The role of Arthrobacter viscosus in the removal of Pb(II) from aqueous solutions

The aim of this paper was to establish the optimum parameters for the biosorption of Pb(II) by dead and living Arthrobacter viscosus biomass from aqueous solution. It was found that at an initial pH of 4 and 26 °C, the dead biomass was able to remove 97% of 100 mg/L Pb(II), while the living biomass removed 96% of 100 mg/L Pb(II) at an initial pH of 6 and 28 ± 2 °C. The results were modeled using various kinetic and isotherm models so as to find out the mechanism of Pb(II) removal by A. viscosus. The modeling results indicated that Pb(II) biosorption by A. viscosus was based on a chemical reaction and that sorption occurred at the functional groups on the surface of the biomass. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy coupled with energy dispersive X-ray microanalysis (SEM-EDX) analyses confirmed these findings. The suitability of living biomass as biosorbent in the form of a biofilm immobilized on star-shaped polyethylene supports was also demonstrated. The results suggest that the use of dead and living A. viscosus for the removal of Pb(II) from aqueous solutions is an effective alternative, considering that up to now it has only been used in the form of biofilms supported on different zeolites.This paper was elaborated with the support of: BRAIN ‘Doctoral scholarships as an investment in intelligence’ project ID 6681, financed by the European Social Found and Romanian Government and Romanian National Authority for Scientific Research, CNCS – UEFISCDI grant PN-II-IDPCE- 2011-3-0559, Contract 265/2011. It was also supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and Bio- TecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte 2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Biosorption potential of dead and living Arthrobacter viscosus biomass in the removal of Cr(VI): Batch and column studies

Batch experiments were conducted with dead and living Arthrobacter viscosus biomass for Cr(VI) removal from aqueous solution. Both dead and living cells successfully reduced Cr(VI) to Cr(III) from aqueous solution in highly acidic pH (pH 1 and 2) with an efficiency of 100% for aqueous solutions having the initial concentrations of Cr(VI) lower than 100 mg/L. Langmuir isotherm and kinetic models based on reduction could simulate chromium removal at 5 and 8 g/L biosorbent dosages and in highly acidic pH conditions (pH = 1-2). Further, the potential use of the Arthrobacter viscosus biomass was examined in an open system, where Cr(VI) removal from aqueous solution was performed by a bacterial biofilm supported on a new type of polyethylene supports. The experiment showed a favorable uptake of chromium ions bound to the biomass, of 20.37 mg/g, with high potential for scaling up. This study showed that the reduction of toxic Cr(VI) to the less toxic Cr(III) by Arthrobacter viscosus, in batch and continuous modes is an efficient and promising technique for wastewaters polluted with chromium.This paper was elaborated with the support of BRAIN project Doctoral scholarships as an investment in intelligence - ID 6681, financed by the European Social Found and Romanian Government and with the support of a grant of the Romanian National Authority for Scientific Research, CNCS – UEFISCDI, project number PN-II-ID-PCE-2011-3-0559, Contract 265/2011. H. Figueiredo is thankful to “FCT – Fundação para a Ciência e Tecnologia” for the financial support through the concession of PhD grant SFRH/BD/28201/2006.info:eu-repo/semantics/publishedVersio

Experimental analysis and mathematical prediction of Cd(II) removal by biosorption using support vector machines and genetic algorithms

We investigated the bioremoval of Cd(II) in batch mode, using dead and living biomass of Trichoderma viride. Kinetic studies revealed three distinct stages of the biosorption process. The pseudo-second order model and the Langmuir model described well the kinetics and equilibrium of the biosorption process, with a determination coefficient, R2 > 0.99. The value of the mean free energy of adsorption, E, is less than 16 kJ/mol at 25°C, suggesting that, at low temperature, the dominant process involved in Cd(II) biosorption by dead T. viride is the chemical ion-exchange. With the temperature increasing to 4050°C, E values are above 16 kJ/mol, showing that the particle diffusion mechanism could play an important role in Cd(II) biosorption. The studies on T. viride growth in Cd(II) solutions and its bioaccumulation performance showed that the living biomass was able to bioaccumulate 100% Cd(II) from a 50 mg/L solution at pH 6.0. The influence of pH, biomass dosage, metal concentration, contact time and temperature on the bioremoval efficiency was evaluated to further assess the biosorption capability of the dead biosorbent. These complex influences were correlated by means of a modeling procedure consisting in data driven approach in which the principles of artificial intelligence were applied with the help of support vector machines (SVM), combined with genetic algorithms (GA). According to our data, the optimal working conditions for the removal of 98.91% Cd(II) by T. viride were found for an aqueous solution containing 26.11 mg/L Cd(II) as follows: pH 6.0, contact time of 3833 min, 8 g/L biosorbent, temperature 46.5°C. The complete characterization of bioremoval parameters indicates that T. viride is an excellent material to treat wastewater containing low concentrations of metal

Bioremediation: an overview on current practices, advances, and new perspectives in environmental pollution treatment

[Excerpt] Environmental pollution generated the need to search for new environmentally friendly, low-cost, and more efficient environmental clean-up techniques for its removal or reduction. Bioremediation, a branch of environmental biotechnology, is nowadays considered as one of the most promising alternatives. This technology uses the amazing ability of microorganisms or plants to accumulate, detoxify, degrade, or remove environmental contaminants. Bioremediation provides the transformation and/or even removal of organic and inorganic pollutants, even when they are present at low concentration. Continuous efforts are still made to understand the mechanisms by which microorganisms and plants remove or transform environmental pollutants. Thus, the purpose of this special issue was to explore different visions on bioremediation, while addressing recent advances and new ideas in the perspective of efficient process scale-up in view of application at larger scales. Authors’ contributions cover various topics with a range of papers including original research and review articles spanning studies in remediation of different environments which outline new findings in the biotechnology field. This special issue contains five papers including one review article and four original research articles. A brief description of these five manuscripts is detailed below. [...]We would like to extend our gratitude to all the authors who submitted their work for consideration in our special issue and to reviewers for their critical feedback. Contributions of Raluca Maria Hlihor and Maria Gavrilescu to this special issue were supported by a grant of the Romanian National Authority for Scientific Research,CNCS-UEFISCDI (Project no. PN-III-P4-ID-PCE-2016-0683, Contract no. 65/2017). Teresa Tavares’ contribution is supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the research project PTDC/AAG-TEC/5269/2014, the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684), and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of NORTE 2020 (Programa Operacional Regional do Norte).info:eu-repo/semantics/publishedVersio

Recent advances in biosorption of heavy metals: support tools for biosorption equilibrium, kinetics and mechanism

Heavy metals are increasingly present in industrial wastes and effluents, which can generate serious concerns for environmental quality and human health. Consequently, there is a continuous expansion of researches for new approaches and developments to guarantee environmental cleaning-up. Although there are some physico-chemical established methods for the removal of heavy metals from various environmental compartments, biosorption gains further confidence as a reliable alternative compared to classical technologies, which are expensive and sometimes unreliable. This paper aims to analyze the biosorption as a biotechnological strategy for the decontamination of aqueous effluents containing heavy metal ions, in terms of its potential for metal immobilization and uptake. The paper also focuses on the most important parameters affecting the removal of heavy metals by various categories of biosorbents both living and non-living forms of biomass and provides new alternatives for modeling and optimization of process equilibrium and kinetics. A special attention was paid to biosorption mechanism, as a factual challenge for process optimization and scale-up. The potential benefits and problems associated to metal removal by biosorption are highlighted.Roumanian National Authority for Scientific Research, CNCS – UEFISCDI, project number PN-II-ID-PCE-2011-3-0559”, Contract 265/2011

Monitoring pesticides degradation in apple fruits and potential effects of residues on human health

The behaviour of 12 pesticides used in the treatment of a variety of apples in areal conditions from a Romanian orchard is studied, considering recommended dosages, different stages of fruit development, environmental and atmospheric conditions. Five treatments were applied in recommended dosage considering the phenological growth phases, at 23 days intervals between treatments. Pesticides degraded quickly in apples during the first days, when 30–50% from the initial concentration is lost. Pesticides residues at harvesting were below the Maximum Residue Level (MRL) in European Union, excepting tebuconazole and chlorothalonil. The estimated lifetime exposure dose was calculated based on pesticide concentrations in apples at harvesting, and average fruit consumption of 197.08 g/ person/day in EU-27 during 2011. These doses for adults and children were below the reference dose (RfD) for each pesticide, suggesting a negligible risks for consumers. Hazard indices below 1 demonstrate that the studied pesticides do not generate health risks to humans. First published online: 18 Mar 201

Bioremediation of Cr(VI) polluted wastewaters by sorption on heat inactivated Saccharomyces cerevisiae biomass

The potential of heat inactivated Saccharomyces cerevisiae in the bioremoval and reduction of Cr (VI) ions from wastewaters was evaluated in terms of metal uptake in time and at equilibrium, and biosorption efficiency, by varying pH, biosorbent doses, contact time and temperature, in batch mode. During the sorption process, the heat inactivated biomass of the yeast Saccharomyces cerevisiae is capable of reducing Cr(VI) to Cr(III). Different kinetic models based on adsorption and reduction are used to represent the kinetic data of Cr(VI) bioremoval by S. cerevisiae, in explaining the biosorption mechanism of heavy metals and potential rate-controlling steps, in the perspective of full-scale process design. The results indicated some potential differences in the Cr(VI) removal mechanism at different experimental conditions. FTIR and SEM analysis were performed as well as to elucidate the mechanism of metal bioremoval by S. cerevisiae. FTIR spectra indicate that heavy metal bioremoval process doesn’t imply in this case the formation of stable covalent bonds, but it is predominantly based on chemical interactions, ion-exchange type. The SEM micrographs of Cr-loaded yeast, indicates that the surface morphology doesn’t change much after chromium ions were uptaken. This leads to the conclusion that Cr(VI) reduction occurs at the interface of the adsorbent.This paper was elaborated with the support of BRAIN project Doctoral scholarships as an investment in intelligence - ID 6681, financed by the European Social Found and Romanian Government and with the support of a grant of the Romanian National Authority for Scientific Research, CNCS - UEFISCDI, project number PN-II-ID-PCE-2011-3-0559", Contract 265/2011

Metale grele: o sursă de contaminare pentru plantele medicinale şi posibile implicaţii asupra sănătăţii umane

Due to the antioxidant properties of medicinal plants and their beneficial effects on human health, theyare used and consumed as natural medical sources. Despite this, due to the current pollution of environmental compartments (soil, water, air), they can be contaminated with various pollutants. Heavy metals are a category of toxic compounds of great interest, due to the negative action on the environment and human health. Although some heavy metals are important in maintaining the proper functioning of plants, in high concentrations, they can become toxic. In the context of heavy metal pollution of the environment and possible contamination of medicinal plants with these pollutants, the need for chemical analysis of toxic plant compounds is necessary. This paper approaches results from literature which show that medicinal plants can be subjected to contamination with heavy metals, and this has the consequence of altering the normal functions of medicinal plants. Moreover, following consumption through the food chain (soil -plant -human or soil -plant -animal -human), human health may be endangered. This paper also investigates the toxic action of heavy metals in plants, represented, in principle, by the production of reactive oxygen species (ROS), enzyme inhibition and damage to antioxidants