Department of Civil and Environmental Engineering, South Dakota State University, Brookings, SD 57007, United States.
Department of Civil and Environmental Engineering, South Dakota State University, Brookings, SD 57007, United States.
Water Res. 2021 May 1;195:116974. doi: 10.1016/j.watres.2021.116974. Epub 2021 Feb 25.
Woodchip bioreactors have emerged as a viable water management tool to reduce nitrate contamination from agricultural subsurface drainage, wastewater, and stormwater. Understanding of denitrification kinetics is critical to the design and application of field woodchip bioreactors. The denitrification process in woodchip bioreactors generally obeys a model of Michaelis-Menten type enzyme kinetics. The objective of this study was to determine Michaelis-Menten model parameters for nitrate removal in laboratory bioreactors using the fresh, composted and aged woodchips. The results showed that the maximum nitrate removal rates (V) were 2.09, 0.88 and 0.30 mg N/L/h, and the half saturation constants (K) were 2.60, 2.16 and 2.01 mg N/L for the composted, fresh and aged woodchip bioreactors at 22 °C. The V values decreased to 0.26 and 0.05 mg N/L/h, and the K values decreased to 1.74 and 1.19 mg N/L when the composted and fresh woodchip bioreactors were operated at 5 °C. Denitrification in woodchip bioreactors can be operationally defined as a zero-order reaction when treating contaminated water with nitrate much higher than the K values. The nitrate removal efficiency of the bioreactors followed the order of composted woodchips > fresh woodchips > aged woodchips. The average nitrate load reduction rates were 8.81-21.0, 7.36-9.78, and 2.46-3.54 g N/m/d for the composted, fresh, and aged woodchip bioreactors at influent nitrate concentrations of 10-50 mg N/L and 22 °C. Woodchip composting before bioreactor installation can be used as a practical strategy to enhance denitrification performance of bioreactors.
木屑生物反应器已成为一种可行的水管理工具，可减少农业地下排水、废水和雨水的硝酸盐污染。了解反硝化动力学对于现场木屑生物反应器的设计和应用至关重要。木屑生物反应器中的反硝化过程通常遵循米氏酶动力学模型。本研究的目的是使用新鲜、堆肥和老化的木屑在实验室生物反应器中确定硝酸盐去除的米氏模型参数。结果表明，在 22°C 下，堆肥、新鲜和老化木屑生物反应器的最大硝酸盐去除速率（V）分别为 2.09、0.88 和 0.30 mg N/L/h，半饱和常数（K）分别为 2.60、2.16 和 2.01 mg N/L。当堆肥和新鲜木屑生物反应器在 5°C 下运行时，V 值降至 0.26 和 0.05 mg N/L/h，K 值降至 1.74 和 1.19 mg N/L。当处理硝酸盐浓度远高于 K 值的受污染水时，木屑生物反应器中的反硝化可以操作定义为零级反应。生物反应器的硝酸盐去除效率按堆肥木屑>新鲜木屑>老化木屑的顺序排列。在 10-50 mg N/L 进水硝酸盐浓度和 22°C 下，堆肥、新鲜和老化木屑生物反应器的平均硝酸盐负荷去除率分别为 8.81-21.0、7.36-9.78 和 2.46-3.54 g N/m/d。在生物反应器安装之前进行木屑堆肥可以作为增强生物反应器反硝化性能的实用策略。
