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- Diverse Arbuscular Mycorrhizal Fungi (AMF) communities colonize plants inhabiting a constructed wetland for wastewater treatmentPublication . Calheiros, Cristina S. C.; Pereira, Sofia I. A.; Franco, Albina R.; Castro, Paula M. L.Constructed wetlands (CWs) are biological wastewater treatment systems that comprise several components where plants and associated organisms play an important role in water depuration. Microbial studies emphasize bacterial dynamics, whereas studies of arbuscular mycorrhizal fungi (AMF) are scarce and the functional role of AMF in aquatic and wetland plants is poorly understood. The aim of this study was to analyze the AMF communities colonizing the roots of Canna indica, Canna flaccida, and Watsonia borbonica inhabiting a CW treating wastewater of a tourism unit. The dynamics of the AMF communities were evaluated by Denaturing Gradient Gel Electrophoresis (DGGE) of 18S rRNA gene amplification products along cold (C) and hot (H) seasons for three consecutive years. DGGE profiles allowed the estimation of AMF species richness (S), and Shannon-Wienner (H) and Pielou (J) indexes, for the different plant species, showing differences between species and along the years. Excised bands from DGGE were analyzed and identified through sequencing for arbuscular mycorrhiza, revealing the presence of AMF strains closely related to Glomus sp., Rhizophagus sp. and Acaulospora sp. genera. Concomitant water quality analyses showed that the system was effective in organic and nutrient removal during the sampling period. Findings from this study suggest that AMF diversity found in the CW is influenced by the water constituents, season, and plant species.
- Constructed Wetlands for freshwater and saline aquaculture wastewater treatment: a microcosm experiencePublication . Jesus, J. M.; Borges, M. T.; Calheiros, Cristina S. C.; Castro, Paula M. L.The aquaculture industry discharges large volumes of nutrient rich wastewater, contributing to eutrophication events. Recent culture intensification methodologies such as recirculation (RAS) and shallow raceway (SRS) systems discharge wastewater with even higher nutrient concentrations, though at lower volumes (Rana et al., 2005). Hence, efluent treatment options are of vital importance. Constructed wetlands (CWs) are a possible but underexplored treatment solution even for high salinity situations (Lymbery et al., 2006) consisting of planted shallow channels, relying upon biological, physical and chemical processes to treat wastewater (EPA, 2000). Therefore, this study aims to extend the knowledge on the possible use of CWs for aquaculture wastewater treatment, either fresh or saline. To fulfill this goal, several microcosms were created simulating subsurface systems with HRT = 7 days and planted with Typha latifolia. Substrate used was expanded clay 8 – 12.5 mm Ø. Macrophyte survival, growth, and nutrient removal (phosphate, nitrite, nitrate and ammonia) were assessed over a period of 4 weeks. Freshwater (simulated) and saline (real) fish farm effluents (recirculation SRS, 2.4% salinity) were tested. Results showed that plants adapted better to freshwater conditions exhibiting higher growth rate. Plants at 2.4% salinity did not growth in height after 2 weeks, but survival remained high.The microcosm wetland system was able to treat the effluent by removing 61%, 78% and 98% of NH4, NO2 and PO4, respectively, in fresh water, and 94%; 78%, 34% and 100% of NH4, NO2, NO3 and PO4, respectively, in saline wastewater. An improvement of removal with time was observed, suggesting the existence of a system adaptation period. The microcosm treatment was able to reduce nutrient concentrations to legally acceptable values. Hence, constructed wetlands can be an adequate solution for aquaculture efffluent treatment. Further studies are necessary, however, to achieve a better adaptation of the plant used to salinity.
- Constructed wetlands for tannery wastewater treatment in Portugal: ten years of experiencePublication . Calheiros, Cristina S. C.; Rangel, António O. S. S.; Castro, Paula M. L.Wastewaters from tannery industry are complex in composition and providing adequate treatment can be difficult. Constructed wetlands (CW) are regarded as an alternative treatment to the conventional biological systems, as a developing cost-effective and environmentally friendly phytoremediation technology. The present review compiles and integrates information on CWs technology for the needs of the tannery sector. The following issues arise as crucial for the implementation of such systems, namely i) an accurate wastewater characterization and an effective pretreatment before reaching the CW, ii) choosing the plants species better adapted to the imposed conditions, iii) substrate selection and iv) range of organic loadings applied. The examples practiced in Portugal give indication that horizontal subsurface flow systems, with expanded clay media, are a suitable option to be considered when dealing with high organic loading tannery wastewater (up to c.a. 3800 kgCODha−1d−1), being resilient to a wide range of hydraulic variations. Plants such as Phragmites and Typha have shown to be adequate for tannery wastewater depuration, with Arundo donax proving resilient to high salinity wastewaters. The flexibility of implementation allows the CW to be adapted to different sites with different configurations, being suitable as main secondary or tertiary treatment stage.
- Constructed wetland implemented in a tourism unit for wastewater treatmentPublication . Calheiros, Cristina S. C.; Mesquita, Raquel B. R.; Brix, Hans; Rangel, António O. S. S.; Castro, Paula M. L.
- Water masses surface temperatures assessment and their effect on surrounding environmentPublication . 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.
- Toxicity abatement of wastewaters from tourism units by constructed wetlandsPublication . Calheiros, Cristina S. C.; Castro, Paula M. L.; Gavina, Ana; Pereira, RuthThe present research intended to investigate the toxicity abatement of domestic wastewater after passing a biosystem composed of a constructed wetland (CW) followed by a pond. The wastewater was generated in a tourism house in a rural and mountainous context and passed through a septic tank before being diverted to a CW followed by a pond. A battery of ecotoxicological tests, comprising microalgae (Raphidocelis subcapitata), macrophytes (Lemna minor), cladocerans (Daphnia magna), and bacteria (Aliivibrio fischeri), was used to assess the toxicity of the wastewater collected before and after the CW and the water of the pond. Physicochemical parameters (pH, conductivity, chemical oxygen demand, biochemical oxygen demand, total suspended solids, phosphates, ammonium, and nitrate) were also determined. The CW was able to remove carbon and nutrients from the water with a concomitant reduction of its toxicity. This study, reinforced the added value of using toxicity tests as a complement to CW operational monitoring to validate the solution and to analyze possible readjustments that may be required to improve efficiency. This study lends further support to the claim that CWs can be a sustainable solution for treating small volumes of domestic wastewater in a rural context.