Next Article in Journal
Does Interlocking Directors’ Green Experience Richness Enhance the Green Innovation Efficiency of Chinese Listed Companies?
Previous Article in Journal
Analysis of Key Factors of Cost Overrun in Construction Projects Based on Structural Equation Modeling
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Sustainability
Volume 17
Issue 5
10.3390/su17052120
sustainability-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Performance of Large-Scale Ornamental Wetlands for Municipal Wastewater Treatment: A Case Study in a Polluted Estuary in the Gulf of Mexico

by
Joaquin Sangabriel Lomeli
1,2,
Sergio Aurelio Zamora-Castro
3,
Teresa Zamora-Lobato
4,
Elber José Sandoval-Herazo
5,6,
Jacel Adame-García
7,
Florentina Zurita
8,
Maria Cecilia Monroy-Pineda
6,
Graciano Aguilar-Cortés
9,
Saúl Rivera
9,* and
Mayerlín Sandoval-Herazo
6,7,9,*
1
Faculty of Engineering, Universidad Veracruzana, Boca del Río 94294, Veracruz, Mexico
2
Department of Civil Engineering, Instituto Tecnológico Superior de Misantla, Tecnológico Nacional de México, Km. 1.8 Carretera a la Loma del Cojolite, Misantla 93821, Veracruz, Mexico
3
Faculty of Engineering, Construction and Habitat, Universidad Veracruzana, Boca del Río 94294, Veracruz, Mexico
4
Division of Graduate Studies and Research, Instituto Tecnológico Superior de Misantla, Tecnológico Nacional de México, Km. 1.8 Carretera a Loma del Cojolite, Misantla 93821, Veracruz, Mexico
5
Programa Multidisciplinario de Posgrado en Ciencias Ambientales, Universidad Autónoma de San Luis Potosí (UASLP), Av. Dr. Manuel Nava, Lomas de San Luis 78240, San Luis Potosí, Mexico
6
Facultad de Ingeniería, Universidad de Sucre, Carrera 28 No. 5-267, Sincelejo 700001, Sucre, Colombia
7
Instituto Tecnológico de Úrsulo Galván, Tecnológico Nacional de México, Carretera Cd Cardel-Chachalacas km 4.5, Úrsulo Galván 91667, Veracruz, Mexico
8
Environmental Quality Research Center, Centro Universitario de la Ciénega, University of Guadalajara, Ocotlán 47820, Jalisco, Mexico
9
Wetlands and Environmental Sustainability Laboratory, Instituto Tecnológico Superior de Misantla, Tecnológico Nacional de México, Km. 1.8 Carretera a la Loma del Cojolite, Misantla 93821, Veracruz, Mexico
*
Authors to whom correspondence should be addressed.
Sustainability 2025, 17(5), 2120; https://doi.org/10.3390/su17052120
Submission received: 3 January 2025 / Revised: 14 February 2025 / Accepted: 24 February 2025 / Published: 1 March 2025
(This article belongs to the Special Issue Water Sustainability: Innovative and Sustainable Technologies for Wastewater Pollution Control in the Context of the Circular Economy)
Browse Figures
Versions Notes

Abstract

:
This study investigates the performance of large-scale ornamental treatment wetlands (TW) for the treatment of municipal wastewater in the municipality of Nautla, Veracruz, Mexico, specifically within a contaminated estuary in the Gulf of Mexico. The research employed a treatment wetland system that integrates mixed flow methods, including vertical subsurface flow (VSSF) and horizontal subsurface flow (HSSF), to optimize operational, maintenance, and energy costs. Over a monitoring period from 15 October 2022 to 17 September 2023, the system achieved remarkable efficiencies in the removal of chemical oxygen demand (COD), NH3-N, NH4-N, NO2-N, NO3-N, total nitrogen (TN), with removal rates of 93.37%, 93.37%,91.36%, 91.29%, 95.74%, 97.36%, 71.69%, 92.26% and 91.45%, respectively. The effluent complied with the water quality standards established by the official Mexican standard NOM-001-SEMARNAT-2021, demonstrating the effectiveness of this TW configuration in treating water characterized by high chemical oxygen demand, nitrogen, and phosphorus levels. The results are especially relevant for tropical climates, where high temperatures and humidity can affect microbial activity and nutrient cycling, potentially enhancing treatment performance and reducing construction and management costs. This research highlights the viability of ornamental treatment wetlands as a sustainable solution for wastewater treatment in tropical climates and provides valuable information for future implementation and design criteria.

Graphical Abstract

1. Introduction

Treatment wetlands (TW) have proven to be a suitable alternative for domestic wastewater treatment [1,2,3] and have been successfully implemented for wastewater treatment in various countries around the world [4,5,6,7,8,9,10,11,12,13]. In many of these countries, wastewater management systems are carefully planned and regulated. Although TW systems have low construction and operating costs, they are easy to construct and maintain, they contribute to biodiversity restoration and provide ecosystem services to the public when designed for this purpose [14].
Despite these advantages, the adoption of TW in developing countries remains limited, even though many of these regions have significant wastewater treatment deficiencies. In Ibero-America and Caribbean, 36 million people in urban areas and 31 million in rural regions lack access to sanitation services [15]. Although government efforts have been substantial, they have not been sufficient to close the gap compared to high-income countries. Furthermore, the main factors limiting the use of TW are the lack of knowledge about the technology, the land requirements for its implementation, the low esthetic value of vegetation and its large-scale costs in urban and interurban areas [16].
Vymazal [17] has highlighted that in recent years there has been a growing trend toward short-term, laboratory-scale studies on treatment wetlands (TWs), often utilizing synthetic wastewater that is easily degradable and not representative of real wastewater. This approach results in the development of a bacterial community that is significantly different from that found in full-scale TWs. Moreover, due to the limited duration of these studies, nutrient uptake is often overestimated, as plants in their early growth stages require higher nutrient uptake. As a result, these studies cannot be considered as a basis for developing design, construction, maintenance, and operational criteria for large-scale TWs, which must address real-world wastewater treatment challenges. Moreover, this situation is more complicated in tropical areas, since most of the research on TW has been carried out in temperate climates and information in tropical climates is limited [18]. Ibero-American and Caribbean countries have major problems in terms of wastewater treatment, especially developing countries such as Mexico and Colombia, where the development of water treatment is slow due to the costs generated by decentralized management, given the territorial dispersion of the population throughout the length and breadth of their territories.
Tropical climates introduce additional challenges to the performance of wastewater treatment systems due to high temperatures, significant precipitation, and elevated humidity levels. These climatic factors significantly influence the biogeochemical processes within wastewater treatment systems, affecting microbial activity, plant growth, and pollutant removal efficiency [19]. High temperatures can accelerate the decomposition of organic matter and nitrogen transformations, while intense rainfall may lead to hydraulic overload, potentially reducing treatment efficiency [20,21,22]. In addition, the vigorous plant growth stimulated by tropical conditions may require more frequent maintenance to prevent clogging and ensure optimal system performance. The lack of large-scale applications and real-world monitoring highlights the need for further research to address these challenges and refine the design and operational strategies of wastewater treatment systems in tropical environments [23]. A recent trend in the design of wastewater treatment systems is the incorporation of ornamental plants, which enhances the esthetic appeal of these systems and makes them more acceptable in urban and peri-urban areas [24]. The use of ornamental plants not only contributes to landscape integration but also fosters public acceptance and promotes biodiversity. However, most studies involving ornamental plants in wastewater treatment systems have been conducted under control conditions, such as microcosms or mesocosms. Their adaptability to real-world climatic conditions, especially in tropical climates remains largely unexplored due to the absence of large-scale studies [25].
In this study, the pollution removal capacity and vegetation development were evaluated under real operating conditions of a large-scale turtle-shaped treatment wetland with polycultures of ornamental plants for the treatment of municipal wastewater in a tropical climate. This research is crucial for decision-makers and the scientific community, as it provides essential information for adapting the design and operational criteria of such systems to effectively control pollution in estuaries of the Gulf of Mexico. In addition, this study contributes to bridging the knowledge gap regarding the implementation of treatment wetlands in tropical regions by providing insights into how climate-related variables influence their performance and demonstrating the potential benefits of integrating ornamental plants for urban wastewater management.

2. Materials and Methods

2.1. Implementation and Description of the System

The large-scale ornamental TW was implemented in the municipal head-municipality of Nautla, Veracruz de Ignacio de la Llave, Mexico in the area where polluted water flows into the estuary (96°46′15.70″ W and 20°12′35.69″ N, Figure 1). The predominant activities in Nautla are fishing, poultry farming, agriculture and livestock. Prior to the TW, the wastewater was concentrated in a 36 m3 pumping sump operating as a sedimentation unit, and then discharged through a 3′ diameter pipe using a 1.5 hp Truper submersible pump.
The TW was divided into a settler and four zones (A, B, C and D) as shown in Figure 1. The settler (area: 7.7 m2, volume 15.785 m3) is directly connected to Zone 1 (area: 54.71 m2, volume 103.949 m3, vegetation: polyculture), which continues its flow to Zone B (area: 325.63 m2, volume: 586.134 m3, vegetation: polyculture) through three inlet points. Zone B flows into Zone C (area: 19.03 m2, volume: 30.448 m3, vegetation: water lilies) and finally Zone D (area: 23.42 m2, volume: 30.6 m3, vegetation: polyculture), where the runoff is discharged into a small stream that flows directly into the sea and is reintegrated into the ecosystem. In order to reduce operating, maintenance and energy costs, a treatment train based on an underground vertical flow wetland (Zone A), an underground horizontal flow wetland (Zones B and D) and a surface horizontal flow wetland (Zone C) was selected (Figure 1). The system is large-scale, with a surface area of 430.49 m2. (The system was constructed with reinforced concrete in the settler and masonry in the rest of the wetland, with an impermeable lining based on cement-sand mortar. The TW cells were filled with two types of substrates, boleo with diameter between 5 and 7″, a constant layer thickness 40 cm high in all areas, filled with crushed gravel with diameters between ½″ to 1 ½″ and 15 cm before the top edge of each wall. The first layer had a porosity of 8% and the second layer had a porosity of 35%, with a total layer porosity of 43% (Figure 2) to promote anaerobic conditions [27,28]. All systems had 3 days of HRT.

2.2. Selection of Ornamental Plant for TW

Criteria for vegetation selection were determined by (i) regional commercial importance [29], (ii) esthetic and landscape value within the study area [25,30], and (iii) availability and accessibility for utilization. Survival, tolerance and productivity under flood conditions had to be considered given the TW environment [31]. Table 1 details the vegetation species used. The selected plant species were mainly sourced from nearby areas to ensure their adaptation to the local environmental conditions. In addition, the other species were sourced from other treatment wetlands with similar climatic and hydrological characteristics, ensuring their resilience to tropical conditions and their suitability for wastewater treatment applications. Furthermore, the ornamental plants employed in the CW were completely isolated from the natural environment, thus preventing the invasion of water bodies by non-native species. The planting strategy involved polycultures across all designated internal zones, with a spacing of 30 cm between specimens, an optimal distance to facilitate system development [32]. Table 1 provides details regarding the vegetation species used.
Different studies have shown that the removal of contaminants is greater with the use of ornamental plants with flowers according to Sandoval et al. [30]. Furthermore, the use of ornamental flowering plants is an excellent landscaping option that can facilitate the use of TWs at the household level in rural and urban areas and that can even generate an economic benefit, according to Rocha et al. [29], because the region of the municipality of Nautla is coastal and part of its economy is based on national and international tourism.
The TW stabilization period was four months (June, July, August and September 2022). Subsequently, the system was monitored for 12 continuous months (16 October 2022 to 17 September 2023) with periodic water quality assessments. The full-scale WT monitoring (no control cells) is in accordance for Standard [33].

2.3. Measurement of Plant Growth

Vegetation development was monitored once every 30 days during the study period, after the adaptation period of four months. Six individuals per species per Zone (A, B, C and D) were randomly selected and marked for continuous measurement. The measured plant parameters were stem thickness, plant height, leaf length and leaf width, which were processed for the averaging and determination of future non-destructive biomass volumes.

2.4. Characteristics and Measurement of Water Quality Parameters

2.4.1. Environmental Variables

Light intensity, ambient temperature, precipitation and relative humidity were the environmental parameters measured, each for 15 days from 16 October 2022 to 17 September 2023, twice daily (9:00–10:00/14:00–15:00). Light intensity was measured by means of a Steren luxmeter model HER-410. Ambient temperature and relative humidity were obtained by means of a hydrometer. Precipitation was measured by means of a pluviometer.

2.4.2. Field Measurement of Water Quality Parameters

The water quality parameters measured directly in the field were pH, total dissolved solids (TDS), dissolved oxygen (DO), water temperature and electrical conductivity (EC). The pH, water temperature, electrical conductivity and total dissolved solids were obtained by means of a Hanna portable multiparametric meter model HI98121, while dissolved oxygen (DO) was measured by a Milwaukee meter, model MW600. These parameters were measured every 15 days during the measurement period, from 16 October 2022 to 17 September 2023, covering a full seasonal cycle.

2.4.3. Laboratory Measurement of Water Quality Parameters

Chemical oxygen demand (COD), ammonia (NH3-N), ammonium (NH4-N), nitrite (NO2-N), nitrate (NO3-N), total nitrogen (TN), phosphate (PO4-P) and total phosphorus (TP) were measured, whose magnitudes were obtained by testing laboratory samples. All water quality parameters in the field were measured every 15 days, ensuring that seasonal variations could be captured. Samples were taken at both the inlet and outlet of the settler and from zones A, B, C and D, giving a total of 10 sampling sites. The samples were immediately placed at a temperature of 4 °C for transfer to the wetlands and environmental sustainability laboratory of the TecNM Misantla campus (approximately 0.5 h) to avoid biochemical changes and organic degradation. The analyses were carried out on the same day and within 24 h. The processing of these parameters was determined in duplicate by standard methods [34]. These analyses were determined by means of a visible spectrophotometer ‘iris’ HI801-01. To assess seasonal fluctuations, the recorded data are analyzed in conjunction with the environmental variables.

2.4.4. Statistical Analysis of Data

The statistical analysis was conducted using Minitab version 16.1.0 (Minitab Inc., State College, PA, USA). The response variables included pH, dissolved oxygen (DO), electrical conductivity (EC), total dissolved solids (TDS), water temperature, ambient temperature, relative humidity, light intensity, COD, NH3-N, NH4-N, NO2-N, NO3-N, TN, PO4-P and TP. Based on the Kolmogorov–Smirnov normality test, as well as assessments of data homogeneity and independence of data, it was concluded that data did not follow a normal distribution at a significance level of p < 0.05. Consequently, the Friedman test for repeated measures was employed, and a post hoc analysis utilizing Dunn’s test was applied to detect significance between treatments and the seasonal variations in water quality parameters. Regarding the statistical analysis of vegetation development, variations in the TW over time were determined, and their correlation with environmental variables was assessed using Pearson correlation with a 95% confidence interval.

3. Results

3.1. Results of Environmental Parameters

During the treatment period, the ambient temperature (Figure 3a) varied from 13.5 to 33 °C, with the maximum temperature in May (33 °C). This temperature range is considered adequate since at temperatures below 20 °C there is a decrease in microbial activity involved in pollutant removal [35]. The average temperature documented for the 12 months of monitoring was 23.28 °C, which is within the optimal range for vegetation development in this type of subtropical climate, as reported by Majumder [36], which is between 12 and 25 °C. The average light intensity was 42,993.75 Lx (Figure 3b), which was within the optimal range (40,000–60,000 Lx) for the ornamental plants [36]. On the other hand, the relative humidity (Figure 3c), values over the entire monitoring cycle range from 72 to 100% with an average of 86.3%. The precipitation (Figure 3d) over the monitoring cycle ranged from 17 to 96 mm; the months with the highest precipitation were August and September; the average precipitation over the monitoring cycle was 51.83 mm.

3.2. Results of Water Quality Parameters Measured in the Field

pH values were within the limits between 6 and 9, which had an appropriate pH range for treatment of wastewater [37]. Figure 4 shows the development of pH over the 12 months of monitoring the system with an average of 7.21. The values ranged from 6.95 to 7.6, which is within the mentioned limits, and these are common pH values for wastewater (Figure 4), being within the typical values for domestic wastewater [38]. In general, values close to neutrality were found during the 12 months duration of the study.
The pH distribution across the different zones exhibited significant differences (p < 0.05). The sedimentation zone revealed notable disparities in pH behavior in comparison to Zone B (p < 0.05) Zone C (p < 0.05) and Zone D (p < 0.05). Furthermore, Zone A exhibited significant differences when compared to Zone C (p < 0.05) and Zone D (p < 0.05).
The correlation analysis of pH concerning environmental variables (light intensity, ambient temperature, relative humidity, and precipitation) commenced with a normality test, which indicated that the data followed a normal distribution. Consequently, the correlation was determined using Pearson’s coefficient. The results indicated no correlation between pH and light intensity and between pH and ambient temperature (p > 0.05). However, a significant inverse correlation was observed between pH and relative humidity (p < 0.05), with a Pearson coefficient of −0.6158 and a confidence interval ranging from −0.8791 to −0.06486, indicating a moderate to strong association. Similarly, the relationship between pH and precipitation demonstrated an analogous inverse correlation of moderate to strong strength (p < 0.05) with a Pearson coefficient of −0.6371 and a confidence interval from −0.8868 to −0.09958.
The next field parameters: DO, water temperature, EC and TDS are shown in Table 2. The TDS ranged from 159.84 ± 1.76 and 171.41 ± 2.00 mg L−1, values which were never above the TDS permissive limit (1000 mg L−1) indicated in the Mexican standard NOM-127-SSA1-2021.
The average DO in the areas, in general, varied from 2.56 ± 0.31 to 3.53 ± 0.29 mg L−1. The highest DO concentration was found in the influent zone and gradually decreased until reaching Zone D where the effluent was located, indicating a 27.5% decrease in DO concentration at the end of the treatment. The temperature remained relatively constant in all zones of the WT, ranging from 24.4 to 25.4 °C.
The DO exhibited significant differences among the different zones (p < 0.05), with the only exceptions being the comparisons from the Settler to Zone A and from Zone D to Zone C, which did not show significant differences (p > 0.99). All other comparisons between zones showed strong significant differences (p < 0.0001). The EC showed differences, especially between the settler and Zone B (p < 0.05) and between the settler and Zone D (p < 0.05). The TDS did not show significant differences between the zones (p > 0.05). The water temperature variation between the zones was statistically significant, specially from the Settler to Zone B (p < 0.0001), from the Settler to Zone D (p < 0.0001), between Zone A and Zone D (p < 0.05) and between Zone C and Zone D (p < 0.05).
Regarding the correlation of DO, EC, and TDS with environmental variables, no significant correlations were identified (p > 0.05) with any variable. Conversely, water temperature did show correlation with ambient temperature and relative humidity (p < 0.05) However, the data did not follow a normal distribution; hence, the Spearman correlation coefficient was employed. The Spearman correlation coefficient of ambient temperature was 0.6480, with a confidence interval ranging from 0.6166 to 0.8946, indicating a direct correlation with a moderate to strong association. In contrast, the correlation with relative humidity yielded a Spearman coefficient of −0.7273, with a confidence interval of −0.9210 to −0.2452, reflecting an inverse correlation with a moderate to strong association.
Overall, none of the parameters analyzed (pH, DO, EC, TDS, and water temperature) exhibited correlations with each other (p > 0.05).

3.3. Results of Parameters Measured in the Laboratory

Figure 5 and Figure 6 show the average concentrations and removal efficiency of COD, NH3-N, NH4-N, NO2-N, NO3-N, TN, PO4-P and TP in the TW system, which showed a gradual decrease in their concentrations throughout the process. The average COD concentration decreased considerably, from an initial concentration of 443.56 ± 14.47 to 29.39 ± 3.61 mg L−1, obtaining an efficiency of 93.37%, which indicates a high reduction in organic matter (Table 3).
The distribution of COD across the various zones exhibited significant differences (p < 0.05). The Settler showed notable differences compared to Zone B (p < 0.05), Zone C (p < 0.001) and Zone D (p < 0.001). Furthermore, Zone A demonstrated significant differences when compared to Zone C (p < 0.05) and Zone D (p < 0.05).
The TW system reduced the initial average NH3-N concentration from 22.81 ± 0.9 to 1.97 ± 0.57 mg L−1, which implies a removal efficiency of 91.36% (Table 3). However, the average annual NH3-N removal concentration was above the permissible limit of 0.50 mg L−1 indicated by the Mexican official standard NOM-127-SSA1-2021 for NH3-N. Meanwhile, the annual average concentration of NH4-N decreased from 57.85 ± 1.61 to 5.04 ± 1.24 mg L−1, obtaining a removal efficiency of 91.29%. However, there is no official Mexican standard for NH4-N that indicates a permissible limit, so the international standard was considered, where the World Health Organization (WHO) indicates that in surface waters the maximum natural concentration of NH4-N is 12 mg L−1, which means that the TW system reduces it to acceptable levels.
The initial concentrations of NO2-N (9.93 ± 0.63 mg L−1) and NO3-N (23.77 ± 1.34 mg L−1) in the TW system were reduced to 0.45 ± 0.08 and 2.05 ± 0.60 mg L−1, respectively. Both final concentrations are below the permissible limit indicated by the Mexican official standard NOM-127-SSA1-2021, 0.90 mg L−1 for NO2-N and 11.00 mg L−1 for NO3-N, indicating a removal efficiency of 95.74% for NO2-N and 97.36% for NO3-N (Table 3).
On the other hand, TN had a removal efficiency of 91.37%, which reduced the 35.71 ± 0.87 to 3.08 ± 0.77 mg L−1 of the annual average TN concentration, which is below the 15.00 mg L−1 discharge limit for the protection of aquatic life, estuaries and urban public use stipulated according to the Mexican official standard [33]. Likewise, the initial average concentrations of TP and PO4-P were reduced from 16.73 ± 0.66 to 1.43 ± 0.36 mg L−1 and from 19.13 ± 0.57 to 1.48 ± 0.64 mg L−1, respectively. Obtaining a removal efficiency of 91.45% and 92.26% for TP and PO4-P, respectively. In addition, the TP and PO4-P concentrations were conformed with the permissible limit of 5.00 mg L−1 that the Mexican official standard [33] indicates for the security and protection of aquatic life in rivers, estuaries and for public use.

3.4. Seasonal Variability in Pollutant Removal

The statistical analysis revealed significant seasonal fluctuations (p < 0.05) in COD and nitrogenous contaminants, with distinct behaviors depending on the season. In summer, COD was lower, likely due to increased microbial activity, while in winter, lower temperatures favor more efficient removal of pollutants. Autumn showed stability in COD, with no significant differences (p > 0.05) compared to other seasons. Regarding nitrogen compounds, concentrations of NH3-N and NH4-N were higher in winter due to reduced microbial activity, while no significant differences were observed between the other seasons. NO2-N and NO3-N, levels remained stable throughout the year, reflecting a consistent removal process. TN concentrations were higher in winter, possibly due to environmental conditions that favor nitrogen accumulation.
Considering the tropical environment of the study area, as illustrated in Figure 5 and Figure 6, the concentrations of COD, NH3-N, NH4-N, NO2-N, NO3-N, TN, PO4-P, and TP exhibited behavior influenced by the seasons. During the wet season (May–September), contaminant concentrations slightly increased, likely due to the increased hydraulic load caused by higher precipitation. This resulted in shorter hydraulic retention times, which primarily affected COD removal efficiency, as reflected by the comparatively higher effluent concentrations during these months. In contrast, during the dry season (October-April), lower precipitation and higher ambient temperatures likely enhanced microbial activity and nutrient absorption by vegetation, improving the removal of nitrogen compounds such as NH3-N and NO3-N. Phosphorus removal (PO4-P, and TP) exhibited greater stability during this period, with effluent concentrations consistently below the maximum thresholds established by Mexican official standard [33]. The results suggest that the tropical environment and seasonal variations play a key role in the efficiency of water treatment, significantly affecting contaminant removal.
The official Mexican standard aims to establish the permissible limits of pollutants in wastewater discharges. In order to ensure compliance with this standard, monthly monitoring was carried out for wastewater discharges to receive bodies such as rivers, streams, canals and drains. The reports on water sampling and analysis results were compared with the permissible limits (Table 3) of the monthly average based on the effluent.

3.5. Correlations Between Pollutants vs. (Water Quality Parameters, Environmental Variables and the Time)

The correlation analysis between pollutant removal and environmental variables shows significant associations, highlighting the influence of seasonal changes on system performance. COD removal efficiency showed strong negative correlations with light intensity and ambient temperature, with Pearson coefficients ranging from −0.7716 to −0.8027, suggesting reduced microbial activity during the wet season. A positive correlation with DO emphasizes the importance of aerobic conditions for organic matter degradation.
Nitrogen species removal (NH3-N, NH4-N, NO2-N, NO3-N, and TN) exhibited similar trends, with strong inverse correlations to light intensity and water temperature and positive correlations to DO. Pearson coefficients for these correlations ranged from −0.6774 to −0.8457 (light intensity and water temperature) and 0.6617 to 0.7066 (DO), indicating that aerobic conditions and favorable pH levels are crucial for nitrification and nitrogen transformation processes. NO2-N removal also showed a strong inverse Spearman correlation with temperature (−0.6655), suggesting efficient conversion to nitrate under higher temperatures during the dry season.
Phosphorus removal (PO4-P and TP) demonstrated strong negative correlations with light intensity and precipitation, with Pearson coefficients ranging from −0.6574 to −0.6770, while positive correlations with DO and pH (0.6325 to 0.6975) highlighted the role of aerobic and pH-favorable conditions in phosphorus uptake and transformation. Overall, the findings underscore the importance of integrating environmental variables into the design and management of treatment wetlands to enhance pollutant removal under variable climatic conditions.
The correlation analysis indicates a significant decrease in contaminants over time, demonstrating an improvement in water quality within the treatment system. The reduction in organic matter (COD) is especially notable (r = −0.9598), facilitated by microbial activity under aerobic conditions. Likewise, nitrogen species (NH3-N, NH4-N, NO2-N, NO3-N, TN) exhibit effective removal (−0.66 to −0.97), influenced by temperature and dissolved oxygen levels. Regarding phosphorus (PO4-P, TP), its reduction is moderate (−0.57 to −0.74), suggesting the influence of chemical precipitation and biological absorption, both favored by aerobic conditions and optimal pH levels (Table 4).

3.6. Result of Vegetation Growth

The growth evaluation of the 13 plants utilized in the TW system was conducted by comparing plant growth, stem diameters, and the quantities of flowers, leaves, and stems (Figure 7). Among the 13 plants used in the TW system, C. papyrus was the largest, although it did not present the greatest growth during the study period. The plant that grew the most during the study was C. hybrids, which increased to 15 times its size during the study, followed by C. indica which increased to 12 times its initial size and C. papyrus and C. esculenta which increased to 4 and 3.7 times their initial sizes, respectively. Stem thickening presented more discrete increases than plant size, with H. psittacorum being the plant that presented the greatest stem thickening, to 2.5 times its initial diameter. C. papyrus showed a similar stem thickening, 2.2 times its initial diameter, and C. esculenta had the third largest stem thickening, 1.5 times its initial diameter.
Among the 13 plants employed in the TW system only seven presented flowers, S. gramina, H. psittacorum, Ruellia sp., C. hybrids, C. indica, S. graminea and E. crassipes. Among seven species, only two species had >10 flowers, S. graminea and Ruellia sp., while the rest had 5–10 flowers per plant, except for S. graminea which presented <5 flowers. Also, only four species presented >60 leaves at the end of the study, C. papyrus the one with the highest number of leaves, followed by Berberis sp., Croposma sp. and Ruellia sp. Finally, C. papyrus was the plant with the highest number of stems, presenting >20 stems per plant at the end of the study, while P. cordata, Berberis sp., B. thunbergii and E. crassipes presented >10 stems and the rest of the species presented <10 stems per plant, except for Sansevieria trifasciata which remained with the same number of stems until the end of the study.
The correlation analysis of vegetation in relation to environmental variables demonstrated statistically significant differences (p < 0.05) concerning luminosity and ambient temperature. No correlation was observed for the environmental variables of relative humidity and precipitation. The correlations between vegetation and both light intensity and ambient temperature were all direct (positive) and showed moderate (0.3–0.5) to strong (0.5–1.0) associations for Sansevieria trifasciata, Canna indica, Canna hybrids, Colocasia esculenta, Ruellia sp. Sagittaria graminea, Pontederia cordata, and Heliconia psittacorum, Berberis sp., and Eichhornia crassipes and reflected significant associations. All correlations present confidence intervals that suggest a robust association.
The Pearson correlation analysis for various plant species (Sansevieria trifasciata, Canna indica, Canna hybrida, Colocasia esculenta, Ruellia sp., Sagittaria graminea, Pontederia cordata, Heliconia psittacorum Berberis sp., Eichhornia crassipes, and Cyperus papyrus) revealed significant negative correlations (p < 0.05) with most water quality parameters, especially nitrogenous compounds (NH3-N, NH4-N, TN) and COD. The negative correlations for these parameters were strong (r > −0.9) for several species, including Eichhornia crassipes, Canna indica, and Colocasia esculenta, indicating their effectiveness in reducing these pollutants. Moderate correlations (−0.6 and −0.7) were observed for NO2-N, NO3-N, and TP across most species. The correlation with PO4-P was generally weak or non-significant. Confidence intervals for most parameters suggested robust associations, with significant reductions in nitrogen compounds and COD. These results highlight the potential of these species in improving water quality especially through the removal of nitrogen and organic matter, while their effect on phosphorus removal was less consistent.

4. Discussions

In the present study, a comprehensive evaluation of the performance of treatment wetlands (TW) utilizing ornamental plants on a large scale for the treatment of municipal wastewater in a contaminated estuary of the Gulf of Mexico was conducted. The findings are promising and underscore the potential of treatment of wetlands as a viable and sustainable option in similar contexts.
The COD removal efficiency reached 93.37%. However, it is pertinent to compare these results with those from other studies. For instance, Rizzo et al. [39] reported an average removal efficiency of 97.50%, utilizing a wetland with more than double the surface area of the one in this study. In contrast, Sandoval et al. [16] documented a removal efficiency of 86.95% in a wetland in Pastorías, Actopan, which treated 18.3 m3/day of domestic wastewater. Similarly, a wetland in China, with almost three times the surface area of our TW, exhibited removal efficiencies of 22.29% [40]. Expanding TWs for broader applications, especially in urban environments, presents challenges such as the need for significant land area, vegetation maintenance, and potential seasonal variations in plant growth.
The selection of ornamental plants may have contributed to the high removal efficiency in our study. In addition, the flowering ornamental plants in constructed wetlands, in monocultures or mixed species, enhance the esthetic appeal while treating wastewater [41,42]. Canna indica and Cyperus papyrus have demonstrated robust growth and high nutrient absorption capacity under wastewater treatment conditions [42,43,44,45]. These plants also promote the development of microorganisms that facilitate nitrification and denitrification processes in the wetland substrate [46,47]. Furthermore, these findings agree with results observed in other tropical environments, where the selection of plant species and local climatic conditions play a significant role in determining the performance efficiency of constructed wetlands.
Furthermore, previous studies have shown that wetlands without vegetation, or with limited vegetative cover, exhibit significantly lower removal rates. For example, investigations in Nigeria revealed that non-vegetated systems achieved COD removals between 41.6% and 44.85% [48].
The NH4-N removal was also significant, with an efficiency of 91.29%, surpassing reports by Li et al. [49] and Wang et al. [50], which documented efficiencies of 44.3% and 28.41%, respectively. This enhancement in NH4-N removal can be attributed to the synergistic interactions between the plants and microorganisms within the system, which are favored by local tropical climatic conditions that support more vigorous vegetative growth and increased microbial activity.
Furthermore, the study indicated that the system achieved removal efficiencies for NO2-N and NO3-N of 95.74% and 97.36%, respectively. These results are significantly higher than those reported by Li et al. [49] in systems treating industrial wastewater, where efficiencies were 84.70% for NO2-N and only 39.90% for NO3-N.
The TN removal efficiency observed in our study exceeded the 42.9% and 52.48% reported by Li et al. [49] and Wang et al. [50], respectively. However, the TN removal efficiency was intermediate compared to the efficiencies reported by Zhu et al. [51], which ranged from 35.4% to 81.3% over a decade of operation.
Regarding TP removal, an efficiency of 91.45% was achieved, which is comparable to other quality parameters. This is noteworthy, as other studies, despite reporting high efficiencies in COD, NO2-N, and NO3-N, showed TP removal efficiencies of less than 51% [39,49]. The capacity of the plants to absorb phosphorus, combined with retention in the substrate, contributes to improving this aspect of treatment.
The incorporation of ornamental plants in treatment wetlands enhances water quality while offering potential economic benefits. In tourism-dependent regions, esthetically appealing wetlands can increase landscape value and attract visitors, reinforcing their dual function as wastewater treatment systems and economic assets. Moreover, vegetation management in tropical climates presents challenges, as excessive plant growth positively influences system performance but necessitates regular pruning to maintain efficiency and prevent flow obstruction—a critical factor in pollutant removal.
The TWs represent a sustainable approach that can be implemented in other tropical regions with similar wastewater treatment challenges. To optimize wetland performance in these contexts, we recommend further research to establish reliable design parameters, assess long-term economic benefits, and address the scalability of the system for urban applications.

5. Conclusions

Most of the extant research on the use of large-scale constructed wetlands has been conducted in template climates, and there is a lack of information on the use of ornamental plants from the tropical and intertropical regions of Mexico. Warmer temperatures and sunlight intensity can provide favorable conditions for the development of ornamental plants, achieving significant nutrient uptake from municipal wastewater. In this study, the optimal plant species was identified as C. papyrus, which exhibited increased height and a substantial increase in the number of stems compared to other species.
This study underscores the potential for integrating ornamental and thematic landscape plants into treatment wetlands, promoting their adaptation to urban environments and fostering public acceptance. Beyond the enhancement of water quality, these systems can augment the esthetic value of urban landscapes, offering economic and social benefits, especially in regions where tourism is a primary economic driver.
Regarding the removal of pollutants, the system was found to be in accordance with the Mexican standard NOM-001-SEMARNAT-2021 for the evaluated parameters, achieving high removal efficiencies for COD (93.37%), TN (91.37%), and TP (91.45%) during the monitoring period. Nevertheless, it is imperative to continue monitoring over extended periods to refine design parameters and assess system performance under seasonal variations. The establishment of reliable operational guidelines, including optimized pruning and maintenance schedules, is imperative for ensuring the long-term effectiveness of large-scale ornamental treatment wetlands in tropical regions. The findings emphasize the importance of ornamental treatment wetlands for wastewater management in other tropical areas facing similar challenges, providing a foundation for future research and environmental policies.

Author Contributions

In Conceptualization, J.S.L., S.R., T.Z.-L. and M.S.-H.; methodology, M.C.M.-P., S.A.Z.-C., T.Z.-L., J.A.-G. and F.Z.; software, E.J.S.-H., G.A.-C., J.A.-G., T.Z.-L. and M.S.-H.; validation, M.C.M.-P., F.Z., E.J.S.-H., G.A.-C. and M.S.-H.; formal analysis, F.Z., S.R. and M.C.M.-P.; investigation, M.C.M.-P. and M.S.-H.; resources; J.S.L. and S.R.; data curation, J.S.L., J.A.-G. and S.R.; writing—original draft preparation, M.C.M.-P. and M.S.-H.; writing—review and editing, G.A.-C. and F.Z.; visualization, M.C.M.-P., J.S.L. and S.R.; supervision, M.S.-H. and E.J.S.-H.; project administration, M.S.-H., S.R. and J.A.-G.; funding acquisition, J.S.L., S.R., S.A.Z.-C. and M.S.-H. All authors have read and agreed to the published version of the manuscript.

Funding

Thanks to the Doctorado en Ingeniería Aplicada offered by the Universidad Veracruzana, Campus Veracruz, registered in the Sistema Nacional de Posgrados (SNP) and the Consejo Nacional de Humanidades, Ciencias y Tecnologías (CONAHCYT) for the funded project No. 19839.24-PD and to tecNM for its funding under the heading PROYECTOS DE INVESTIGACIÓN CIENTÍFICA, DESARROLLO TECNOLÓGICO E INNOVACIÓN 2024 (SCIENTIFIC RESEARCH, TECHNOLOGICAL DEVELOPMENT AND INNOVATION PROJECTS 2024).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

All relevant data are included in this paper. Additional data supporting the conclusions can be requested from the corresponding author.

Acknowledgments

The are very grateful to the government of the state of Veracruz, headed by Cuitláhuac García Jiménez, and to the Environmental Attorney Sergio Rodríguez Cortés for carrying out this project financed with public resources. Special thanks to Luis Carlos Sandoval Herazo, for his liaison and advisory work during the entire period of the project.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Yan, Y.; Chen, Y.; Wu, X.; Dang, H.; Zeng, T.; Ma, J.; Tang, C. Enhanced nitrogen removal from rural domestic sewage via partial nitrification-anammox in integrated vertical subsurface flow constructed wetland. Environ. Res. 2023, 233, 116338. [Google Scholar] [CrossRef] [PubMed]
  2. Wu, H.; Wang, R.; Yan, P.; Wu, S.; Chen, Z.; Zhao, Y.; Cheng, C.; Hu, Z.; Zhuang, L.; Guo, Z.; et al. Constructed wetlands for pollution control. Nat. Rev. Earth Environ. 2023, 4, 218–234. [Google Scholar] [CrossRef]
  3. Rasool, S.; Rasool, T.; Gani, K.M. Unlocking the potential of wetland biomass: Treatment approaches and sustainable resource management for enhanced utilization. Bioresour. Technol. Rep. 2023, 23, 101553. [Google Scholar] [CrossRef]
  4. Hollstein, M.; Comerford, M.; Uhl, M.; Abel, M.; Egan, S.P.; Stadler, L.B. Impact of a natural disturbance on the performance and microbial communities in a full-scale constructed wetland for industrial wastewater treatment. Front. Environ. Sci. 2023, 11, 572. [Google Scholar] [CrossRef]
  5. Wilkinson, S.R.; Naeth, M.A.; Dhar, A. Potential of macrophytes for wastewater remediation with constructed floating wetlands in cold climates. Water 2023, 15, 2479. [Google Scholar] [CrossRef]
  6. Bydalek, F.; Ifayemi, D.; Reynolds, L.; Barden, R.; Kasprzyk-Hordern, B.; Wenk, J. Microplastic dynamics in a free water surface constructed wetland. Sci. Total Environ. 2023, 858, 160113. [Google Scholar] [CrossRef]
  7. Peñacoba-Antona, L.; Ramirez-Vargas, C.A.; Wardman, C.; Carmona-Martinez, A.A.; Esteve-Núñez, A.; Paredes, D.; Brix, H.; Arias, C.A. Microbial electrochemically assisted treatment wetlands: Current flow density as a performance indicator in real-scale systems in Mediterranean and Northern European locations. Front. Microbiol. 2022, 13, 843135. [Google Scholar] [CrossRef]
  8. Song, S.; Wang, B.; Yang, T.; Gu, Y.; Sheng, S.; Zhao, D.; An, S.; Li, A. Performance and Bacteria Communities of a Full-Scale Constructed Wetland Treating the Secondary Effluent after Multi-Years’ Operation. Processes 2023, 11, 1469. [Google Scholar] [CrossRef]
  9. Zhang, N.; Shen, C.; Wei, H.; Liu, H.; Wang, Z.; Hou, L.; Tie, J. Application of Subsurface Flow Constructed Wetland System for Purification of Secondary Effluent from Municipal Wastewater Treatment Plant. Pol. J. Environ. Stud. 2023, 32, 973–979. [Google Scholar] [CrossRef]
  10. Vymazal, J.; Láska, J.; Hnátková, T. The retention of nitrogen and phosphorus in aboveground biomass of plants growing in constructed wetlands treating agricultural drainage. Ecol. Eng. 2023, 194, 107044. [Google Scholar] [CrossRef]
  11. Lei, Y.; Wagner, T.; Rijnaarts, H.; de Wilde, V.; Langenhoff, A. The removal of micropollutants from treated effluent by batch-operated pilot-scale constructed wetlands. Water Res. 2023, 230, 119494. [Google Scholar] [CrossRef] [PubMed]
  12. Gonzalez-Flo, E.; Romero, X.; García, J. Nature based-solutions for water reuse: 20 years of performance evaluation of a full-scale constructed wetland system. Ecol. Eng. 2023, 188, 106876. [Google Scholar] [CrossRef]
  13. Nocetti, E.; Hadad, H.R.; Di Luca, G.A.; de las Mercedes Mufarrege, M.; Maine, M.A. Pollutant removal modeling in a hybrid wetland system for industrial wastewater treatment. J. Water Process Eng. 2023, 53, 103794. [Google Scholar] [CrossRef]
  14. Lavrnić, S.; Nan, X.; Blasioli, S.; Braschi, I.; Anconelli, S.; Toscano, A. Performance of a full scale constructed wetland as ecological practice for agricultural drainage water treatment in Northern Italy. Ecol. Eng. 2023, 154, 105927. [Google Scholar] [CrossRef]
  15. United Nations Children’s Fund; World Health Organization. Progress on Household Drinking Water, Sanitation and Hygiene 2000–2022: Special Focus on Gender; World Health Organization: New York, NY, USA, 2023. [Google Scholar]
  16. Sandoval-Herazo, L.C.; Marín-Muñiz, J.L.; Alvarado-Lassman, A.; Zurita, F.; Marín-Peña, O.; Sandoval-Herazo, M. Full-Scale constructed wetlands planted with ornamental species and PET as a substitute for filter media for municipal wastewater treatment: An experience in a Mexican rural community. Water 2023, 15, 2280. [Google Scholar] [CrossRef]
  17. Vymazal, J. Do laboratory scale experiments improve constructed Wetland treatment technology? Environ. Sci. Technol. 2018, 52, 12956–12957. [Google Scholar] [CrossRef]
  18. Casierra-Martínez, H.A.; Charris-Olmos, J.C.; Caselles-Osorio, A.; Parody-Muñoz, A.E. Organic matter and nutrients removal in tropical constructed wetlands using Cyperus ligularis (Cyperaceae) and Echinocloa colona (Poaceae). Water Air Soil Pollut. 2017, 228, 338. [Google Scholar] [CrossRef]
  19. Nyer, S.C.; Volkenborn, N.; Aller, R.C.; Graffam, M.; Zhu, Q.; Price, R.E. Nitrogen transformations in constructed wetlands: A closer look at plant-soil interactions using chemical imaging. Sci. Total Environ. 2022, 816, 151560. [Google Scholar] [CrossRef]
  20. Kumar, A.; Bhattacharya, T.; Mukherjee, S.; Sarkar, B. A perspective on biochar for repairing damages in the soil–plant system caused by climate change-driven extreme weather events. Biochar 2022, 4, 22. [Google Scholar] [CrossRef]
  21. Ndayambaje, P.; MacIvor, J.S.; Cadotte, M.W. Plant diversity on green roofs: A review of the ecological benefits, challenges, and best management practices. Nat.-Based Solut. 2024, 6, 100162. [Google Scholar] [CrossRef]
  22. Vigevani, I.; Corsini, D.; Mori, J.; Pasquinelli, A.; Gibin, M.; Comin, S.; Szwałko, P.; Cagnolati, E.; Ferrini, F.; Fini, A. Captura de contaminación por partículas mediante diecisiete especies leñosas que crecen en parques o a lo largo de carreteras en dos ciudades europeas. Sustainability 2022, 14, 1113. [Google Scholar] [CrossRef]
  23. Boano, F.; Caruso, A.; Costamagna, E.; Ridolfi, L.; Fiore, S.; Demichelis, F.; Galvão, A.; Pisoeiro, J.; Rizzo, A.; Masi, F. A review of nature-based solutions for greywater treatment: Applications, hydraulic design, and environmental benefits. Sci. Total Environ. 2020, 711, 134731. [Google Scholar] [CrossRef] [PubMed]
  24. Gobinath, R.; Ganapathy, G.P.; Gayathiri, E.; Kırgız, M.S.; Naiboğlu, N.; de Sousa Galdino, A.G.; Khatib, J. Sustainable Ecosystem Development and Landscaping for Urban and Peri-Urban Areas. In Sustainability of Natural Resources; CRC Press: Boca Raton, FL, USA, 2024; pp. 61–74. [Google Scholar]
  25. García-Ávila, F.; Avilés-Añazco, A.; Cabello-Torres, R.; Guanuchi-Quito, A.; Cadme-Galabay, M.; Gutiérrez-Ortega, H.; Alvarez-Ochoa, R.; Zhindón-Arévalo, C. Application of ornamental plants in constructed wetlands for wastewater treatment: A scientometric analysis. Case Stud. Chem. Environ. Eng. 2023, 7, 100307. [Google Scholar] [CrossRef]
  26. CEIEG. Cuadernillos Municipales 2022. Comité de Información Estadística y Geográfica del Estado de Veracruz. 2022. Available online: http://ceieg.veracruz.gob.mx/wp-content/uploads/sites/21/2022/09/Nautla.CM_.Ver_.2022.4.pdf (accessed on 1 July 2024).
  27. Rodriguez-Dominguez, M.A.; Konnerup, D.; Brix, H.; Arias, C.A. Constructed wetlands in Latin America and the Caribbean: A review of experiences during the last decade. Water 2020, 12, 1744. [Google Scholar] [CrossRef]
  28. García-Valero, A.; Acosta, J.A.; Faz, Á.; Gómez-López, M.D.; Carmona, D.M.; Terrero, M.A.; El Bied, O.; Martínez-Martínez, S. Swine Wastewater Treatment System Using Constructed Wetlands Connected in Series. Agronomy 2024, 14, 143. [Google Scholar] [CrossRef]
  29. Rocha, C.S.; Rocha, D.C.; Kochi, L.Y.; Carneiro, D.N.M.; Dos Reis, M.V.; Gomes, M.P. Phytoremediation by ornamental plants: A beautiful and ecological alternative. Environ. Sci. Pollut. Res. 2022, 29, 3336–3354. [Google Scholar] [CrossRef]
  30. Sandoval, L.; Zamora-Castro, S.A.; Vidal-Álvarez, M.; Marín-Muñiz, J.L. Role of wetland plants and use of ornamental flowering plants in constructed wetlands for wastewater treatment: A review. Appl. Sci. 2019, 9, 685. [Google Scholar] [CrossRef]
  31. Sepúlveda, R.; Leiva, A.M.; Vidal, G. Performance of Cyperus papyrus in constructed wetland mesocosms under different levels of salinity. Ecol. Eng. 2020, 151, 105820. [Google Scholar] [CrossRef]
  32. Rodrigo, M.A. Wetland restoration with hydrophytes: A review. Plants 2021, 10, 1035. [Google Scholar] [CrossRef]
  33. SEMARNAT. Norma Oficial Mexicana NOM-001-SEMARNAT-2021, que Establece los Límites Permisibles de Contaminantes en las Descargas de Aguas Residuales en Cuerpos Receptores Propiedad de la Nación. Secretaría de Medio Ambiente y Recursos Naturales. Diario Oficial de la Federación, 11 March 2021. [Google Scholar]
  34. Rice, E.W.; Bridgewater, L.; American Public Health Association. Standard Methods for the Examination of Water and Wastewater, 23rd ed.; American Public Health Association: Washington, DC, USA, 2012. [Google Scholar]
  35. Colares, G.S.; Dell’Osbel, N.; Barbosa, C.V.; Lutterbeck, C.; Oliveira, G.A.; Rodrigues, L.R.; Bergmann, C.P.; Lopez, D.R.; Rodriguez, A.L.; Vymazel, J.; et al. Floating treatment wetlands integrated with microbial fuel cell for the treatment of urban wastewaters and bioenergy generation. Sci. Total Environ. 2021, 766, 142474. [Google Scholar] [CrossRef]
  36. Majumder, A.; Gupta, A.K.; Ghosal, P.S.; Varma, M. A review on hospital wastewater treatment: A special emphasis on occurrence and removal of pharmaceutically active compounds, resistant microorganisms, and SARS-CoV-2. J. Environ. Chem. Eng. 2021, 9, 104812. [Google Scholar] [CrossRef] [PubMed]
  37. Rajpurohit, P.; Behera, M. High-strength domestic wastewater treatment using Epipremnum aureum as the cathodic plant in a constructed wetland-microbial fuel cell. J. Water Process Eng. 2025, 69, 106724. [Google Scholar] [CrossRef]
  38. Pico-Macias, J.J.; Cruz-Macias, B.A. Caracterización de aguas residuales en el Hospital Oncológico Solca-Manabí. MQRInvestigar 2024, 8, 839–858. [Google Scholar] [CrossRef]
  39. Rizzo, A.; Bresciani, R.; Martinuzzi, N.; Masi, F. Online monitoring of a long-term full-scale constructed wetland for the treatment of winery wastewater in Italy. Appl. Sci. 2020, 10, 555. [Google Scholar] [CrossRef]
  40. Chen, C.; Yang, G.; Chen, X.; Li, P.; Chen, J.; Yan, M.; Guo, C. Treatment Effect of Long-Term Subsurface-Flow Constructed Wetland on Mariculture Water and Analysis of Wetland Bacterial Community. Water 2024, 16, 1054. [Google Scholar] [CrossRef]
  41. Karungamye, P.N. Potential of Canna indica in constructed wetlands for wastewater treatment: A review. Conservation 2022, 2, 499–513. [Google Scholar] [CrossRef]
  42. Hidayah, E.N.; Cahyonugroho, O.H.; Pachwarya, R.B.; Ramanathan, A.L. Efficiency of a pilot hybrid wastewater treatment system comprising activated sludge and constructed wetlands planted with Canna lily and Cyperus papyrus. Water Environ. J. 2021, 35, 647–656. [Google Scholar] [CrossRef]
  43. Di Luca, G.A.; de las Mercedes Mufarrege, M.; Hadad, H.R.; Maine, M.A.; Nocetti, E.; Campagnoli, M.A. Floating treatment wetlands with Canna indica for the removal of Cr (III) and Cr (VI) from water: A comprehensive study. Sci. Total Environ. 2024, 940, 173642. [Google Scholar] [CrossRef]
  44. Phewnil, O.; Chunkao, K.; Prabhuddham, P.; Pattamapitoon, T. Application of different aquatic plants in an alternated fill and drain wetland system of Phetchaburi municipal wastewater treatment in Thailand. Environ. Sci. Pollut. Res. 2024, 31, 1304–1313. [Google Scholar] [CrossRef]
  45. Aboulsoud, Y.I.; Elkhouly, A.A. A Literature Review on Potentiality of Some Egyptian Halophytes in Wastewater Treatment in Constructed Wetland. J. Environ. Sci. Mansoura Univ. 2023, 52, 70–87. [Google Scholar] [CrossRef]
  46. Yu, G.; Zheng, D.; Wang, W.; Long, Y.; Chen, J.; Chen, H.; Wang, Y.; He, S. Effects of micro/nanoplastics on microorganisms and plants in constructed wetlands during the nitrogen removal process: A review. Chem. Eng. J. 2024, 496, 153778. [Google Scholar] [CrossRef]
  47. Malyan, S.K.; Yadav, S.; Sonkar, V.; Goyal, V.C.; Singh, O.; Singh, R. Mechanistic understanding of the pollutant removal and transformation processes in the constructed wetland system. Water Environ. Res. 2021, 93, 1882–1909. [Google Scholar] [CrossRef] [PubMed]
  48. Udom, I.J.; Mbajiorgu, C.C.; Oboho, E.O. Development and evaluation of a constructed pilot-scale horizontal subsurface flow wetland treating piggery wastewater. Ain Shams Eng. J. 2018, 9, 3179–3185. [Google Scholar] [CrossRef]
  49. Li, Y.; Zhang, H.; Zhu, L.; Chen, H.; Du, G.; Gao, X.; Pu, Y. Evaluation of the long-term performance in a large-scale integrated surface flow constructed wetland–pond system: A case study. Bioresour. Technol. 2020, 309, 123310. [Google Scholar] [CrossRef]
  50. Wang, H.; Liu, R.; Chen, Q.; Xia, H.; Zhang, Y. Novel Chitosan-FeS@ biochar-added constructed wetland microcosms for NH4+/NO3− and Pb removal: Performance and mechanism. J. Environ. Chem. Eng. 2023, 11, 110400. [Google Scholar] [CrossRef]
  51. Zhu, Y.; Cui, L.; Li, J.; Wang, R.; Vymazal, J.; Li, W.; Lei, Y.; Zhang, M.; Hao, T.; Wei, J. Long-term performance of nutrient removal in an integrated constructed wetland. Sci. Total Environ. 2021, 779, 146268. [Google Scholar] [CrossRef]
Sustainability 17 02120 g001
Figure 1. Geographical location of Nautla, Veracruz, Mexico [26] and distribution of implemented wetland system (Table 1).
Figure 1. Geographical location of Nautla, Veracruz, Mexico [26] and distribution of implemented wetland system (Table 1).
Sustainability 17 02120 g001
Sustainability 17 02120 g002
Figure 2. Treatment Wetlands cell types of flow.
Figure 2. Treatment Wetlands cell types of flow.
Sustainability 17 02120 g002
Sustainability 17 02120 g003
Figure 3. Environmental parameters (a) Ambient temperature (°C), (b) Light intensity (Lux), (c) Relative humidity (%) (d) Precipitation (mm), recorded measurements were set at 9–10 h and 14–15 h during the treatment period. The recorded values are presented with the mean ± standard error.
Figure 3. Environmental parameters (a) Ambient temperature (°C), (b) Light intensity (Lux), (c) Relative humidity (%) (d) Precipitation (mm), recorded measurements were set at 9–10 h and 14–15 h during the treatment period. The recorded values are presented with the mean ± standard error.
Sustainability 17 02120 g003
Sustainability 17 02120 g004
Figure 4. Development of pH in the system in the treatment period. The documented values are presented with the mean ± standard error.
Figure 4. Development of pH in the system in the treatment period. The documented values are presented with the mean ± standard error.
Sustainability 17 02120 g004
Sustainability 17 02120 g005
Figure 5. Concentrations of pollutants (a) COD; (b) NH3-N; (c) NH4-N; (d) NO2-N; (e) NO3-N; (f) TN; (g) PO4-P; (h) TP. The recorded values are presented with the mean ± standard error.
Figure 5. Concentrations of pollutants (a) COD; (b) NH3-N; (c) NH4-N; (d) NO2-N; (e) NO3-N; (f) TN; (g) PO4-P; (h) TP. The recorded values are presented with the mean ± standard error.
Sustainability 17 02120 g005
Sustainability 17 02120 g006
Figure 6. Removal efficiency (a) COD; (b) NH3-N; (c) NH4-N; (d) NO2-N; (e) NO3-N; (f) TN; (g) PO4-P; (h) TP. The recorded values are presented with the mean ± standard error.
Figure 6. Removal efficiency (a) COD; (b) NH3-N; (c) NH4-N; (d) NO2-N; (e) NO3-N; (f) TN; (g) PO4-P; (h) TP. The recorded values are presented with the mean ± standard error.
Sustainability 17 02120 g006
Sustainability 17 02120 g007
Figure 7. Vegetation development (a) Sansevieria trifasciata, (b) Canna indica, (c) Canna hybrids, (d) Colocasia esculenta, (e) Ruellia sp., (f) Sagittaria graminea, (g) Pontederia cordata, (h) Heliconia psittacorum, (i) Croposma sp. (j) Berberis sp., (k) Berberis thunbergii (l) Cyperus papyrus, (m) Eichhornia crassipes. The recorded values are presented with the mean ± standard error.
Figure 7. Vegetation development (a) Sansevieria trifasciata, (b) Canna indica, (c) Canna hybrids, (d) Colocasia esculenta, (e) Ruellia sp., (f) Sagittaria graminea, (g) Pontederia cordata, (h) Heliconia psittacorum, (i) Croposma sp. (j) Berberis sp., (k) Berberis thunbergii (l) Cyperus papyrus, (m) Eichhornia crassipes. The recorded values are presented with the mean ± standard error.
Sustainability 17 02120 g007
Table 1. Description of the ornamental plant used in the Treatment Wetlands.
Table 1. Description of the ornamental plant used in the Treatment Wetlands.
#Plant Species Number of IndividualsZone
1Sansevieria trifasciataSustainability 17 02120 i00180A, B & D
2Canna indicaSustainability 17 02120 i002128B
3Canna hybridsSustainability 17 02120 i003112A, B & D
4Colocasia esculentaSustainability 17 02120 i004128A, B & D
5Ruellia sp.Sustainability 17 02120 i00564B & D
6Sagittaria gramineaSustainability 17 02120 i00664B & D
7Pontederia cordataSustainability 17 02120 i00764D
8Heliconia psittacorumSustainability 17 02120 i008128A, B & D
9Croposma sp.Sustainability 17 02120 i00932B
10Berberis sp.Sustainability 17 02120 i01032B
11Berberis thunbergiiSustainability 17 02120 i01132B
12Cyperus papyrusSustainability 17 02120 i012112A, B &D
13Eichhornia crassipesSustainability 17 02120 i013846C
Table 2. Field parameters measured throughout the study (Mean ± standard deviation, n = 48).
Table 2. Field parameters measured throughout the study (Mean ± standard deviation, n = 48).
ParameterInfluentSettlerZone AZone BZone CZone D (Effluent)
TDS (mg L−1)170.93 ± 1.61168.24 ± 1.62171.41 ± 2.00159.84 ± 1.76161.95 ± 1.67160.94 ± 1.68
EC (μS cm−1)1236.4 ± 10.961373.0 ± 12.41263.4 ± 20.41173.4 ± 22.361251.4 ± 18.641197.2 ± 25.84
Temperature (°C)25.39 ± 0.1125.30 ± 0.1625.12 ± 0.2024.61 ± 0.1524.57 ± 0.1724.41 ± 0.11
DO (mg L−1)3.53 ± 0.293.49 ± 0.223.52 ± 0.212.99 ± 0.292.58 ± 0.262.56± 0.31
Table 3. Concentration and percentage of removal efficiency per TW system zone (a) COD; (b) NH3-N; (c) NH4-N; (d) NO2-N; (e) NO3-N; (f) TN; (g) PO4-P; (h) TP. The recorded values are presented with the mean ± standard error.
Table 3. Concentration and percentage of removal efficiency per TW system zone (a) COD; (b) NH3-N; (c) NH4-N; (d) NO2-N; (e) NO3-N; (f) TN; (g) PO4-P; (h) TP. The recorded values are presented with the mean ± standard error.
ParameterUnitsInfluentSettlerZone AZone BZone CZone D
(Effluent)		Maximum Permissible Limits NOM-001-SEMARNAT-2021.
CODConcentration (mg L−1)443.56 ± 14.47 2237.58 ± 15.16 2152.56 ± 12.36 294.26 ± 7.32 140.96 ± 5.57 129.39 ± 3.61 1150
Removal (%)046.4465.6178.7590.7793.37
NH3-NConcentration (mg L−1)22.81 ± 0.9015.66 ± 0.8611.1 ± 0.688.38 ± 0.685.19 ± 0.601.97 ± 0.57N.A.
Removal (%)031.3551.3463.2677.2591.36
NH4-NConcentration (mg L−1)57.85 ± 1.6139.36 ± 1.9229.31 ± 1.4018.78 ± 1.3111.03 ± 1.405.04 ± 1.24N.A.
Removal (%)031.9649.3367.5480.9391.29
NO2-NConcentration (mg L−1)9.93 ± 0.635.65 ± 0.534.01 ± 0.322.04 ± 0.230.96 ± 0.120.45 ± 0.08N.A.
Removal (%)043.159.6279.4690.3395.47
NO3-NConcentration (mg L−1)23.77 ± 1.3415.82 ± 1.189.43 ± 0.985.69 ± 0.693.02 ± 0.672.05 ± 0.60N.A.
Removal (%)033.4560.3376.0687.2991.38
TNConcentration (mg L−1)35.71 ± 0.87 222.23 ± 1.01 117.76 ± 0.91 112.54 ± 0.92 18.26 ± 1.04 13.08 ± 0.77 125
Removal (%)037.7550.2764.8876.8791.37
PO4-PConcentration (mg L−1)19.13 ± 0.5712.25 ± 0.768.44 ± 0.535.25 ± 0.612.8 ± 0.571.48 ± 0.64N.A.
Removal (%)035.9655.8872.5685.3692.26
TPConcentration (mg L−1)16.73 ± 0.66 211.01 ± 0.66 17.26 ± 0.63 15.54 ± 0.61 13.62 ± 0.51 11.43 ± 0.36 115
Removal (%)034.1956.666.8978.3691.45
1 Complies permissible limit; 2 Does not comply permissible limit.
Table 4. Contaminant correlation matrix (COD, NH3-N, NH4-N, NO2-N, NO3-N, TN, PO4-P and TP) vs. (water quality parameters, environmental variables and the time).
Table 4. Contaminant correlation matrix (COD, NH3-N, NH4-N, NO2-N, NO3-N, TN, PO4-P and TP) vs. (water quality parameters, environmental variables and the time).
VariableLight IntensityTemperatureRelative HumidityPrecipitationpHDOECTDSWater TemperatureTime (Months)
COD−0.7716 (**)−0.8027 (**)−0.2119 (ns)−0.2267 (ns)0.5704 (ns)0.6249 (*)0.0367 (ns)−0.1868 (ns)−0.2507 (ns)−0.9598 (***)
NH3-N−0.7704 (**)−0.7416 (**)−0.2207 (ns)−0.2518 (ns)0.5530 (ns)0.6800 (*)0.0267 (ns)−0.2428 (ns)−0.1802 (ns)−0.9695 (***)
NH4-N−0.6774 (*)−0.6281 (*)−0.2911 (ns)−0.3506 (ns)0.6617 (*)0.7066 (*)0.1610 (ns)−0.1192 (ns)−0.0177 (ns)−0.9400 (***)
NO2-N−0.4974 (ns)−0.6655 (*)0.0489 (ns)−0.1119 (ns)0.5674 (ns)0.3783 (ns)−0.1608 (ns)−0.0489 (ns)−0.3217 (ns)−0.6635 (*)
NO3-N−0.6758 (*)−0.5917 (*)−0.0085 (ns)−0.0648 (ns)0.4281 (ns)0.6789 (*)0.1144 (ns)0.0128 (ns)−0.1831 (ns)−0.7469 (**)
TN−0.8457 (***)−0.7703 (**)−0.1853 (ns)−0.1333 (ns)0.4842 (ns)0.6743 (*)0.0807 (ns)−0.2156 (ns)−0.2527 (ns)−0.9430 (***)
PO4-P−0.6770 (*)−0.4059 (ns)−0.1337 (ns)0.1253 (ns)0.2244 (ns)0.6975 (*)0.2930 (ns)0.0257 (ns)−0.0131 (ns)−0.5763 (*)
TP−0.6574 (*)−0.4334 (ns)−0.5075 (ns)−0.5863 (ns)0.6325 (*)0.6358 (*)0.1379 (ns)−0.4779 (ns)0.1330 (ns)−0.7416 (**)
(*) = Significant (p < 0.05), (**) = Highly significant (p < 0.01), (***) = Extremely significant (p < 0.001), (ns) = Not significant.
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Lomeli, J.S.; Zamora-Castro, S.A.; Zamora-Lobato, T.; Sandoval-Herazo, E.J.; Adame-García, J.; Zurita, F.; Monroy-Pineda, M.C.; Aguilar-Cortés, G.; Rivera, S.; Sandoval-Herazo, M. Performance of Large-Scale Ornamental Wetlands for Municipal Wastewater Treatment: A Case Study in a Polluted Estuary in the Gulf of Mexico. Sustainability 2025, 17, 2120. https://doi.org/10.3390/su17052120

AMA Style

Lomeli JS, Zamora-Castro SA, Zamora-Lobato T, Sandoval-Herazo EJ, Adame-García J, Zurita F, Monroy-Pineda MC, Aguilar-Cortés G, Rivera S, Sandoval-Herazo M. Performance of Large-Scale Ornamental Wetlands for Municipal Wastewater Treatment: A Case Study in a Polluted Estuary in the Gulf of Mexico. Sustainability. 2025; 17(5):2120. https://doi.org/10.3390/su17052120

Chicago/Turabian Style

Lomeli, Joaquin Sangabriel, Sergio Aurelio Zamora-Castro, Teresa Zamora-Lobato, Elber José Sandoval-Herazo, Jacel Adame-García, Florentina Zurita, Maria Cecilia Monroy-Pineda, Graciano Aguilar-Cortés, Saúl Rivera, and Mayerlín Sandoval-Herazo. 2025. "Performance of Large-Scale Ornamental Wetlands for Municipal Wastewater Treatment: A Case Study in a Polluted Estuary in the Gulf of Mexico" Sustainability 17, no. 5: 2120. https://doi.org/10.3390/su17052120

APA Style

Lomeli, J. S., Zamora-Castro, S. A., Zamora-Lobato, T., Sandoval-Herazo, E. J., Adame-García, J., Zurita, F., Monroy-Pineda, M. C., Aguilar-Cortés, G., Rivera, S., & Sandoval-Herazo, M. (2025). Performance of Large-Scale Ornamental Wetlands for Municipal Wastewater Treatment: A Case Study in a Polluted Estuary in the Gulf of Mexico. Sustainability, 17(5), 2120. https://doi.org/10.3390/su17052120

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop