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Analysis of nitrification efficiency and microbial community in a membrane bioreactor fed with low COD/N-ratio wastewater.

Ma J, Wang Z, Zhu C, Liu S, Wang Q, Wu Z - PLoS ONE (2013)

Bottom Line: In this study, an approach using influent COD/N ratio reduction was employed to improve process performance and nitrification efficiency in a membrane bioreactor (MBR).Besides sludge reduction, membrane fouling alleviation was observed during 330 d operation, which was attributed to the decreased production of soluble microbial products (SMP) and efficient carbon metabolism in the autotrophic nitrifying community. 454 high-throughput 16S rRNA gene pyrosequencing revealed that the diversity of microbial sequences was mainly determined by the feed characteristics, and that microbes could derive energy by switching to a more autotrophic metabolism to resist the environmental stress.Further, ammonia oxidation was the rate-limiting step during the full nitrification.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai, PR China.

ABSTRACT
In this study, an approach using influent COD/N ratio reduction was employed to improve process performance and nitrification efficiency in a membrane bioreactor (MBR). Besides sludge reduction, membrane fouling alleviation was observed during 330 d operation, which was attributed to the decreased production of soluble microbial products (SMP) and efficient carbon metabolism in the autotrophic nitrifying community. 454 high-throughput 16S rRNA gene pyrosequencing revealed that the diversity of microbial sequences was mainly determined by the feed characteristics, and that microbes could derive energy by switching to a more autotrophic metabolism to resist the environmental stress. The enrichment of nitrifiers in an MBR with a low COD/N-ratio demonstrated that this condition stimulated nitrification, and that the community distribution of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) resulted in faster nitrite uptake rates. Further, ammonia oxidation was the rate-limiting step during the full nitrification.

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Related in: MedlinePlus

Hierarchical cluster analysis of R0–R5 bacterial communities.The y-axis is the clustering of the 174 most abundant OTUs (3% distance) in reads. The OTUs were divided into seven zones (Z1–Z7). Sample communities were clustered based on complete linkage method. The color intensity of scale indicates relative abundance of each OTU read. Relative abundance was defined as the number of sequences affiliated with that OTU divided by the total number of sequences per sample.
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pone-0063059-g003: Hierarchical cluster analysis of R0–R5 bacterial communities.The y-axis is the clustering of the 174 most abundant OTUs (3% distance) in reads. The OTUs were divided into seven zones (Z1–Z7). Sample communities were clustered based on complete linkage method. The color intensity of scale indicates relative abundance of each OTU read. Relative abundance was defined as the number of sequences affiliated with that OTU divided by the total number of sequences per sample.

Mentions: In order to further compare the population dynamics of heterotrophs, AOB, and NOB with COD/N ratio variations, hierarchical cluster analysis and bacterial taxonomic identification were conducted to illustrate the differences of the six bacterial community structures. In this study, the 174 most abundant OTUs were assigned into seven zones (Z1–Z7) according to the phylogenetic relationship, and taxonomic complexity of the zones is shown in Figure 3. It could be observed that three clusters were identified from the six bacterial communities by hierarchical cluster analysis: Cluster I (R0, R1, R2 and R3), Cluster II (R4) and Cluster III (R5). The microbial community structures in Cluster I (R0, R1, R2 and R3) exhibited high homology, especially in Z2–Z4 (Figure 3), and R5 was separated from Cluster I and R4, having only 0.04% similarity. These results show that sequence homology was mainly determined by feed characteristics (e.g. COD/N ratio and organic substrate composition), and particular bacteria were selectively enriched in their individual bioreactors.


Analysis of nitrification efficiency and microbial community in a membrane bioreactor fed with low COD/N-ratio wastewater.

Ma J, Wang Z, Zhu C, Liu S, Wang Q, Wu Z - PLoS ONE (2013)

Hierarchical cluster analysis of R0–R5 bacterial communities.The y-axis is the clustering of the 174 most abundant OTUs (3% distance) in reads. The OTUs were divided into seven zones (Z1–Z7). Sample communities were clustered based on complete linkage method. The color intensity of scale indicates relative abundance of each OTU read. Relative abundance was defined as the number of sequences affiliated with that OTU divided by the total number of sequences per sample.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3646889&req=5

pone-0063059-g003: Hierarchical cluster analysis of R0–R5 bacterial communities.The y-axis is the clustering of the 174 most abundant OTUs (3% distance) in reads. The OTUs were divided into seven zones (Z1–Z7). Sample communities were clustered based on complete linkage method. The color intensity of scale indicates relative abundance of each OTU read. Relative abundance was defined as the number of sequences affiliated with that OTU divided by the total number of sequences per sample.
Mentions: In order to further compare the population dynamics of heterotrophs, AOB, and NOB with COD/N ratio variations, hierarchical cluster analysis and bacterial taxonomic identification were conducted to illustrate the differences of the six bacterial community structures. In this study, the 174 most abundant OTUs were assigned into seven zones (Z1–Z7) according to the phylogenetic relationship, and taxonomic complexity of the zones is shown in Figure 3. It could be observed that three clusters were identified from the six bacterial communities by hierarchical cluster analysis: Cluster I (R0, R1, R2 and R3), Cluster II (R4) and Cluster III (R5). The microbial community structures in Cluster I (R0, R1, R2 and R3) exhibited high homology, especially in Z2–Z4 (Figure 3), and R5 was separated from Cluster I and R4, having only 0.04% similarity. These results show that sequence homology was mainly determined by feed characteristics (e.g. COD/N ratio and organic substrate composition), and particular bacteria were selectively enriched in their individual bioreactors.

Bottom Line: In this study, an approach using influent COD/N ratio reduction was employed to improve process performance and nitrification efficiency in a membrane bioreactor (MBR).Besides sludge reduction, membrane fouling alleviation was observed during 330 d operation, which was attributed to the decreased production of soluble microbial products (SMP) and efficient carbon metabolism in the autotrophic nitrifying community. 454 high-throughput 16S rRNA gene pyrosequencing revealed that the diversity of microbial sequences was mainly determined by the feed characteristics, and that microbes could derive energy by switching to a more autotrophic metabolism to resist the environmental stress.Further, ammonia oxidation was the rate-limiting step during the full nitrification.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai, PR China.

ABSTRACT
In this study, an approach using influent COD/N ratio reduction was employed to improve process performance and nitrification efficiency in a membrane bioreactor (MBR). Besides sludge reduction, membrane fouling alleviation was observed during 330 d operation, which was attributed to the decreased production of soluble microbial products (SMP) and efficient carbon metabolism in the autotrophic nitrifying community. 454 high-throughput 16S rRNA gene pyrosequencing revealed that the diversity of microbial sequences was mainly determined by the feed characteristics, and that microbes could derive energy by switching to a more autotrophic metabolism to resist the environmental stress. The enrichment of nitrifiers in an MBR with a low COD/N-ratio demonstrated that this condition stimulated nitrification, and that the community distribution of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) resulted in faster nitrite uptake rates. Further, ammonia oxidation was the rate-limiting step during the full nitrification.

Show MeSH
Related in: MedlinePlus