Impact of plant density and microbial composition on water quality from a free water surface constructed wetland

Abstract

Aims: To correlate microbial community composition and water quality changes within wetland cells containing varying plant densities and composition in a free water surface (FWS) constructed wetland. Methods and Results: Water chemistry was monitored weekly for nitrate, orthophosphate, and suspended solids, at various sites throughout the wetland for 6 months. Treatment ponds with 50% plant cover had about a 96·3% nitrate removal. The average change between the influent and effluent was 50–60% nitrate removal and 40–50% orthophosphate removal. Community profile of total DNA, generated by using denaturing gradient gel electrophoresis (DGGE), was used to determine the major microbial composition associated with the wetland sediment, rhizosphere, and surface water. Bacterial cloned libraries were constructed, and 300 clones were analysed by amplified ribosomal DNA restriction analysis (ARDRA) and grouped into operational taxonomic units (OTUs). A total of 35, 31, and 36 different OTU were obtained from sediment, rhizosphere, and surface water, respectively. The bacterial members within the dominant group of our clone library belonged to unclassified taxa, while the second predominant group consisted of members of the phylum Proteobacteria. The dominant organisms within the class were in the γ, β, and δ classes. Conclusion: Microbial diversity as determined by Shannon‐Weaver index (H) was higher in the wetland cells with 50% plant density than the 100%. This was in agreement with the most efficient wetland contaminant removal units. Significance and Impact of the Study: This study provides evidence that wetlands with 50% plant cover may promote the growth of diverse microbial communities that facilitate decomposition of chemical pollutants in surface water, and improve water quality.

Temporal and Spatial Patterns of Eukaryotic and Bacterial Communities Found in Vernal Pools

“…Ibekwe et al (14) also observed an abundance of Betaproteobacteria in the soil and rhizosphere of a wetland. These authors suggest that Alphaproteobacteria and Betaproteobacteria may be important in such systems for the degradation of organic matter (14,16). The prevalence of fungal groups and Alphaproteobacteria and Betaproteobacteria in vernal pools suggests that microbial communities are rich in heterotrophic organisms.…”

Determination of Denitrification Genes Abundance in Environmental Samples

“…In many laboratories, utilization of commercial kits for DNA isolation is also frequent. Among them are MoBIO PowerSoil DNA kit (MoBIO) [19,24,62], ultra clean soil DNA kit (Ozyme, MoBIO) [5,61,99], and fast DNA spin kit for soil (BIO 101/Q-Biogene) [29,50,55,102].…”

Unit Process Wetlands for Removal of Trace Organic Contaminants and Pathogens from Municipal Wastewater Effluents

“…In vegetated treatment wetlands, the density and type of plants affect microbial community dynamics (Ibekwe et al, 2006;Calheiros et al, 2009) by providing labile forms of organic carbon, surfaces for biofilm growth, and oxygen gradients (Reddy and D'Angelo, 1997). The ability of decaying plants to create anoxic zones in surface and subsurface flow constructed wetlands is important for the transformation of trace organic contaminants, because some compounds are more readily transformed under aerobic conditions (e.g., ibuprofen) while others (e.g., tonalide and galaxolide) are more readily transformed under anaerobic conditions (Hijosa-Valsero et al, 2010).…”