Spatial-Temporal Changes in Removal of Fecal Indicators and Diversity of Bacterial Communities in a Constructed Wetland with Ornamental Plants

Cristina S C Calheiros,Albina R Franco,Sofia I A Pereira,Paula M L Castro

doi:10.3390/app11093875

Cristina S C Calheiros, Albina R Franco + Show 2 more

Open Access

https://doi.org/10.3390/app11093875

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Abstract

The present study was undertaken in a constructed wetland (CW), setup in a tourism house, for domestic wastewater treatment. The influence of season variations on the abundance of fecal indicator organisms (total coliforms and Escherichia coli) in the wastewater and in the substrate and the roots of plants inhabiting the inlet and outlet zones of the CW was evaluated along three consecutive years. The structure and diversity of bacterial communities associated to the CW’s substrate of inlet and outlet zones was also analyzed overtime. Wastewater was characterized for physicochemical and microbiological parameters and the bacterial communities colonizing the substrate surface, were analyzed by Denaturing Gradient Gel Electrophoresis (DGGE). The CW was effective in removing COD, BOD5, TSS, PO43−, NH4+, NO3−, and NO2−. It was also effective in removing fecal indicators, with a generalized decrease of total coliforms and E. coli in the substrate and in the wastewater from inlet to outlet of up to 2–3 log. The structure and composition of bacterial communities associated with the substrate was mainly influenced by the year rather than by the season or the CW zone.

Highlights

Constructed wetlands (CWs) have been widely used in the last decades as an ecological technology for treating different types of wastewater [1,2,3]
The CW was effective in removing chemical oxygen demand (COD), BOD5, total suspended solids (TSS), PO43−, NH4+, NO3−, and NO2−, showing no significant differences between the analyzed seasons
Concerning the microbiological parameters, the present study showed that season variations did not influence the inflow of total coliforms and E. coli across three consecutive years in wastewater

Summary

Introduction

Constructed wetlands (CWs) have been widely used in the last decades as an ecological technology for treating different types of wastewater [1,2,3]. These biological systems constitute an environmentally friendly and sustainable alternative to conventional treatments while providing a plethora of ecosystem services with huge impacts on nature and human wellbeing [4,5]. CWs are considered natural biodiversity hotspots favoring the establishment of plants, microorganisms, and animals [6,7,8]. One of the most important functions of vegetation is the oxygenation of the CWs bed, as oxygen influences redox potential and microbial activity [12]

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