The review aims to report the state-of-the-art constructed wetlands (CW) in the Latin America and Caribbean (LAC) region not limited to national and local conditions. The aim is with a broader view, to bring updated and sufficient information, to facilitate the use of the CW technology in the different countries of LAC. Thus, 520 experiences extracted from the 169 reviewed documents in 20 countries were analyzed. According to the data, horizontal subsurface flow wetlands are the most reported CW in the region (62%), the second most common CW technology in the region is free water surface CW (17%), then vertical flow systems (9%), followed by intensified constructed wetlands (8%), and finally French systems (4%). The performance for nutrient removal is analyzed, finding that the mean of Chemical Oxygen Demand (COD), Total Nitrogen (TN), and Total Phosphorous (TP) removal efficiencies varies from 65% to 83%, 55% to 72%, and 30% to 84%, respectively. The results suggest a generally good performance for COD and TN removal, but a low performance for TP removal. Regarding plant species used for CWs, 114 different plant species were reported, being until now the most extensive report about plant species used in CWs in the LAC region.

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The potential of using the biomass of four wetland plant species (Iris pseudacorus, Juncus effusus, Phragmites australis and Typha latifolia) grown in treatment wetland systems and under natural conditions were tested to produce high-value materials using hydro-thermal liquefaction (HTL). The results show that the wetland plants biomass is suitable for biocrude and biochar production regardless of the origin. The hydrothermal liquefaction products’ (biocrude, biochar, aqueous and gaseous phase) yields vary according with the specific biomass composition of the species. Furthermore, the results show that the biomass composition can be affected by the growing condition (treatment wetland or natural unpolluted conditions) of the plants. None of the single components seems to have a determinant effect on the biocrude yields, which reached around 30% for all the analyzed plants. On the contrary, the biochar yields seem to be affected by the composition of the biomass, obtaining different yields for the different plant species, with biochar yields values from around 12% to 22%, being that Phragmites australis is the one with the highest average yield. The obtained aqueous phase from the different plant species produces homogeneous compounds for each plant species and each growing environment. The study shows that biomass from treatment wetlands is suitable for biocrude production. The environmental value of this biomass lies on the fact that it is considered a residual product with no aggregated value. The treatment wetland biomass is a potential sustainable source for biofuel production since these plants do not need extra land or nutrients for growing, and the biomass does not compete with other uses, offering new sources for enhancing the bioeconomy concepts.