ABSTRACT

Expanded vermiculite was used as an adsorbent to remove ammonia nitrogen from landfill leachate. Bench and pilot-scale adsorption experiments were performed with leachate collected from a closed sanitary landfill located in Curitiba, southern Brazil. At the bench-scale, two different heights of vermiculite and three different flow rates were tested using a fixed-bed column. These tests produced an average uptake capacity of 33.4 mg g⁻¹ for the ammonia nitrogen concentration of 2,560 mg L⁻¹. The Yan model was used to determine the breakthrough and the exhaustion times due to the best fit of the data to this model. At the pilot-scale, the flow rate was determined from the shortest length of the mass transfer zone obtained from bench-scale experiments. Tests were performed using one stainless-steel column filled with 26.2 kg of expanded vermiculite, which resulted in a bed height of 1.6 m. A leachate flow rate of approximately 350 L d⁻¹ was applied to achieve the required contact time of 8.3 h. At this scale, an average uptake capacity of 18.1 mg g⁻¹ was obtained for the ammonia nitrogen concentration of 1,193 mg L⁻¹. It is worth mentioning that the flow rate and the concentration of the adsorbate in the feeding solution are fundamental to improve the operational time of the fixed-bed column. The main goal of this research was the determination of operating conditions to scale-up the adsorption process of ammonia nitrogen onto expanded vermiculite. The contact time was a key parameter to reach this goal.

摘要

以膨胀蛭石为吸附剂去除垃圾渗滤液中的氨氮。使用从位于巴西南部库里蒂巴的封闭式卫生垃圾填埋场收集的渗滤液进行了小型和中试规模的吸附实验。在实验室规模上，使用固定床柱测试了两种不同高度的蛭石和三种不同的流速。^{对于 2,560 mg L -1}的氨氮浓度，这些测试产生了 33.4 mg g ^-1的平均吸收能力. 由于数据最适合该模型，Yan 模型用于确定突破和耗尽时间。在中试规模中，流量由从实验室规模实验中获得的传质区的最短长度确定。使用一个装有 26.2 kg 膨胀蛭石的不锈钢柱进行测试，得到 1.6 m 的床层高度。^{应用大约 350 L d -1}的渗滤液流速以实现所需的 8.3 小时接触时间。^{在此规模下，对于 1,193 mg L -1}的氨氮浓度，获得了18.1 mg g ^-1的平均吸收能力. 值得一提的是，进料溶液中吸附物的流速和浓度是提高固定床柱运行时间的基础。本研究的主要目标是确定操作条件，以扩大氨氮在膨胀蛭石上的吸附过程。接触时间是实现这一目标的关键参数。