人们对饮用水水源中高氯酸盐的存在越来越担忧，这促使 研究去除这种化合物的处理方法。生物处理 填料床反应器，如生物活性炭（BAC），已被证明是一种有效的方法 可行的选择。高氯酸盐被生长的高氯酸盐还原菌（PRB）去除 BAC中的生物膜。PRB和其他异养菌构成生物膜。PRB可以利用 高氯酸盐作为电子受体。然而，PRB也可以在可用的情况下使用氧气。 因此，保持较低的氧气浓度对于完成对污染物的去除非常重要 高氯酸盐。 生物过滤器中的反洗有两个目的。首先，定期反洗是必要的 防止过滤器堵塞和过度压降所必需的，其次， 为了保持生物膜的活性并确保良好的外部质量，需要进行反洗 污染物转移到生物膜（Hozalski和Bouwer，1998年）。以前的研究 研究表明，生物活性炭过滤器中的生物量以薄生物膜的形式保留 附着在碳纤维表面，也以大型微生物的形式存在 堆积在内部的骨料（高达几百微米）- 粒子空间 纤维之间（Choi等人，2003年）。这些大骨料可以被视为厚骨料 与碳纤维上的薄生物膜相比，扩散受限的生物膜 很可能被完全穿透。反冲洗预计会冲洗掉很大一部分 这些松散附着的骨料（Delahaye等人，1999年）。生物膜直接附着在 碳纤维更耐剪切，其中只有一小部分直接连接 生物量预计会在反洗过程中损失。因此，反冲洗不仅应该 减少系统中的总生物量，但预计也会改变 厚的生物膜（即大型微生物聚集体）到薄的生物膜（直接连接到 碳纤维表面）。 这篇论文证明了大骨料对维护 在进水氧浓度增加的情况下去除高氯酸盐。传质 大骨料的局限性导致厌氧区在这些区域的中心发展 骨料，允许去除高氯酸盐。随着氧气的增加 浓度在体相时，碳纤维表面的薄生物膜会 完全渗透，不允许去除高氯酸盐。 因此 本文所验证的假设是，BAC过滤器的剧烈反洗仅具有 对高氯酸盐去除的影响有限，只要整体中的氧气浓度 相位较低。然而，反洗后，BAC过滤器更容易受到污染 大部分大型微生物的损失导致的体相氧浓度 聚合。为了验证这一假设，操作了实验室规模的BAC过滤器，并使用高氯酸盐 在密集反洗前后对去除情况进行监测。 包括6个参考文献、图表。

Growing concerns over the presence of perchlorate in drinking water sources has promoted research on treatment methods to remove this compound. Biological treatment using packed bed reactors, such as biological activated carbon (BAC), has been proven to be a viable option. Perchlorate is removed by perchlorate reducing bacteria (PRB) growing as biofilms in BAC. PRB and other heterotrophs constitute the biofilm. PRB can utilize perchlorate as electron acceptor. However, PRB can also use oxygen when available. Therefore, maintaining low oxygen concentrations is important to accomplish removal of perchlorate. Backwashing in biological filters serves two purposes. First, regular backwashing is necessary to prevent clogging and excessive pressure drops across the filter and, second, backwashing is necessary to maintain an active biofilm and ensure good external mass transfer of the contaminant to the biofilm (Hozalski and Bouwer, 1998). A previous study has shown that biomass in BAC filters is retained both in the form of thin biofilm attached to the surface of the carbon fibers and also in the form of large microbial aggregates (up to several hundred micrometers) that accumulate in the inter-particle space between the fibers (Choi et al., 2003). These large aggregates can be viewed as thick biofilms that are diffusion limited in contrast to the thin biofilms on the carbon fibers that are likely to be fully penetrated. Backwashing can be expected to washout a large fraction of these loosely attached aggregates (Delahaye et al., 1999). Biofilm directly attached to the carbon fibers is more resistant to shear and only a smaller fraction of this directly attached biomass is expected to be lost during backwashing. Thus, backwashing should not only reduce the total biomass in the system, but also is expected to change the relative amount of thick biofilms (i.e., large microbial aggregates) to thin biofilms (directly attached to the surface of the carbon fibers). This paper demonstrates that large aggregates are important to maintain perchlorate removal in cases of increased influent oxygen concentrations. Mass transfer limitations in the large aggregates cause anaerobic zones to develop in the center of these aggregates, allowing for perchlorate removal to take place. With increased oxygen concentrations in the bulk phase, the thin biofilms on the surface of the carbon fibers will be fully penetrated and will not allow for perchlorate removal to occur. Thus, the hypothesis tested in this paper is that vigorous backwashing of a BAC filter has only a limited influence on perchlorate removal as long as oxygen concentrations in the bulk phase are low. However, after backwashing, BAC filters are more vulnerable to increased bulk phase oxygen concentrations due to the loss of the majority of the large microbial aggregates. To test this hypothesis, a lab-scale BAC filter was operated and perchlorate removal was monitored before and after intensive backwashing. Includes 6 references, figures.