Hess Angelika, Bettex Cécile, Morgenroth Eberhard
Eawag: Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland.
ETH Zürich, Institute of Environmental Engineering, 8093, Zürich, Switzerland.
Water Res X. 2020 Nov 18;9:100078. doi: 10.1016/j.wroa.2020.100078. eCollection 2020 Dec 1.
Highly variable flow has to be expected in decentralized greywater treatment and can lead to intermittent operation of the treatment system. However, few studies have addressed the influence of variable flow on the treatment performance of a biological activated carbon filter (BAC). In this study, we investigated the influence of intermittent flow using small-scale BAC columns, which treat greywater as a second treatment step following a membrane bioreactor (MBR). Three operating strategies to respond to variable flow were evaluated. The activated carbon was characterized before and after the experiments in terms of biological activity and sorption capacity. The performance of the BAC filters was assessed based on total organic carbon (TOC) removal, TOC fractions and growth potential. No significant differences were observed between constant flow compared to on-off operation with intermittent flow over the range of tested influent concentrations. Peaks with high TOC during 24 h periods were attenuated by sorption and biological degradation. Adsorbed TOC was released after switching back to normal concentrations for influent concentrations more than 5 times higher than usually observed, the BAC functioned as a temporary sink. In line with these results, the high influent TOC values led to increased biological activity in the filter but did not influence the sorption capacity. The experiments showed that intermittent flow does not negatively impact the performance of a BAC and that there is no need for additional equalization tanks to buffer the variable flow, for example in household-scale greywater treatment.
分散式中水（灰水）处理中流量变化很大，这可能导致处理系统间歇性运行。然而，很少有研究探讨流量变化对生物活性炭滤池（BAC）处理性能的影响。在本研究中，我们使用小型BAC柱研究了间歇流的影响，该小型BAC柱作为膜生物反应器（MBR）之后的第二步处理来处理中水。评估了三种应对流量变化的运行策略。在实验前后对活性炭的生物活性和吸附能力进行了表征。基于总有机碳（TOC）去除率、TOC组分和生长潜力对BAC滤池的性能进行了评估。在测试进水浓度范围内，与间歇流的开关操作相比，恒流操作未观察到显著差异。24小时内高TOC峰值通过吸附和生物降解得以减弱。对于进水浓度比通常观察到的高出5倍以上的情况，在恢复到正常浓度后，吸附的TOC会释放出来，此时BAC起到了临时汇的作用。与这些结果一致，进水TOC值高导致滤池中生物活性增加，但不影响吸附能力。实验表明，间歇流不会对BAC的性能产生负面影响，例如在家庭规模的中水（灰水）处理中，无需额外的均衡池来缓冲流量变化。
