Model of raw wastewater addition for the anaerobic-adding raw wastewater-intermittent aeration process based on kinetics of denitrification and alkalinity balance
基于碱度平衡与反硝化动力学的厌氧加原水间歇曝气工艺配水比例模型

A batch denitrification experiment was carried out to investigate the influence of concentration of BOD5 and NOx-N(the sum of NO-3-N and NO-2-N) on the rate of denitrification.The results showed that the conversion of NOx-N was a zero order reaction with respect to the concentration of NOx-N in the presence of enough BOD5,thus independent of the concentration of NOx-N.The relationship between conversion rate of NOx-N and the concentration of BOD5 fit well to the Monod equation under limited BOD5 conditions.A mathematical model was derived based on the Monod equation and alkalinity balance.When the ratio of alkalinity to the ammonia concentration was less than 3.82,it was impossible to balance the alkalinity only by addition of raw wastewater,hence additional alkalinity must be added.If the ratio of alkalinity to ammonia concentration was more than 6.90,the process of anaerobic-adding raw wastewater-intermittent aeration was not suitable to the treatment of digested effluent because the Sequential Batch Reactor(SBR) could treat digested effluent directly without adding raw wastewater.Since the ratio of alkalinity to the concentration of ammonia for digested effluent of swine wastewater mostly ranges from 3.82 to 6.90,the process of anaerobic-adding raw wastewater-intermittent aeration is suitable to the treatment of swine wastewater.The mathematical model shows that the proportion of raw wastewater needed increases with increasing hydraulic retention time,the number of reactors,and biomass concentration,capacity of decanter and ratio of nitrite,but drops with increased number of SBR cycles.