Abstract
Although constructed wetlands (CWs) are widely used around the world with various substrates, the mechanisms of how these modified substrates affect wastewater treatment are still unknown. In this study, CW microcosms were established with and without ceramsite as a substrate, and the wastewater treatment efficiencies were evaluated during 71 days of incubation. Using the 16S rRNA high-through sequencing, the mechanisms of how CW substrate changed the microbial community was quantified. The results showed that compared to soil as substrate, the use of ceramsite as substrate material enhanced the removal of pollutants from CW systems, particularly under a short retention time (1.5-day) condition. There were more beneficial microorganism groups (nitrogen, sulfur, phosphate) in the ceramsite CW system than the non-ceramsite CW system, particularly in the bottom layers. Moreover, the CW with ceramsite substrate had more nitrification function. All of these results suggested that the ceramsite CW system enhanced the removal of pollutants because it increased the concentration of key microbes that are necessarily for nutrient cycles.
Highlights
Overloading nitrogen (N) will cause a deterioration of water quality and lead to the eutrophication of aquatic ecosystems [1,2]
The pollutant removal efficiency in constructed wetlands (CWs) using the mixture of ceramsite and wetland soil was significantly better than that in CWs without ceramsite, and this result was more obvious under a shorter hydraulic retention time (HRT) condition (Figure 2)
No significant difference was found in the removal rates of all pollutants in CWs with treatment A and treatment B under a longer HRT condition
Summary
Overloading nitrogen (N) will cause a deterioration of water quality and lead to the eutrophication of aquatic ecosystems [1,2]. It is necessary to reduce N as well as other pollutants from domestic and industrial wastewater before discharging it into natural water bodies. Compared to wastewater treatment plants and anaerobic digester reactors, constructed wetlands (CWs) are more economically and environmentally friendly. CWs are comprehensive systems that remove pollutants (organic compounds, N, and phosphorus (P) via various processes, including sedimentation, filtration, volatilization, plant uptake and microbial degradation) [5,6]. It is well recognized that the removal of nutrient pollutants is primarily due to microbial degradation [7,8,9].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
