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- Evaluation of different substrates in constructed wetlands planted with Typha latifolia for the treatment of tannery wastewaterPublication . Calheiros, Cristina S. C.; Rangel, António O. S. S.; Castro, Paula M. L.
- Phytoremediation as a biotechnological tool for environmental restorationPublication . Marques, Ana P. G. C.; Rangel, António O. S. S.; Calheiros, Cristina S. C.; Oliveira, Rui S.; Franco, Albina R.; Vosatka, Miroslav; Dodd, John C.
- Toxicity assessment of high salinity tannery wastewater for the treatment in constructed wetlands.Publication . Silva, Gabriela; Calheiros, Cristina S.C.; Quitério, Paula V.B.; Crispim, Luís F.C.; Brixc, Hans; Moura, Sandra G.C.; Castro, Paula M.L.
- Evaluation of different substrates to support the growth of Typha latifolia in constructed wetlands treating tannery wastewater over long-term operationPublication . Calheiros, Cristina S. C.; Rangel, António O. S. S.; Castro, Paula M. L.The aim of this study was to investigate the performance of horizontal subsurface flow constructed wetlands planted with Typha latifolia treating tannery wastewater under long-term operation. Two expanded clay aggregates (Filtralite® MR3–8-FMR and Filtralite® NR3–8-FNR) and a fine gravel-FG were used as substrate for the constructed wetland units plus one unit with FMR was left as an unvegetated control. The systems were subject to three hydraulic loadings, 18,8 and 6cm d⁻¹, and to periods of interruption in the feed. The relationship between the substrate, plant development and removal efficiency, especially of organic matter, was investigated. Organic loadings up to 1800 kg BOD5 ha⁻¹ d⁻¹ and 3849 kg COD ha⁻¹ d⁻¹ were applied leading to mass removals of up to 652 kg BOD₅ ha⁻¹ d⁻¹ and 1869 kg COD ha⁻¹ d⁻¹, respectively. The three different substrates were adequate for the establishment of T. latifolia, although the clay aggregates allowed for higher plant propagation levels. The units with FNR and FMR achieved significantly higher COD and BOD₅ removal when compared to the FG and to the unplanted units. The systems proved to be tolerant to high organic loadings and to interruptions in feed suggesting this technology as a viable option for the biological treatment of tannery wastewater.
- Use of different types of plants for the uptake of contaminantsPublication . Calheiros, Cristina S.C.; Marques, Ana P. G. C.; Oliveira, Rui S.; Rangel, António O. S. S.; Castro, Paula M. L.
- Long term performance of constructed wetlands for tannery wastewater treatmentPublication . Calheiros, Cristina S. C.; Duque, Anouk F.; Moura, Alexandra; Henriques, Isabel S.; Correia, António; Rangel, António O. S. S.; Castro, Paula M. L.
- The effects of tannery wastewater on the development of different plant species and chromium accumulation in phragmites australisPublication . Calheiros, Cristina S. C.; Rangel, António O. S. S.; Castro, Paula M. L.Toxicity tests were performed to assess the effect of tannery wastewater with different treatment levels on two wetland plants, Phragmites australis and Typha latifolia, which are frequently used in constructed wetlands (CWs) for water treatment, and thus deepen the knowledge on their capacity to withstand the application of industrial wastewater. Trifolium pratense, a plant generally used as an indicator in toxicity tests, was included as a control. End points measured were germination percentage, shoot length, root elongation, and biomass growth of the plants. When tannery effluent, with a low treatment level, was supplied to the wetland plants germination occurred even at effluent concentrations of 100%, whereas germination of T. pratense was completely inhibited, almost invariably, at effluent concentration of 50%. Higher germination levels were achieved when the plants were exposed to effluent originating from the outlet of constructed wetland pilot units, allowing germination of all tested plants, indicating a significant decrease in its toxicity level. Experiments conducted with the same plants using different growing substrata as the germination matrix, namely expanded clay aggregates (Filtralite® MR3-8 and Filtralite® NR3-8) and two types of sand (fine gravel and standard sand) have shown that higher germination levels were achieved in standard sand and that P. australis was the plant species showing higher germination in all cases, reinforcing the robustness of this plant to environmental stress. The phytoextraction potential of P. australis, was evaluated by subjecting the plant to tannery wastewater supplemented with 50 and 150 mg Cr/L. After 6 weeks of exposure, levels up to 4825, 883, and 627 mg Cr/kg were found in the rhizome, shoot, and leaves, respectively, although phytotoxic signs in the plant were evident. This plant might not be considered a chromium hyperacumulator, but the potential to extract and accumulate this metal on its rhizomes is high.
- Isolation and characterization of polymeric galloyl-ester- degrading bacteria from a tannery discharge placePublication . Franco, A. R.; Calheiros, C. S. C.; Pacheco, C. C.; Marco, P. De; Manaia, C. M.The culturable bacteria colonizing the rhizosphere of plants growing in the area of discharge of a tannery effluent were characterized. Relative proportions of aerobic, denitrifying, and sulfate-reducing bacteria were determined in the rhizosphere of Typha latifolia, Canna indica, and Phragmites australis. Aerobic bacteria were observed to be the most abundant group in the rhizosphere, and plant type did not seem to influence the abundance of the bacterial types analyzed. To isolate bacteria able to degrade polyphenols used in the tannery industry, enrichments were conducted under different conditions. Bacterial cultures were enriched with individual polyphenols (tannins Tara, Quebracho, or Mimosa) or with an undefined mixture of tannins present in the tannery effluent as carbon source. Cultures enriched with the effluent or Tara tannin were able to degrade tannic acid. Six bacterial isolates purified from these mixed cultures were able to use tannic acid as a sole carbon source in axenic culture. On the basis of 16S ribosomal DNA sequence analysis, these isolates were closely related to organisms belonging to the taxa Serratia, Stenotrophomonas maltophilia, Klebsiella oxytoca, Herbaspirillum chlorophenolicum, and Pseudomonas putida.
- Treatment of tannery wastewater in a constructed wetlands operating in series with different plant speciesPublication . Calheiros, Cristina S. C.; Rangel, António O.S.S.; Castro, Paula M.L.The treatment of tannery wastewater has been a very important issue for pollution control in leather producing countries due to its high pollutant content. Biological processes offer a natural way of treating wastewaters, when compared to more aggressive types of treatment. Constructed wetlands can be an alternative to more conventional biological treatment systems. The species Phragmites australis, Typha spp, Scirpus spp. and Phalaris arundinacea are some of the plants frequently used in subsurface flow constructed wetlands. The present study aimed at assessing the performance of constructed wetland systems operating in series for the treatment of wastewater derived from a tannery plant. Pilot units were operated with horizontal subsurface flow and planted with Typha latifolia and Phragmites australis in an expanded clay matrix. They were subject to two different hydraulic loadings: 180mm/d and 60 mm/d. For an hydraulic loading of 180 mm/d, maximum removal efficiencies of 2100 KgCOD/had (48%) were achieved for unit 1 and 1500 KgCOD/had (33%) for unit 2. For an hydraulic loading of 60 mm/d, maximum removal efficiencies of 360 KgCOD/had (66%) were achieved for unit 1 and of 250 KgCOD/had (60%) for unit 2. No significant differences in performance were found between units with different plant species.
- Biotreatment of tannery wastes with a PhytoSystemPublication . Calheiros, Cristina S. C.; Rangel, António O. S. S.; Castro, Paula M. L.
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