Chemical Engineering Department, The City College of New York, CUNY, New York, NY 10031, United States of America.
Chemical Engineering Department, The City College of New York, CUNY, New York, NY 10031, United States of America.
Sci Total Environ. 2020 Jun 25;723:138031. doi: 10.1016/j.scitotenv.2020.138031. Epub 2020 Mar 18.
Experiments were conducted with simulated Municipal Solid Waste (MSW) to understand the impact of pressure, moisture, and temperature on MSW decomposition under simulated landfill conditions. Three experimental phases were completed, where the first two phases provided baseline results and assisted in fine tuning parameters such as pressure, temperature, gas composition, and moisture content for phase three. The manuscript focuses on the results from third phase. In the third phase, the composition of the gases evolved from representative MSW samples was tested over time in two pressure conditions, 101 kilopascals (kPa) (atmospheric pressure) and 483 kPa, with varying moisture contents (38 to 55 wt%) and controlled temperatures (50 to 200 °C) in the presence of biological inhibitors. The headspace in the reactor in phase three was pressurized with gas mixture of 50/50 (vol%) of methane (CH) and carbon dioxide (CO) setting the initial CH/CO gas composition ratio to 1.0 at time t = 0 days. The results established moisture ranges that affect hydrogen (H) production and the CH/CO ratio at different temperature and pressure conditions. Results show that at 85 °C, there was a change in the CH/CO ratio from 1.0 to 0.3. Additionally, moisture contents from 47 to 43.5 wt% caused the CH/CO ratio to increase from 1.0 to 1.2, yet from 43.5 to 38 wt%, the ratio reversed and declined to 0.3, returning to 1.0 for moisture levels below 38 wt%. Thus, moisture levels above 47 wt% and below 38 wt%, for the system tested, allow thermal reactions to proceed without a measured change in CH/CO ratio. H generation rates follow a similar trend with moisture, yet definitively increase with increased pressure from 101 kPa to 483 kPa. The observed change in solid MSW and gas composition under controlled pressure, moisture, and temperature suggests the presence of thermal reactions in the absence of oxygen.
进行了模拟城市固体废物（MSW）的实验，以了解压力、湿度和温度对模拟垃圾填埋条件下 MSW 分解的影响。完成了三个实验阶段，前两个阶段提供了基准结果，并协助调整了压力、温度、气体组成和第三阶段的水分含量等参数。本文重点介绍第三阶段的结果。在第三阶段，在两种压力条件下（101 千帕斯卡（kPa）（大气压）和 483 kPa），随着时间的推移，测试了来自代表性 MSW 样品的气体组成，同时保持水分含量（38 至 55wt%）和控制温度（50 至 200°C），并存在生物抑制剂。在第三阶段，反应器的顶部空间用 50/50（体积%）的甲烷（CH）和二氧化碳（CO）的混合气体加压，将初始 CH/CO 气体组成比设定为 1.0，时间为 t=0 天。结果确定了在不同温度和压力条件下影响氢气（H）生成和 CH/CO 比的水分范围。结果表明，在 85°C 时，CH/CO 比从 1.0 变为 0.3。此外，水分含量从 47 到 43.5wt%导致 CH/CO 比从 1.0 增加到 1.2，但从 43.5 到 38wt%，该比值反转并下降到 0.3，当水分水平低于 38wt%时，该比值恢复到 1.0。因此，对于测试的系统，水分水平高于 47wt%且低于 38wt%允许热反应进行，而 CH/CO 比没有变化。H 生成率与水分呈相似趋势，但随着压力从 101 kPa 增加到 483 kPa 而明确增加。在受控压力、湿度和温度下观察到的固体 MSW 和气体组成的变化表明，在没有氧气的情况下存在热反应。
