Application of zeolite-Arthrobacter viscosus system for the removal of heavy metal and dye : chromium and azure B

A hybrid system combining the ion-exchange properties of a NaY zeolite and the characteristics of the bacterium Arthrobacter viscosus was investigated to treat polluted effluents with dye and toxic metals. In this study, the dye and the metal ion employed were a thiazine dye, Azure B, and chromium (VI), respectively. Initially, the removal of dye by the zeolite was tested. The analysis of dye equilibrium isotherms data was done using Langmuir, Freundlich, Sips and Redlich–Peterson models. Redlich–Peterson model gave the better fitting to data. In the dye adsorption studies, pseudo-second order kinetics showed the more reliable results. Operating at the optimised conditions in the treatment of single pollutants, a mixture of dye and metal solutions was treated reaching a removal higher than 50% for chromium (VI) and higher than 99% for dye, in 8 days.This work was supported by Fundacao para a Ciencia e Tecnologia (FCT-Portugal) and Xunta de Galicia under programme 08MDS034 314PR. The authors are grateful to University of Vigo for financial support of the research of Emilio Rosales under a mobility grant

Biosorption of heavy metal and dyes : a promising technology leather wastewater treatment

The presence of dyes and heavy metals is usual in industrial processes like chrome tanning in tannery industry and their removal may be an environmental problem. Different techniques were developed and applied for the treatment of dyes and heavy metals in effluents. Among them, adsorption showed to be an economic, simple operation and an effective technique. Zeolites have a strong affinity for cations of transition metals, but only little affinity for anions and non-polar organic molecules. The application of a zeolite to heavy metal removal may be improved by the presence of microorganisms. The aim of this work is the treatment of an effluent containing dyes and toxic metals. Several operation parameters such as pH, concentration and kinetic behavior were studied. This innovative process for treating dyes and heavy metal effluents showed that the zeolite-biomass system is able to perform the removal of a combination of Azure B and chromium(VI). A mixture of dye and metal solutions was treated reaching a removal higher than 50% in the case of chromium (VI) and higher than 99% for dye, in 8 days

Heterogeneous electro-Fenton treatment: preparation, characterization and performance in groundwater pesticide removal

In this work the preparation, characterization and performance of Y-zeolite as catalyst for electro-Fenton treatment of pesticides was carried out. Initially iron supported Y-zeolite (Fe-Y) was prepared and evaluated for the degradation of imidacloprid and chlorpyrifos. Kinetics studies determined that the pesticides removal followed a pseudo-first-order kinetic model. However, the reusability of this catalyst was not appropriated and to enhance its recyclability, Fe-Y catalyst was embedded in alginate (Al-Fe-Y). The new catalyst showed similar degradation efficiency; and the recyclability was improved. This study demonstrated that Al-Fe-Y could be efficiently used to remove commonly pesticides, imidacloprid and chlorpyrifos, of aqueous medium.This work has been supported by the Xunta de Galicia (EM2012/083). The authors are thankful to the Ramón y Cajal programme for Marta Pazos’ financial support and to C.A.C.T.I. from Vigo University for providing access to their Electron Microscopy Service

Removal of Di-(2-ethylhexyl)phthalate (DEHP) from water using a LECA-Pseudomonas putida Biobarrier

The removal and biodegradation of an organic toxic pollutant, di-(2-ethylhexyl) phthalate (DEHP), has been investigated. Initially, a screening of different degrading bacteria has been developed and Pseudomonas putida showed the highest degradation ability. This bacterium was immobilised in an inert support, light expanded clay aggregate (LECA). After the biofilm formation on the LECA, the degradation of DEHP was evaluated operating in a fixed bed reactor. In addition, several studies of DEHP adsorption on LECA were carried out in order to determine the mechanism of the degradation process that takes place. The degradation studies demonstrated that the developed system can be applied to DEHP removal and the degradation is due to adsorption process and the activity of P. putida

Development of permeable reactive biobarrier for the removal of PAHs by Trichoderma longibrachiatum

In this work, the formation of permeable reactive biobarriers (PRBBs) using Trichoderma longibrachiatum over nylon sponge as bioreactive medium for removal of polycyclic aromatic hydrocarbons (PAHs) was studied. Colony formation was pretested without PAH presence by inoculation of fungus into nylon sponge. The fungus formed a large quantity of strongly adhesive biofilm among nylon sponge. Afterwards, the ability of the developed bioreactive medium was tested to remediate phenanthrene in aqueous medium and in soil. In aqueous medium, a 90% of phenanthrene concentration reduction was observed after 14 d. However, the pollutant removal in soil requires previous fungus colonization and the attained level was around 70% after 28 d. Subsequently, the formed bioreactive material was used in a glass column reactor to evaluate its application as PRBBs. Mixtures of phenanthrene, benzo[a]anthracene and pyrene at several concentrations, from 100 to 400 μM, were treated. In all cases, the performance of the PRBB was satisfactory and total PAH removals were achieved. These results suggest that PRBBs of T. longibrachiatum supported on nylon sponge can be an effective method for the treatment of PAHs.This research was funded by Spanish Ministry of Science and Innovation and FEDER Funds (Project CTM 2011-25389) and for financial support of Marta Pazos under the Ramon y Cajal programme and Marta Cobas under the final project master grant "Campus do Mar Knowledge in depth"

Enhanced selective metal adsorption on optimised agroforestry waste mixtures

The aim of this work is to ascertain the potentials of different agroforestry wastes to be used as biosorbents in the removal of a mixture of heavy metals. Fern (FE), rice husk (RI) and oak leaves (OA) presented the best removal percentages for Cu(II) and Ni(II), Mn(II) and Zn(II) and Cr(VI), respectively. The performance of a mixture of these three biosorbents was evaluated, and an improvement of 10% in the overall removal was obtained (19.25 mg/g). The optimum mixture proportions were determined using simplexcentroid mixture design method (FE:OA:RI = 50:13.7:36.3). The adsorption kinetics and isotherms of the optimised mixture were fit by the pseudo-first order kinetic model and Langmuir isotherm. The adsorption mechanism was studied, and the effects of the carboxylic, hydroxyl and phenolic groups on metal–biomass binding were demonstrated. Finally, the recoveries of the metals using biomass were investigated, and cationic metal recoveries of 100% were achieved when acidic solutions were used.This work has been funded by the Spanish Ministry of Economy and Competitiveness, Xunta de Galicia and ERDF Funds (Projects CTM 2011-25389 and GRC 2013/003). The authors are grateful to Xunta de Galicia for financial support of the researcher Emilio Rosales under a postdoctoral Grant and the Spanish Ministry of Economy and Competitiveness for financial support of the researcher Marta Pazos under a Ramon y Cajal Grant

Removal of Cr(VI) from aqueous solutions by a bacterial biofilm supported on zeolite : optimisation of the operational conditions and scale-up of the bioreactor

The aim of this study was to investigate the feasibility of a bioreactor system and its scale-up to remove Cr(VI) from solution. The bioreactor is based on an innovative process that combines bioreduction of Cr(VI) to Cr(III) by the bacterium Arthrobacter viscosus and Cr(III) sorption by a specific zeolite. Batch studies were conducted in a laboratory-scale bioreactor, taking into account different operating conditions. Several variables, such as biomass concentration, pH and zeolite pre-treatment, were evaluated to increase removal efficiency. The obtained results suggest that the Cr removal efficiency is improved when the initial biomass concentration is approximately 5 g L–1 and the pH in the system is maintained at an acidic level. Under the optimised conditions, approximately 100 % of the Cr(VI) was removed. The scale-up of the developed biofilm process operating under the optimised conditions was satisfactorily tested in a 150-L bioreactor.Xunta de Galicia - programa Angeles Alvariñ

Prevalence of BRCA1 and BRCA2 Jewish mutations in Spanish breast cancer patients

We screened the 185delAG and 5382insC (BRCA1) and the 6174delT (BRCA2) mutation in 298 Spanish women with breast cancer. Two women (one with Sephardic ancestors) presented the 185delAG mutation and the same haplotype reported in Ashkenazim with this mutation. This suggests a common origin of the 185delAG in both Sephardic and Ashkenazi populations. © 1999 Cancer Research Campaig

Assessment of Arthrobacter viscosus as reactive medium for forming permeable reactive biobarrier applied to PAHs remediation

Polycyclic aromatic hydrocarbons (PAHs) are significant environmental contaminants as they are present naturally as well as anthropogenically in soil, air and water. In spite of their low solubility, PAHs are spread to the environment, and they are present in surface water, industrial effluent or groundwater. Amongst all remediation technologies for treating groundwater contaminated with PAHs, the use of a permeable reactive biobarrier (PRBB) appears to be the most cost-effective, energy efficient, and environmentally sound approach. In this technology, the microorganisms are used as reactive medium to degrade or stabilize the contaminants. The main limits of this approach are that the microorganisms or consortium used for forming the PRBB should show adequate characteristics. They must be retained in the barrier-forming biofilm, and they should also have degradative ability for the target pollutants. The aim of the present work is to evaluate the viability of Arthrobacter viscosus as bioreactive medium for forming PRBB. Initially, the ability of A. viscosus to remove PAHs, benzo[a]anthracene 100 μM and phenanthrene 100 μM was evaluated operating in a batch bench-scale bioreactor. In both cases, total benzo[a]anthracene and phenanthrene removals were obtained after 7 and 3 days, respectively. Furthermore, the viability of the microorganisms was evaluated in the presence of chromium in a continuous mode. As a final point, the adhesion of A. viscosus to sepiolite forming a bioreactive material to build PRBB was demonstrated. In view of the attained results, it can be concluded that A. viscosus could be a suitable microorganism to form a bioreactive medium for PAHs remediation.This work has been supported by the Spanish Ministry of Economy and Competitiveness and FEDER Funds (Project CTM 2011-25389). Marta Pazos received financial support under the Ramon y Cajal programme and Marta Cobas under the final project master grant "Campus do Mar Knowledge in depth"