Phospholipid fatty acid (PLFA) profiles in four full-scale activated sludge reactors (ASR1 ~ 4) treating municipal wastewater, South Korea, were monitored to evaluate the influence of influent water quality on microbial community structure (MCS) and the effect of the MCS on effluent water quality. In ASR1 ~ 3, PLFA profiles were very similar, regardless of the influent water quality and seasonal differences, and 16:17c/15:0iso2OH and 16:0 were dominant. PLFA profiles in ASR4 during summer and autumn were very similar to those in ASR1 ~ 3, but increases in specific fatty acids, 16:1ω5c, 11methyl18:1ω7c and 15:0iso3OH, were found in ASR4 during winter and spring, with relatively high total suspended solid (TSS) concentrations in the effluent. 16:1ω5c and 15:0iso3OH, possibly related with Flexibacter sp., caused a bulking problem in the activated sludge. The community diversity indices such as Shannon diversity and equability decreased in summer but increased in autumn in all the ASRs. Canonical correspondence analysis results suggested that the influent BOD concentration played the most important role in changing MCS, followed by influent TSS concentration. In addition, the TSS and total phosphorus concentrations in the effluent were significantly affected by the change of the MCS.
[Show abstract][Hide abstract] ABSTRACT: Microbiological analysis of activated sludge is an important tool for monitoring wastewater treatment plants (WWTP). The utilization of the sludge biotic index (SBI) provides helpful information in examining the quality of biological treatment process and has been tested for several different systems. Although its utilization has been increasing, it is still not widespread, especially in Brazil. Also, its applicability has been considered limited for some particular systems. Thus, it becomes important to evaluate the relations among operational and biological parameters of each WWTP in order to characterize the system and its variations. In this work, microscopic analysis were performed once a week for 1 year (n = 54) and the results were compared to the physicochemical, operational parameters and efficiency of the plant along the period. The four seasons were comprised and analyzed, as we cannot neglect the influence of environmental changes in this subtropical region. Not only had we found a strong influence of the evaluated parameters on the structure of the biological community but there is also a good correspondence of SBI with the performance of the WWTP. More importantly, including microscopic analysis in the operational routine made it possible to notice even the slightest changes in the biological community that were not enough to diminish the SBI classification of the sludge, but were satisfactorily informative to show in advance to operators when to take corrective actions about an increase of COD and BOD in the influent and when it was necessary to discard the exceeding sludge.
[Show abstract][Hide abstract] ABSTRACT: To elucidate the bacterial community dynamics in a full-scale wastewater treatment plant (WWTP) and the relatedness among bacterial communities in the influent, effluent and sludge, the structure and metabolic ability of the bacterial community throughout a full-scale WWTP employing a conventional activated sludge process was investigated during a period of 10 months. The bacterial community structure was analyzed by terminal-restriction fragment length polymorphism targeting eubacterial 16S rRNA genes, while a Biolog assay was applied to assess the metabolic ability of the activated sludge. Influent bacterial community structure was generally stable. In contrast, the bacterial community structure in the effluent was similar to that in the influent in some cases, while in other cases it was unique and differed greatly from that in the influent and sludge. These results suggest that temporal variations of the effluent bacterial community may be useful to predict the wastewater treatment performance and settleability of activated sludge. The bacterial community structure in the sludge was relatively stable and was rarely impacted by the influent populations. Biolog assay also revealed that activated sludge maintained a remarkably similar metabolic potential of organic compounds over time due to functional redundancy, in which the minor populations played a significant role.
Journal of Bioscience and Bioengineering 01/2014; 118(1). DOI:10.1016/j.jbiosc.2013.12.008 · 1.88 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The ability of a nitrifying sludge to oxidize p-cresol was evaluated in a sequential batch reactor (SBR). p-Cresol was first transformed to p-hydroxybenzaldehyde and p-hydroxybenzoate, which were later mineralized. The specific rates of p-cresol consumption increased throughout the cycles. The bacterial population dynamics were monitored by using denaturing gradient gel electrophoresis (DGGE) and sequencing of DGGE fragments. The ability of the sludge to consume p-cresol and intermediates might be related to the presence of species such as Variovorax paradoxus and Thauera mechernichensis. p-Cresol (25 to 200 mg C/L) did not affect the nitrifying SBR performance (ammonium consumption efficiency and nitrate production yield were close to 100% and 1, respectively). This may be related to the high stability observed in the nitrifying communities. It was shown that a nitrifying SBR may be a good alternative to eliminate simultaneously ammonium and p-cresol, maintaining stable the respiratory process as the bacterial community.
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