Microbial Community Assessment in Wetlands for Water Pollution Control: Past, Present, and Future Outlook

Abstract

Abstract:The field of treatment wetlands (TWs) is rapidly expanding and, arguably, is tasked with studying and understanding one of the most complex water treatment systems available. Microbial communities are generally considered to be responsible for the majority of wastewater constituent degradation in TWs. However, they are also known to be spatially heterogeneous, temporally dynamic, as well as structurally and functionally diverse. Presented here is a meta-analysis of all peer reviewed TW journal articles which utilized a microbial community assessment methodology over the period of 1988 to July 2016. A total of 1101 papers were reviewed, 512 from 1988 to 2012, 215 of which included a microbial community assessment aspect and were subsequently classified as representing past research, and 589 from 2013 to July 2016, 196 of which were classified as representing current TW microbial community research. In general, TW microbial community research has increased over time, with a marked surge in the past four years. Microbial community structure is currently the most commonly used methodological type followed by activity, enumeration and function, respectively. Areas of research focus included nitrogen transformations (156), organic degradation (33), and emerging contaminants (32), with general characterization studies also accounting for a significant proportion (243). Microbial communities from a range of TW systems have been investigated over the last four years with meso-scale (10-1000 L) being the most commonly studied system size followed by large-scale (>100,000 L), micro-scale (<10 L), and pilot-scale (1000-100,000 L). Free water surface flow (SF), horizontal subsurface flow (HF), and vertical flow (VF) systems are being studied in approximately equal proportions with the majority of studies focused on gaining fixed media/biofilm samples for analysis (rather than from the rhizosphere or interstitial water). Looking at efforts from a regional perspective shows Asia to be publishing the majority of research with a main focus on VF systems and structural community assessment. European and North American studies are generally more evenly distributed among structure, function, activity, and enumeration with the majority of studies completed on HF systems. South America, Africa, and Oceania published fewer studies but focused on structural community assessment with a selection of HF, SF and VF investigations. Great strides are being made in the field of microbial community assessment in TWs with functional assessment methods being developed, better utilized, and being related directly to water treatment. The use of high-powered metagenomics sequencing such as Illumina HiSeq instrumentation is on the rise, as is the development and utilization of functional assays such as DNA microarrays and community level physiological profiling allowing for more complete community assessment. Used in concert with activity, enumeration and newly implemented stable isotope methodologies, the field of TWs is certainly moving a...

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

“…79 CW design has been demonstrated to be an important factor affecting the 80 composition of microbial communities (Button et al, 2015, Lv et al, 2017a. For 86 2016, 32 studies focused on the microbial communities of CWs and their role in the 87 removal of emerging contaminants (Weber, 2016). Of these studies, none 88 investigated the effects of CW design on microbial community metabolic function 89 when treating pharmaceuticals.…”

Constructed Wetlands for Water Treatment: New Developments

“…[6] looks into the past, present, and future of microbial community assessment in the field of CWs. This review covers a meta-analysis on microbial community assessment methodology and its applications for focused pollutant degradation, system size and design, and regional trends.…”

“…This review covers a meta-analysis on microbial community assessment methodology and its applications for focused pollutant degradation, system size and design, and regional trends. Future horizons indicate that the combination of high-powered metagenomic sequencing, the development and utilization of functional assays such as DNA microarrays, and community level physiological profiling, in concert with activity assessment, enumeration, and newly-implemented stable isotope methodologies are moving the knowledge on CWs beyond the black-box paradigm [6].…”

In-depth assessment of microbial communities in the full-scale vertical flow treatment wetlands fed with raw domestic wastewater

“…From very early on, scientists have paved the way for microbial community assessment and provided evidence of the strong impact that the microorganisms have on pollutant degradation in treatment wetlands (TWs). Beginning in the 1980s, the literature started to report the use of activity and enumeration techniques and, from 2008, structural assessments and functional studies started to become more popular [8].…”