氯胺消毒管网“三氮”与总氯变化的预测模型

为探讨氯胺消毒供水管网的水质问题,建立了一种试验规模的氯胺消毒供水管网水质模拟系统。基于质量守恒原理和双Monod方程建立了该系统的硝化与氯胺衰减动力学耦合模型,并通过试验对该模型进行了验证。模型中的部分参数采用非线性多项式回归方法进行估计。应用该模型确定了活性氨氧化菌(AOB)和亚硝酸盐氧化菌(NOB)的数量。该模型对管网模拟系统内氨氮、硝酸盐氮与总氯的预测值与实测值基本一致,但对亚硝酸盐氮的预测值与实测值存在较大偏差。

Ways on how to use models for predicting concentration changes of free ammonia,nitrite,nitrate and chloramine in the pilot-scale chloraminated distribution system

This paper focuses on the study of how to use models for predicting concentration changes of free ammonia,nitrite,nitrate and chloramine in the pilot-scale chloraminated distribution system.In order to investigate problems in this connection,we have built up a pilot-scale chloraminated distribution system based on the recirculation design concept.We have also developed a set of nitrification and residual chloramine decay kinetic coupling models on the basis of the principle of mass conservation and Double-Monod equation to describe the changes of the free ammonia,nitrite,nitrate and chloramine concentrations in the stable chloraminated distribution system.The coupling model we suggested consists of six equations,including two Double-Monod equations for ammonia or nitrite nitrogen as a nutrient substrate,and four mass conservation equations for the ammonia nitrogen,nitrite nitrogen,nitrate nitrogen and the total chlorine.The models we have established were tested and verified by a few groups of experimental data.And then,we necessarilly estimated the parameters concerning the models,such as those involved in the practical use of nonlinear multi-response regression based on the experimental data.Besides,we have also defined some other parameters by referring to the related literature and the experiments involved,in addition to defining the active ammonia-oxidizing bacteria(AOB) and nitrite-oxidizing bacteria(NOB) biomasses in the pilot-scale system by this predictive model,which may help to simulate and predict the variations of free ammonia,nitrate and chloramine concentrations in the mentioned system,though there might be some errors between the model predications and the experimental results for nitrite.Moreover,since the total chlorine decaying rate tends to be closely related to the concentrations of organic matter(including NOM and SMP,etc.) and nitrite nitrogen,there comes the need to reduce the decaying rate of the total chlorine so as to ensure the pipe network peripheral to maintain a certain degree of residual chlorine,reduce the organic matter concentration in the treated water,and finally get rid of nitrite accumulation.Therefore,it would be more suitable if the models developed were able to predict and simulate the variations of free ammonia,nitrite,nitrate and chloramine concentrations in the long-distance pipeline and pipe network peripheral.