Environmental, Economic, and Social Potentialities of Ornamental Vegetation Cultivated in Constructed Wetlands of Mexico

: Sustainable development implies the proper use of natural resources, such as water resources, but the environmental, economic, and social beneﬁts should also be considered. In the water sector, for example, sanitation is one of the challenges that arise in rural localities. However, issues related to it may be solved with the use of constructed wetlands (CWs), which may allow the cultivation of ornamental plants with phytoremediation properties. Through a content analysis, the environmental, economic, and social potential of ornamental species used in Mexico for phytoremediation in CWs is documented in this study. The environmental potential of the plants was considered based on their phytoremediation properties. The economic potential was determined from research articles and from the National Agri-Food Information System. The social potential was analyzed considering the ornamental and artisanal use of the plants. In total, 21 species of phytoremediation plants were identiﬁed. Anthurium andreanum and Zantedeschia aethiopica stand out for their commercial value, reported in 2018 to be 272,875 and 30,318 USD, respectively, at the national level. The social potential was identiﬁed by the ornamental or artisanal use for ﬂower arrangements and weaving. This study reveals that the use of CWs with ornamental vegetation is a sustainable option to clean wastewater, reuse water, and generate economic incentives. Thus, it is essential to provide the community with adequate training for the management of CWs in those sites that lack treatment systems. constructed (CW),


Introduction
Capitalist development is based on an extractivism system that, with a high demand for natural resources [1], causes great environmental deterioration. Therefore, at the international level, the 2030 Agenda for Sustainable Development includes 17 goals [2] that encompass the three aspects of sustainability: environmental, economic, and social. Making more efficient use of natural resources is an obligation.
In this regard, international policies provide guidelines for the desired development, such as the 2030 Agenda [2], a document that emphasized the commitment to protect the planet from environmental degradation through sustainable consumption, as well as the concept of sustainable development, which is based on meeting the needs of the present generation without compromising the ability of future generations to meet their own needs (Brundtland Report) [3].
This study can help select appropriate plant species to improve the removal of pollutants.
On the other hand, it can improve the aesthetics of CWs, making them attractive to the eye with sophisticated and innovative forms, as observed for the Olentangy River Wetland Research Park in Ohio State University, Columbus, a wetland shaped like a kidney, allusive to the belief that wetlands are the kidneys of plants [23].
Likewise, CWs are recommended to be built in small towns where government investment is scarce. These sanitation systems require small investments for their construction, operation, and maintenance [24]. In social participation schemes, operation and maintenance can be carried out by the community.

Materials and Methods
The research was carried out through content analysis [19], predominantly on qualitative research. The literature review methodology in our study (see Figure 1) was based on Colicchia and Strozzi [25], Piñar [26], and Ponis and Ntalla [27].
The methodological steps of this study are shown in Figure 1. We started by defining the research question, then interpreted the results, following a total of nine stages with a quality control process in the final stages.
The research question we addressed was: "What is the environmental, economic, and social potential of ornamental species in Mexico for phytoremediation?"  The methodological steps of this study are shown in Figure 1. We started by defining the research question, then interpreted the results, following a total of nine stages with a quality control process in the final stages.
The research question we addressed was: "What is the environmental, economic, and social potential of ornamental species in Mexico for phytoremediation?" We searched databases using researchgate.net, academia.edu, TESIUNAM; in addition, articles on the web of science, Scopus, and ISI Web of Knowledge were reviewed, as well as publications of Instituto Mexicano de Tecnología del Agua, a database that reports ornamental species used in Mexico and contains free-access resources. For all search engines, we used keywords such as phytoremediation, ornamental plants, constructed wetlands (CW), and pollutant removal. We focused on ornamental vegetation (unit of analysis) used for phytoremediation in CW, due to its high pollutant removal efficiency in water and its attractiveness for cultivation in CW, to which it gives a pleasant appearance, facilitating their acceptance. We focused on the characterization, commercialization, and uses of ornamental plants with phytoremediation properties to describe a possible second use of these plants, besides the decorative one.
A horizontal text analysis [26] allowed us to identify common properties of contaminant and parameters that were at the basis of different studies on CWs. Furthermore, a quantitative technique was used to determine the frequency of the parameters analyzed and the number of species identified as ornamental with phytoremediation properties. Likewise, the plants were classified by their potential to purify the soil and air.
To detect the environmental value of the ornamental plants used in phytoremediation processes, we reviewed studies that evaluated the purification of wastewater by removing pollutants identified by the parameters of Biological Oxygen Demand (BOD 5 ), Chemical Oxygen Demand (COD), Fats and Oils (G and A), Total Suspended Solids (SST), Total Dissolved Solids (TDS), Fecal Coliforms (CF), Chloride (Cl), Phosphorus (P), Nitrogen (N), Ammonium (NH 4 ), Phosphate (PO 4 ), Ibuprofen (C 13 H 18 O 2 ), Arsenic (As), Sulfate (SO 4 ), Volatile solids (SV), and Nitrate (NO 3 ). In this regard, from a total of 55 papers, 41 were selected because they contain reports of removal efficiencies greater than 50%. The information was integrated into an excel database with variables such as species, type of parameter analyzed, removal efficiency, and type of wetland.
Regarding the economic value of the species used in wetlands, the market value of ornamental plants was recorded on the basis of publications and reports of the Sistema de Información Agroalimentaria de Consulta (SIACON-NG), with information as of 2018 reported by the Secretaría de Agricultura, Ganadería, Pesca y Alimentación (SAGARPA). Through a database generated with searches in the SIACON-NG on the selected species with environmental potential, information on the commercial value at the national level was integrated.
The analysis of the social potential (ornamental, artisanal, medicinal, and food) of the ornamental species cultivated in the selected constructed wetlands was carried out through 21 publications that addressed this aspect.
In total, 84 publications were analyzed to support the information we present, of which 22 scientific articles used for the review are included in the Journal citation report, (47%); the additional bibliographic material was obtained from reliable primary and secondary sources.

Results
Environmental potential shown in Figure 2. from the analysis of CW projects where ornamental flowers were used as a phytoremediation process, 21 species of plants were identified ( Table 1). The role of these species in the wastewater purification process consists in absorption/filtering of pollutants through the roots [12,16]. In the same way, they can degrade chemical compounds, including drugs such as Ibuprofen [13].

Environmental Potential
The polluting parameters mostly analyzed in phytoremediation processes in constructed wetlands are shown in Figure 3. BOD 5 and COD of urban public wastewater discharges were the most examined parameters. They both describe the degree of water contamination. The ornamental species most commonly used in phytoremediation appeared to be Zantedeschia aethiopica and Spathiphyllum blandum.

Environmental Potential
The polluting parameters mostly analyzed in phytoremediation processes i structed wetlands are shown in Figure 3. BOD5 and COD of urban public wastewat charges were the most examined parameters. They both describe the degree of wate tamination. The ornamental species most commonly used in phytoremediation app to be Zantedeschia aethiopica and Spathiphyllum blandum. BOD5 reduction by plants oscillated between 70 and 89%; likewise, COD red resulted to be 70-86%, and reduction of PO4 and fats and oils were found to amo 70-84% and 70-82%, respectively. The choice of plants, in addition to their phytore ation properties, responded to several factors such as the type of wastewater dis (municipal, industrial, others) and the climate. ation properties, responded to several factors such as the type of wastewater discharge (municipal, industrial, others) and the climate.

Economic Potential
This may vary with respect to the intended use for the aerial mass of the plants and refers to the commercialization of cut flowers, foliage, stems, and plants in pots [9,74]. Other factors that may influence the commercialization are the regional and traditional uses of plants that vary locally, that is, customs and traditions influence the demand of certain specific species in different regions and seasons of the year.
As a consequence of the recognition of the ornamental value of plants, in Mexico the production of these species has increased. The economic value of these plants is registered by the SAGARPA, through the Information System of Agrifood information. The main contributions by plant species are shown in Table 2, which also includes Anthurium and Zantedeschia aethiopica, as they are the only species with characteristics for phytoremediation that appear in commercial statistics. This allows us to visualize some preference in the use of these plants and the opportunity for their commercialization. Another important strategy to strengthen the use of ornamental plants is production networks. Regarding this, the Macro Ornamental Network [9] that operates in Mexico was established as a strategic plan to join forces and generate knowledge, as well as to preserve and take advantage of native ornamental resources in a sustainable way. The purpose of the network is to promote the sustainable use of plants for the benefit of the society through the participation of educational institutions, research institutions, government agencies, and producer associations. It is observed that the CW phytoremediation species are not constituted as networks, which translates into an area of opportunities for the administration of CW crops to potentiate the crops.
Among the species analyzed, Zantedeschia aethiopica and Anthurium stand out for their production, [54] and, in the case of heliconia, there is a total of 50 ha cultivated in Mexico [40].

Social Potential
In this study, the social potential was classified as ornamental, artisan, medicinal, and food. Therefore, plant species can be used as raw material in the elaboration of handicrafts, flower arrangements, and the cultivation of seedlings in pots that can be marketed in small quantities, as shown by some works [13,48]. At the same time, a culture promoting the efficient use of natural resources would develop in localities where CW planted with ornamental flowers are constructed, such as the Pinoltepec project in the municipality of Emiliano Zapata, Veracruz, Mexico [13]. To take advantage of the social potential that ornamental plants have, it is important to describe their uses considering the benefits they provide to the society, i.e., artisanal, ornamental, cultural, and medicinal benefits (Figure 4).  The use of ornamental plants in rural localities, where their cultivation in CW is feasible, gains importance because these localities regularly lack flower shops to satisfy plant demand for religious events, family, civic, and cultural festivities. Thus, the cultivation of these species may represent an opportunity for local trade: in addition to representing an income-generating opportunity, it may reduce costs due to the expenses of moving to nearby locations for plant acquisition.
Of the phytoremediation plants identified, 90.5% have an ornamental use, and the rest can be used in artisanal activities; they both have the potential to be commercialized and used in social and cultural local events.

Discussion
The construction of wastewater treatment systems based on CWs and phytoremediation processes has gained great importance in recent years. Several authors [19,31,47] agree that for pollutants, such as COD, BOD5, nitrates, phosphates, metals, and some drugs, phytoremediation plants provide removal efficiencies greater than 50%. CWs with phytoremediation plants are an ecotechnology that contributes to the recovery of ecosystems because they supply them with good quality water, in addition to allowing the reuse of second use of water in some non-food activities. Other pollutants are not considered sufficiently in purification studies using ornamental plants, as is the case of ibuprofen (0- The use of ornamental plants in rural localities, where their cultivation in CW is feasible, gains importance because these localities regularly lack flower shops to satisfy plant demand for religious events, family, civic, and cultural festivities. Thus, the cultivation of these species may represent an opportunity for local trade: in addition to representing an income-generating opportunity, it may reduce costs due to the expenses of moving to nearby locations for plant acquisition.
Of the phytoremediation plants identified, 90.5% have an ornamental use, and the rest can be used in artisanal activities; they both have the potential to be commercialized and used in social and cultural local events.

Discussion
The construction of wastewater treatment systems based on CWs and phytoremediation processes has gained great importance in recent years. Several authors [19,31,47] agree that for pollutants, such as COD, BOD 5 , nitrates, phosphates, metals, and some drugs, phytoremediation plants provide removal efficiencies greater than 50%. CWs with phytoremediation plants are an ecotechnology that contributes to the recovery of ecosystems because they supply them with good quality water, in addition to allowing the reuse of second use of water in some non-food activities. Other pollutants are not considered sufficiently in purification studies using ornamental plants, as is the case of ibuprofen (0-50%), analyzed in CWs vegetated with Spathiphyllum wallisii and As (0-50%), investigated using species of tame grass and Zantedeschia aethiopica.
These systems are recommended owing to their low construction, operation, and maintenance costs [11]. Hernández [48] reports that a CW operating in Pinoltepec, Veracruz, with a capacity of 20 m 3 /day was built with an investment of 140,000.00 USD, while a conventional system with a capacity of 1080 m 3 /day, required an investment of 301,414.86 USD plus the expenses of operation, for a total amount of 1964.63 USD per month.
On the other hand, in an application for the treatment of wastewater of aquatic origin, Betanzo [75] in Veracruz, Mexico, reported an investment of 53,057 USD for the construction of a CW to treat 3108 m 3 with a hydraulic retention time of 72 h. In this sense, it is evident that the use of CW is an economical option in contrast to conventional treatment systems.
One of the main concerns regarding the reproduction of plant species is the spread of invasive species; however, no official records were found classifying some of the 21 ornamental species as invasive. In other countries, the use of Typha latifolia is suggested. However, this plant can invade channels; therefore, its use must be well managed.
As for the economic aspect, the crops that have been used the most in CW projects are Zantedeschia aethiopica and Spathiphyllum blandum. However, Anthurium andreanum has also given good results in phytoremediation [12] and has great commercial value for decoration and as a potted plant [51,58], in addition to its long shelf life [59]. According to previous research [12,55], it can be a convenient option, considering the recommendations according to the type of climate. In a study carried out in the areas of Xalapa and Actopan, [36] through surveys, the preference and acceptance of ornamental plants was determined. It was reported that 84% of the sample indicated that the plants have potential for sale and distribution because they are attractive for decorating houses, parks, gardens, in addition to being showy and having high durability.
The alternative of wastewater sanitation based on constructed wetlands has given good results at the level of experimentation, but there are few cases analyzed in small towns, such as those that operate in the states of Mexico, Quintana Roo, Michoacán, Morelos, Hidalgo, Oaxaca, and Veracruz [16,73]. This means that this is an area offering opportunities for projects involving social participation and social capital, that may raise awareness of the common good of natural resources [76], as well as promote entrepreneurship [77] to guarantee the continuation of the projects.
In specific cases, the environmental, economic, and social potential of the floristic species cultivated in CWs has been proved in some projects, as is the case of the town of Pinoltepec, Veracruz [50,55], where the commercialization of cultivated hydrophytic plants operates under flooding and in the presence of high concentrations of nutrients. These species are: Typha domingensis, Cyperus papyrus, and C. alternifolius, as well as plants that produce flowers, such as Zantedeschia aethiopica, Lilium spp., Anthurium spp., and Hedychium coronarium. This coincides with the recommendations of other authors [16,31] to use phytoremediation, adding the benefit that this practice promotes social organization through groups that can take charge of the administration of wetlands.
At the international level, there are few CW projects operated by social groups. In India, there is a record of a CW operated by a group of women from a cooperative society in Mhaswad. The project was developed in order to facilitate rural development and empower women by implementing a CWs [78].
The benefits that the ecotechnology of constructed wetlands cultivated with ornamental plants would generate if they were implemented in a percentage of the 182,675 localities in Mexico with a population of less than 2500 inhabitants have not been measured [79]. This ecotechnology would contribute to the sanitation of the receiving sources of wastewater discharges, and the local trade of floristic products would be promoted.
The analysis we carried out suggests that it is advisable to link the phytoremediation processes to the environmental, economic, and social potentials of plants, which makes them more attractive in the operation because they represent an opportunity to generate income while, at the same time, contributing to environmental, economic and social sustainability.
However, the public sector, in particular, municipal authorities, have not shown interest in the implementation of CWs, which has resulted in the absence of alternative treatment infrastructures in small towns [80][81][82], even though CWs represents a tool for sustainable development. In addition, there are public policies that allow access to financial resources for the construction of CWs, considering that the Operating Rules for the Drinking Water, Drainage, and Treatment Program in charge of Comisión Nacional del Agua, allow sanitation actions "Preferably with technologies that do not require electrical energy, chemical reagents, or specialized labor" [9]. Furthermore, the promotion of community participation is mentioned as a necessary element for the population of small towns to appropriate the alternative technologies and contribute to sustainable local development.

Conclusions
This study revealed that the use of the 21 species of ornamental plants in constructed wetlands is a sustainable alternative, since, in addition to having phytoremediation characteristics by removing pollutants, they are raw material for artisanal elaboration, economically favoring their users. In addition to the social aspect, some of these plants have medicinal properties or can simply be used as ornamental plants at home.
Zantedeshia aethipica and Anturium spp. have a high market value (6 million of Mexican pesos in 2018), better vase life, and good aesthetic appearance, up to 25 days in the case of Heliconias, Zingiber spectabile and Anthurium andreanum.
Thus, their use in constructed wetlands is recommended. Training of community groups in the maintenance of wetlands, the use of ornamental vegetation, and the good management of natural resources is also suggested.
Social participation will be essential in the operation and maintenance stage of CWs to guarantee the continuity of projects and good environmental practices, for which the management of government support or derived initiatives is recommended.