【作者】 陆品品；

【导师】 张晓健；

【作者基本信息】 清华大学 ， 土木工程， 2013， 博士

【摘要】 本研究选取我国南方湿热地区某城市的供水系统作为研究对象。该供水系统具有多水源供水、多种净水工艺、高水温、多种管材、不同管龄、超大管网等突出特点，在生物稳定性研究方面具有很强的复杂性、代表性和挑战性。本论文通过对比该城市不同供水管网的水质生物稳定性，判别控制生物稳定性的主要指标，分析不同净水技术的处理能力，提出适用于我国南方湿热地区城市管网的生物稳定性的综合控制对策。主要研究成果如下：（1）对该市供水管网水质生物稳定性的长期监测表明，该城市局部供水管网存在较为明显的细菌再生长问题。采用统计软件分析，确定余氯、水力停留时间是细菌生长的主要影响因素，余氯越高，管网中细菌越少；水力停留时间越长，管网中细菌越多。（2）对采用好水源（Ⅱ类）、深度处理工艺的水厂供水管网进行了重点研究，首次将“生物稳定特性曲线”应用于实际供水管网研究，给出了维持管网生物稳定所需的余氯和可生物同化有机碳（AOC, assimilable organic carbon）的定量边界条件：维持余氯在1.11-1.73mg/L可保证该供水管网生物稳定，且技术上可以实现；而降低有机基质至AOC=7-47μg/L才能控制生物稳定性，远超出水厂处理能力；确定华南地区高水温供水管网中生物稳定性主要受余氯控制，与北方地区受余氯和营养基质双重控制的特性明显不同。研究发现，管道生物膜冲刷脱落是管网水中细菌的主要来源，搭建了生物膜模拟反应器进行其消毒灭活特性研究，1.0mg/L的氯胺或者0.5mg/L的自由氯能够将管壁生物膜充分灭活至100CFU/cm2量级。（3）对细菌再生长的深入研究表明，耐氯细菌在该城市供水管网中普遍存在。经鉴定发现了3株耐氯细菌，分别为产粘液分支杆菌（条件致病菌）、藤泽氏甲基杆菌、鞘氨醇单胞菌（新种）。耐氯细菌对消毒剂的抗性：产粘液分支杆菌>鞘氨醇单胞菌>藤泽氏甲基杆菌。抗性最强的分支杆菌能够被0.4mg/L的自由氯和0.4mg/L的二氧化氯灭活。因此，应改用自由氯或二氧化氯消毒作为管网消毒剂。（4）根据上述研究结果，系统确定了华南地区高水温供水管网中保障生物稳定性的技术策略：保障生物稳定性需维持管网水高余氯；灭活耐氯细菌需要采用游离氯或二氧化氯消毒；实现更换消毒剂并维持高余氯，可以通过更换优质水源、使用生物预处理、深度处理工艺来改善出厂水中消毒剂的衰减特性。更多还原

【Abstract】 The drinking water supply system in one city in hot and humid South China wasselected as the investigation objective. This water supply system has the representativeprofile of multi water sources, multi water treatment processes, multi pipe materials,different pipe ages and super huge networks, which make this investigation highlycomplex, representative and challenging.In this paper, the bio-stability of different sub networks in this city was compared,the principal index of bio-stability judgment was identified, the capacity of differentwater treatment processes to control bio-stability was analyzed and the comprehensivemeasures suitable for this city in South China was presented to improve the bio-stability.The results and achievements of this paper were given as below:According to the long term monitoring of water quality in the networks all overthis city, certain parts of the network bear obvious bacteria re-growth problem. Residualchloramine concentration and hydraulic retention time were identified as the principlefactors influencing the bacteria re-growth by the analysis with software SPSS. Thehigher chloramine concentration was maintained in networks, the fewer bacteria couldsurvive; the longer hydraulic retention time was, the more bacteria existed in networks.Emphasis was given to the sub-network fed by the water treatment plant with goodsource water (Ⅱ) and advanced treatment process (ozone and biological activatedcarbon). As far as the author knew, it was the first time that the Biostability Curve wasapplied in real drinking water distribution system. The quantitative boundary wasdetermined by the Biostability Curve for achieving the bio-stability in the networks:maintaining residual chloramine at1.11-1.73mg/L which is practical for water industry,or keeping the AOC concentration as low as7-47μg/L which is far beyond the drinkingwater plant’s capacity. Therefore, the bio-stability issue in the distribution system withhigh water temperature in South China is dominantly affected by residual chloramine,which is quite different with the previous report that the bio-stability in networks inNorth China is controlled by both residual chloramine and organic substrate. Furtherinvestigation indicated that the detachment of biofilm from pipe wall by flushing wasthe main source of bacteria in bulk water. The inactivation characteristic of biofilm was studied by the simulative biofilm annular reactors. The results indicated that1.0mg/L ofmonochloramine or0.5mg/L of free chlorine could successfully inactive the biofilmbacteria to the level of100CFU/cm2.Further investigation was conducted on the re-grown bacteria. It was found that thechloramine-resistant bacteria survived pervasively in the distribution systems all overthis city. Three kinds of chloramine-resistant bacteria, i.e. Mycobacterium mucogenicum,Methylobacterium fujisawaense, Sphingomonas sp.(new strain) were identified in thedistribution system. Mycobaterium, one well-known opportunistic pathogen, was highlyresistant to disinfectant; Sphingomonas was moderately resistant to disinfectant whileMethylobacterium was relatively lowly resistant to disinfectant. Free chlorine of0.4mg/L or chlorine dioxide of0.4mg/L could effectively inactivate Mycobateriumwhile chloramine could hardly inactivate Mycobaterium. Therefore, the free chlorine orchlorine dioxide was necessary to eliminate the resistant bacteria.Based on the aforementioned results, the control strategy was established toguarantee the bio-stability in the high-temperatured distribution system in South China.The high residual chloramine was necessary to maintain the bio-stability in thedistribution system, the free chlorine or chlorine dioxide should be applied if theresistant bacteria existed. To maintain the sufficient residual chlorine, esp. free chlorineor chlorine dioxide, the finished water quality should be improved by switching to goodwater source and updating the water treatment process with biological pre-treatment oradvanced treatment process of ozone and activated carbon.更多还原