Biologia reprodutiva de Madracis decactis (Lyman, 1859) (Cnidaria, Scleractinia) de recifes do sul da Bahia, Brasil

The reproductive biology of the scleractinian coral Madracis decactis (Lyman, 1859) was studied in southern Bahia reefs, the most extensive and richest reef areas of the South Atlantic. Madracis decactis is one of the most widespread zooxanthellate corals in Brazil and can be found at the edges of the reefs on exposed or cryptic areas. The objective of this study was to investigate patterns of the sexual reproduction of M. decactis. Information about sexuality, gonad arrangement, mode of development, gametogenesis and temporal patterns of the reproductive cycle were obtained using histological procedures. The results showed that M. decactis is a hermaphroditic species and probably presents a brooding mode of development in southern Bahia reefs. Reproductive cycle is annual and lasts about four months. Female and male gametes started to develop at different times, with spermaries appearing in approximately the second month of oogenesis and lasting about two months. Gametogenesis started on the summer onset (December) and was complete at early autumn (April). Mature gametes were not present in samples collected between the end of March and April. Evidences suggested that fecundation, embryogenesis and the possible planulae release occurred within this period, of approximately one month.A biologia reprodutiva do coral escleractíneo Madracis decactis (Lyman, 1859) foi estudada nos recifes do sul da Bahia, a mais extensa e rica área recifal do Atlântico Sul. Madracis decactis é um dos corais zooxantelados mais amplamente distribuídos do Brasil, podendo ser encontrado nas bordas dos recifes em locais expostos ou abrigados. O objetivo deste estudo foi investigar padrões na reprodução sexual de M. decactis. Informações sobre sexualidade, arranjo das gônadas, modo de desenvolvimento, gametogênese e padrões temporais do ciclo reprodutivo foram obtidas através de procedimentos histológicos. Os resultados mostraram que M. decactis de recifes do sul da Bahia é uma espécie hermafrodita e provavelmente incubadora de larvas. O ciclo reprodutivo é anual e dura cerca de quatro meses. Gametas masculinos e femininos começaram seu desenvolvimento em momentos diferentes, com cistos espermáticos aparecendo aproximadamente no segundo mês da ovogênese e durando cerca de dois meses. A gametogênese se iniciou no começo do verão (dezembro) e completou-se no princípio do outono (abril). Não foram observados gametas maduros nas amostras coletadas entre o final de março e abril. Evidências sugeriram que a fecundação, a embriogênese e a possível liberação de plânulas ocorreram dentro desse período, com duração de cerca de um mês

Treatment of chromium(VI) solutions in a pilot-scale bioreactor through a biofilm of arthrobacter viscosus supported on GAC

The aim of this work is to evaluate the applicability of a biofilm to the removal of chromium in solution, at a pilot scale. The effect of the initial concentration of metal on the biosorption behavior of an Arthrobacter viscosus biofilm supported on granular activated carbon, in batch and column essays was also analyzed. Six isotherm equations have been tested in the present study. The best fit was obtained with the Freundlich model. It was observed that as the initial chromium concentration increases, the uptake increases too, but the removal percentage decreases, with values between 95.20% (C0 = 5 mg/l) and 38.28% (C0 = 1000 mg/l). The batch adsorption studies were used to develop a pilot bioreactor able to remove chromium from aqueous solutions. Data obtained in a pilot-scale reactor showed an average removal percentage of 99.9%, during the first 30 days, for the initial concentration of 10 mg/l and an average removal percentage of 72%, for the same period and for the initial concentration of 100 mg/l. Uptake values of 11.35 mg/g and 14.55 mg/g were obtained, respectively, for the initial concentration of 10 and 100 mg/l. The results obtained are very promising and encourage the utilization of this biofilm in environmental applications.FEDERFundação para a Ciência e a Tecnologia (FCT

Treatment of chromium solutions in a 15 dm3 pilot bioreactor

Chromium is a heavy metal with large industrial applications such as in textile dying, chemicals and pigments production, wood preservation, tanning activity and electroplating for surface treatment. The treatment of wastewater containing this metal with biological methods is strongly recommended, especially when in the form of Cr (VI) due its high toxicity. The biosorption system consists of a bacterial biofilm supported on granular activated carbon (GAC), placed in contact with the polluted solutions. The bacterium used for the formation of the biofilm was Arthrobacter viscosus. Two concentrations of chromium were used: 10 mg/l and 100 mg/l, with a flow rate of 25 mg/l. The data obtained in a pilot-scale reactor showed an average removal percentage of 99.9%, during the first 30 days, for the initial concentration of 10 mg/l and average removal percentage of 72%, for the same period and for the initial concentration of 100 mg/l. Uptake values of 11.35 mg/gGAC and 14.55 mg/gGAC were obtained, respectively, for the initial concentration of 10 and 100 mg/l. The presence of functional groups on the cell wall surface of the biomass that may interact with the metal ion was confirmed by FTIR. The results obtained are very promising and encourage the utilization of this biofilm in environmental applications

A sustained approach to environmental catalysis: Reutilization of chromium from wastewater

Wastewater pollution with heavy metals is an issue of great environmental concern. The future development of clean technologies for the treatment of wastewater loaded with heavy metals entails environment friendly and sustainable processes that may allow simultaneously the recovery of the metals and their reutilization as value-added catalysts to be used in environmental applications. This is the first review regarding the biorecovery of metals and their further reutilization as heterogeneous catalysts. In this regard, metallic residues that generally would be considered as a waste at the end of the treatment process can be reutilized and transformed into value-added catalysts to be used in environmental applications. This review is focused in two broad areas: the biorecovery of chromium by a combined biosorption system consisting of bacteria supported on zeolites, and the catalytic reutilization of the metal-loaded zeolites in the oxidation of organic compounds, both in gaseous and liquid phase. After an overview describing the main subjects in the field of heavy metals recovery, biosorption, zeolites and catalytic oxidation, in the following sections special emphasis will be given to the main results and findings regarding these clean technologies of biorecovery and reuse of metals in catalytic reactions of environmental concern.B. Silva is thankful for the Project “BioEnv—Biotechnology and Bioengineering for a sustainable world,” REF. NORTE-07-0124-FEDER-000048, cofunded by the Programa Operacional Regional do Norte (ON.2 – O Novo Norte), QREN, FEDER. The authors are grateful to FCT and FEDER (European Fund for Regional Development)-COMPETE-QREN-EU for financial support to the Research Centres, PEst-OE/EQB/LA0023/2013, and PEst-C/QUI/UI0686/2013 (F-COMP-01-0124-FEDER-037302)

Modified low cost adsorbent (cedar) for the removal of Pb (II), Ni (II) and Zn (II) from aqueous solutions

Increased industrialization and population have a negative impact on the environment through the discharge of waste containing heavy metals. The aim of this work is to assess the sorption capacity of a modified low cost adsorbent (cedar) on the removal of lead, nickel and zinc ions from aqueous solutions at 60 mg/L for each metal. Alkaline treatment was applied to cedar to improve the adsorption process by the activation of the sorption sites. Kinetic assays were performed in batch mode at different adsorbent concentrations, from 0.5 g/L to 7.5 g/L. The pH of zero point of charge obtained for modified cedar was 5.13. Scanning Electron Microscopy-Energy Dispersive Spectroscopy was used to compare the morphology and chemical composition of the unmodified and modified cedar. The results revealed that alkaline treatment with potassium hydroxide is effective on the removal of these metals from aqueous solutions. The adsorption of lead (II), nickel (II) and zinc (II) onto modified cedar is dependent on the adsorbent concentration, being the maximum uptake reached for each ion at 2.5 g/L, 25.8 mg/g for Pb and 7.7 mg/g for Ni and Zn.info:eu-repo/semantics/publishedVersio

Application of an E. coli biofilm supported on Kaolin to the removal of Cd(II), Cr(VI), Fe(III) and Ni(II) from aqueous solutions

The pollution caused by heavy metals is one the major environmental problems that is imperative to be solved. New technologies, easy to implement and to adapt to any system, deserve special attention and are the focus of this presentation. This paper aims to investigate the biosorption behaviour of a biofilm of E. coli supported on kaolin clay for the treatment of cadmium, iron, nickel and chromium aqueous solutions. The effect of metals initial concentrations were studied and the relationship between pH and removal efficiency were analysed. Adsorption characteristics of a biosorbent can be depicted by an adsorption isotherm. Langmuir, Redlich-Peterson and Sips are commonly used for the description of adsorption data and were applied to the experimental results described by this report. The presence of functional groups in the suspended biomass that may have a role in biosorption process was confirmed by FTIR. It was demonstrated that a biofilm of E. coli supported on kaolin is able to remove Cr (VI), Cd (II), Ni (II) and Fe (III) from aqueous solutions. The isotherms were fitted and the best fit for chromium and nickel was obtained with the Redlich-Peterson model isotherm and for cadmium the best fit was the obtained with the Sips model. In terms of removal percentage, the results showed 100% of removal for iron for the whole range of concentrations tested. For cadmium, the removal percentage remains around 70% for all the initial concentrations tested (between 67.1% and 78.9%) and is higher than the obtained for nickel and chromium. The analyses by FTIR showed that functional groups on the biomass, such as hydroxyl, carboxyl and phosphate groups, may be the main binding sites for biosorption of the studied heavy metals by E. coli. Finally, the metal affinity to the biofilm was found to follow the sequence Fe > Cd > Ni > Cr and the preference of a sorbent for a metal may be explained on the basis of electronegativity of the metal ions and on the basis of the cation/anion state.Fundação para a Ciência e a Tecnologia (FCT)FEDERMinas de Barqueiros, S.A

Adsorption of lead and nickel from aqueous solution on natural sepiolite

Heavy metals are a serious environmental problem due to their toxicity and abundance. The capacity of a natural clay (sepiolite) for heavy metals adsorption, Pb2+ and Ni2+, has been assessed using a batch method. The effect of mass of adsorbent on the process and the competitive adsorption between the two metals has been investigated. The adsorption of Pb2+ and Ni2+ increases with increasing dosage of natural sepiolite. The maximum removal of Pb2+ and Ni2+ by sepiolite, starting from a solution with both metals, was 98% and 59%, respectively. The experiments demonstrated that Pb2+ was adsorbed by natural sepiolite more efficiently than Ni2+. The conclusion of this study is that natural sepiolite can efficiently adsorb cationic species, which may have an interesting environmental application such as the removal of those species from polluted waters.info:eu-repo/semantics/publishedVersio

Competitive adsorption of heavy metals by two different types of soils

Soil is a key element in human survival and can be described by various definitions according to its main utility. Nowadays, it is accepted that soil is a very complex heterogeneous medium which consists of solid phases containing minerals and organic matter and soil solution, defined as the fluid phase where soil reactions, transport and adsorption occurs (Alloway, 1995). Unfortunately, in the last decades, soils have been used as a deposit of residues. Therefore, the contamination and pollution of soils, sediments, surface and groundwater are of main concern. There are several ions and compounds of organic or inorganic nature that can contaminate soil and water. The inorganic contaminants include heavy metals like cadmium, chromium, cooper, lead and zinc, which are focused in this study. These metals are commonly present in industrial wastes (electroplating, textile and dyes, etc.), in fertilizers or in sewage sludge, but they can also contaminate soils through atmospheric deposition or runoff water (Serrano et al., 2005). Since adsorption is well recognized as the main process affecting the mobility of heavy metals through soils (Bradl, 2004), the aim of this work is the study the non competitive adsorption of these five metals, as well as the competitive adsorption in two different typical soils of the North of Portugal The soil samples were collected in Póvoa de Varzim, from O-horizon and A-horizon (0 cm -30 cm), one from a culture land and another from a beach land. To evaluate the adsorption equilibrium, batch tests were performed by adding to 2 g of air dried soil, 20 mL of 0.01 M CaCl2 solution, containing different initial concentrations of Pb [Pb(NO3)2], Cd [CdN2O6·4H2O], Cu [Cu(NO3)2·3H2O], Zn [Zn(NO3)2·6H2O] and Cr [K2Cr2O7], isolated (non-competitive system) and coupled (competitive system).To eliminate the mass effect, the multi-metal solutions were prepared in terms of molar concentrations (Echeverría et al., 1998). To avoid precipitation the pH of initial solution was adjusted to 2. Isotherm models like Freundlich and Langmuir equations were adjusted to experimental data. Batch tests are useful for the understanding of the adsorption process. However, advection and dispersion may occur in dynamic systems justifying the need of flow experiments (Miretzky et al., 2006). For continuous experiments, soil samples were packed in a column (25 cm × 3.2 cm) and a single – or multi – element solution of 50 mg/L was pass upwards during seven days. Then, using the CXTFIT code, the convection-dispersion equation was adjusted to the breakthrough curves in order to determine the retardation factor (R) and to compare the behavior of the different ions and soils