Comparative study of microbial community structure in integrated vertical-flow constructed wetlands for treatment of domestic and nitrified wastewaters

Abstract

Microbial processes play a vital important role in the removal of contaminants in constructed wetland (CW). However, the microbial physiology and community structure can be influenced by environmental conditions. In this study, four pilot-scale integrated vertical-flow constructed wetlands (IVCWs) were employed to treat domestic and nitrified wastewaters. The microbial properties, along with their response to wastewater quality characteristics and seasonal variation, were determined. The results showed higher Shannon-Weiner diversity (H) and evenness (E) index of fatty acids (FAs), and relative abundances of signature FAs in down-flow cells and in the systems fed with domestic wastewater (DW). The relative abundances of fungi and gram-negative and aerobic bacteria were greater in up-flow cells. The dominant anaerobic bacteria found in most cells might be accounted for the prevailing anaerobic environment within the wetland beds, which could mean that the system fed with nitrified wastewater (NW) should perform better in nitrogen removal. The redundancy analysis (RDA) showed that pollutant concentrations, especially organic matter, influence the FA compositions greatly, and the most significant difference of microbial community structures was detected in down-flow cells fed with DW and up-flow ones with NW. The branched FAs, which could be used to represent anaerobic bacteria, were observed in down-flow cells treating DW and had a significant positive correlation with chemical oxygen demand (COD) concentration, probably suggesting the important role of anaerobic bacteria in organic matter degradation in the IVCWs. Seasonal variation, however, did not greatly influence the microbial community structure in the IVCWs.

Comparative evaluations of organic matters and nitrogen removal capacities of integrated vertical-flow constructed wetlands: Domestic and nitrified wastewater treatment

“…[3,5] However, anaerobic decomposition might account for a considerable proportion in the IVCWs, especially at high COD LR due to the low DO levels in the wetland beds. [18,19] COD mass removal rate of the IVCWs increased with the increasing LRs, which was consistent with the results obtained in other CWs, [20][21][22][23][24] and was probably due to the enhanced microbial production and metabolism under higher LR. [20] Nevertheless, a tendency of leveling off for mass removal rate at high LR was observed by Dan et al, [23] suggesting that the organics removal capacity of CW was not infinite.…”

Seasonal Variation of Nutrient Removal in a Full-Scale Artificial Aerated Hybrid Constructed Wetland

“…The optimum temperatures for nitrification and denitrification are ranges within 28-36 °C and 60-70 °C, respectively, whereas temperatures lower than 5 °C can inhibit the activities of both nitrifying and denitrifying bacteria and consequently decrease nitrogen removal rates [31]. However, pH, mass loading, available carbon and nitrogen, redox condition, and microbial diversity in CWs can also influence nitrogen removal rates in addition to the temperature [31,32].…”

Influence of substrate type on microbial community structure in vertical-flow constructed wetland treating polluted river water

“…Due to its advantages of low cost, easy maintenance, and environmental friendliness, constructed wetland (CW) has been widely used in treatment of industrial, agricultural, and municipal wastewater (Chang et al 2015;Ji et al 2012;Mulling et al 2014;Xiong et al 2015;Zhi and Ji 2014) and polluted surface water (Dzakpasu et al 2015;Tu et al 2014). Biofilm microbial community, attached to the surfaces of substrate materials (or filter media) in CW, plays crucial roles in the reduction of degradable organic pollutants and transformation of inorganic pollutants including nitrogen, sulfate, and phosphate (Iasur-Kruh et al 2010;Liu et al 2013;Ramond et al 2012).…”

“…Biofilm microbial community, attached to the surfaces of substrate materials (or filter media) in CW, plays crucial roles in the reduction of degradable organic pollutants and transformation of inorganic pollutants including nitrogen, sulfate, and phosphate (Iasur-Kruh et al 2010;Liu et al 2013;Ramond et al 2012). In addition, microbial assemblage is sensitive to operational and environmental conditions, and its structure is a good indicator for the status of CW ecosystem (Chang et al 2015). Previous studies using traditional molecular biology approaches [e.g., denaturing gradient gel electrophoresis (DGGE), terminal restriction fragment length polymorphism (TRFLP), and clone library analysis] have greatly aided in our understanding of microbial community structure in CW ecosystem (Arroyo et al 2013;Elsayed et al 2014;Iasur-Kruh et al 2010;Morato et al 2014).…”

“…Previous studies using traditional molecular biology approaches [e.g., denaturing gradient gel electrophoresis (DGGE), terminal restriction fragment length polymorphism (TRFLP), and clone library analysis] have greatly aided in our understanding of microbial community structure in CW ecosystem (Arroyo et al 2013;Elsayed et al 2014;Iasur-Kruh et al 2010;Morato et al 2014). A variety of factors have also been found to influence the structure of CW microbial community, such as layer depth (Bouali et al 2014;Iasur-Kruh et al 2010), operational time (Bouali et al 2014), plant type (Menon et al 2013), plant species richness , plant development (Zhao et al 2012), wastewater quality characteristics (Chang et al 2015;Zhao et al 2012), flow (Arroyo et al 2013), and water depth (Morato et al 2014). These previous studies mainly focused on CW systems treating industrial and municipal wastewater, yet microbial community in CW systems purifying polluted surface water has received little attention.…”