Floating wetland islands to promote water quality enhancement and ecosystem restoration

Funder

Organizational Unit

Publications

Growing substrates for aromatic plant species in green roofs and water runoff quality: pilot experiments in a Mediterranean climate

Publication . Monteiro, Cristina M.; Calheiros, Cristina S. C.; Palha, Paulo; Castro, Paula M. L.

Green roof technology has evolved in recent years as a potential solution to promote vegetation in urban areas. Green roof studies for Mediterranean climates, where extended drought periods in summer contrast with cold and rainy periods in winter, are still scarce. The present research study assesses the use of substrates with different compositions for the growth of six aromatic plant species - Lavandula dentata, Pelargonium odoratissimum, Helichrysum italicum, Satureja montana, Thymus caespititius and T. pseudolanuginosus, during a 2-year period, and the monitoring of water runoff quality. Growing substrates encompassed expanded clay and granulated cork, in combination with organic matter and crushed eggshell. These combinations were adequate for the establishment of all aromatic plants, allowing their propagation in the extensive system located on the 5th storey. The substrate composed of 70% expanded clay and 30% organic matter was the most suitable, and crushed eggshell incorporation improved the initial plant establishment. Water runoff quality parameters - turbidity, pH, conductivity, NH4(+), NO3(-), PO4(3-) and chemical oxygen demand - showed that it could be reused for non-potable uses in buildings. The present study shows that selected aromatic plant species could be successfully used in green roofs in a Mediterranean climate.

2017Journal article

Restricted access

Presence of microbial pathogens and genetic diversity of listeria monocytogenes in a constructed wetland system

Publication . Calheiros, Cristina S. C.; Ferreira, Vânia; Magalhães, Rui; Teixeira, Paula; Castro, Paula

The potential of constructed wetlands (CWs) as a low technology for wastewater treatment is timely but there is a need to understand the route of pathogenic bacteria (Listeria monocytogenes and Salmonella spp.) and indicator organisms (Enterobacteriaceae and Escherichia coli) present in wastewater within those systems and to what extent they can compromise the further use of the plants (enabling in-house ornamental use) and water reuse (irrigation purposes). In the present study the fate of potential pathogenic bacteria within a CW, with ornamental plants, and an outlet pond established in a tourism house for wastewater treatment was assessed. The fate of pathogenic bacteria in lettuce, both plant tissues and soil, subject to irrigation with water contaminated either with L. monocytogenes or E. coli (indicator organism) was investigated. The uptake of indicator organisms by the CW ornamental plants was low and there was a decrease, from the CW wastewater inlet to the outlet, of up to 3 log for Enterobacteriaceae and up to 2 log for E. coli. Concerning Salmonella spp. no detection was registered in the water, plant tissues or substrate within the CW. On the other hand, several L. monocytogenes isolates were retrieved from water, root and substrate samples, found to have a high susceptibility to a battery of antibiotics. The irrigation of lettuce with water containing pathogenic bacteria (L. monocytogenes) and indicator organisms (E. coli) must be considered with caution since both bacteria were detected in the soil growing media and internalization of L. monocytogenes in roots was observed. These issues are poorly investigated and to our knowledge not addressed in the sphere of CWs.

2017Journal article

Restricted access

Substrate influence on aromatic plant growth in extensive green roofs in a Mediterranean climate

Publication . Monteiro, Cristina M.; Calheiros, Cristina S. C.; Martins, João P.; Costa, Francisco M.; Palha, Paulo; Freitas, Sara de; Ramos, Nuno M. M.; Castro, Paula M. L.

Green roofs have been described as technical solutions to overcome urban environmental problems, such as decrease of vegetation and stormwater management. In the present study, two pilot 20 m2 extensive green roofs were implemented in an urban Mediterranean region, at a 1st storey on a warehouse building structure, in order to test the adequacy of different substrates for supporting aromatic plants (Lavandula dentata, Helichrysum italicum, Satureja montana, Thymus caespititius and Thymus pseudolanuginosus). Experimental substrates included expanded clay and granulated cork as main components, supplemented with organic matter and crushed egg shell. A commercial substrate that obeys to FLL guidelines was also tested. Plant growth was assessed and compared within each platform. All experimental substrates proved to be adequate for vegetation growth, with the combination of 70% expanded clay, 15% organic matter and 15% crushed egg shell showing the best results regarding plant establishment and growth over time. Water runoff quality parameters - turbidity, pH, conductivity, NH4+, NO3−, PO43− - met standard values required for water reuse for non-potable purposes, such as toilet flushing or irrigation. Preliminary qualitative thermographic measurements comparing surface temperature of different plant species and the substrate showed that temperature of vegetation surface was lower than substrate, reinforcing green roofs benefits of lowering air temperature in their surroundings. The present research shows that aromatic vegetation combined with clay substrates are suitable for green roofs located in countries of the Mediterranean region.

2017Journal article

Restricted access

Water masses surface temperatures assessment and their effect on surrounding environment

Publication . Calheiros, Cristina S. C.; Barreira, Eva; Ramos, Nuno M. M.; Castro, Paula M. L.

The aim of this study was to evaluate the effect of water masses on the surface temperature with direct impact on the surrounding area. Three systems were used for the study: a fully vegetated system (subsurface flow constructed wetland (CW)), a lake with no vegetation and a lake partially vegetated with Lemna minor. Infrared thermography was applied for the different systems analysis, allowing the determination of the surface temperature spatial distribution. In general, the presence of plants and water in the analyzed systems contributed to lowering the surface temperatures when comparing to its surroundings. Differences up to about 22 degrees C were observed in the temperature between the CW canopy and the surrounding soil, and up to about 19 degrees C between the lake and the surrounding border. Different plant species (Canna flaccida, Canna indica and Zantedeschia aethiopica) inhabiting the CW were also compared and slightly higher average surface temperatures were observed for C. indica. The above mentioned results are relevant in terms of supporting a strategy for water systems inclusion, for example a lake or a CW, in a site as means of having influence in the surface temperature and to some extent in the heat island effect supporting a sustainable environmental management.

2017Journal article

Restricted access

Culturable bacteria associated to the rhizosphere and tissues of Iris pseudacorus plants growing in a treatment wetland for winery wastewater discharge

Publication . Calheiros, Cristina S. C.; Pereira, Sofia I. A.; Castro, Paula M.L.

Winery wastewater is of great concern due to its complex composition, characterized by high organic content and high amounts of readily and slowly biodegradable and recalcitrant compounds. In the present study, the culturable bacteria from rhizo (interstitial water and substrate) and endosphere (inside roots and shoots) of Iris pseudacorus plants inhabiting a treatment wetland mesocosm receiving winery wastewater, were isolated and identified. The innovative approach combined the use of these plants with a substrate based on used cork stoppers, as a support. Of the 53 bacterial isolates retrieved from the rhizo (interstitial water and substrate) and endosphere (root and shoot) of I. pseudacorus plants, the class γ-Proteobacteria was predominant in the shoot and root tissues (72%), but it was also present in the interstitial water and substrate (28%). In total, 13 different genera were found. Pseudomonas and Bacillus were the most represented genera in the rhizosphere while Rahnella and Pseudomonas were dominant in the endosphere of Iris plants. Plant tissues and the water-substrate shared 31% of the genera. Used cork stoppers supported plant growth and can be valorized as substrate in constructed vegetated systems for wastewater treatment and future bioremediation developments may be assisted by the use of resilient bacteria retrieved from such harsh environments.

2018Journal article

Restricted access