Richard Tom L, Walker Larry P, Gossett James M
Department of Agricultural and Biological Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Biotechnol Prog. 2006 Jan-Feb;22(1):60-9. doi: 10.1021/bp050171d.
Oxygen is a critical control variable for composting and other solid-state biodegradation processes. In this study we examined the effect of varying oxygen concentrations (1%, 4%, and 21% O2 (v/v)) on biodegradation kinetics under different substrate (sewage sludge and synthetic food waste), temperature (35, 45, 55, and 65 degrees C), and moisture (36-60% H2O) conditions. Three forms of a saturation or Monod-type model and one form of an exponential model were evaluated against data from extensive experiments under carefully controlled environmental conditions. The exponential model performed well at temperatures from 35 to 55 degrees C but had problems at higher temperatures. The Monod-type models yielded the best fit based on R2 values. Multiple linear regression was used to express the oxygen half-saturation coefficient as a function of temperature and moisture. For a modified one-parameter saturation model the half-saturation coefficient varied from -0.67% to 1.74% v/v O2 under the range of conditions typical of composting systems. While the positive correlation of biodegradation rate with oxygen concentration reported by previous researchers held true for temperatures below 55 degrees C, an inverse relationship was found at 65 degrees C. Although this study did not directly examine anaerobic conditions, the results under microaerophilic conditions suggest oxygen may not offer kinetic advantages for extreme thermophilic biodegradation processes.
氧气是堆肥及其他固态生物降解过程中的一个关键控制变量。在本研究中，我们考察了不同氧气浓度（1%、4%和21% O₂（体积/体积））在不同底物（污水污泥和合成食物垃圾）、温度（35、45、55和65摄氏度）以及湿度（36 - 60% H₂O）条件下对生物降解动力学的影响。针对在精心控制的环境条件下进行的大量实验所获得的数据，评估了三种形式的饱和或莫诺德型模型以及一种指数模型。指数模型在35至55摄氏度的温度范围内表现良好，但在较高温度下存在问题。基于R²值，莫诺德型模型拟合效果最佳。使用多元线性回归将氧气半饱和系数表示为温度和湿度的函数。对于修正的单参数饱和模型，在堆肥系统典型的条件范围内，半饱和系数在 -0.67%至1.74% v/v O₂之间变化。虽然先前研究人员报道的生物降解速率与氧气浓度的正相关关系在55摄氏度以下的温度时成立，但在65摄氏度时发现了相反的关系。尽管本研究未直接考察厌氧条件，但微需氧条件下的结果表明，对于极端嗜热生物降解过程，氧气可能不具有动力学优势。
