Identification of Archaeal population in the granular sludge of an UASB reactor treating sewage at low temperatures

Abstract

Effect of low temperature on up-flow anaerobic sludge bed (UASB) reactor performance treating raw sewage was investigated in terms of the variations in methanogenic diversity using the 16S rRNA based Fluorescence In-Situ Hybridization (FISH) technique. The diversity of microorganisms present in the anaerobic granular sludge and the structure of the granules operated at 13 degrees C have been investigated using FISH combined with CSLM (Confocal Scanning Laser Microscopy). According to FISH results, archaeal cells representing methanogens were found intensively dominant in the bottom sampling port of the UASB reactor and acetoclastic Methanosaeta was the abundant methanogen. Other methanogens such as Methanosarcina and Methanobacterium like species were also observed. The abundance of originally mesophilic Methanosaeta-related Archaea under low temperature at all sampling days revealed the microbial adaptation to psychrophilic conditions. This might be attributed to the enzymatic alterations in Methanosaeta cells originating from seed sludge, which were exposed to sub-mesophilic temperatures at start-up and then to psychrophilic conditions during gradual decreases of temperature. According to CSLM observation, even though the sludge retained in the reactor kept its granular form as a whole, the majority of the granules had a tendency to be partly broken and they lost their rigidity when raw sewage was fed following synthetic sewage. Besides, Methanosaeta related species prevailing in seed sludge have noticeably lost their long filamentous forms and deteriorated during raw sewage feeding. Members of the order Methanobacteriales constituted the major hydrogenothrophic methanogens present in the psychrophilic UASB reactor, whereas the other hydrogenothrophic methanogens--members of the order Methanococcales and Methanogenium relatives--were absent.

Removal of residual dissolved methane gas in an upflow anaerobic sludge blanket reactor treating low-strength wastewater at low temperature with degassing membrane

“…These results indicate that the UASB process with degasification is a promising technology for effective CH 4 recovery in low-strength wastewater treatment. Because of the economical benefits offered by the UASB process, its application to low-strength wastewater treatment has recently attracted much attention (Elmitwalli et al, 2003;Angenent et al, 2001;Gomec et al, 2008;Matsushige et al, 1990). At an HRT of 3.3 h, D-CH 4 remained at a high concentration (51 ± 3 mg COD L -1 ), and hence, the total CH 4 recovery efficiency was as low as 76 ± 2% during the degasification period (phase 6.2).…”

“…Improvements in reactor design and operational conditions have helped overcome many of the disadvantages of anaerobic wastewater treatment that limited its application to high-strength wastewater treatment at mesophilic or thermophilic temperatures and have allowed for successful operation of anaerobic wastewater treatment reactors at low temperatures (Dhaked et al, 2010;Lettinga et al, 1999;Lettinga et al, 2001;Trzcinski and Stuckey 2010;Luostarinen and Rintala 2005;Madden et al, 2010;Xing et al, 2009;McKeown et al, 2009). In addition, several studies have focused on anaerobic wastewater treatment of low-strength wastewaters at lower temperatures (Elmitwalli et al, 2003;Angenent et al, 2001;Gomec et al, 2008;Matsushige et al, 1990). A drop in temperature causes a change in the physical and chemical properties of wastewater, and this can significantly affect the reactor performance.…”

Effect of Seasonal Temperature on the Performance and on the Microbial Community of a Novel AWFR for Decentralized Domestic Wastewater Pretreatment

“…To date, the molecular biology tools have been extensively developed. Nevertheless, most of the studies still applied the techniques of terminal restriction fragment length polymorphism (T-RFLP) [27], fluorescence in situ hybridization (FISH) [19,28], denaturing gradient gel electrophoresis (DGGE) [29][30][31] and quantitative polymerase chain reaction (q-PCR) [32]. Compared to the conventional ones, the high-throughput sequencing, especially Illumina MiSeq sequencing, is becoming one of the most popular molecular tools for microbial community analysis due to low-cost, fast turnaround time producing several gigabases of sequence and greater coverage [33].…”

Influence of Pre-Hydrolysis on Sewage Treatment in an Up-Flow Anaerobic Sludge BLANKET (UASB) Reactor: A Review

“…The TVS reduction of the two-phase system was 53%, which was higher than the one-phase system [87]. The pretreatment of complex wastewater containing a high fraction of suspended solids in a UASR reactor involves a two-phase system with a high loaded UASB reactor as first stage [83]. The applied high loading rate in the first stage reactor will result in little if any gas production, and therefore a high suspended solids removal was achieved [83].…”

“…• Raw sewage used in this study presented a weak character, which was due to seawater addition into the sewerage system to prevent purification and for cleaning the pipes during the sampling period in summer. [83] Note: (1) "-" = Information not provided. (2) All values are in mg/L unless otherwise mentioned.…”