Department of Civil and Environmental Engineering, American University of Beirut, Lebanon.
Department of Civil and Environmental Engineering, American University of Beirut, Lebanon.
Waste Manag. 2018 Mar;73:165-180. doi: 10.1016/j.wasman.2017.12.003. Epub 2017 Dec 14.
This study examines the performance and fouling potential of flat sheet (FS) and hollow fiber (HF) membrane bioreactors (MBRs) during the treatment of high strength landfill leachate under varying solid retention times (SRT = 5-20 days). Mixed-liquor bacterial communities were examined over time using 16S rRNA gene sequence analysis in an attempt to define linkages between the system performance and the microbial community composition. Similarly, biofilm samples were collected at the end of each SRT to characterize the microbial communities that evolved on the surface of the FS and HF membranes. In general, both systems exhibited comparable removal efficiencies that dropped significantly as SRT was decreased down to 5 days. Noticeably, ammonia and nitrite oxidizing bacteria were not detected at the tested SRTs. This suggests that the nitrifiers were not enriched, possibly due to the high organic and ammonium content of the leachate that led to low TN and NH removal efficiency. The steady-state fouling rate of both membranes increased linearly with the decrease in SRT at an estimated factor of 1.1 and 1.2 for the FS- and HF-MBR, respectively, when the SRT was reduced from 15 to 10 days and from 10 to 5 days. Similar dominant genera were detected in both MBRs, including Pseudomonas, Aequorivita, Ulvibacter, Taibaiella, and Thermus. Aequorivita, Taibaiella; Thermus were the dominant genera in the biofilms. Hierarchical clustering and non-metric multidimensional scaling revealed that while the mixed liquor communities in the FS-MBR and HF-MBRs were dynamic, they clustered separately. Similarly, biofilm communities on the FS and HF membranes differed in the dynamic bacterial community structure, especially for the FS-MBR; however this was less dynamic than the mixed liquor community.
本研究考察了在不同固体停留时间（SRT=5-20 天）下，平板（FS）和中空纤维（HF）膜生物反应器（MBR）处理高强度垃圾渗滤液时的性能和结垢潜力。通过 16S rRNA 基因序列分析，随时间检查混合液细菌群落，试图定义系统性能与微生物群落组成之间的联系。同样，在每个 SRT 结束时收集生物膜样品，以表征在 FS 和 HF 膜表面上演变的微生物群落。一般来说，两个系统都表现出相当的去除效率，当 SRT 降至 5 天时，去除效率显著下降。值得注意的是，在测试的 SRT 下未检测到氨和亚硝酸盐氧化菌。这表明硝化菌没有富集，可能是由于渗滤液中的有机和铵含量高，导致 TN 和 NH 去除效率低。当 SRT 从 15 天降至 10 天和从 10 天降至 5 天时，两种膜的稳态结垢速率均随 SRT 的降低呈线性增加，估计 FS-MBR 和 HF-MBR 的分别为 1.1 和 1.2 倍。在两个 MBR 中都检测到了相似的优势属，包括假单胞菌、拟杆菌、黄杆菌、太白菌和嗜热菌。在生物膜中，拟杆菌、太白菌、嗜热菌是优势属。层次聚类和非度量多维标度分析表明，虽然 FS-MBR 和 HF-MBR 中的混合液群落是动态的，但它们是分开聚类的。同样，FS 和 HF 膜上的生物膜群落的细菌群落结构也存在差异，尤其是 FS-MBR；然而，这比混合液群落的动态性要小。
