塑料管材输配水过程中有机物释放规律研究

Research of organic compounds migration from polymeric pipes

研究了目前给水管网中常用的3种塑料管材,未增塑聚氯乙烯（uPVC）,聚乙烯（PE）和无规共聚聚丙烯（PPR）管在输配水过程中有机物的释放规律.通过静态管段实验模拟给水管网中不同输配水状态,选取总有机碳（TOC）为综合评价指标,考察了不同塑料管材中有机物随时间的迁移释放特性,并分析了管材有机物释放对管网水中余氯消耗的影响.随着管材输配水次数的增加,uPVC管释放至水中的TOC浓度和TOC释放速率分别在0.03mg/L和0.04μg/（d·cm^2）以下,而PE管和PPR管在输配水过程中TOC的释放浓度和释放速率在初期最大[PE：0.19mg/L,0.25μg/（d·cm^2）;PPR：0.07mg/L,0.09μg/（d·cm^2）],且后期递减并趋于平稳[PE：0.03～0.08mg/L,0.05～0.10μg/（d·cm^2）;PPR：0.01～0.03mg/L,0.01～0.04μg/（d·cm^2）].随着水力停留时间的增加,不同管材释放的有机物浓度持续升高.不同管材有机物的释放能力排序为：PE〉PPR〉uPVC.各管材的有机物释放特性直接影响管网水的余氯消耗特性,且管材的有机物释放量越多,管网水的余氯消耗越快.PE管的使用易引起水体有机污染问题.本研究明确了3种常用塑料管材的有机物释放规律,将进一步为与塑料管材安全性能评价相关的国家标准的修订提供理论依据.

Polymeric pipes, such as unplasticized polyvinyl chloride pipe（uPVC）, polypropylene random pipe（PPR） and polyethylene pipe（PE） are increasingly used for drinking water distribution networks. This work was designed to determine the TOC migration characteristics of three types of polymer pipes（uPVC, PE and PPR） into drinking water and investigate the influence of TOC migration on the chlorine decay in water. Migration tests were carried out under stagnant conditions with different migration times to simulate drinking water distribution in pipes. Experiment results showed TOC release differed significantly with different plastic materials. With the proceeding migration period, the amount TOC and TOC migration rate from uPVC pipe kept below 0.03mg/L and 0.04μg/（d·cm^2）, respectively. Moreover, both PPR and PE pipes showed an initial maximum migration of TOC（0.19mg/L and 0.25μg/（d·cm^2） for PE; 0.07mg/L and 0.09μg/（d·cm^2） for PPR）, and then a decline trend over migration period to a relative steady level（0.03～0.08mg/L and 0.05～0.10μg/（d·cm^2） for PE; 0.01～0.03mg/L and 0.01～0.04μg/（d·cm^2） for PPR）. During long migration times, TOC concentrations of different pipe materials increased over time, indicating that under long stagnant conditions the drinking water quality could deteriorate fast with the consistent migration of organic compounds and the dramatic consumption of chlorine to a very low level. The order of materials with respect to the ability of TOC migration was observed as PE PPR uPVC. Chlorine consumption during all migration tests followed the shape of TOC migration. Overall, this study presented an investigation of the organic migration of plastic pipes, which might contribute to the improvement of the national standards related with plastic pipes.