Microbial communities from different types of natural wastewater treatment systems: Vertical and horizontal flow constructed wetlands and biofilters

Abstract

The prokaryotic microbial communities (Bacteria and Archaea) of three different systems operating in Denmark for the treatment of domestic wastewater (horizontal flow constructed wetlands (HFCW), vertical flow constructed wetlands (VFCW) and biofilters (BF)) was analysed using endpoint PCR followed by Denaturing Gradient Gel Electrophoresis (DGGE). Further sequencing of the most representative bacterial bands revealed that diverse and distinct bacterial communities were found in each system unit, being γ-Proteobacteria and Bacteroidetes present mainly in all of them, while Firmicutes was observed in HFCW and BF. Members of the Actinobacteria group, although found in HFCW and VFCW, seemed to be more abundant in BF units. Finally, some representatives of α, ß and δ-Proteobacteria, Acidobacteria and Chloroflexi were also retrieved from some samples. On the other hand, a lower archaeal diversity was found in comparison with the bacterial population. Cluster analysis of the DGGE bacterial band patterns showed that community structure was related to the design of the treatment system and the organic matter load, while no clear relation was established between the microbial assemblage and the wastewater influent.

Elucidation of major contributors involved in nitrogen removal and transcription level of nitrogen-cycling genes in activated sludge from WWTPs

“…1), core genera populations existed in all the samples. Among the shared genera, members of Thauera, Rhodobacter, Hyphomicrobium and Paracoccus are functionally important denitrifiers as previously reported16. Planctomyces, Prirellula , and Gemmata , which belong to the Planctomycetes phylum, are considered major players in the global nitrogen and carbon cycles.…”

Review of Constructed Wetlands for Acid Mine Drainage Treatment

“…The COD and nitrification removal rates were also higher than several reported in literature [73,84,112]. Although there are few studies on removal kinetics changes in organic compounds by heavy metal-tolerant bacteria, those results have been the most forceful.…”

“…Most of the constructed wetlands (CW) studies indicate that microorganisms are the main component of these treatment systems, because they interact more with wastewater, packing medium and vegetation to achieve the removal of contaminants [34,[72][73][74][75].…”

Removal of organic carbon, nitrogen, emerging contaminants and fluorescing organic matter in different constructed wetland configurations

“…Despite CWs have been traditionally considered as 'black boxes', the research and technical development in the technology over the last decades has shown that the system's design and operation parameters influence the dominating environmental conditions inside the wetland, which, in turn affects degradation processes [9,10]. While dissolved oxygen concentration is one of the main limiting factors for biodegradation processes in traditional horizontal subsurface flow CW (HF) operating mostly under anoxic/anaerobic conditions due to the permanent saturation of the wetland bed, unsaturated vertical flow CW (VF) units were developed to increase the oxygen transfer capacity by specific design and operational conditions, such as intermittent feeding and resting periods [1,11].…”