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Membrane biofilm development improves COD removal in anaerobic membrane bioreactor wastewater treatment.

Smith AL, Skerlos SJ, Raskin L - Microb Biotechnol (2015)

Bottom Line: High membrane fouling significantly improved permeate quality, but resulted in dissolved methane in the permeate at a concentration two to three times the equilibrium concentration predicted by Henry's law.Restoring fouled membranes to a transmembrane pressure (TMP) near zero by increasing biogas sparging did not disrupt the biofilm's treatment performance, suggesting that microbes in the foulant layer were tightly adhered and did not significantly contribute to TMP.The results describe an attractive operational strategy to improve treatment performance in low-temperature AnMBR by supporting syntrophy and methanogenesis in the membrane biofilm through controlled membrane fouling.

View Article: PubMed Central - PubMed

Affiliation: Department of Civil and Environmental Engineering, University of Michigan, 2350 Hayward Road, Ann Arbor, MI, 48109, USA.

No MeSH data available.


(A) Relative abundance of methanogens identified at the genus level based on 16S rDNA sequencing and (B) relative activity of methanogens identified at the genus level based on 16S rRNA sequencing. Data were obtained for suspended biomass samples collected from start-up to the end of Phase 2 and in biofilm samples obtained at the end of Phase 2. Data are expressed as percentages and were normalized using the total number of 16S rDNA sequences (A) and 16S rRNA sequences (B) (including Bacteria and Archaea). Numbers within bars in (B) represent the relative activity of Methanosaeta spp. based on 16S rRNA sequence data normalized to the 16S rRNA sequences of all Archaea. A truncated y-axis (0–35%) is shown to accentuate changes in methanogen abundance and activity.
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fig03: (A) Relative abundance of methanogens identified at the genus level based on 16S rDNA sequencing and (B) relative activity of methanogens identified at the genus level based on 16S rRNA sequencing. Data were obtained for suspended biomass samples collected from start-up to the end of Phase 2 and in biofilm samples obtained at the end of Phase 2. Data are expressed as percentages and were normalized using the total number of 16S rDNA sequences (A) and 16S rRNA sequences (B) (including Bacteria and Archaea). Numbers within bars in (B) represent the relative activity of Methanosaeta spp. based on 16S rRNA sequence data normalized to the 16S rRNA sequences of all Archaea. A truncated y-axis (0–35%) is shown to accentuate changes in methanogen abundance and activity.

Mentions: High-throughput sequencing of both 16S rDNA and 16S rRNA was employed to study controlled membrane fouling during Phase 2, and the terms ‘relative abundance’ and ‘relative activity’, respectively, are used to report the results of these sequencing efforts. The relative abundance and relative activity levels of populations differed greatly in suspended and biofilm biomass (Fig. 3). The 16S rDNA sequence data indicated that the suspended and biofilm community comprised < 10% methanogens. The hydrogenotrophic methanogens were more abundant than the acetoclastic methanogens in the suspended biomass 26 days after start-up and in the biofilm biomass at the end of Phase 2 (Fig. S5A), suggesting the hydrogen utilization pathway became more important after biomass adaptation to the psychrophilic temperature. A shift towards hydrogenotrophic methanogenesis has also been observed previously in other anaerobic systems when transitioning from mesophilic to psychrophilic conditions using DNA-based analyses and specific methanogenic activity assays (McHugh et al., 2013; Collins et al., 2006; Connaughton et al., 2006), and has been explained by increased hydrogen solubility and thus increased substrate availability for hydrogenotrophic metabolisms (Lettinga et al., 2001). In contrast to 16S rDNA sequence data, 16S rRNA sequencing indicated that the relative activity of acetoclastic and hydrogenotrophic methanogens was similar in our system (Fig. S5B). MF and HF biofilms also had substantially greater activity of methanogens relative to the suspended biomass and LF biofilm on day 138. Specifically, methanogens represented 33% and 34% of the combined bacterial and archaeal activity in MF and HF biofilms, respectively, in comparison to only 15% in the suspended biomass and LF biofilm (Fig. 3). These observations correlated with the low levels of acetate and propionate and high dissolved methane oversaturation by the end of Phase 2 (Fig. 2), and suggest that a high level of methanogenesis occurred in the MF and HF biofilms.


Membrane biofilm development improves COD removal in anaerobic membrane bioreactor wastewater treatment.

Smith AL, Skerlos SJ, Raskin L - Microb Biotechnol (2015)

(A) Relative abundance of methanogens identified at the genus level based on 16S rDNA sequencing and (B) relative activity of methanogens identified at the genus level based on 16S rRNA sequencing. Data were obtained for suspended biomass samples collected from start-up to the end of Phase 2 and in biofilm samples obtained at the end of Phase 2. Data are expressed as percentages and were normalized using the total number of 16S rDNA sequences (A) and 16S rRNA sequences (B) (including Bacteria and Archaea). Numbers within bars in (B) represent the relative activity of Methanosaeta spp. based on 16S rRNA sequence data normalized to the 16S rRNA sequences of all Archaea. A truncated y-axis (0–35%) is shown to accentuate changes in methanogen abundance and activity.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4554476&req=5

fig03: (A) Relative abundance of methanogens identified at the genus level based on 16S rDNA sequencing and (B) relative activity of methanogens identified at the genus level based on 16S rRNA sequencing. Data were obtained for suspended biomass samples collected from start-up to the end of Phase 2 and in biofilm samples obtained at the end of Phase 2. Data are expressed as percentages and were normalized using the total number of 16S rDNA sequences (A) and 16S rRNA sequences (B) (including Bacteria and Archaea). Numbers within bars in (B) represent the relative activity of Methanosaeta spp. based on 16S rRNA sequence data normalized to the 16S rRNA sequences of all Archaea. A truncated y-axis (0–35%) is shown to accentuate changes in methanogen abundance and activity.
Mentions: High-throughput sequencing of both 16S rDNA and 16S rRNA was employed to study controlled membrane fouling during Phase 2, and the terms ‘relative abundance’ and ‘relative activity’, respectively, are used to report the results of these sequencing efforts. The relative abundance and relative activity levels of populations differed greatly in suspended and biofilm biomass (Fig. 3). The 16S rDNA sequence data indicated that the suspended and biofilm community comprised < 10% methanogens. The hydrogenotrophic methanogens were more abundant than the acetoclastic methanogens in the suspended biomass 26 days after start-up and in the biofilm biomass at the end of Phase 2 (Fig. S5A), suggesting the hydrogen utilization pathway became more important after biomass adaptation to the psychrophilic temperature. A shift towards hydrogenotrophic methanogenesis has also been observed previously in other anaerobic systems when transitioning from mesophilic to psychrophilic conditions using DNA-based analyses and specific methanogenic activity assays (McHugh et al., 2013; Collins et al., 2006; Connaughton et al., 2006), and has been explained by increased hydrogen solubility and thus increased substrate availability for hydrogenotrophic metabolisms (Lettinga et al., 2001). In contrast to 16S rDNA sequence data, 16S rRNA sequencing indicated that the relative activity of acetoclastic and hydrogenotrophic methanogens was similar in our system (Fig. S5B). MF and HF biofilms also had substantially greater activity of methanogens relative to the suspended biomass and LF biofilm on day 138. Specifically, methanogens represented 33% and 34% of the combined bacterial and archaeal activity in MF and HF biofilms, respectively, in comparison to only 15% in the suspended biomass and LF biofilm (Fig. 3). These observations correlated with the low levels of acetate and propionate and high dissolved methane oversaturation by the end of Phase 2 (Fig. 2), and suggest that a high level of methanogenesis occurred in the MF and HF biofilms.

Bottom Line: High membrane fouling significantly improved permeate quality, but resulted in dissolved methane in the permeate at a concentration two to three times the equilibrium concentration predicted by Henry's law.Restoring fouled membranes to a transmembrane pressure (TMP) near zero by increasing biogas sparging did not disrupt the biofilm's treatment performance, suggesting that microbes in the foulant layer were tightly adhered and did not significantly contribute to TMP.The results describe an attractive operational strategy to improve treatment performance in low-temperature AnMBR by supporting syntrophy and methanogenesis in the membrane biofilm through controlled membrane fouling.

View Article: PubMed Central - PubMed

Affiliation: Department of Civil and Environmental Engineering, University of Michigan, 2350 Hayward Road, Ann Arbor, MI, 48109, USA.

No MeSH data available.