Antibiotic-Resistant Gene Behavior in Constructed Wetlands Treating Sewage: A Critical Review

Abstract

The main objective of this review is to evaluate the performance of constructed wetlands (CWs) used to reduce antibiotic-resistant genes (ARGs) during sewage treatment. To accomplish this objective, statistical and correlation analyses were performed using published data to determine the influence of operational and design parameters on ARG reduction in CWs. The effects of design and operational parameters, such as different CW configurations, seasonality, monoculture and polyculture, support medium, and hydraulic retention time (HRT), on ARG removals, were analyzed. A comparison of ARG reduction under different CW configurations showed that the hybrid configuration of surface flow (SF)–vertical subsurface flow (VSSF) achieved the highest reductions, with values of 1.55 ulog. In this case, aeration is considered an important factor to reduce ARGs in CWs, and it should be considered in future studies. However, statistical analyses showed that the ARG reductions under different CW configurations were not significant (p > 0.05). The same behavior was observed when the effects of operational factors on ARG reductions were analyzed (p > 0.05). The results of this study show that CWs are not optimal technologies to reduce ARGs in sewage. The combination of CWs with advanced wastewater technologies can be a solution for enhancing ARG reduction and reducing the spread of antibiotic resistance.

Partially saturated vertical surface flow constructed wetland for emerging contaminants and antibiotic resistance genes removal from wastewater: The effect of bioaugmentation with Trichoderma

“…VSSF-CW could remove ARGs from wastewater by directly eliminating microorganisms but different ARGs had different removal efficiencies implying the need of a screening of a large number of ARGs for the evaluation of water treatment performances. Overall, these results indicated that the studied wetlands were not able to significantly reduce either the bacterial load of the influent wastewater or the prevalence of most ARGs within the bacterial community (Monsalves et al, 2022).…”

Heterogeneous Antibiotic Resistance Gene Removal Impedes Evaluation of Constructed Wetlands for Effective Greywater Treatment

“…Interestingly, new ARGs may occur in the bacterial population even without antibiotic exposure, as is the case for tetracycline-resistant genes [60]. The resistance of the tetracycline family is a natural phenomenon that gives bacteria adaptive advantages for obtaining resources in the environment compared to other competing species [32]. In addition, tetracycline-resistant genes are highly likely to be transferred to indigenous environmental bacteria and can migrate quickly to the surface of biofilms, especially gene tetW [53].…”

“…ARGs can be removed via biodegradation of the genetic material, antibiosis, adsorption, and filtration [32], of which biodegradation is the primary pathway [33]. Antibiosis is the production of specific antibiotics by fungi or bacteria to inhibit the growth of competing bacteria and thereby decrease ARG abundance [34].…”

Enhanced Treatment of Decentralized Domestic Sewage Using Gravity-Flow Multi-Soil-Layering Systems Coupled with Iron-Carbon Microelectrolysis

“…Based on the factorial analysis [18,41], the numeric relation between the factors and the responses can be simulated and shown as following a polynomial regression formula (6). The factorial polynomial regression equations for eight responses are shown as…”

“…It also caused potential eutrophication and even the nitrate contamination of groundwater [4]. This issue is of growing concern in remote rural areas and small communities all over the world [5,6].…”