用生物活性炭法去除饮用水中氯仿的试验研究

本文简述了饮用水中三卤甲烷类特别是氯仿的米源和危害;阐述了粒状活性炭过滤吸附和臭氧化—粒状活性炭过滤吸附两种流程的生物活性炭法去除氯仿的效能与机理。试验发现,各活性炭柱在运行初期,均有较高的去除率,其中北京X—11型炭的吸附性能高于太原ZJ—15型炭,并从Lundelius规则和炭层中的生物活性的角度进行了解释。活性炭流程的出水氯仿穿透点为4000～5000床体积;臭氧—活性炭流程为12000～15000床体积。并对臭氧活性炭流程除氯仿效能较好的原因进行了探讨。两种流程的炭柱出水中氯仿比原水中的氯仿浓度高。作者认为这是炭层中的微生物在厌氧条件下将有机物先降解为各种羧酸最后降解为甲烷,而甲烷与水中的游离氯发生自由基取代反应形成氯仿所致。

THE REMOVAL OF CHLOROFORM FROM POTABLE WATER BY BIOLOGICAL ACTIVATED CARBON PROCESS

After the sources and harms of trihalomethanes especially the chloroform in potable water are summarized, the efficiency and mechanism of removing chloroform by two biological activated carbon processes, i.e. (A) filtration and adsorption by granular activated carbon and (B) ozonation and filtration and adsorption by granular activated carbon, are described. It has been found that during the initial operation period chloroform can be effectively removed by both types of activated carbon columns, X-11 type carbon from Beijing is even more effective than ZJ-15 carbon from Tai Yuan. The mechanism is explained by Lundelius rule and biological activities in carbon columns. The 100% chloroform breakthrough bed volumes for both processes A and B are 4000-5000 and 12000-15000 respectively. The reason for better efficiency of removing chloroform by process B is discussed.Chloroform contents of effluents from carbon columns of both processes are higher than that of the untreated water. It is assumed that organic substances undergo microbic degradations in carbon columns under anaerobic conditions to become various kinds of carboxylic acids first and then to methane. Finally, chloroform is formed by reaction of methane and free chlorine present in water,