环流生物反应器降流区输氧浓度影响因素

Factors Affecting Oxygen Delivery Concentration in Downflow Zone of Loop Bioreactor

环流生物反应器降流区输氧浓度主要受导流筒直径、导流筒溢流堰口高度及曝气量等因素影响,其对反应器污水脱氮除磷处理效果有重要影响。为考察以上影响因素对降流区输氧能力影响,采用数值模拟与实验结合的方法对环流反应器降流区输氧能力进行研究,通过自定义程序耦合Higbie传质理论模拟氧传质,对比不同曝气强度下反应器溶解氧浓度及溢流量模拟与实测值,结果显示误差在8%以内,表明数值模拟模型及方法正确可行。随后探究了曝气量、导流筒直径及导流筒溢流堰口高度对降流区输氧能力的影响。结果表明:曝气量由20 L/min增至50 L/min时,氧体积传质系数由2.04 h^(-1)增至4.45 h^(-1);导流筒直径由325 mm降至250 mm时,氧体积传质系数由3.99 h^(-1)增至4.42 h^(-1);导流筒溢流堰口高度由10 mm增至25 mm时,氧体积传质系数由4.17 h^(-1)降至4.00 h^(-1);增大曝气量和减小导流筒直径能明显提升降流区输氧能力。总之,可通过调整曝气量,导流筒直径及导流筒溢流堰口高度控制降流区输氧能力,以构建耗缺氧区域。通过响应面分析,得到导流筒直径250 mm、导流筒溢流堰口高度10 mm时,反应器降流区输氧能力较优。

The downflow zone oxygen transfer capacity of the loop bioreactor is mainly affected by factors such as the diameter of the guide tube, the height of the overflow weir of the guide tube, and the aeration volume, which have important effects on the denitrification and phosphorus removal treatment effect of the reactor wastewater.To investigate the influence of the above factors on the oxygen transfer capacity of the downflow zone, a combination of numerical simulation and experiments was used to study the oxygen transfer capacity of the downflow zone of the circulating reactor.A custom program coupled with Higbie mass transfer theory was used to simulate oxygen mass transfer.The dissolved oxygen concentration and overflow volume simulated under different aeration intensities were compared with the measured values, and the results showed an error within 8%,indicating that the numerical simulation model and method were correct and feasible.Subsequently, the effects of aeration volume, guide tube diameter, and guide tube overflow weir height on the oxygen transfer capacity of the downflow zone were explored.The results showed that when the aeration volume increased from 20 L/min to 50 L/min, the oxygen volumetric mass transfer coefficient increased from 2.04 h^(-1) to 4.45 h^(-1);when the guide tube diameter decreased from 325 mm to 250 mm, the oxygen volumetric mass transfer coefficient increased from 3.99 h^(-1) to 4.42 h^(-1);when the guide tube overflow weir height increased from 10 mm to 25 mm, the oxygen volumetric mass transfer coefficient decreased from 4.17 h^(-1) to 4.00 h^(-1);increasing the aeration volume and reducing the guide tube diameter can significantly enhance the oxygen transfer capacity of the downflow zone.The oxygen transfer capacity of the downflow zone can be controlled by adjusting the aeration volume, guide tube diameter, and guide tube overflow weir height to construct an anoxic zone.Response surface analysis showed that when the guide tube diameter is 250 mm and the guide tube overflow weir height is 10 mm, the oxygen transfer capacity of the reactor downflow zone is optimal.