Impacts of design configuration and plants on the functionality of the microbial community of mesocosm-scale constructed wetlands treating ibuprofen

Abstract

Microbial degradation is an important pathway during the removal of pharmaceuticals in constructed wetlands (CWs). However, the effects of CW design, plant presence, and different plant species on the microbial community in CWs have not been fully explored. This study aims to investigate the microbial community metabolic function of different types of CWs used to treat ibuprofen via community-level physiological profiling (CLPP) analysis. We studied the interactions between three CW designs (unsaturated, saturated and aerated) and six types of mesocosms (one unplanted and five planted, with Juncus, Typha, Berula, Phragmites and Iris) treating synthetic wastewater. Results show that the microbial activity and metabolic richness found in the interstitial water and biofilm of the unsaturated designs were lower than those of the saturated and aerated designs. Compared to other CW designs, the aerated mesocosms had the highest microbial activity and metabolic richness in the interstitial water, but similar levels of biofilm microbial activity and metabolic richness to the saturated mesocosms. In all three designs, biofilm microbial metabolic richness was significantly higher (p < .05) than that of interstitial water. Both the interstitial water and biofilm microbial community metabolic function were influenced by CW design, plant presence and species, but design had a greater influence than plants. Moreover, canonical correlation analysis indicated that biofilm microbial communities in the three designs played a key role in ibuprofen degradation. The important factors identified as influencing ibuprofen removal were microbial AWCD (average well color development), microbial metabolic richness, and the utilization of amino acids and amine/amides. The enzymes associated with co-metabolism of l-arginine, l-phenyloalanine and putrescine may be linked to ibuprofen transformations. These results provide useful information for optimizing the operational parameters of CWs to improve ibuprofen removal.

Keywords: Community-level physiological profiling (CLPP); Forced aeration; Horizontal subsurface flow; Ibuprofen; Vertical flow; Wetland plants.