Elhadi S L N, Huck P M, Slawson R M
Department of Civil Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2L 3G1, Canada.
Water Sci Technol. 2004;49(9):273-80.
The quality of drinking water is sometimes diminished by the presence of certain compounds that can impart particular tastes or odours. One of the most common and problematic types of taste and odour is the earthy/musty odour produced by geosmin (trans-1, 10-dimethyl-trans-9-decalol) and MIB (2-methylisoborneol). Taste and odour treatment processes including powdered activated carbon, and oxidation using chlorine, chloramines, potassium permanganate, and sometimes even ozone are largely ineffective for reducing these compounds to below their odour threshold concentration levels. Ozonation followed by biological filtration, however, has the potential to provide effective treatment. Ozone provides partial removal of geosmin and MIB but also creates other compounds more amenable to biodegradation and potentially undesirable biological instability. Subsequent biofiltration can remove residual geosmin and MIB in addition to removing these other biodegradable compounds. Bench scale experiments were conducted using two parallel filter columns containing fresh and exhausted granular activated carbon (GAC) media and sand. Source water consisted of dechlorinated tap water to which geosmin and MIB were added, as well as, a cocktail of easily biodegradable organic matter (i.e. typical ozonation by-products) in order to simulate water that had been subjected to ozonation prior to filtration. Using fresh GAC, total removals of geosmin ranged from 76 to 100% and total MIB removals ranged from 47% to 100%. The exhausted GAC initially removed less geosmin and MIB but removals increased over time. Overall the results of these experiments are encouraging for the use of biofiltration following ozonation as a means of geosmin and MIB removal. These results provide important information with respect to the role biofilters play during their startup phase in the reduction of these particular compounds. In addition, the results demonstrate the potential biofilters have in responding to transient geosmin and MIB episodes.
饮用水的质量有时会因某些能赋予特定味道或气味的化合物的存在而降低。最常见且成问题的味道和气味类型之一是由土臭素（反式 -1,10 - 二甲基 - 反式 -9 - 十氢化萘醇）和2 - 甲基异冰片醇（MIB）产生的土腥味/霉味。包括粉末活性炭以及使用氯、氯胺、高锰酸钾，甚至有时使用臭氧进行氧化在内的味道和气味处理工艺，在将这些化合物降低到其气味阈值浓度水平以下方面大多无效。然而，臭氧氧化后接生物过滤有提供有效处理的潜力。臭氧能部分去除土臭素和MIB，但也会产生其他更易于生物降解且可能导致不良生物不稳定性的化合物。随后的生物过滤除了能去除这些其他可生物降解的化合物外，还能去除残留的土臭素和MIB。使用两个装有新鲜和耗尽的颗粒活性炭（GAC）介质及沙子的平行过滤柱进行了实验室规模的实验。原水由添加了土臭素和MIB的脱氯自来水以及一种易生物降解有机物混合物（即典型的臭氧氧化副产物）组成，以便模拟在过滤前已进行臭氧氧化的水。使用新鲜的GAC时，土臭素的总去除率在76%至100%之间，MIB的总去除率在47%至100%之间。耗尽的GAC最初去除的土臭素和MIB较少，但去除率随时间增加。总体而言，这些实验结果对于臭氧氧化后使用生物过滤作为去除土臭素和MIB的方法是令人鼓舞的。这些结果提供了关于生物滤池在启动阶段对减少这些特定化合物所起作用的重要信息。此外，结果表明生物滤池在应对土臭素和MIB的瞬时事件方面具有潜力。
