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_max) were 2.09, 0.88 and 0.30 mg N/L/h, and the half saturation constants (K_m) were 2.60, 2.16 and 2.01 mg N/L for the composted, fresh and aged woodchip bioreactors at 22 °C. The V_max values decreased to 0.26 and 0.05 mg N/L/h, and the K_m 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_m 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/m³/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.

木片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，废水和雨水对硝酸盐的污染。了解反硝化动力学对于现场木片生物反应器的设计和应用至关重要。木片生物反应器中的反硝化过程通常遵循Michaelis-Menten型酶动力学模型。这项研究的目的是确定使用新鲜的，堆肥的和老化的木片在实验室生物反应器中去除硝酸盐的Michaelis-Menten模型参数。结果表明，最大硝酸盐去除率（V _max）为2.09、0.88和0.30 mg N / L / h，半饱和常数（K _m堆肥，新鲜和老化的木屑生物反应器在22°C时的N / L分别为2.60、2.16和2.01 mg N / L。当堆肥和新鲜木片生物反应器在5°C下操作时，V _max值降至0.26和0.05 mg N / L / h，K _m值降至1.74和1.19 mg N / L。当用远远高于K _m值的硝酸盐处理污水时，可将木片生物反应器中的反硝化定义为零级反应。生物反应器的硝酸盐去除效率遵循堆肥木片>新鲜木片>老化木片的顺序。平均硝酸盐负荷降低率是8.81-21.0、7.36-9.78和2.46-3.54 g N / m ³/ d用于进水硝酸盐浓度为10-50 mg N / L和22°C的堆肥，新鲜和老化的木片生物反应器。安装生物反应器之前的木屑堆肥可用作增强生物反应器反硝化性能的实用策略。