饮用水活性炭除微污染技术的生物安全性研究

针对饮用水水源的微污染问题,活性炭深度处理技术应用日益受到关注.应用研究中发现,随着炭层中生物颗粒和非生物颗粒的积累,出水中的细菌数较多,并多与细小的活性炭颗粒一起流出,对出水的生物安全性造成影响.研究表明,出水中游离细菌的增多使得在氯或氯胺的灭活效率达99%以上的条件下,未被失活的细菌数量依然处于较高的水平;出水中的细菌容易吸附在疏水性的活性炭颗粒上而受到保护,使氯或氯胺的消毒效率下降,包括病原体在内的微生物大量存活.炭粒携带未被灭活的细菌进入管网后,可吸附在管壁上,形成生物膜,造成二次生物污染.活性炭技术不能有效去除贾第鞭毛虫囊和隐孢子虫卵,甚至出现活性炭工艺出水中“两虫”数量增多的现象.另外,活性炭滤池的进水水质和运行方式等都会影响活性炭出水的生物安全性.而细菌检测技术水平则会影响对饮用水安全性的准确评价.

Study of drinking water biotic security on micro-polluted water treatment by activated carbon process

The accumulation of biologic and non-biologic particles in activated carbon filter may increase the number of bacteria in the effluent,which could influence the biotic security of product water attaching to released fine GAC particles.It was proved that the amount increase of individual bacteria resulted in the uninactivated bacteria still in a higher level of quantity under the inactivation rate above 99% with chlorine or chloramines condition.The inactivation effect on microorganism of chlorine or chloramines was weakened as to abundant organisms including pathogen survive after the disinfection process.The bacteria carried by GAC particles could enter the distribution system,attach to the pipe surface,and develop into a bioflim,which would cause secondary biotic pollution.The pathogenic protozoa such as Giardia and Cryptosporidium could not be effectively removed by GAC filtration even the amount of those increased in the effluent from GAC filter compared with that of sand filtration.The biotic security of GAC filter effluent would be influenced by the following factors such as the water quality of sand filter effluent and the operation condition.In addition,the bacteriological counting techniques would give inadequate results in estimating the biotic security of drinking(water.)