The use of constructed wetlands (CWs) for wastewater treatment has earned high interest around the world. However, innovations to improve its removal efficiency and adoption have been suggested in the last decades. For instance, the use of ornamental flowering plants (OFP), which make wetland treatment systems more aesthetic and is an option for the production of commercial flowers while the water is cleansed. The objectives of this study were to identify through a bibliometric analysis (2000–2022) the main OFP that have been used in CWs and their functionality as phytoremediators (removal effects), as well as the authors, collaborations, main investigations, and the countries where such investigations have been carried out. To this respect, 10,254 studies on CWs were identified. The United States and China were the leading countries in the use of this eco-technology. Subsequently, regarding the use of OFP, the analysis revealed 92 studies on this matter in which Mexico has three researchers who lead the use of OFP in CWs (almost 40% of publications of CWs with OFP), where the main species studied include Canna hybrids, Zantedeschia aethiopica, Strelitzia reginae, Iris species, Spathiphyllum sp., and Anturium sp. These species may remove between 30–90% of pollutants of organic compounds, 30–70% of heavy metals and drugs, and about 99.9% of pathogens. Thus, this study may help researchers to identify OFP for new CWs design, and to know new future research directionsand collaboration approaches in this area using multipurpose alternatives like those of CWs with OFP. More research can still be carried out on the use of CWs with OFP in temperate climates, as well as evaluating the influence of different substrates and water flow on the growth of these plants.

The assessment of constructed wetlands (CWs) has gained interest in the last 20 years for wastewater treatment in Latin American regions. However, the effects of culture systems with different ornamental species in CWs for phytoremediation are little known. In this study, some chemical parameters such as total suspended solids (TSS), chemical oxygen demand (COD), phosphate (PO₄-P), and ammonium (NH₄-N) were analyzed in order to prove the removal of pollutants by phytoremediation in CWs. The environmental impact index based on eutrophication reduction (EI-E) was also calculated to estimate the cause-effect relationship using CWs in different culture conditions. C. hybrids and Dieffenbachia seguine were used in monoculture and polyculture (both species mixed) mesocosm CWs. One hundred eighty days of the study showed that CWs with plants in monoculture/polyculture conditions removed significant amounts of organic matter (TSS and COD) (p > 0.05; 40–55% TSS and 80–90% COD). Nitrogen and phosphorous compounds were significantly lower in the monoculture of D. seguine (p < 0.05) than in monocultures of C. hybrids, and polyculture systems. EI-E indicator was inversely proportional to the phosphorous removed, showing a smaller environmental impact with the polyculture systems (0.006 kg PO₄³⁻ eq removed) than monocultures, identifying the influence of polyculture systems on the potential environmental impacts compared with the phytoremediation function in monocultures (0.011–0.014 kg PO₄³⁻ eq removed). Future research is required to determine other types of categories of environmental impact index and compare them with other wastewater treatment systems and plants. Phytoremediation with the ornamental plants studied in CWs is a good option for wastewater treatment using a plant-based cleanup technology.

This study aimed to explore the impact of various ornamental plants (Heliconia psittacorum, Etlingera elatior, Spatyphilum walisii) grown in different filter media (porous river rock (PR) and tepezyl (TZ)) on the removal of pollutants in vertical-subsurface-microcosm treatment wetlands (TWs). This study also sought to assess the adaptability of these plant species to TW conditions. Twenty-four microcosm systems were utilized, with twelve containing PR and twelve containing TZ as the filter media. Each porous media type had three units planted with each species, and three were left unplanted. Rural community wastewater was treated in the TWs. The results showed no significant differences in the effects of the porous media on pollutant removal performance (p > 0.05). However, it was noted that while both porous media were efficient, TZ, a residue of construction materials, is recommended for sites facing economic constraints. Additionally, the removal efficiency was found to be independent of the type of ornamental plant used (p > 0.05); however, the measured parameters varied with plant spp. The adaptation of the plants varied depending on the species. H. psittacorum grew faster and produced a larger number of flowers compared to the other species (20–22 cm). S. wallisii typically produced 7–8 flowers. E. elatior did not produce flowers, and some plants showed signs of slight disease and pests, with the leaves turning yellow. In terms of plant biomass, the type of porous media used did not have a significant effect on the production of above (p = 0.111) or below-ground biomass (p = 0.092). The removal percentages for COD in the presence and absence of plants were in the ranges of 64–77% and 27–27.7%, respectively. For TN, the numbers were 52–65% and 30–31.8%, and for N-NO₃, they were 54–60% and 12–18%. N-NH₄ saw removal rates of 67–71% and 28–33%, while P-PO₄ saw removal rates of 60–72% and 22–25%. The difference in removal percentages between microcosms with and without plants ranged from 30 to 50%, underscoring the importance of plants in the bio-removal processes (phytoremediation). These results reveal that incorporating ornamental plants in TWs with TZ for wastewater in rural areas holds great promise for enhancing the visual appeal of these systems and ultimately gaining public approval. Our findings also enable us to offer recommendations for selecting suitable plants and substrates, as well as designing combinations for TWs.

Constructed Wetlands (CWs) are a type of nature-based solution that uses ecological engineering to treat wastewater. The legal feasibility of implementing CWs as a treatment system in urban residential areas has been researched in various Latin American countries, including Chile, Peru, Colombia, Panama, and Guatemala. However, research regarding the legal feasibility of implementing CWs in urban areas, particularly in Multifamily Housing Units of Social Interest (MHUSI) in Mexico, was not found. Thus, this research aims to analyze the legal feasibility of CWs as wastewater treatment systems in the MHUSI of Xalapa, Veracruz, Mexico. To achieve this objective, a qualitative exploratory study was conducted. The study involved a documentary investigation to gather information about the background of the research, as well as content analysis to scrutinize legal documents such as laws, regulations, decrees, and Mexican Official Standards. The documental research focused on the search for regulatory documents, such as laws, regulations, decrees and standards, both at the federal level and at the state and municipal level. The content analysis focused on identifying the subsections, fractions and articles of the regulations found on water and sanitation, environmental impact and urban development applicable to the wastewater treatment systems of the MHUSI of Xalapa, Veracruz, Mexico. The research revealed that in Mexico, regulations mandate MHUSI to have a treatment plant in situations where it is not feasible to connect to the municipal sewage network. However, the use of CWs on a large scale to mitigate pollution from discharges has not been identified as a solution. After careful analysis, it has been determined that installing CWs wastewater treatment systems in MHUSI is legally feasible. In Veracruz, in terms of environmental impact, wastewater treatment systems no require an Environmental Impact Statement, which simplifies the procedures for this type of systems. In terms of urban development, MHUSI must incorporate a wastewater treatment system into their infrastructure. Regarding water and sanitation, no restrictions were found beyond guaranteeing compliance with the maximum permissible limits of contaminants established in Mexican standards. Finally, it was found that CWs are a method accepted by CONAGUA for the treatment of wastewater; in addition, this entity has a published manual and an inventory that includes them as a recognized process. However, it is crucial to ensure that the operation of these systems adheres to the regulations governing environmental impact and the permissible levels of contaminants in wastewater discharges to municipal sewage networks. This study is the first in Mexico to examine the legal viability of CWs as wastewater treatment systems in urban environments, specifically in MHUSI, providing a background that can contribute to the development of policies and regulations in this field. It is recommended to carry out technical, structural and financial feasibility studies to implement CWs in MHUSI in Xalapa, Veracruz, Mexico., aspects that were not addressed in this research.

El uso de los humedales como sistemas de tratamiento de aguas residuales es una alternativa prometedora en localidades rurales, ya que es económica y fácil de operar. Debido a su practicidad, al implementarlos es necesario analizar su funcionamiento en torno a remoción de contaminantes, pues esto ayuda a tomar consideraciones en el diseño y apoya en la replicabilidad de los mismos, por su potencial para disminuir la polución hídrica y mejorar la calidad de vida. Por ello, el presente trabajo evaluó la remoción de contaminantes en las aguas residuales tratadas a través de un humedal construido sembrado con plantas ornamentales en la localidad de San Marcos Atexquilapan, Naolinco Ver., mediante la recopilación de 6 parámetros; Temperatura, pH, Conductividad eléctrica (CE), Solidos Disueltos Totales (TDS), Demanda Química de Oxígeno (DQO) y Carbono Orgánico Total (TOC). Dicho estudio tuvo una duración de 180 días (6 meses). La zona de estudio presentó una temperatura promedio de 20.73 °C. Las aguas tratadas alcanzaron remociones máximas de 47 % en DQO, 50 % en SDT, 60 % en COT, 72 % en CE, y un pH fluctuante alrededor de 6. Aunque estos resultados son relevantes, es necesario optimizar las condiciones de diseño para mejorar la eficiencia en la remoción de contaminantes. Además, al comparar con estudios de otros autores, se identificó que los bajos porcentajes de remoción podrían estar relacionados con las condiciones climáticas, el proceso de adaptación de las plantas debido a que el sistema tiene apenas 12 meses de operación, así como factores externos como la sobrecarga orgánica.