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

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

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

Aerobic granular sludge has EPS-producing bacteria able to tolerate salt

The aerobic granular sludge (AGS) process is a promising biotechnology which relies on the formation of compact biomass granules. Granulation occurs due to the overproduction of extracellular polymeric substances (EPS) by some microbes in response to stress conditions. EPS protect bacteria from the effect of toxic or inhibiting compounds present in the wastewater, such as salts. One of the current challenges is to use the AGS process to treat high salinity wastewater, commonly produced by agro-food and chemical industries. The main objective of this study was to screen for EPS-producing bacteria bacteria in an AGS reactor treating synthetic saline wastewater contaminated with a toxic compound. Several bacterial isolates were obtained from the reactor biomass. Genomic DNA was extracted and isolates (30) were grouped according to species similarity, based on RAPD profiles. Isolates displaying unique profiles (15) were subsequently identified by 16S rRNA gene sequencing analysis. Bacteria highly related to Pseudomonas, Aeromonas, Stenotrophomonas, Flavobacterium and Pseudoxanthomonas were obtained. Isolates SG4 (Stenotrophomonas) and FG10 (Flavobacterium) belong to bacterial genera associated to EPS production in granules. These were selected for growth and biofilm formation assays with increasing NaCl concentrations (0 to 35 g L-1). Both isolates were able to grow in the presence of 35 g NaCl L-1, despite at a lower growth rate. Although salt increase affected biofilm production, SG4 was the best biofilm producer. EPS production by SG4 in the presence of 10 and 20 g L-1 of NaCl was compared. EPS was extracted and the content in proteins, humic acids and carbohydrates was quantified. SG4 was able to produce more EPS in the presence of 10 g L-1 (123 mg g-1 VSS) compared to 20 g L-1 of NaCl (77.6 mg g-1 VSS). EPS-producing bacteria with ability to tolerate high salinity were retrieved from an AGS process treating synthetic wastewater. Further research is required to gain more knowledge on these bacteria and their importance for the robustness of a process treating saline wastewater.info:eu-repo/semantics/publishedVersio

Activity of nitrifying bacteria in aerobic granular sludge treating food industry wastewater

Aerobic Granular Sludge (AGS) is an innovative wastewater biological treatment, which uses less energy and space compared to other technological solutions. AGS presents a diverse microbial community responsible for the simultaneous removal of carbon and nutrients. These communities are protected by extracellular polymeric substances (EPS), which provide a compact structure to the granules. As a result, bacteria present in the aerobic granules are more resistant to variable wastewater composition, as commonly produced in food industry. In this study, carbon and NH4+ removal from a fish canning plant wastewater was evaluated using an AGS-SBR (sequential batch reactor), operated during 90 days. Chemical oxygen demand (COD) at the outlet was below the discharge limit of 125 mg O2 L-1 throughout the operation. Nitrification occurred during the first 23 days of operation. Between days 24 and 60, nitrification was completely inhibited, without ammonium removal from the wastewater. Nitrifying bacteria recovered their activity right after a decrease in the wastewater organic load, showing that the inhibition of the nitrification process was reversible. This study will contribute to our knowledge on the application of the AGS process to food industry wastewater treatment.N/