Civil and Environmental Engineering Department, National University of Singapore, 1 Engineering Drive 2, #07-03 E1A, 117576, Singapore.
Civil and Environmental Engineering Department, National University of Singapore, 1 Engineering Drive 2, #07-03 E1A, 117576, Singapore.
Water Res. 2020 Sep 1;182:115991. doi: 10.1016/j.watres.2020.115991. Epub 2020 May 27.
A critical challenge in the application of membrane bioreactors (MBR) for domestic wastewater treatment is its high energy consumption caused by continuous aeration for biofouling control. To reduce energy consumption and mitigate fouling in membranes, alternative configurations using dynamic shear-enhanced filtration by membrane reciprocation, rotation, and vibration to mechanically impose shear on membrane surfaces have been recently introduced. However, although these methods are effective at lowering energy usage, the nutrient removal efficiencies and microbial community compositions of these systems have not been well studied. In this study, a lab-scale no-aeration reciprocation membrane bioreactor was used to characterize the microbial composition, functional profile and nutrient removal of the reciprocation MBR system operated under hypoxic conditions. Microbial community analysis showed Proteobacteria (35%) and Saccharibacteria (27%) to be the most abundant phyla in the sludge and the biofilm samples, respectively. Nitrogen and phosphorus removal efficiencies were observed at 70% and 50% while the chemical oxygen demand concentration had about a 99% decrease in the effluent. Quantitative PCR of nutrient-removing genes revealed the presence of complete ammonia-oxidizing organisms (comammox) with a mean abundance of 1.88 × 10 gene copies/g sludge, which explains the high ammonia removal despite a low abundance of canonical ammonia-oxidizing bacteria (AOB). Fluorescence in-situ hybridization showed a prevalence of nitrite-oxidizing bacteria (NOB) with clusters that are distant from other nutrient-removing communities, suggesting that their metabolism is not dependent on ammonia oxidizers. The reciprocation MBR configuration may be a suitable, more energy-efficient alternative to conventional air-scouring systems because of its biofouling mitigation and promising nutrient removal performed by the diverse microbial communities in its system.
在应用膜生物反应器（MBR）处理生活污水时，一个关键的挑战是生物污垢控制需要连续曝气，导致其能耗很高。为了降低能耗和减轻膜污染，可以采用膜往复、旋转和振动等动态剪切增强过滤的替代配置，通过机械方式在膜表面施加剪切力。然而，尽管这些方法在降低能耗方面非常有效，但这些系统的营养去除效率和微生物群落组成尚未得到充分研究。在这项研究中，使用了一个实验室规模的无曝气往复膜生物反应器，以表征在缺氧条件下运行的往复 MBR 系统的微生物组成、功能谱和营养去除情况。微生物群落分析表明，在污泥和生物膜样品中，变形菌门（Proteobacteria）（35%）和厚壁菌门（Firmicutes）（27%）是最丰富的菌门。在缺氧条件下，氮和磷的去除效率分别达到 70%和 50%，而化学需氧量（COD）在出水中的浓度降低了约 99%。营养物质去除基因的定量 PCR 显示，存在完整氨氧化生物（comammox），其平均丰度为 1.88×10基因拷贝/g 污泥，这解释了尽管氨氧化细菌（AOB）丰度较低，但氨去除率很高的原因。荧光原位杂交（FISH）显示，亚硝酸盐氧化菌（NOB）的丰度很高，且其与其他营养去除群落的聚类距离较远，表明其代谢不依赖于氨氧化菌。往复 MBR 配置可能是传统空气擦洗系统的一种合适的、更节能的替代方案，因为它的生物污垢缓解和系统中多样化微生物群落的有前景的营养去除效果。
