Mechanisms of pathogen removal by macrophytes in constructed wetlands

Presence of bacteria and bacteriophages in full-scale trickling filters and an aerated constructed wetland

“…2). The effect of temperature on pathogens removal in CW still remains a controversial issue in published literature with contradicting results reported by various authors (Reinoso et al, 2008;Wu et al, 2016;Alufasi et al, 2017). For example, it has been found that increased temperatures enhance the removal of indicator bacteria in HF CW, but had no effect on bacteria removal performance in VFCW (Winward et al, 2008).…”

“…The exact mechanism(s) that result in this improved performance are not yet clear (Wu et al, 2016;Alufasi et al, 2017). This could be possibly attributed to the added air in the bed, since this is the main modification of aerated wetlands compared to…”

Removal processes of indicator organisms and opportunistic pathogens in an anaerobic digester‐constructed wetland system

“…These bacteria draw their energy necessary for oxidation from organic matter such as carbonaceous substrates (Kadlec and Wallace, 2008). The presence of plant may be involved in the removal of indicator and pathogenic microorganisms in VF-CW 2 and HF-CW 2 due to their ability to increase filtration and sedimentation into the bed by their roots, to operate like a supporter of microbial community development keen on the root systems (Fountoulakis et al, 2017), to supply oxygen transfer from aerial tissues to the rhizosphere (Button et al, 2015), to produce bactericidal compounds (Avelar et al, 2014;Alufasi et al, 2017). Several studies have indicated the effect of plants on E. coli or FC concentration reduction (El Hamouri et al, 2007;Tunçsiper et al, 2012;Carballeira et al, 2016).…”

“…The application of an anaerobic digester prior to the hybrid subsurface flow CW present an interesting tool to avoid bed filter clogging by TSS and to enhance the treatment in terms of organic matter, nutrients but also to achieve low indicators organisms concentrations (El‐Khateeb and El‐Gohary, 2003; De Sousa et al , 2003; Barros et al , 2006; Green et al , 2006; El Hamouri et al , 2007; Ruiz et al , 2008; El‐Khateeb et al , 2009; Singh et al , 2009; Ayaz et al , 2015). The efficiency of pathogen removal in constructed wetland systems depends on a number of mechanisms including physical, chemical and biological mechanisms, alone or in combination such as mechanical filtration, temperature, pH, dissolved oxygen, design of CW, adsorption to organic matter, adhesion to biofilm, exudation, and predation… (Díaz et al , 2010; Wu et al , 2016; Alufasi et al , 2017). The objectives of this study are to investigate and evaluate: (1) the overall performance of a hybrid constructed wetland CW 2 with settler/digester, followed by a vertical subsurface flow system and an horizontal subsurface flow system vegetated with Phragmites australis connected in series (settler/digester 2 , VF‐CW 2 and HF‐CW 2 ) in rural wastewater treatment; (2) the influence of seasonal variation in CW 2 performance and (3) the mechanisms and major environmental factors relative to indicator organisms and opportunistic pathogens removal in the settler/digester 2 , in VF‐CW 2 and in HF‐CW 2 .…”

Plant health: feedback effect of root exudates-rhizobiome interactions

“…Recently, improvements have been made in decrypting the tightly regulated processes and stimuli alterations of root exudate flux demonstrating the complexity in the plant rhizosphere defense system. However, in the absence of pathogen induction, plants exude other high molecular weight compounds for defense (Alufasi et al 2017; Preston 2017). The extent and nature of exudation varies with the age of the plant.…”