The production of both aboveground and belowground plant biomass in constructed wetlands (CW) is a poorly understood topic, although vegetation plays an important role in the process of pollutant removal from wastewater. The objective of this study was to evaluate the aboveground and belowground biomass production of Typha latifolia and Canna hybrids in a large-scale constructed wetland treating swine wastewater in tropical climates. Parameters, such as temperature, DO, pH, COD, TSS, TN, TP, and TC, as well as destructive and non-destructive biomass, were evaluated. It was found that, despite the high concentrations of pollutants, the vegetation adapted easily and also grew healthily despite being exposed to high concentrations of pollutants from swine water. Although Typha latifolia (426 plants) produced fewer plants than Canna hybrids (582 plants), the higher biomass of the Typha latifolia species was slightly higher than that of Canna hybrids by 5%. On the other hand, the proximity of the water inlet to the system decreased the capacity for the development of a greater number of seedlings. As for the elimination of pollutants, after treatment in the constructed wetland, COD: 83.6 ± 16.9%; TSS: 82.2 ± 17.7%; TN: 94.4 ± 15.8%; TP: 82.4 ± 23.2%; and TC: 94.4 ± 4.4% were significantly reduced. These results show that wetlands constructed as tertiary systems for the treatment of swine wastewater produce a large amount of plant biomass that significantly helps to reduce the concentrations of pollutants present in this type of water in tropical areas. The use of these plants is recommended in future wetland designs to treat swine wastewater.

Partially saturated vertical constructed wetlands (PSV-CWs) and free-flow vertical constructed wetlands (FFV-CWS) are treatment systems for which there is limited information on their operation in tropical climates and even scarcer information on their use for municipal/swine wastewater treatment. In this work, the removal of pollutants from municipal wastewater mixed with swine effluents was evaluated using PSV-CWs and FFV-CWs, at pilot scale, with the presence and absence of vegetation in a tropical climate. Six vertical flow CWs made up of polyvinyl chloride (1 m high and 0.5 m in diameter) were used; three were operated with free-flow conditions and three with partially saturated conditions. In each type of configuration, two reactors were planted with an individual of Heliconia latispatha, and one remained without vegetation. They were fed with municipal wastewater mixed with 50% of swine wastewater. Their ability to remove COD, TSS, TP, TN, N-NH₄, and N-NO₃ and plant development were evaluated. Heliconia latispatha registered better results of adaptation and vegetative development in the PSV-CWs in comparison with FFV-CWs measured as total biomass (5697.1 g/m² and 5095.7 g/m², respectively). PSV-CWs were slightly better for TSS elimination (4.21%), while FFV-CWs presented a better performance for TN removal (3.76%), N-NH₄ (3.94%) and N-NO₃ (4.76%) in the systems with vegetation; no significant difference (p ˃ 0.05) was found between the two types of CWs for the removal of COD and TP. However, significant differences (p ˂ 0.05) were found between the systems with vegetation and those without vegetation in both configurations. These results demonstrate that PSV-CWs represent a better option for the treatment of municipal/swine wastewater since their efficiency was slightly higher than, or similar to that of, FFV-CWs and allowed a better development of H. latispatha.

The aim of this 2-year study was to evaluate the influence of bed depth (40 and 60 cm) on the development of tropical ornamental species (Alpinia purpurata, Heliconia latispatha and Strelitzia reginae) and on the removal of different contaminants such as chemical oxygen demand (COD), nitrate (N-NO₃), ammonium (N-NH₄), total nitrogen (TN), total phosphorus (TP), total suspended solids (TSS), total coliforms (TCs) and fecal coliforms (FCs), in horizontal subsurface flow constructed wetlands (HSSF-CWs) for municipal wastewater treatment. The results showed that the depth of 60 cm favored the removal of COD, with removal efficiencies of 94% for the three plant species. The depth of 40 cm was most effective for the removal of N-NH₄ (80–90%). Regarding the removal of TN, the removals were similar for the different plants and depths (72–86%). The systems only achieved up to 60% removal of TCs and FCs. The depth of the CWs substrate and its saturation level influenced the development of ornamental vegetation, particularly flower production. For Heliconia latispatha, a bed depth level of 60 cm was more suitable, while for Alpinia purpurata 40 cm was better, and for Strelitzia reginae in both cases there was no flower production. The impact of bed depth on contaminant removal depends on the specific type of contaminant.

The aim of this research was to evaluate the efficiency of horizontal subsurface flow-constructed wetlands (HSSFWs) planted with Hippeastrum striatum and Heliconia lastisphata for the treatment of contaminated river waters by wastewater from the dairy industry (WDI) and domestic wastewater in tropical climates over a study period of 136 days. Cell with a real volume of 780,000 mL and a flow rate of 1.805 mL s⁻¹. The hydraulic retention time was determined to be 5 days. 12 individuals of Hippeastrum striatum were planted at a distance of 20 cm from each other in one cell, while in another cell, 12 individuals of Heliconia spp. were planted. An adaptation period was determined for both species. Subsequently, the experiment was started, and the elimination percentages obtained were as follows: COD: 67.94 ± 1.39%, 63.17 ± 2.63%; TSS: 56.49 ± 5.73%, 48.78 ± 5.87%; N-NH₄: 51.06 ± 2.16%, 50.80 ± 1.91%; TN: 44.36 ± 5.73%, 30.59 ± 5.87%; TP: 47.00 ± 5.32%, 35.57 ± 4.06%; DO: 50.23 ± 1.61%, 47.74 ± 1.34%; and pH: 6.81 ± 0.07, 6.52 ± 0.1, for Heliconia lastisphata and Hippeastrum striatum, respectively. These results demonstrate that both macrophyte species can be used for the treatment of wastewater from the dairy industry using HSSFWs; cheese factories could be involved in the development of constructed wetland systems to reduce the environmental impact of the industry.

Glyphosate (GLY) is the most widely used herbicide in agriculture worldwide, posing a significant contamination risk to rivers, lakes, wetlands, and soils. Its ultimate fate represents a potential threat to the health of both terrestrial and aquatic ecosystems. This study evaluated the removal efficiency of glyphosate and conventional pollutants in mesocosm-scale horizontal subsurface flow-constructed wetlands planted with Canna indica, Heliconia psittacorum, and Alpinia purpurata in runoff water contaminated with glyphosate. Additionally, the study examined the performances of these species in monoculture and polyculture settings of tropical ornamental plants. Canna indica exhibited the highest growth (up to 160 cm) in both monoculture and polyculture conditions, as well as the highest removal efficiencies for total nitrogen (TN), total phosphorus (TP), and phosphate (PO₄³⁻), achieving a 91%, 93%, and 98% removal, respectively. Polyculture systems demonstrated a superior ammonium removal efficiency, reaching 94%. Alpinia purpurata (>5 ppm after 40 days) and Heliconia psittacorum (>5 ppm after 200 days) were the most effective species for glyphosate removal. Glyphosate can be effectively removed from aquatic environments through constructed wetlands planted with ornamental species, offering a sustainable approach to mitigating herbicide contamination in water bodies.

Veracruz, Mexico, boasts abundant water resources. However, the region is facing challenges stemming from population growth and industrial expansion, leading to a notable increase in wastewater discharge into surface water bodies. This discharge has resulted in significant alterations to water quality. In this study, we analyzed the water quality in the Bobos River, Veracruz, with a focus on sustainability. A total of 12 samples were collected from various points along the reservoir. Parameters including temperature, pH, dissolved oxygen (DO), conductivity, total nitrogen (TN), nitrate, chemical oxygen demand (COD), total phosphorus (TP), phosphate, dissolved solids (DSs), and fecal coliforms (FCs) were measured and analyzed. The pH levels ranged from slightly acidic (6.40 ± 0.71) to slightly alkaline (8.65 ± 0.07), with the lowest dissolved oxygen concentration recorded at 0.15 ± 0.07 mg L⁻¹. Conductivity varied between 0.26 and 3.81 mS. Total nitrogen concentrations ranged from 0.21 ± 3.8 to 0.491 ± 1.3 mg L⁻¹. Dissolved solid concentrations were measured at 0.39 ± 0.05 mg L⁻¹, while the final sampling point exhibited elevated values for temperature, nitrate, chemical oxygen demand, total phosphorus, and coliforms (30.35 ± 0.21 °C, 0.35, 389.00 ± 11.31, 13.20 ± 0.85 mg L⁻¹, and 3.2 × 105 ± 3.707107 × 10⁴, respectively). To address these concerning trends and safeguard public health and environmental integrity, the implementation of continuous monitoring and stringent control measures is imperative.