Green roofs as a biotechnological solution to increase water retention in urban areas

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Epifluorescence microscope methods for bacterial enumeration in a 4-chlorophenol degrading consortium

Epifluorescence microscope methods, namely BacLight, direct epifluorescence filter technique and Rhodamine 123, consistently underestimated plate bacterial counts in a 4-chlorophenol degrading consortium. Cells capable of passing through 0.2 mgrm filters, referred as `ultramicrocells', were found. Although cell counts were higher when traditional methods were used, BacLight and direct epifluorescence filter technique were convenient techniques for the systematic monitoring of bacteria involved in biodegradation processes, as results were consistent and available within a short time

Nutrient removal in an aerobic granular sludge system facing events of saltwater intrusion

The presence of saltwater in wastewater treatment plants (WWTP) can have diverse origins, for instance from the discharge of industrial saline effluents or the saltwater use for toilet flushing. However, in coastal regions, especially during high tide level, saltwater intrusion occurs changing the wastewater composition, posing a challenge for the nearby WWTPs. The impact of the variable salinity levels of the wastewater over a day can affect the biological removal processes, a topic scarcely studied for granular systems. Aerobic granular sludge (AGS) is one of the most promising biotechnologies for wastewater treatment, mainly due to AGS extraordinary properties, such as the simultaneous nutrient removal capability, good settling properties, and the simplicity of operation. In this study, the nutrients removal performance of an AGS system treating domestic wastewater with variable saltwater concentrations was evaluated. First, the reactor was operated for 4 months stepwise increasing the saltwater concentration (up to 15 g L-1). Then, the saltwater concentration of the wastewater was variable during each day, fluctuating from basal (7.5 g L-1) to maximum salinity (22.5 g L-1) levels to mimic flood tide events. During the first stage of operation, the AGS capacity for carbon, ammonium and phosphate removal increased over time, with most of the carbon and nutrients being removed. In the second stage, the saltwater daily intrusion variation due to tidal cycles did not affect neither the granular structure nor the reactor removal performance, as the granulation processes continued to occur and the biomass was able to efficiently treat the wastewater. The AGS system capacity to deal with saltwater intrusion during high tides showed that this technology is promising to use by utilities situated along the coast with saltwater intrusion events.info:eu-repo/semantics/publishedVersio

Green roofs runoff coefficient: different time-scale approaches to estimate its value

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Extensive green roofs: different time approaches to runoff coefficient determination

Stormwater runoff in green roofs (GRs) is represented by the runoff coefficient, which is fundamental to assess their hydraulic performance and to design the drainage systems downstream. Runoff coefficient values in newly installed GR systems should be estimated by models that must be feasible and reproduce the retention behavior as realistically as possible, being thus adjusted to each season and climate region. In this study, the suitability of a previously developed model for runoff coefficient determination is assessed using experimental data, and registered over a 1 year period. Results showed that the previously developed model does not quite fit the experimental data obtained in the present study, which was developed in a distinct year with different climate conditions, revealing the need to develop a new model with a better adjustment, and taking into consideration other variables besides temperature and precipitation (e.g., early-stage moisture conditions of the GR matrix and climate of the study area). Runoff coefficient values were also determined with different time periods (monthly, weekly, and per rain event) to assess the most adequate approach, considering the practical uses of this coefficient. The monthly determination approach resulted in lower runoff coefficient values (0–0.46) than the weekly or per rain event (0.017–0.764) determination. When applied to a long-term performance analysis, this study showed no significant differences when using the monthly, weekly, or per rain event runoff, resulting on a variation of only 0.9 m3 of annual runoff. This indicates that the use of monthly values for runoff coefficient, although not suitable for sizing drainage systems, might be used to estimate their long-term performance. Overall, this pilot extensive GR of 0.4 m2 presented an annual retention volume of 469.3 L, corresponding to a retention rate of 89.6%, in a year with a total precipitation of 1089 mm. The assessment of different time scales for runoff coefficient determination is a major contribution for future GR performance assessments, and a fundamental decision support tool.info:eu-repo/semantics/publishedVersio

Green roofs runoff coefficient: different time-scale approaches to estimate its value

The high impermeabilization in densely populated areas brings numerous problems concerning stormwater management, mainly when intense precipitation events occur. This is frequent in the beginning of the winter/rainy season in the Mediterranean region, namely in Portugal. Implementation of nature-based solutions in general, and green roofs in particular, can minimize the damages caused by such events in urban areas. The reduction of stormwater runoff in Green Roofs (GR), can be estimated with the runoff coefficient, a parameter that assesses their hydraulic performance and contributes to the design of the drainage systems downstream. Due to their natural characteristics, GR have variable performance throughout the year and so models used to determine runoff coefficients should reproduce this behaviour as realistically as possible, adjusted to each season and climate region. In this study, monthly runoff coefficient determination, using experimental data, was assessed through the use of a previous developed model. Runoff coefficient was also determined using different time periods (monthly, weekly and per rain events) to assess the most adequate approach, considering the practical uses of this coefficient. The monthly determination approach resulted in lower runoff coefficient values, than the weekly or per rain-event determination. However, when applied to a long-term performance analysis, this study showed no significant differences when using the monthly, weekly or per rain-event runoff. Furthermore, the results revealed the need to improve the model for extensive Green Roofs determination, taking into consideration other variables besides temperature and precipitation (e.g. early-stage moisture conditions of the GR matrix). The assessment of different time scales for runoff coefficient determination is a major contribution for GR future performance assessment, and a fundamental decision support tool.info:eu-repo/semantics/publishedVersio

Selection and acclimatization of strains of edible mycorrhizal fungi for improved field persistence

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The effect of phosphate-solubilizing rhizobacteria on Zea mays growth on P-deficient soils

P-deficiency in soils is a limiting factor for plant growth. Several phosphate-solubilizing rhizobacteria (PSB) were used to enhance growth of Zea maysgrowing in a P-deficient soil. Strains were screened for their ability to solubilize P and to produce plant growth promoting (PGP) substances. The best-P solubilizing strains Rhodococcus sp. EC35, Pseudomonas sp. EAV and Arthrobacter nicotinovoransEAPAA were inoculated in maize growing in P-deficient soils without P fertilization and amended with soluble (KH2PO4) and insoluble P (Ca3(PO4)2). Results showed that PSB significantly enhanced Z. mays biomass production in all Ptreatments. Without P fertilization, bacterial inoculation increased plant dry biomass by ca. 20%, while under soluble P conditions the enhancement was higher. Pseudomonas sp. EAV was the strain that better performed improving rootand shoot biomass by 104% and 60%, respectively. In soils amended with insoluble P, plant biomass was also positive influenced by bacterial inoculation. Plant growth enhancement seems to be related not only to Psolubilization but also to other PGP traits, such as IAA and ACC-deaminase. This work shows that PSB may be used as bioinoculants and consequently constitute an attractive alternative to the phosphatic fertilizers amendments used to improve crop production

Plant growth promoting potential of rhizobacteria isolated from a contaminated area

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The mycorrhizal status of Phragmites australis in several polluted soils and sediments of an industrialised region of Northern Portugal

Roots of Phragmites australis from three polluted soils and sediments (a periodically flooded stream bank containing organic pollutants, a high-pH drying sedimentation pond and an acidic, periodically flooded sand polluted by industrial effluents) were sampled over a 1-year cycle of plant growth to assess the degree of colonisation by arbuscular mycorrhizal fungi (AMF). At the dry sedimentation pond, root samples of Juncus effusus and Salix atrocinerea were also taken to assess the presence of AMF throughout the year. Root colonisation was low (<5% root length colonised) but arbuscule presence peaked in P. australis during the spring and autumn prior to flowering. These changes in arbuscule abundance were also seen in a parallel greenhouse trial using seed taken from one of the sites. Roots of J. effusus contained mainly vesicular colonisation but arbuscule activity peaked during the winter months (December–March). S. atrocinerea roots were found to be ectomycorrhizal throughout the year but the fine feeder roots were colonised by AMF. The results confirm that semi-aquatics, like P. australis, can become arbuscular mycorrhizal but that this status changes during the year depending on soil moisture content and plant phenology. The influence of AMF in these polluted soils is uncertain but the potential exists to establish a more diverse plant ecosystem during the landscaping of these areas (phytostabilisation) by management of adapted plant and AMF ecotypes