Soil toxicity in a protected area in Brazil: Cytotoxic, genotoxic, and toxic effects.

The Campos de Palmas Wildlife Refuge (CPWR) (Brazil) is a full protection Conservation Unit (CU) formed by private properties, where the use of land and natural resources are allowed sustainably according to the rules of the CU Management Plan. Inadequate practices of land use and occupation within this CU can affect its quality and the organisms that depend on them. Considering the above, the objective of the present study was to biomonitor different land uses and occupations within the CPWR and its surroundings, during the four seasons of a year, using the bioindicators Allium cepa (cytotoxicity and genotoxicity tests) and Eisenia fetida (leakage test). The soil samples were collected in areas of silviculture, agriculture, and native grasslands within the CU and agriculture outside the limits of the CPWR. The use by silviculture (spring) and native grassland (summer) showed cytotoxic effects for A. cepa. The use by agriculture outside the CPWR (spring) showed genotoxic effect and stimulation of mitotic cell division. For the animal bioindicator, the use by agriculture within the CPWR (winter), native grassland (autumn and spring), silviculture (autumn and spring), and agriculture outside the CU (spring) showed a toxic effect. A PCA analysis showed a correlation between the results of toxicity, cytotoxicity, and genotoxicity with the presence of macronutrients and metals in the evaluated soil samples. Possibly influenced by their soil composition characteristics (silviculture and native grassland) or the management of agricultural areas. In addition, samples from the rainy season (spring) showed higher ecotoxicity. These results show that biomonitoring through different organisms is important for evaluating environmental quality and indicate the need for the implementation of preventive measures in the CPWR to avoid the toxic, cytotoxic, and genotoxic effects found. They also ensure the integrity of this CU and the active protection of the environment and biodiversity.

Effect of elemental composition assigned to antrotopic pollution on the quality of the water and sediment of the Marrecas river (PR, Brazil) as highlighted by multivariate statistical analyses.

In recent years, several environmental pollutants have been monitored in surface waters and sediments. However, few studies apply multivariate statistics to identify the main components and correlate them temporally and spatially. In this sense, the present study sought to monitor the quality of water and sediments in the Rio Marrecas/Brazil, through the analysis of physicochemical parameters and trace elements, as well as to identifying sources of contamination, using multivariate statistics. For this purpose, sampling was carried out in nine locations for a period of 12 months. The Total Reflection X-ray Fluorescence (TXRF) technique was used to quantify the 15 elements identified in water and sediment samples. Through multivariate statistical analyses, the most significant elements, their correlations and possible pollutant sources were defined, and the pollution index (HPI) and assessment index (HEI) of heavy metals were applied. The parameters pH and BOD5 do not comply with Brazilian legislation. Based on PCA and Spearman correlation, there was strong evidence of contamination of the water naturally, composed of the elements Ti, V, Mn, Fe, and of anthropogenic origin composed of the elements Ca, Ni, Cu, Zn. These findings provide insights to determine the impacts of heavy metals on human health and the environment.

Insights into brewery wastewater treatment by the electro-Fenton hybrid process: How to get a significant decrease in organic matter and toxicity.

This work aimed to perform selective experimental arrays based on the electro-Fenton hybrid (EFH) process for pollutants abatement and toxicity reduction in brewery wastewater (BW). Fenton and electrocoagulation (EC) methods were assessed preliminarily, including the Fe2+ catalyst yield and H2O2 loss. Each method performance on reducing total organic carbon (TOC) was assessed using a 33 full factorial design (FFD). Firstly, Fe2+ species were produced in short time ranges with the electric current density at 50 A m-2 and electrical conductivity at 1200 µS cm-1, followed by EFH experiments with an initial addition of 9.0 g L-1 H2O2. In three levels, initial pH (2.5-3.5) values, Fe2+ production-dedicated time (5-15 min), and H2O2 renovating percentage (70-90%) were also evaluated, assessing TOC removal. Secondly, nine EFH kinetics, upon the addition of an initial 9.0 g L-1 H2O2 along with H2O2 addition at 82.5%, every 5 min, and three levels for pH (3.0-3.4) were carried out, beginning after three Fe2+ production-dedicated times (4-6 min). Thirdly, another 60 min kinetic experiment was proposed, with an initial 6 min EC process, followed by a 39 min EFH process, and finally, a 15 min EC process, assessing TOC removal and remaining toxicity. A significant improvement in TOC removal performance, about 90%, along with high toxicity reduction was attained after a refined EFH-based treatment. Therefore, keeping permanent EFH conditions with more suitable parameters provided a unique perspective for removing highly significant pollutants.

Adsorption study of heavy metals in aqueous solutions aiming at the treatment of contaminated groundwater.

This study evaluates the application of the vegetal activated carbon (AC), vegetable AC impregnated with Ag and Cu (0.08% m/m) and cationic SupergelTM SGC650H resin for adsorption of Fe3+ and Pb2+ ions in closed and batch system. The best adsorption capacities were obtained by using the cationic resin SGC650H, pH 3, temperature of 30 °C and stirring speed of 100 rpm. Thus, the kinetic and equilibrium experiments, in mono- and bicomponent, were performed using SGC650H resin, wherein the kinetic models of pseudo-first and pseudo-second order presented a good fit to the kinetic data, for mono- and bicomponent, respectively. The Langmuir isotherm adequately represented the monocomponent equilibrium data, showing maximum adsorption capacities values of 7.18 and 4.00 meq g-1 for Fe3+ and Pb2+, respectively. An inhibitory effect between the metal species was verified by fitting the modified extended Langmuir isotherm model to the binary equilibrium data, which allowed to predict changes in the surface affinity to the adsorbent by the metal ions. Based on the observed results, the use of SGC650H resin presents great potential for water treatment systems contaminated with heavy metals.

Complex mathematical analysis of photobioreactor system.

Modeling as a tool solves extremely difficult tasks in life sciences. Recently, schemes of culturing of microalgae have received special attention because of its unique features and possible uses in many industrial applications for renewable energy production and high value products isolation. The goal of this review is to present the use of system analysis theory applied to microalgae culturing modeling and process development. The review mainly focuses on the modeling of the key steps of autotrophic growth under the integral biorefinery concept of the microalgae biomass. The system approach follows systematically a procedure showing the difficulties by modeling of sub-systems. The development of microalgae kinetics and computational fluid dynamics (CFD) studies were analyzed in details as sub-systems in advanced design of photobioreactor (PBR). This review logically follows the trends of the modeling procedure and clarifies how this approach may save time and money during the research efforts. The result of this work is a successful development of a complex PBR mathematical analysis in the frame of the integral biorefinery concept.

Insights on limits of detection, precision and accuracy in TXRF analysis of trace and major elements in environmental solid suspensions.

In this work, the analytical capability of the total reflection X-ray fluorescence technique with the S2 PICOFOX spectrometer was investigated. A set of certified reference materials was prepared as solid particulate for TXRF analysis. Experimental data of sensitivity, limits of detection and recovery for many elements were obtained. Good sensitivity and limits of detection with a good recovery range of around 90-110% were achieved. Thus, the TXRF technique exhibits a good analytical potential for its applicability on different materials.

Insights on the criteria of selection of vegetable and mineral dielectric fluids used in power transformers on the basis of their biodegradability and toxicity assessments.

Leakage of transformer dielectric fluids is a concern because it may pose a risk of environmental contamination. In this study, the deleterious effects of vegetable and mineral dielectric fluids in water bodies were investigated using biodegradability and acute toxicity tests with Danio rerio and Artemia salina. Regarding biodegradability, all four tested vegetable oils (soy, canola, sunflower and crambe) were considered as easily biodegradable, presenting degradation rates significantly higher than the Lubrax-type mineral fluid. Acute toxicity tests were performed in two separate experiments without solution renewal. In the first experiment, the organisms were exposed in direct contact to different concentrations of vegetable (soy) and mineral (Lubrax) oils. Total soy-type vegetable oil has a higher toxic effect than Lubrax-type mineral oil. In the second experiment, the organisms were exposed to increasing percentages of the water-soluble fraction (WSF) of both types of tested oils. The LC50 values for the water-soluble fraction of the Lubrax-type mineral oil were about 5 and 8% for the Danio rerio and Artemia salina bioindicators, respectively, whereas the vegetable oil did not present toxic effect, regardless of its WSF. These results have shown that a strict selection of dielectric fluids and monitoring the leakage from power transformers is a serious duty of environmental protection agencies.

Soybean plant-based toxicity assessment and phytoremediation of soils contaminated by vegetable and mineral oils used in power electrical transformers.

In this work, deleterious effects in soils due to the presence of dielectric fluids were investigated. For this purpose, vegetable (Envirotemp® FR3) and mineral (Lubrax AV 66 IN) oils were used for simulating a set of soils contaminated in different oil contents (0.5, 1.0, 2.0, 2.5, 5.0, 7.5 and 10%) in which three 120-days soybean crop periods (SCP) were carried out using the species Glycine max (L.) Merr. Both soil and soybean plant samples were analysed on following the changes on chemical attributes, content of oils and greases (COG) in soils and phytotechnical characteristics of soybean plant. No significant changes on soil chemical attributes were found. For a 0.5% vegetable oil fraction, COG removals of 35, 60 and 90% were observed after the 1st, 2nd, and 3rd SCPs, respectively, whereas removals of 25, 40 and 70% were observed for 0.5% mineral oil fraction after the 1st, 2nd, and 3rd SCPs, respectively. There was an effectively accumulated removal on all tested oil fractions as being proportional to the integrated 120-days SCPs, suggesting a lesser number of crops for a complete abatement of oil fraction in soil. A 100% recovery on the seedlings emergence fractions was also evidenced, revealing that at least a number of 7 and 9 SCPs should be applied continuously in soils contaminated by vegetable and mineral oils, respectively, in order to no longer jeopardize soybean plant growth. Finally, an empirical prediction of the number of SCPs necessary for the complete removal of oil from the soil was proposed.

Groundwater quality monitoring of the Serra Geral aquifer in Toledo, Brazil.

In this work, a physical-chemical, elemental and microbiological groundwater monitoring was performed on wells of the Serra Geral aquifer, located in the western region of the Brazilian state of Paraná, along with an evaluation of the elemental composition of soil sediments in the region of groundwater monitoring. The monitoring was carried out in 10 wells distributed throughout the rural area of the municipality of Toledo-PR. Elemental analyses were performed using the analytical technique of total reflection X-ray fluorescence spectrometry. From the results obtained, it was observed that in some wells, iron and lead concentrations were above the maximum limits allowed by the Brazilian legislation in some months, demonstrating that the evaluated groundwater is susceptible to contamination. By the analysis of the soil sediments, the presence of iron and lead in the region soil/rock was verified, which may be associated to rainwater percolation making it necessary to periodically monitor the groundwater consumed by the population of the municipality of Toledo-PR.

Aplicação da técnica de eletrocoagulação no tratamento de efluentes de abatedouro de aves / Application of the electrocoagulation technique on the treatment of wastewaters coming from a poultry slaughterhouse

RESUMO Neste trabalho a técnica de eletrocoagulação (EC) foi aplicada no tratamento de efluentes de abatedouro de aves. Um planejamento experimental fatorial completo 3³, foi realizado com o intuito de obter os valores ótimos de três variáveis do processo EC (corrente elétrica, pH e tempo de eletrólise). O desempenho foi avaliado pela eficiência da remoção da cor, a turbidez e a demanda química de oxigênio (DQO). As condições ótimas do processo foram obtidas para o pH inicial 8, tempo de eletrólise de 50 min e intensidade de corrente de 2 A. Entre os parâmetros de qualidade avaliados, os valores da cor e turbidez na condição ótima de operação estão de acordo com a legislação brasileira de lançamentos de efluentes líquidos em corpos de água receptores, classe III. Embora houvesse uma boa redução na quantidade inicial de DQO (de 9.252 para 830 mgL-1), esta não possui um limite recomendado pela legislação ambiental em vigor. Contudo, um polimento adicional dentro de um sistema integrado de processos levaria a valores ainda menores. Do ponto de vista do custo operacional e a substancial redução dos poluentes (90-99%), a eletrocoagulação pode ser considerada como uma técnica alternativa e promissora a ser aplicada no tratamento de efluentes de abatedouros de aves.

ABSTRACT In this work an electrocoagulation (EC) process was applied on the treatment of poultry slaughterhouse wastewaters. A 33 full factorial experimental design was carried out for obtaining optimal values of three EC reactor parameters (electric current, initial pH and electrolysis time). The performance was evaluated by the removal efficiency of color, turbidity and COD. The optimum process conditions were obtained for the initial pH 8 , electrolysis time of 50 min and electric current of 2 A. Among the evaluated quality parameters, the values of color and turbidity at the optimum operation condition are in accordance with the Brazilian legislation for liquid effluent discharges into receiving 3rd class water bodies. Although there was a good reduction on the initial amount of COD (from 9252 to 830 mgL-1), such parameter has no a recommended limit value in this regard. However, an additional polishing in an integrated process would lead to even lower values. From the point of view of operating costs and substantial reduction of pollutants (90-99%), the electrocoagulation technique can be considered a promising alternative one to be applied on the wastewaters treatment from poultry slaughterhouses.

Study of the involved sorption mechanisms of Cr(VI) and Cr(III) species onto dried Salvinia auriculata biomass.

Removal of Cr(VI) species by dried biomass of the aquatic macrophyte Salvinia auriculata was studied in order to understand the involved sorption mechanisms. Kinetic tests were carried out under the conditions such as concentration range of Cr(VI) from 50 to 250 mg L-1 and a temperature of 30 °C. Modification of the biosorbent by the presence of Cr(VI) species was assessed by analysis of its porosity, density and infrared molecular absorption spectrum. A series of experimental approaches involving directed chemical modifications on the biosorbent surface was performed. The main functional groups involved in the sorption mechanisms were identified. The gas sorption analyser was applied and proved that a strong chemical effect of Cr(VI) species on the surface took place, resulting in a leaching organic matter with an obvious and significant increase in the porosity parameters. The intra-particle diffusion model revealed different mass transfer zones into the adsorbent during Cr(VI) removal. New combined Langmuir and Dubinin-Radushkevich isotherm was the best to fit the equilibrium data of Cr(VI) species removal. Finally, Cr(VI) removal was mainly mediated by a redox process where Cr(III) species were formed.

Potential of Salvinia auriculata biomass as biosorbent of the Cr(III): directed chemical treatment, modeling and sorption mechanism study.

In this work, the mechanism of the Cr(III) sorption by Salvinia auriculata biosorbent was studied in two stages. To understand the influence of the sorption parameters on the Cr(III) uptake, preliminary tests were performed. First, S. auriculata biomass was separately treated with base and acid solutions. Second, acid and base treatment of samples was performed based on the knowledge data base of our group. It was achieved a higher Cr(III) sorption capacity above 15 mg g-1 as associated to an increase of the micro-pores specific area and biosorbent volume. The obtained kinetic data of raw and treated biosorbents were well described by the intra-particle diffusion model. In this model, Cr(III) adsorption onto treated biomass is progressively improved with appearing of different mass transfer zones from out layer up to micro-porous layers. The equilibrium data of raw biomass were best described by the Langmuir isotherm, whereas the equilibrium data of the treated biomass were best fit by a combination of both Langmuir and Dubinin-Radushkevich isotherms. At low concentrations the adsorption most likely occurred on the outer monolayer, as proposed by the Langmuir model, followed by the adsorption on the micro-porous layers, as validated by the Dubinin-Radushkevich isotherm.

Determination of the mass transfer limiting step of dye adsorption onto commercial adsorbent by using mathematical models.

Reactive blue 5G dye removal in a fixed-bed column packed with Dowex Optipore SD-2 adsorbent was modelled. Three mathematical models were tested in order to determine the limiting step of the mass transfer of the dye adsorption process onto the adsorbent. The mass transfer resistance was considered to be a criterion for the determination of the difference between models. The models contained information about the external, internal, or surface adsorption limiting step. In the model development procedure, two hypotheses were applied to describe the internal mass transfer resistance. First, the mass transfer coefficient constant was considered. Second, the mass transfer coefficient was considered as a function of the dye concentration in the adsorbent. The experimental breakthrough curves were obtained for different particle diameters of the adsorbent, flow rates, and feed dye concentrations in order to evaluate the predictive power of the models. The values of the mass transfer parameters of the mathematical models were estimated by using the downhill simplex optimization method. The results showed that the model that considered internal resistance with a variable mass transfer coefficient was more flexible than the other ones and this model described the dynamics of the adsorption process of the dye in the fixed-bed column better. Hence, this model can be used for optimization and column design purposes for the investigated systems and similar ones.

Influence of lead-doped hydroponic medium on the adsorption/bioaccumulation processes of lead and phosphorus in roots and leaves of the aquatic macrophyte Eicchornia crassipes.

In this study, lead bioaccumulation by the living free-floating aquatic macrophyte Eicchornia crassipes in different hydroponic conditions with variations in phosphorus and lead concentrations was investigated. A set of growth experiments in hydroponic media doped with lead and phosphorus within a wide concentration range was performed for 32 days in a greenhouse. All experiments were carried out with periodic replacement of all nutrients and lead. The concentration of lead and nutrients in biomass was determined by synchrotron radiation-excited total reflection X-ray fluorescence. By increasing the lead concentration in the medium, a reduction in biomass growth was observed, but a higher phosphorus retention in roots and leaves was shown at lower lead concentrations. In addition, an increase in the amount of bioaccumulated lead and phosphorus in roots was observed for higher lead and phosphorus concentrations in the medium, reaching saturation values of 4 mg Pb g(-1) and 7 mg P g(-1), respectively. Four non-structural kinetic models were tested, to represent the bioaccumulation of lead and phosphorus in roots. Pseudo-second order and irreversible kinetic models described the lead bioaccumulation data well, however, an irreversible kinetic model better fitted phosphorus uptake in roots.

Toxicity assessment of tannery effluent treated by an optimized photo-Fenton process.

In this work, an optimized photo-Fenton process was applied to remove pollutants from tannery industrial effluent (TIE) with its final toxicity level being assessed by a lettuce-seed-based bioassay test. A full 33 factorial design was applied for the optimization of long-term photo-Fenton experiments. The oPtimum conditions of the photo-Fenton process were attained at concentration values of 0.3 g Fe(2+) L(-1) and 20 g H2O2 L(-1) and pH3, for 120 min UV irradiation time. Reactor operating parameter (ROP) effects on the removal of chemical oxygen demand, colour, turbidity, total suspended solids and total volatile solids were evaluated, suggesting that a broad range of ROP values are also suitable to give results very near to those of the photo-Fenton experiments under optimal conditions. Based on the low calculated median lethal dose (LD50) values from a lettuce-seed-based bioassay test, we suggest that recalcitrant substances are present in treated TIE samples. A possible cause of the high toxicity level could partly be attributed to the nitrate concentration, which was not completely abated by the photo-Fenton process. Apart from this, the photo-Fenton process can be used as a part of an industrial effluent treatment system in order to abate high organic pollutant loads.

Elements concentration analysis in groundwater from the North Serra Geral aquifer in Santa Helena-Brazil using SR-TXRF spectrometer.

In this work the analysis of elements concentration in groundwater was performed using the synchrotron radiation total-reflection X-ray fluorescence (SR-TXRF) technique. A set of nine tube-wells with serious risk of contamination was chosen to monitor the mean concentration of elements in groundwater from the North Serra Geral aquifer in Santa Helena, Brazil, during 1 year. Element concentrations were determined applying a SR-TXRF methodology. The accuracy of SR-TXRF technique was validated by analysis of a certified reference material. As the groundwater composition in the North Serra Geral aquifer showed heterogeneity in the spatial distribution of eight major elements, a hierarchical clustering to the data was performed. By a similarity in their compositions, two of the nine wells were grouped in a first cluster, while the other seven were grouped in a second cluster. Calcium was the major element in all wells, with higher Ca concentration in the second cluster than in the first cluster. However, concentrations of Ti, V, Cr in the first cluster are slightly higher than those in the second cluster. The findings of this study within a monitoring program of tube-wells could provide a useful assessment of controls over groundwater composition and support management at regional level.

Optimised photocatalytic degradation of a mixture of azo dyes using a TiO(2)/H(2)O(2)/UV process.

The aim of the present study was to optimise the photocatalytic degradation of a mixture of six commercial azo dyes, by exposure to UV radiation in an aqueous solution containing TiO(2)-P25. Response surface methodology, based on a 3(2) full factorial experimental design with three replicates was employed for process optimisation with respect to two parameters: TiO(2) (0.1-0.9 g/L) and H(2)O(2) (1-100 mmol/L). The optimum conditions for photocatalytic degradation were achieved at concentrations of 0.5 g TiO(2)/L and 50 mmol H(2)O(2)/L, respectively. Dye mineralisation was confirmed by monitoring TOC, conductivity, sulfate and nitrate ions, with a sulfate ion yield of 96% under optimal reactor conditions. Complete decolorisation was attained after 240 min irradiation time for all tested azo-dyes, in a process which followed a pseudo-first kinetic order model, with a kinetic rate constant of approximately 0.018 min(-1). Based on these results, this photocatalytic process has promise as an alternative for the treatment of textile effluents.

Potencial de biossorção do zinco pela macrófita egeria densa / Biosorption potential of zinc by egeria densa macrophytes

Neste trabalho, foi estudada a capacidade de biossorção da macrófita aquática Egeria densa seca na remoção do íon zinco. Os testes cinético e de equilíbrio foram realizados em sistema de batelada com temperatura, agitação e pH controlados. Os resultados obtidos na cinética de biossorção demonstram uma rápida remoção do zinco (II), com tempo de equilíbrio em torno de 45 minutos e taxa de remoção superior a 70 por cento. O modelo cinético de pseudo-segunda ordem foi o que melhor representou os dados experimentais. No estudo do equilíbrio, verificou-se que o modelo de Langmuir ajustou-se melhor aos dados experimentais, com capacidade máxima de sorção de 0,92 mequiv g-1 e razão entre as taxas de sorção e dessorção de 0,829 L g-1 em pH 5. Os resultados obtidos demonstram que a macrófita E. densa tem potencial para ser utilizada em sistemas de tratamento de efluentes industriais.

In this paper, the removal potential on Zn ion by macrophyte Egeria densa has been studied. The influence of the metal solution pH, the plant drying and the metal solution temperature, and biosorbent grain size was previously studied in batch systems. Adsorption kinetic and equilibrium experiments of metals onto E. densa were performed under controlled temperature and permanent shaking. In adsorption kinetic tests for Zn (II) the equilibrium time was around 45 min. The biosorption kinetic data were well fitted by a pseudo-second order model. The equilibrium data at pH 5 were described a rather better by the Langmuir isotherm than the Freundlich one, with an adsorption rate and maximum metal content values of 0,829L g-1and 0,92 mequiv g-1, respectively, for Langmuir model. The macrophytes E. densa could be used as biosorbent material in industrial effluent treatment system.