The role of food/microorganism ratio in denitrification reactors: how it affects the sizing and operation of the denitrification process

Abstract Two calculation models of the Specific Denitrification Rate (SDNR) are analyzed to highlight the sensitivity of this parameter to the Food:Microorganisms ratio in the denitrification reactor (F:MDEN). One of these models is empirical while the second was elaborated on a deterministic basis. Both models reveal a linear dependence of SDNR20°C on F:MDEN and in a first approximation they are comparable only in a narrow range of concentration of dissolved oxygen (DO) in denitrification, specifically DO=0.25-0.35 mg L-1. These values frequently occur in well designed and well operated sewage treatment plants. Outside this range, the role of F:MDEN must necessarily be examined in combination with DO because of the relevant influence of the latter on the efficiency of the denitrification process.摘要 本文分析了比反硝化速率（Specific Denitrification Rate, SDNR）的两种计算模型，以阐明该参数对反硝化反应器内碳源与微生物比值（Food:Microorganisms ratio，即F:MDEN）的敏感性。其中一款模型为经验模型，另一款则基于确定性方法构建。两款模型均显示，20℃条件下的比反硝化速率（SDNR20℃）与F:MDEN呈线性相关关系；在初步近似条件下，二者仅在反硝化过程溶解氧（dissolved oxygen, DO）浓度处于0.25~0.35 mg·L⁻¹的窄区间内具有可比性。该溶解氧浓度区间常见于设计与运维规范的污水处理厂中。超出该区间后，由于溶解氧对反硝化工艺效率存在显著影响，必须结合溶解氧一同考察F:MDEN的作用。