Ana C. Freitas

Olive oil mill wastewaters before and after treatment: a critical review from the ecotoxicological point of view

The olive oil mill wastewater (OMW) is a problematic and polluting effluent which may degrade the soil and water quality, with critical negative impacts on ecosystems functions and services provided. The main purpose of this review paper is presenting the state of the art of OMW treatments focusing on their efficiency to reduce OMW toxicity, and emphasizing the role of ecotoxicological tests on the evaluation of such efficiency before the up-scale of treatment methodologies being considered. In the majority of research works, the reduction of OMW toxicity is related to the degradation of phenolic compounds (considered as the main responsible for the toxic effects of OMW on seed germination, on bacteria, and on different species of soil and aquatic invertebrates) or the decrease of chemical oxygen demand content, which is not scientifically sound. Batteries of ecotoxicological tests are not applied before and after OMW treatments as they should be, thus leading to knowledge gaps in terms of accurate and real assessment of OMW toxicity. Although the toxicity of OMW is usually high, the evaluation of effects on sub-lethal endpoints, on individual and multispecies test systems, are currently lacking, and the real impacts yielded by its dilution, in freshwater trophic chains of receiving systems can not be assessed. As far as the terrestrial compartment is considered, ecotoxicological data available include tests only with plants and the evaluation of soil microbial parameters, reflecting concerns with the impacts on crops when using OMW for irrigation purposes. The evaluation of its ecotoxicity to other edaphic species were not performed giving rise to a completely lack of knowledge about the consequences of such practice on other soil functions. OMW production is a great environmental problem in Mediterranean countries; hence, engineers, chemists and ecotoxicologists should face this problem together to find an ecologically friend solution.

Marine biotechnology advances towards applications in new functional foods

The marine ecosystem is still an untapped reservoir of biologically active compounds, which have considerable potential to supply food ingredients towards development of new functional foods. With the goal of increasing the availability and chemical diversity of functional marine ingredients, much research has been developed using biotechnological tools to discover and produce new compounds. This review summarizes the advances in biotechnological tools for production of functional ingredients, including enzymes, for the food industry. Tools involving biotechnological processes (bioreactors, fermentations, bioprocessing) and those involving genetic research designated as molecular biotechnology are discussed highlighting how they can be used in the controlled manipulation and utilization of marine organisms as sources of food ingredients, as well as discussing the most relevant shortcomings towards applications in new functional foods.

Optical fiber biosensor coupled to chromatographic separation for screening of dopamine, norepinephrine and epinephrine in human urine and plasma

An optical fiber biosensor has been developed for the determination of catecholamines (dopamine, norepinephrine and epinephrine) based on the recognition capacity of the enzyme laccase. In this study, a glass tube constituted by a fused silica fiber coated with a film of polystyrene/divinylbenzene resin (PS/DVB) was used for catecholamines separation. Firstly, the analyzer was tested for calibration and its analytical performance for catecholamines detection was compared with a classical analytical method, namely high performance liquid chromatography-electrochemical detector (HPLC-ED). The developed analytical device shows a high potential for catecholamines quantification with a detection limit of 2.1, 2.6 and 3.4 pg mL(-1) for dopamine, norepinephrine and epinephrine, respectively. The analytical sensitivity, inferred from the slope of the calibration curves established for a range of concentrations between 5 and 125 pg mL(-1), was found to be 0.344, 0.252 and 0.140 dB/pg mL(-1) for dopamine, norepinephrine and epinephrine, respectively. Furthermore, catecholamines speciation with the PS/DVB fiber was completely achieved in 3 min. The analytical performance of the reported sensor was also evaluated and found adequate for catecholamines determination in human urine and plasma samples.

Biological treatment of the effluent from a bleached kraft pulp mill using basidiomycete and zygomycete fungi

Three white-rot fungi (Pleurotus sajor caju, Trametes versicolor and Phanerochaete chrysosporium) and one soft-rot fungi (Rhizopus oryzae) species confirmed their potential for future applications in the biological treatment of effluents derived from the secondary treatment of a bleached kraft pulp mill processing Eucalyptus globulus. Among the four species P. sajor caju and R. oryzae were the most effective in the biodegradation of organic compounds present in the effluent, being responsible for the reduction of relative absorbance (25-46% at 250 nm and 72-74% at 465 nm) and of chemical oxygen demand levels (74 to 81%) after 10 days of incubation. Laccase (Lac), lignin (Lip) and manganese peroxidases (MnP) expression varied among fungal species, where Lac and LiP activities were correlated with the degradation of organic compounds in the effluent treated with P. sajor caju. The first two axes of a principal component analysis explained 88.9% of the total variation among sub-samples treated with the four fungus species, after different incubation periods. All the variables measured contributed positively to the first component except for the MnP enzyme activity which was the only variable contributing negatively to the first component. Absorbances at 465 nm, LiP and Lac enzyme activities were the variables with more weight on the second component. P. sajor caju revealed to be the only species able to perform the biological treatment without promoting an increment in the toxicity of the effluent to the Vibrio fischeri, as it was assessed by the Microtox assay. The opposite was recorded for the treatments with the other three species of fungus. EC(50-5 min) values ranging between 28 and 57% (effluent concentrations) were recorded even after 10 to 13 days of treatment with P. chrysosporium, R. oryzae or with T. versicolor.

Toxicity and organic content characterization of olive oil mill wastewater undergoing a sequential treatment with fungi and photo-Fenton oxidation.

Olive oil mill wastewater (OOMW) is responsible for serious environmental problems. In this study, the efficiency of two treatments involving fungi and photo-Fenton oxidation, sequentially applied to OOMW was analyzed for organic compounds degradation and toxicity mitigation. The treatment with fungi (especially Pleurotus sajor caju) of diluted OOMW samples promoted a reduction of their acute toxicity to Daphnia longispina. Although this fungi species have not induced significant color reduction it was responsible for 72,91 and 77% reductions in chemical oxygen demand (COD), total phenolic and organic compound contents. After biological treatment, photo-Fenton oxidation seemed to be an interesting solution, especially for color reduction. However, the OOMWs remained highly toxic after photo-Fenton oxidation. Considering the second sequence of treatments, namely photo-Fenton oxidation followed by biological treatment, the former revealed, once more, a great potential because it can be applied to non-diluted OOMW, with significant reductions in COD (53-76%), total phenolic content (81-92%) and organic compounds content (100%). Despite fungal species still have demonstrated a high capacity for bioaccumulation of organic compounds, resulting from photo-Fenton oxidation, the biological treatment did not cause substantial benefits in terms of COD, total phenolic content and toxicity reduction.

Chemical composition of red, brown and green macroalgae from Buarcos bay in Central West Coast of Portugal.

Six representative edible seaweeds from the Central West Portuguese Coast, including the less studied Osmundea pinnatifida, were harvested from Buarcos bay, Portugal and their chemical characterization determined. Protein content, total sugar and fat contents ranged between 14.4% and 23.8%, 32.4% and 49.3% and 0.6-3.6%. Highest total phenolic content was observed in Codium tomentosum followed by Sargassum muticum and O. pinnatifida. Fatty acid (FA) composition covered the branched chain C13ai to C22:5 n3 with variable content in n6 and n3 FA; low n6:n3 ratios were observed in O. pinnatifida, Grateloupia turuturu and C. tomentosum. Some seaweed species may be seen as good sources of Ca, K, Mg and Fe, corroborating their good nutritional value. According to FTIR-ATR spectra, G. turuturu was associated with carrageenan seaweed producers whereas Gracilaria gracilis and O. pinnatifida were mostly agar producers. In the brown algae, S. muticum and Saccorhiza polyschides, alginates and fucoidans were the main polysaccharides found.

Degradation of phenols in olive oil mill wastewater by biological, enzymatic, and photo-Fenton oxidation.

Background, aim, and scopeOlive oil mill wastewater (OOMW) environmental impacts minimization have been attempted by developing more effective processes, but no chemical or biological treatments were found to be totally effective to mitigate their impact on receiving systems. This work is the first that reports simultaneously the efficiency of three different approaches: biological treatment by two fungal species (Trametes versicolor or Pleurotus sajor caju), enzymatic treatment by laccase, and chemical treatment by photo-Fenton oxidation on phenols removal.Materials and methodsThose treatments were performed on OOMW with or without phenol supplement (p-coumaric, vanillin, guaiacol, vanillic acid, or tyrosol). OOMW samples resulted from treatments were extracted for phenols using liquid–liquid extraction and analyzed by gas chromatography coupled to mass spectrometry.ResultsTreatment with T. versicolor or P. sajor caju were able to remove between 22% and 74% and between 8% and 76% of phenols, respectively. Treatment by laccase was able to reduce 4% to 70% of phenols whereas treatment by photo-Fenton oxidation was responsible for 100% phenols reduction.DiscussionRange of phenol degradation was equivalent between T. versicolor, P. sajor caju and laccase for p-coumaric, guaiacol, caffeic acid, and tyrosol in supplemented OOMW, which enhances this enzyme role in the biological treatment promoted by these two species.ConclusionsPhenols were removed more efficiently by photo-Fenton treatment than by biological or enzymatic treatments.Recommendations and perspectivesUse of fungi, laccase, or photo-Fenton presents great potential for removing phenols from OOMW. This should be further assessed by increasing the application scale and the reactor configurations effect on the performance, besides a toxicity evaluation of treated wastewater in comparison to raw wastewater.

High performance liquid chromatography coupled to an optical fiber detector coated with laccase for screening catecholamines in plasma and urine

An analytical method based on separation by high performance liquid chromatography (HPLC) and detection by optical fiber (OF) coated with an enzyme (laccase), has been developed for separation and quantification of catecholamines, namely epinephrine, dopamine and norepinephrine. The application of OF as a detector in this analytical system relies on the variation of the reflected optical power detected when the catecholamines eluted from the HPLC column act as the substrate of the laccase immobilized on a tip of a single-mode OF. The developed method shows a high linearity in a range between 5 and 125 pg/mL and detection limits of 3.5, 2.9 and 3.3 pg/mL for epinephrine, dopamine and norepinephrine, respectively. The analytical performance of the proposed method was compared with a classical analytical method, namely high performance liquid chromatography-electrochemical detector (HPLC-ED) regarding catecholamines detection, showing great analytical advantages such as low cost of equipment. Additionally, the proposed method was applied to catecholamines determination in actual samples of plasma and human urine.

Impact of enzyme- and ultrasound-assisted extraction methods on biological properties of red, brown, and green seaweeds from the central west coast of Portugal.

Seaweeds are an excellent source of bioactive compounds, and therefore the use of sustainable and food compatible extraction methods such as enzyme-assisted (EAE) and ultrasound-assisted extraction were applied on Sargassum muticum, Osmundea pinnatifida, and Codium tomentosum. Extracts were evaluated for proximate characterization and biological properties. Higher extraction yields were observed for C. tomentosum EAE (48-62%; p < 0.05 for Cellulase and Viscozyme), followed by O. pinnatifida (49-55%; p < 0.05 except Alcalase) and S. muticum (26-31%; p < 0.05). S. muticum extracts presented the highest nitrogen (25 ± 2 mg/glyoph extract) and total phenolics (261 ± 37 μgcatechol equiv/glyoph extract) contents, whereas higher sugars (78 ± 14 mgglucose equiv/glyoph extract) including sulfated polysaccharide (44 ± 8 mgNa2SO4 acid/glyoph extract) contents characterized O. pinnatifida extracts. A higher effect on hydroxyl-radical scavenging activity (35-50%) was observed for all extracts, whereas S. muticum Alcalase and C. tomentosum Cellulase extracts exhibited higher prebiotic activity than fructooligosaccharides. O. pinnatifida and C. tomentosum EAE showed inhibitory potential against α-glucosidase (38-49%).

Disposable immunosensors for C-reactive protein based on carbon nanotubes field effect transistors.

Label-free immunosensors based on single-walled carbon nanotubes field effect transistor (NTFET) devices were developed for the detection of C-reactive protein (CRP) which is currently the best validated inflammatory biomarker associated with cardiovascular diseases. The immunoreaction principle consists in the direct adsorption of CRP specific antibodies (anti-CRP) to single-walled carbon nanotubes (SWCNTs) networks. Such anti-CRP are the molecular receptors of CRP antigens which, in turn, can be detected by the developed NTFET devices in a linear dynamic range of 10(-4)-10(2) μg/mL. Thus, typical values of CRP (in blood serum) for healthy persons (<1 μg/mL), and higher levels (>5 μg/mL) corresponding to pathological states, can be both detected with the NTFET immunosensors, becoming an advantageous alternative as the basis for the development of analytical instrumentation for assessment of risk of occurrence of cardiovascular diseases. A log-log linear regression was applied to the experimental data with a correlation coefficient of r=0.9962 (p<0.001), and there is no statistical difference (from ANOVA) between individual NTFET devices (p=0.9582), demonstrating acceptable reproducibility. According to the experimental results, the estimate of detection limit (LOD, 10(-4)μg/mL) is 3-fold lower than that of some conventional immunoassay techniques for blood serum (e.g., LOD of 0.2 μg/mL for high-sensitivity enzyme-linked immunosorbent assay), and the dynamic range (10(-4)-10(2)μg/mL) is about 6-fold higher. Furthermore, this simple and low-cost methodology allows the use of sample volumes as low as 1 μL for the label-free detection of CRP.