摘要

       不适当的卫生条件可能导致传染病的传播和通过受污染的水产生的抗微生物（AMR）。不幸的是，废水处理在许多发展中国家和新兴国家并不普遍，特别是在远离中央下水道的农村和城市周边地区。因此，需要小规模、更可持续的处理方案，例如好氧反硝化-下流悬挂海绵（DDHS）生物反应器。对DDHS反应器进行了应用评价，其化学需氧量和氨氮去除率分别达到79%和84%以上，总氮去除率达到71%。通过绕过DDHS系统顶层的一部分未经处理的废水来促进反硝化作用，提高了TN的去除率。然而，目前尚不清楚这种旁路对处理后废水中AMR基因（ARG）和移动遗传元素（MGE）水平的影响。高通量qPCR用于量化DDHS生物反应器中ARG和MGE的水平，作为旁路百分比（0、10、20和30%体积比）的函数。所有系统均获得了90%以上的ARGs还原率，尽管不同旁路方式的出水ARGs和总氮水平不同，但在约20%旁路时达到了协同最优还原率。ARGs的去除率与细菌的去除率平行，尽管出水细菌往往具有更大的遗传可塑性，这是基于每个细胞更高的表观MGE水平。总的来说，随着旁路的增加，TN的去除率增加，ARG的去除率降低，因此需要在每个DDHS应用中进行协同优化，以达到局部目标TN和AMR的排放水平。

        Inadequate sanitation can lead to the spread of infectious diseases and antimicrobial resistance (AMR) via contaminated water. Unfortunately, wastewater treatment is not universal in many developing and emerging countries, especially in rural and peri-urban locations that are remote from central sewers. As such, small-scale, more sustainable treatment options are needed, such as aerobic-Denitrifying Downflow Hanging Sponge (DDHS) bioreactors. In this study, DDHS reactors were assessed for such applications, and achieved over 79% and 84% removal of Chemical Oxygen Demand and Ammonium, respectively, and up to 71% removal of Total Nitrogen (TN) from domestic wastes. Elevated TN removals were achieved via bypassing a fraction of raw wastewater around the top layer of the DDHS system to promote denitrification. However, it was not known how this bypass impacts AMR gene (ARG) and mobile genetic element (MGE) levels in treated effluents. High-throughput qPCR was used to quantify ARG and MGE levels in DDHS bioreactors as a function of percent bypass (0, 10, 20 and 30% by volume). All systems obtained over 90% ARG reduction, although effluent ARG and TN levels differed among bypass regimes, with co-optimal reductions occurring at ~20% bypass. ARG removal paralleled bacterial removal rate, although effluent bacteria tended to have greater genetic plasticity based on higher apparent MGE levels per cell. Overall, TN removal increased and ARG removal decreased with increasing bypass, therefore co-optimization is needed in each DDHS application to achieve locally targeted TN and AMR effluent levels.

        https://www.sciencedirect.com/science/article/pii/S0048969718312014?via%3Dihub