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 NH3 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.
Bibliographical noteFunding Information:
This study was partially funded through the Dar Al-Handasah (Shair & Partners) endowed Chair at the American University of Beirut and the Division of Biological and Environmental Sciences and Engineering at KAUST.
We are indebted to ACWA and GE Power & Water for providing the membranes and for their guidance during the installation of the experimental setup. Special thanks are extended to the Council for Development & Reconstruction for providing access to the Naameh landfill as well as to Laceco and the landfill management for facilitating and assisting during leachate sample collections., This study was partially funded through the Dar Al-Handasah (Shair & Partners) endowed Chair at the American University of Beirut and the Division of Biological and Environmental Sciences and Engineering at KAUST.
© 2017 Elsevier Ltd
- 16S rRNA gene sequencing
- Flat sheet
- Hollow fiber
- Landfill leachate
- Membrane bioreactor
ASJC Scopus subject areas
- Waste Management and Disposal