Abstract
The structure of microbial consortia in wastewater treatment facilities is a resultant of environmental conditions created by the operational parameters of the purification process. In the research, activated sludge from nine Polish wastewater treatment plants (WWTPs) was investigated at a molecular level to determine the impact of the complexity of biological treatment line and the influent composition on the species structure and the diversity of bacterial consortia. The community fingerprints and technological data were subjected to the canonical correspondence and correlation analyses. The number of separated biological processes realized in the treatment line and the presence of industrial wastewater in the influent were the key factors determining the species structure of total and ammonia-oxidizing bacteria in biomass. The N2O-reducers community composition depended significantly on the design of the facility; the highest species richness of denitrifiers was noted in the WWTPs with separated denitrification tanks. The contribution of industrial streams to the inflow affected the diversity of total and denitrifying bacterial consortia and diminished the diversity of ammonia oxidizers. The obtained data are valuable for engineers since they revealed the main factors, including the design of wastewater treatment plant, influencing the microbial groups critical for the stability of purification processes.Electronic supplementary materialThe online version of this article (doi:10.1007/s11274-013-1273-9) contains supplementary material, which is available to authorized users.
Highlights
In wastewater treatment plants (WWTPs), the removal of nutrients should be maintained at a level ensuring the concentrations of pollutants in the effluent in accordance with the legal requirements
To the correspondence analysis (CCA) analysis, next to metadata obtained by DGGE, the technological data such as the COD/N and BOD/COD ratios, TKN and COD in the influent, the presence (IN ?) or absence (IN-) of industrial wastewater in the influent, the presence of the denitrification tanks (DT) and the number of processes designed to occur in the biological treatment line of WWTP (PR) were taken
To analyze the bacterial assemblages, the DNA isolated from the biomass was amplified using the specific primer sets and the obtained products were separated in DGGE
Summary
In wastewater treatment plants (WWTPs), the removal of nutrients should be maintained at a level ensuring the concentrations of pollutants in the effluent in accordance with the legal requirements. For this purpose, the alternating oxygen conditions must occur in the technological systems to enable the efficient nitrogen and phosphorus elimination from wastewater. In the WWTPs with a low flow rate, the biological treatment is performed only in aeration tanks, alternating oxic conditions may occur spontaneously as a result of limited oxygen diffusion into large flocs or thick biofilm. The species structure of microbial communities in WWTPs decides the efficiency of the wastewater treatment. The high species richness of microbial community ensures conservation of a given functionality and a quick recovery of the consortia after the stress conditions because of the functional redundancy and the alternative ways to use the flow of energy (Fernandez et al 1999)
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