological and physico-chemical systems. The activated carbon produced from agricultural residues - rice husk ash (RHA), appears as an alternative treatment, mainly for color reduction in landfill leachate. This study determined the best operational condition for the slurry treatment using a fixed-bed column. The column was filled with activated RHA and support material (sand). The column heights studied were 5 cm (C1) and 20 cm (C2) of adsorbent. The column with 20 cm of RHA and sand intercalated with the coal layer showed better efficiency in removal of the chemical oxygen demand (COD), with COD removal efficiency of 88.91% and rupture time of 120 min. The removal of apparent color was 87.40% with the rupture time of 40 min and true color removal of 86.64% with rupture time of 50 min. Activated rice husk ash was shown to be promising for post-treatment of the leachate with substantial efficiency.

摘要：卫生填埋是当前城市固体废物最主流的处置方式。但在有机质降解过程中，会产生高污染风险的深色液体——垃圾渗滤液（landfill leachate），需经高效处理后方可排入水体。目前可用于该渗滤液处理的技术包括生物处理系统与物理化学处理系统等。由农业废弃物稻壳灰（rice husk ash, RHA）制备的活性炭，可作为一种颇具潜力的渗滤液处理替代方案，尤其适用于降低渗滤液的色度。本研究确定了采用固定床柱（fixed-bed column）进行浆液处理的最优运行工况。实验柱装填有活化稻壳灰与支撑材料砂。本研究设置的吸附剂柱高分别为5 cm（C1组）与20 cm（C2组）。其中，装填20 cm稻壳灰活性炭且砂与活性炭层交错排布的固定床柱，对化学需氧量（chemical oxygen demand, COD）的去除效果更佳：COD去除率达88.91%，穿透时间为120 min。该柱对表观色度的去除率为87.40%，对应穿透时间为40 min；对真色度的去除率为86.64%，对应穿透时间为50 min。实验结果表明，活化稻壳灰用于垃圾渗滤液的后处理颇具应用前景，且具备可观的处理效率。