Microbial Systems Ecology, Department of Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, the Netherlands.
Faculty of Geosciences, Department of Earth Sciences, Utrecht University, 3584 CB Utrecht, the Netherlands.
Water Res. 2024 Sep 15;262:122059. doi: 10.1016/j.watres.2024.122059. Epub 2024 Jul 8.
The demand for safe drinking water is constantly challenged by increasing biohazards. One widely used solution is implementing indoor-operated slow sand filtration (SSF) as one of the final barriers in water production. SSF has gained popularity due to its low energy consumption and efficient removal of biohazards, especially microorganisms, without using chemicals. SSF involves both physical-chemical and biological removal, particularly in the "Schmutzdecke", which is a biofilm-like layer on the sand bed surface. To achieve the optimal performance of SSF, a systematic understanding of the influence of SSF operating parameters on the Schmutzdecke development and filter filtration performance is required. Our study focused on three operational parameters, i.e., sand material, sand size, and the addition of an inoculum (suspension of matured Schmutzdecke), on the mini-scale filters. The effects of these parameters on the Schmutzdecke development and SSF removal performance were studied by biochemical analyses and 16S amplicon sequencing, together with spiking experiments with Escherichia coli (E. coli) in the mini-scale filters. Our results indicate that the mini-scale filters successfully developed Schmutzdeckes and generated bacterial breakthrough curves efficiently. The sand size and material were found to have an impact on Schmutzdecke's development. The addition of inoculum to new filters did not induce significant changes in the microbial community composition of the Schmutzdecke, but we observed positive effects of faster Schmutzdecke development and better removal performance in some inoculated filters. Our study highlights the value of mini-scale filters for SSF studies, which provide insights into Schmutzdecke microbial ecology and bacterial removal with significantly reduced requirements of materials and effort as compared to larger-scale filters. We found that operational parameters have a greater impact on the Schmutzdecke biochemical characteristics and removal performances than on the microbial community composition. This suggests that Schmutzdecke characteristics may provide more reliable predictors of SSF removal performance, which could help to improve safe drinking water production.
安全饮用水的需求不断受到生物危害增加的挑战。一种广泛使用的解决方案是在水生产中最后一道屏障中实施室内运行慢砂过滤（SSF）。SSF 由于其低能耗和高效去除生物危害，特别是微生物，而无需使用化学物质，因此越来越受欢迎。SSF 涉及物理化学和生物去除，特别是在“Schmutzdecke”中，这是砂床表面的生物膜状层。为了实现 SSF 的最佳性能，需要系统地了解 SSF 操作参数对 Schmutzdecke 发展和过滤器过滤性能的影响。我们的研究重点是三个操作参数，即砂材料、砂粒径和接种物（成熟 Schmutzdecke 悬浮液）的添加，在小型过滤器上。通过生化分析和 16S 扩增子测序以及在小型过滤器中用大肠杆菌（E. coli）进行接种实验，研究了这些参数对 Schmutzdecke 发展和 SSF 去除性能的影响。我们的结果表明，小型过滤器成功地开发了 Schmutzdeckes 并有效地产生了细菌突破曲线。发现砂粒径和材料对 Schmutzdecke 的发展有影响。向新过滤器添加接种物不会导致 Schmutzdecke 微生物群落组成发生重大变化，但我们观察到在一些接种过滤器中 Schmutzdecke 发展更快和去除性能更好的积极影响。我们的研究强调了小型过滤器在 SSF 研究中的价值，与较大规模的过滤器相比，小型过滤器在材料和工作量方面的要求显著降低，为 Schmutzdecke 微生物生态学和细菌去除提供了深入的了解。我们发现操作参数对 Schmutzdecke 的生化特性和去除性能的影响大于对微生物群落组成的影响。这表明 Schmutzdecke 特性可能提供更可靠的 SSF 去除性能预测指标，这有助于改善安全饮用水生产。
