Constructed Wetlands and the role of the fungal community for wastewater treatment: A review

Abstract

Improvements in the performance of wastewater treatment systems with the so-called nature-based solutions (NBSs) are a challenge regarding the study and development of bench, pilot and real scales units. The huge number of micropollutants, macropollutant load factors, the relationship between microorganisms and macrophytes, possible toxicity changes in the roots of macrophytes in phytoremediation systems, landscape integration and the possibility of making degraded areas recovered through wastewater treatment plants are topics increasingly recurrent. Constructed Wetlands (CWs) are among the NBSs and also considered clean and efficient technologies helping to treat wastewater, with promising results in all issues considered here. Furthermore, studies have reported that microbial association in CWs. mainly fungi. increases the effectiveness of the treatment of different types of wastewaters. Therefore, the objective of this study was to analyze, by bibliometric review, the relationships between the main configurations of CWs used for the treatment of wastewaters and the composition of their fungal community. Data obtained from the bibliometric review were used to gather information about CWs systems, main macrophytes planted on them and associated fungi. As results, a total of 90 articles that address the searched terms (constructed Wetlands AND fungi) were obtained, besides to a variation in fungal composition, covering mainly Arbuscular Mycorrhizal Fungi (AMF). The greatest diversity of fungi was found Subsurface Flow Constructed Wetlands, while the greatest diversity of macrophytes was found in Subsurface Vertical Flow Constructed Wetlands systems. Pragmatis australis was the main macrophyte used in the Superficial Horizontal Flow Constructed Wetlands systems. Finally, the results showed that the fungal community present in CWs plays an important role in the removal of pollutants by different mechanism such as hydrolysis, volatilization, sorption, biodegradation and photolysis. Furthermore, AMF help reduce the stress caused by micropollutants suffered by macrophytes, improve tolerance to the environment, nutrient absorption and assist in denitrification processes.