Biological ion exchange (BIEX) drinking water filters have been shown in lab- and pilot-scale systems to exhibit 40–60% removal of dissolved organic carbon (DOC) with minimal maintenance or operational needs. Three mechanisms are understood to contribute to DOC removal in BIEX filters: primary IEX (chloride-based DOC removal), secondary IEX (sulphate-based) and biodegradation. However, there is limited understanding of the biotic contributions to BIEX. This study investigated the contributions of biodegradation by operating BIEX filters beyond secondary IEX exhaustion. ‘Exhausted’ BIEX filters performed similarly to biological activated carbon (BAC) with DOC removal around 5%, while BIEX filters during secondary IEX showed 41% removal using the same influent. Monthly 16S rRNA gene amplicon sequencing revealed differences in the taxonomic profiles of microbial communities between BIEX and BAC filters with the same influent water, despite similarities in biological contributions to treatment performance. BIEX filters contained Janthinobacterium, Bacillariophyta, Flavobacterium, Mycobacterium and Nitrospira species, while BAC had Staphylococcus, Chryseobacterium, Bacteroides, Aquicella and Chryseolinea. Variances were attributed to contrasting filter media surface characteristics encouraging different microbial populations. BIEX filters reduced effluent cellular ATP by around 70%, leading to a hypothesized benefit of waterborne microbe removal. Based on these findings, we recommend that BIEX drinking water filters be optimized for DOC removal through secondary IEX and not necessarily for biological performance.

中文翻译：

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对生物离子交换的生物学贡献

生物离子交换 (BIEX) 饮用水过滤器已在实验室和中试规模系统中得到证明，可去除 40-60% 的溶解有机碳 (DOC)，且维护或操作需求极低。据了解，三种机制有助于 BIEX 过滤器去除 DOC：初级 IEX（基于氯化物的 DOC 去除）、次级 IEX（基于硫酸盐）和生物降解。然而，人们对 BIEX 的生物贡献了解有限。本研究调查了在二次 IEX 耗尽之外操作 BIEX 过滤器对生物降解的贡献。 “耗尽”BIEX 过滤器的性能与生物活性炭 (BAC) 类似，DOC 去除率约为 5%，而二级 IEX 期间的 BIEX 过滤器在使用相同进水时显示出 41% 的去除率。每月 16S rRNA 基因扩增子测序揭示了相同进水的 BIEX 和 BAC 过滤器之间微生物群落分类特征的差异，尽管对处理性能的生物学贡献相似。 BIEX 过滤器含有詹蒂诺杆菌属、硅藻门、黄杆菌属、分枝杆菌属和硝化螺菌属，而 BAC 则含有葡萄球菌属、金杆菌属、拟杆菌属、Aquicella和Chryseolinea属。差异归因于对比过滤介质表面特征鼓励不同的微生物种群。 BIEX 过滤器将流出的细胞 ATP 减少了约 70%，从而产生了去除水生微生物的假设效益。基于这些发现，我们建议对 BIEX 饮用水过滤器进行优化，以通过二级 IEX 去除 DOC，但不一定要优化生物性能。