【作者】 虞介泽；

【导师】 张土乔； 李聪；

【作者基本信息】 浙江大学 ， 市政工程， 2013， 博士

【摘要】 为了对管网水质运行情况进行评价,优化管网水质,本研究中采用扩展余氯-I/O模型和THMs-I/O模型作为计算基础,建立管网水质服务水平-加氯总费用多目标优化模型。此外,由于水质监测点在反映实际管网水质服务水平时存在误差,故本论文对管网水质服务水平进行了修正。首先,为使余氯-I/O模型在余氯快慢反应共存时仍适用,并且提高THMs各组分的计算效率,本文推导了扩展余氯-I/O模型和THMs-I/O模型。采用管网末端的饮用水和水厂滤后水各自进行了加氯实验。结果表明当初始余氯质量浓度大于某个阈值后,快反应在0.5小时内基本完成,水质监测点的余氯质量浓度与加氯点上参与慢反应的初始余氯质量浓度符合线性比例关系。基于实验结果,本文提出了扩展余氯-I/O模型的适用条件。在中试管网中验证扩展余氯-I/O模型,结果表明扩展余氯-I/O模型优于传统的余氯-I/O模型。采用基于余氯消耗的THMs各组分生成模型拟合THMs各组分的质量浓度。考虑温度、初始余氯质量浓度和溴离子质量浓度为影响因素,采用正交实验观察三因素对模型中的THMs各组分线性比例系数的影响。实验结果表明,THMs各组分线性比例系数受溴离子质量浓度的影响最大,而受温度和初始余氯质量浓度的影响较小。在中试管网中验证THMs-I/O模型,结果显示实测值与预测值间的相对误差在9%以内。其次,为研究管网水质运行情况的评价模型,本文引入余氯服务水平概念,初步探讨了管网水质服务水平评价函数,改进了二次加氯优化模型。参考余氯服务水平和《生活饮用水卫生标准》,建立了THMs各组分的服务水平。考虑加权平均值、加权连乘值和加权标准差三类函数,用于建立关联余氯及THMs各组分服务水平的管网水质服务水平表达式。本文采用管网水质服务水平-加氯总费用多目标模型对管网水质运行情况进行评价。结合一管网算例,采用EPANET_MSX模拟余氯衰减和THMs各组分生成,利用实数编码的非支配排序遗传算法(NSGA-Ⅱ)进行优化,得到各种情况下的Pareto前沿面。计算结果表明,加权平均表达式为关联余氯和THMs服务水平的最优方式。二次加氯点布置于水塔出水口和管网末端即可,过多的二次加氯点不仅不能显著提高管网水质服务水平,还会加大加氯总费用。余氯衰减系数对pareto面的影响最大,故改善水质更换老旧管道是提高管网水质服务水平且节省加氯总费用最可行的方法。最后,本文研究了水质监测点在反映实际管网水质服务水平时存在误差的现象,探讨了管网水质服务水平的修正。模拟结果表明,随着水质监测点数量的增加,误差有减小的趋势,但不呈现单调递减。当水质监测点数量较多时,误差可忽略。论文比较了水质监测点覆盖率和水质监测点数量占管网节点总数的比率拟合误差的效果,结果显示后者较优。通过一大型管网验证,结果表明修正后的管网水质服务水平更加接近于实际管网水质服务水平。本论文得到了水体污染控制与治理重大专项：饮用水水质监控预警及应急技术研究与示范(2008ZX07420-004)、潮汐影响地区饮用水安全保障技术集成与示范(2009ZX07424-001)和山地丘陵城市饮用水安全保障共性技术研究与示范(2009ZX07424-004)以及国家自然科学基金(51208455)的资助。更多还原

【Abstract】 To evaluate and optimize the water quality in water distribution systems, extensional residual chlorine-I/O model and THMs-I/O model were studied and used as the calculation basis to build the multi-objective optimization model beween service level of water quality in water distribution systems and chlorination costs. In addition, there are errors when water quality monitoring stations respond the real service level of water quality in water distribution systems. Therefore, the service level of water quality in water distribution system was corrected in this study.Firstly, in order to make the residual chlorine-I/O models suitable in residual chlorine slow and fast reaction coexistence and improve computational efficiency of optimization model, extensional chlorine-I/O model and THMs-I/O model were derivated. The experiments were conducted to investigate chlorine decay with tap water at the end of the pipe network and filtrated water of water plant. The results showed that fast reaction of chlorine decay basically finish when initial chlorine mass concentration is above some value. Therefore, the chlorine mass concentration of water quality monitoring stations is linearly proportional relationship with initial mass concentration in slow reaction on chlorination boosters. Moreover, extensional chlorine-I/O model was presented in the pilot-scale water distribution system. The results showed that the extensional chlorine-I/O model is better than traditional chlorine-I/O model. In addition, to match generation of THMs, formation model of THMs based on chlorine consumption was proposed. The effect of three factors including temperature, initial chlorine concentration and bromine ion concentration, on proportional coefficient of the linear model were studied. Experiment results showed that bromine ion concentration had the most effect on the proportional coefficient of the linear model, and the proportional coefficient was independent on temperature and initial chlorine concentration. Moreover, the THMs-I/O model was proved in the pilot-scale water distribution systems and the simulation results showed that the error between real value and predictive value is below9%.Secondly, to study an evaluation model of water quality in water distribution systems, concept of residual chlorine servicel level was proposed to study the evaluation function of residual service level and improve the optimization model in rechlotination. By reference to chlorine performance and "Standards for Drinking Water Quality", service level of each component of THMs was established. Three kinds of expressions, which named weighted average value, standard deviation and multiplication, were used to measure service level of water quality. Multi-objective optimization model of service level of water quality and rechlorination cost was proposed. Chlorine decay and THMs generation were simulated using EPANETMSX. An improved non-dominated sorted genetic algorithm-Ⅱ with integer code was adopted to optimize the model, and pareto fronts could be obtained under different conditions. Results showed that the weighted average expression was the optimal way to correlate residual chlorine and THMs formation. It was enough that boosters be located on outlet of water tower and end of water distribution systems. Too much number of boosters can not significantly improve service level of water quality, but can increase total cost of rechlorination. Therefore, improving water quality and replacement of old pipes was the most feasible method to improve service level of water quality and save total cost of rechlorination.Finally, as there are errors when water quality monitoring stations respond the real service level of water quality in water distribution systems, the service level of water quality in water distribution system was corrected in this study. The results showed that, with the number of water quality monitoring stations increases, the errors tended to decrease and it was not monotonically decrease.The errors would be ignored when the number of water quality monitoring stations was large. In this thesis, chlorine monitoring coverage and ratio between the number of chlorine monitoring stations and node number of water distribution system were used to compare their measurement errors. The results showed that later could be better to measure the errors. By verifying a water distribution system in a large-sized city, the results showed that the corrected service level formula of water quality is closer to the real service level of water quality. The corrected service level formula of water quality was providing a theoretical foundation for running and controlling water distribution systems.This thesis was kindliy supported by National Major Project of Science&Technology Ministry of China (2008ZX07420-004,2009ZX07424-001and2009ZX07424-004) and National Natural Science Foundation of China (No.51208455).更多还原