Evaluation and mathematical modeling of the removal of particulate matter in a real-scale lawn channel

ABSTRACT A mathematical model was applied to describe the removal of particulate matter in a real-scale lawn-lined channel. For this purpose different initial concentrations (Co) of particulate matter were investigated, as follows: 65; 131; 196 ; 262 and 327 mg/L. The hydrographs investigated, containing suspended solids, were discharged into a 100 m long channel with a 2% slope. The particulate matter was measured by analyzing turbidity and total suspended solids (TSS) at 26 sites throughout the length of the channel. The experimental data were fitted to the model using nonlinear regression parameters (kd) and (C *), which correspond to the decay kinetics constant and minimum limiting values of the removal curve, respectively. Fractions removed and mathematical fitting were assessed and performed for each isolated event and also for the set of results. On average, the magnitude of the relative error ranged from 0.83% to 5.11%, with the highest average value obtained for the lowest concentration of particulate matter (65 mg L -1). Regarding the values obtained for the decay constants (kd), which represent the frequency of removal of particulate matter, it is noted that it tends to a minimum value for the higher initial concentrations of particles (Co) . This fact indicates that the higher the initial concentration of particulate matter (Co), the greater the extent of travel required for its removal, with a maximum observed at around 80 m, for concentrations above 196 mg.L -1 .

摘要 本研究采用数学模型描述实际规模植草衬砌渠道内的颗粒物去除过程。为此，设置了65、131、196、262及327 mg/L共5组不同的颗粒物初始浓度（Co）开展试验。将携带悬浮固体的试验水文过程线排入长100米、坡度为2%的渠道中。沿渠道全程布设26个采样点，通过测定浊度与总悬浮颗粒物（TSS）来量化颗粒物浓度。采用非线性回归方法对试验数据进行模型拟合，得到衰减动力学常数（kd）与去除曲线的最小极限值（C*）两个参数，二者分别对应颗粒物的衰减动力学常数与去除曲线的最小极限值。分别针对单次独立试验事件与全部试验结果集合，评估了颗粒物去除率与模型拟合效果。整体而言，相对误差的平均值介于0.83%至5.11%之间，其中最低初始颗粒物浓度（65 mg/L）组对应的平均相对误差最高。对于表征颗粒物去除速率的衰减常数（kd），研究发现随着初始颗粒物浓度（Co）升高，该常数趋于最小值。该现象表明，颗粒物初始浓度（Co）越高，其完成去除所需的迁移距离越长；当初始浓度高于196 mg/L时，所需迁移距离的最大值约为80米。