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- Sulphate reducing bacteria for metals bioremediationPublication . Duarte, José Cardoso; Sàágua, M. C.; Paixão, Susana M.; Baeta-Hall, Lina; Costa, Clara
- New approaches to olive mill wastes bioremediationPublication . Duarte, José Cardoso; Pires, Susana; Paixão, Susana M.; Sáágua, M. C.Remediation of olive mill wastewater (OMW) is an important issue associated with olive-oil manufacturing, a widespread activity in the Mediterranean area. This high organic loading effluent contains water, organic acids, high-molecular-weight polyphenols such as tannins, antocyanins and catechins, which are considered to be responsible for its brownish black colour and ecotoxic properties. The composition of OMWs is highly variable with respect to each individual component, depending on the process conditions and on the agricultural specificities. Thus, different approaches are applicable concerning to OMW treatment and valorisation , considering the specificities of its production and in particular the oil extraction process. Besides there are several physical, physico-chemical, biological and combined processes to OMW detoxification, each may represent an opportunity for a specific condition. It is important to explore new possibilities that are both environmentally sustainable and economically viable. Under the biological processes the use of fungi and in particular white-rot fungi present a potential interesting alternative for depollution and biological chemicals production or for protein production for feeding. In this aspect we have been testing the ability of a “white-rot” fungus, Bjerkandera paranensis, to use undiluted OMW from a two phase process mill. A chronic ecotoxicity test (Vibrio fisheri growth inhibition test) demonstrated that the growth of this fungus contributed for a significant decrease of the OMW ecotoxicity and demonstrating the potential for further studies with this strain for an alternative biological route to OMW treatment and valorization.
- Bioethanol production from agricultural wastesPublication . Duarte, José Cardoso; Sàágua, M. C.; Baeta-Hall, Lina; Correia, Anabela; Ribeiro, Belina; Lourenço, V.; Pereira, J.; Paixão, Susana M.In this study, different strains of Saccharomyces cerevisiae have been screened for the ability of bioethanol production. Yeasts were grown in synthetic liquid medium containing two different substrates: sucrose at different concentrations (10 to 400g/l) and cane molasses (120g/l of sucrose). The screening was made in batch regime and the growth rates, ethanol and biomass productions were determined. The results indicate a flocculent yeast strain – F as the more suitable microorganism to produce ethanol, presenting the highest value of growth rate (0.49h-1) and ethanol yield (0.40g/g) with 120g/l of sucrose concentration. In addition, ethanol production was also studied in a continuous process with the selected yeast strain (F strain), with sucrose and cane molasses (120g/l) at different dilution rates (0.05-0.5 h-1). Data showed that when dilution rate raised to 0.4h-1 the highest sugar conversion, 85% and 90%, were achieved with an ethanol production of 40.5g/l and 50.8g/l for sucrose and molasses, respectively.
- Detoxification of olive mill wastewaters using a packed-bed batch reactorPublication . Paixão, Susana M.; Sàágua, M. C.; Baeta-Hall, Lina; Correia, Anabela; Ribeiro, Belina; Duarte, José CardosoOlive oil production is a traditional agricultural industry in Mediterranean countries and Portugal is one of the ten major producers. This industry generates an effluent, olive mill wastewater (OMW), which does not undergo any treatment and, usually, is stored in evaporation lagoons or spread on the land. Disposal of olive oil mill wastewaters is a serious environmental problem due to its high organic loading, presence of polyphenols and tannins, high content in suspended solids and acidity, which contributes to its ecotoxicity. In this work, a biological treatment system: a packed-bed batch reactor was applied to a Portuguese OMW using its autochthon microbial population as inoculum. Thus, the biodegradation potential of OMW’ microrganisms naturally present in these wastewaters was assessed monitoring several physico-chemical parameters along the process. Ecotoxicity tests (Pseudomonas putida growth inhibition test and Vibrio fisheri growth inhibition test) were carried out to follow the detoxification capacity of the system as well as its potential to be used in the treatment of this type of agroindustrial effluent. In this aerobic treatment, an active microbial community with high degradation ability for the OMW organic load was detected, accounting for 80%, 71% and 61% removal of COD, TSS and phenols, respectively. In addition, a significant decrease in the chronic toxicity of the treated OMW to both bacteria, V. fisheri (62.8%) and P. putida (64.3%), was also observed after 140 days of treatment, highlighting the detoxification potential of the system studied
- Sulphate-reducing bacteria from mining environments for metals bioremediationPublication . Paixão, Susana M.; Baeta-Hall, Lina; Barreiros, M. Alexandra; Anselmo, Ana; Duarte, José Cardoso; Sàágua, M. C.Toxic heavy metals and metalloids constitute an international pollution problem that not only impacts public health but also is of environmental and economic importance. Several conventional treatment technologies for removing metals are available. These techniques, based on chemical methods of neutralisation and precipitation, even though quick and effective, present several disadvantages, such as the need for building additional treatment plants, the high cost of the chemical reagents used and the generation of an important volume of sludge which need further treatment. Prokaryotes with physiological activity of sulphate reduction are found in several environmental sites containing metals and these microorganisms have developed several different strategies for detoxification and resistance to toxic elements that are potentially useful for bioremediation. Since sulphate-reducing bacteria (SRB) are found in a large number of contaminated sites containing toxic metals, it is apparent that these organisms have a functional defence system that enables them to persist and even grow under metal stress. The enzymatic metal reduction by SRB offers an alternative to chemical processes to remediate environments containing metals. Acid mine drainage (AMD) is one of the most important source of heavy metal environmental pollution. AMD is characterised by its high acidity (≤3), high concentration of metals (e.g. Cu, Fe, Zn, A1, Pb, As and Cd) and high concentration of dissolved sulphates (≥3000 ppm). Taking advantage of the fact that SRB are present in these mining environments, several samples were collected from S. Domingos abandoned mine (Portugal) and screened for their ability to sulphate reduction, metal resistance and bioremediation. In this context, the most promising consortium of SRB (SRB no. 6) was grown in matrices column reactors, using lactate and ethanol as an electron donor source for the production of H2S from sulphates. Metal resistance was tested in batch using different metal concentration for Cu, Zn and Fe. The results obtained for this SRB inoculum, showed 97% of sulphate reduction (3750—350 mg/l) in the reactors, and a metal tolerance to Fe, Cu and Zn, at concentrations until 260 mg/l, 40 mg/l and 80 mg/l, respectively, in the batch assays, being observed a sulphate reduction (2000—0 mg/l) and a significant metals concentration decrease in the growth medium. Further studies are being carried out to apply this mining inoculum for the design of reactors for AMD bioremediation
- Olive Mill wastewater bioremediation towards detoxificationPublication . Paixão, Susana M.; Ribeiro, Belina; Sàágua, M. C.; Baeta-Hall, Lina; Correia, Anabela; Duarte, José CardosoOlive oil production is a traditional agricultural industry in Mediterranean countries and Portugal is one of the ten major producers. This industry generates an effluent, olive mill wastewater (OMW), which does not undergo any treatment and, usually, is stored in evaporation lagoons or spread on the land. Disposal of olive oil mill wastewaters is a serious environmental problem due to its high organic loading, presence of polyphenols and tannins, high content in suspended solids and acidity, which contributes to its ecotoxicity. In this work it was intended to study the biodegradation of OMW by microrganisms naturally present in these wastewaters. Thus, an aerobic biological treatment system: a packed-bed batch reactor was applied to a OMW from a mill on northern of Portugal, exploring its autochthon microbial population as inoculum. The biodegradation ability of OMW by microrganisms naturally present in these wastewaters was assessed, by following the evolution of the process and monitoring several of its physico-chemical parameters. Furthermore, an ecotoxicological evaluation, using chronic toxicity tests (Pseudomonas putida growth inhibition test and Vibrio fischeri growth inhibition test), was performed to follow the detoxification capacity of the system as well as its potential to be used in the treatment of this type of agroindustrial effluent.
- Kinetics of a packed-bed bacth reactor for the treatment of olive oil wastewaters from a Portuguese millPublication . Ribeiro, Belina; Correia, Anabela; Paixão, Susana M.; Baeta-Hall, Lina; Sàágua, M. C.; Duarte, José CardosoOlive oil production is a traditional agricultural industry in Mediterranean countries and Portugal is one of the ten major producers. This industry generates an effluent, olive mill wastewater. This effluent does not undergo any treatment and is usually stored in evaporation lagoons or spread on the land. This can have a negative impact in the environment since this effluent has a high level of organic matter leading to a high chemical oxygen demand. In addition it has also a high content of polyphenols that contributes to the ecotoxicity of this effluent.Different techniques for the treatment of these wastewaters have been studied. In this work a 60 litre vessel was filled with a packaging of plastic material consisting of a cubic geometry (Biological Carrier Media from Rauschert). The non-inoculated reactor was filled with effluent from an olive mill farm (from Alfândega da Fé, Trás-os-Montes) and the effluent was re-circulated daily for homogeneity. COD, colour, nitrogen, solids and phosphorous were measured to follow the evolution of the system. Microbial composition and polyphenols were also evaluated. As an indicator of the microbial activity in the reactor, lipase activities were measured. Ecotoxicity tests were carried out to follow the detoxification capacity of the system as well as its potential for using in the treatment of this type of agroindustrial effluent.
- Functional screening of a metagenomic library obtained from soils water of S. Domingos's minePublication . Pereira, Paula Sá; Baeta-Hall, Lina; Sàágua, M. C.; Paixão, Susana M.; Duarte, José Cardoso; Anselmo, Ana
- Olive Mill wastewater bioremediation by Bjerkandera paranensis: a sustainability and technological evaluationPublication . Duarte, José Cardoso; Pires, Susana; Paixão, Susana M.; Sàágua, M. C.Remediation of olive mill wastewater (OMW) is an important issue associated with olive-oil manufacturing, a widespread activity in the Mediterranean area. This high organic loading effluent contains water, organic acids, high-molecular-weight polyphenols such as tannins, antocyanins and catechins, which are considered to be responsible for its brownish black colour and toxic properties. The composition of OMWs is highly variable with respect to each individual component, depending on the process conditions and on the agricultural specificities. In this work, the ability of a “white-rot” fungus, Bjerkandera paranensis, to use undiluted OMW from a two phase process mill (COD = 11.1 gl-1; Phenol Content = 3.9 gl-1; ColourAbs395nm = 7.8) as a substrate was studied. The biodegradation potential of B. paranensis was assessed monitoring several physico-chemical parameters. A chronic ecotoxicity test (Vibrio fisheri growth inhibition test) was carried out to follow the detoxification ability of this fungus. In work, the results demonstrate that OMW was a suitable medium for cultivation of B. paranensis, with corresponding changes in the physico-chemical properties of the OMW. The results showed that B. paranensis removed 93% phenols and 54% COD from the culture medium within 21 days of treatment. In addition, the IC50s values obtained for the different treated samples showed a significant decrease in the effluent chronic toxicity to V. fischeri when the OMW pH was adjusted to 6.0 prior to the treatment (71.8 %), highlighting the OMW detoxification capacity of B. paranensis
- Metals recovery from mine lead concentrates:screening of bioleaching microbial communitiesPublication . Duarte, José Cardoso; Sàágua, M. C.; Paixão, Susana M.; Baeta-Hall, Lina; Nogueira, Carlos; Pereira, Paula Sá; Anselmo, Ana