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Diclofenac is a commercial non-steroidal anti-inflammatory drug commonly present as a pollutant in naturally occurring water sources and wastewaters. In this work, the adsorption of diclofenac onto chitosan-coated magnetic nanosystems is proposed as a possible tool for remediation. Experimental and theoretical studies have been carried out to reveal the mechanisms associated with diclofenac interactions among all the components of the nanosystem. Mechanisms are presented, analyzed and discussed. A toxicological study in mice was carried out to evaluate the parameters associated with neurotoxicity of the nanodevice. The elucidation of the mechanisms implied in the adsorption process of diclofenac onto magnetic chitosan nanocomposites suggests that diclofenac remediation from water is possible by adsorption onto chitosan. The strategy innovates the commonly used methodologies for diclofenac remediation from pharmaceutical wastes. This magnetic nanotechnology would not induce damage on the nervous system in a murine model, in case of traces remaining in water sources.

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Removal of cyanobacteria from the water column using a coagulant and a ballast compound is a promising technique to mitigate nuisance. As coagulant the organic, biodegradable polymer chitosan has been promoted. Results in this study show that elevated pH, as may be common during cyanobacterial blooms, as well as high alkalinity may hamper the coagulation of chitosan and thus impair its ability to effectively remove positively buoyant cyanobacteria from the water column. The underlying mechanism is likely a shielding of the protonated groups by anions. Inasmuch as there are many chitosan formulations, thorough testing of each chitosan prior to its application is essential. Results obtained in glass tubes were similar to those from standard jar tests demonstrating that glass tube tests can be used for testing effects of coagulants and ballasts in cyanobacteria removal whilst allowing far more replicates. There was no relation between zeta potential and precipitated cyanobacteria. Given the well-known antibacterial activity of chitosan and recent findings of anti-cyanobacterial effects, pre-application tests are needed to decipher if chitosan may cause cell leakage of cyanotoxins. Efficiency- and side-effect testing are crucial for water managers to determine if the selected approach can be used in tailor-made interventions to control cyanobacterial blooms and to mitigate eutrophication.

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Shrimp farm aquaculture causes environmental impacts, notably decreased water quality due to the release of nutrient-rich effluents. Pond wastewater is usually discharged without treatment, and tidal conditions are not taken into account in the management plans. However, natural variability of nutrients makes difficult field evaluation and attribution of impacts. Here we implemented a three-dimensional coupled hydrodynamic-biogeochemical model (spatial resolution=50m×50m, time resolution=4s) in order to evaluate the dispersion conditions under specific tidal conditions of nutrient discharges from a semi-intensive shrimp farm during spring and neap tide. Ammonia was quickly assimilated by plankton and its concentration recovered initial levels 10days after the beginning of the harvest. Due to the higher salinity of the pond effluents, shrimp farm discharges accumulate in waters and sediments of the upper lagoon creeks, mostly affecting the benthos, thus implying a potential risk of shrimp farm self-contamination. Maximum concentrations of most biogeochemical tracers occurred when the harvest ends and the ponds are fully emptied. We show that maximum nutrient concentrations can be reduced by ~10% when the harvest ends during spring tides compared to harvests ending during neap tides. This work may be useful to improve the management of shrimp farm effluents by reducing, easily and at little cost, nutrient impacts on tropical and sub-tropical receiving ecosystems.

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Esta investigación tuvo por objetivo obtener una bio-resina intercambiadora de cationes utilizando cáscaras de guineo o plátano, la cual reduzca la concentración de metales pesados en agua contaminada. A esta bio-resina se le realizaron pruebas fisicoquímicas: densidad seca aparente, pH y solubilidad en agua y solventes orgánicos. Se evaluó su efectividad filtrando agua contaminada con metales pesados, tales como hierro, cromo y níquel (Fe3+, Cr6+ y Ni2+), variando las condiciones de tiempo de contacto, temperatura y el tipo de cáscara. La cuantificación de la concentración de los metales en el agua filtrada se llevó a cabo por espectrofotometría visible. Se llegó a la conclusión que la bio-resina obtenida es efectiva para disminuir la concentración de metales pesados en agua, teniendo especial afinidad química por el cromo hexavalente; metal pesado que logró remover arriba del 90%. Las condiciones óptimas de operación de la bio-resina son a 30°C y 90 minutos de tiempo de contacto con la muestra. Además, las pruebas fisicoquímicas, permitieron tipificarla preliminarmente como una resina de intercambio catiónico débil con un grado de entrecruzamiento bajo.

This research aimed to obtain a cation exchange bio-resin, using plantain or banana peels, that reduces the concentration of heavy metals in contaminated water. The bio-resin underwent physico-chemical tests like apparent dry density, pH, solubility in water and organic solvents. Its effectiveness was tested by filtering contaminated water with heavy metals such as iron, chromium and nickel (Fe3+, Cr6+ y Ni2+) and by varying contact time conditions, temperature and type of peel. The measure of concentration of metals in filtered water was taken through visible spectrophotometry. We concluded that the resulting bio-resin is effective in reducing the concentration of heavy metals in water, showing special chemical affinity with hexavalent chromium, a heavy metal that was able to remove above 90%. The bio-resin optimum working conditions are 30°C and 90 minutes of contact with the sample. Also, the physico-chemical tests allowed to preliminary typify it as a weak cation exchange resin with a low degree of crosslinking.

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Sludge from the textile industry was used as a low-cost adsorbent to remove the dye Reactive Red 2 from an aqueous solution. Adsorbents were prepared through the thermal and chemical treatment of sludge originating from physical-chemical (PC) and biological (BIO) effluent treatment processes. The adsorbent characterization was carried out through physical-chemical analysis, X-ray fluorescence (XRF) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, pHPZC determination, Boehm titration method, Brunauer-Emmett-Teller (BET) surface area analysis and scanning electron microscopy (SEM). Batch kinetic experiments and adsorption isotherm modeling were conducted under different pH and temperature conditions. The results for the kinetic studies indicate that the adsorption processes associated with these systems can be described by a pseudo-second-order model and for the equilibrium data the Langmuir model provided the best fit. The adsorption was strongly dependent on the pH but not on the temperature within the ranges studied. The maxima adsorption capacities were 159.3 mg g(-1) for the BIO adsorbent and 213.9 mg g(-1) for PC adsorbent at pH of 2 and 25 °C.

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We studied the adsorption of paraquat onto polyurethane foam (PUF) when it was in a medium containing sodium dodecylsulfate (SDS). The adsorption efficiency was dependent on the concentration of SDS in solution, because the formation of an ion-associate between the cationic paraquat and the dodecylsulfate anion was found to be a fundamental step in the process. A computational study was carried out to identify the possible structure of the ion-associate in aqueous medium. The obtained data demonstrated that the structure is probably formed from four units of dodecylsulfate bonded to one paraquat moiety. The results showed that 94% of the paraquat present in 45 mL of a solution containing 3.90 × 10(-5) mol L(-1) could be retained by 300 mg of PUF, resulting in the removal of 2.20 mg of paraquat. The experimental data were reasonably adjusted to the Freundlich isotherm and to the pseudo-second-order kinetic model. Also, the application of Morris-Weber and Reichenberg models indicated that both film-diffusion and intraparticle-diffusion processes were active during the control of the adsorption kinetics.

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Molasses-based distilleries are one of the most polluting industries generating large volumes of high strength wastewater called vinasse. Different processes covering anaerobic, aerobic as well as physicochemical methods have been employed to treat this effluent. This study evaluated the microbial communities present in the vinasse during different stages of its treatment by traditional and molecular methods. The analysis of the efficiency of each treatment was performed by physicochemical parameters and toxicity analysis. The treatment of vinasse was performed in the following steps: high flow fermentation; filtration; chemical flakes; low-flow fermentation; filtration; and neutralization. The physicochemical analysis in different stages of the vinasse treatment demonstrated that phases of treatment influenced the performance of the evaluated parameters. Among the 37 parameters, 9 were within the limits established by the Commission for Environmental Policy of Minas Gerais, Brazil (COPAM), especially BOD (96.7% of pollution reduction), suspended solids (99.9%), pH, copper (88%), iron (92.9%), and manganese (88%). Some parameters, even after treatment, did not fit the maximum allowed by legislation. The microbial population decreased reaching 3 log CFU/ml present in the steps of the flakes chemical and disinfection treatment of vinasse. Lactobacillus brevis and Pichia kudriavzevii were present in all stages of the treatments, showing that these microorganisms were resistant and demonstrated that they might be important in the treatment of vinasse. The vinasse showed a significant reduction of pollution load after the disinfection treatment however still should not be discarded into water bodies because the high values of tannins and sediment solids, but suggest the use of the effluent in the cooling coil during the distillation process of the beverage.

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This work proposes the use of tree termite nest as an adsorbent for the reduction/removal of Cr(VI) present in aqueous solution. In laboratory experiments, adsorption of Cr(VI) was sensitive to pH in the range investigated (2-5), with maximum adsorption capacity achieved at pH 2 (3.70 ± 0.04 mg g(-1), representing 93.2% removal of Cr). The termite nest was characterized by off-line pyrolysis GC/MS (py-GC/MS), infrared spectroscopy (FTIR), and electron paramagnetic resonance spectroscopy (EPR). Pyrolysis of the adsorbent produced a complex mixture of aromatic compounds, including the guaiacyl and syringilic derivatives that are characteristic of lignocellulosic materials. Infrared spectroscopy revealed deprotonation of the carboxylic acid group of the biomass with increasing pH, which was associated with a decrease in the capacity for adsorption of Cr(VI). The EPR g-factor for the termite nest samples varied between 2.0037 and 2.0038, indicating the presence of organic free radicals that were responsible for the redox reaction. A second line with g-factor values of 1.9790, only observed for the samples after contact with Cr(VI) solutions at different pH values, was assigned to Cr(III)-Cr(III) exchange coupled pairs, which explained the capacity of the adsorbent to retain a large portion of the Cr(III) ions produced after reduction of Cr(VI) to Cr(III). Fixed-bed column experiments showed that the termite nest had a maximum adsorption capacity of 18.60 mg Cr g(-1), an adsorption efficiency varying between 60.8 and 97.4%, and a desorption efficiency varying between 54.5 and 91.4%, for three successive cycles. The adsorbent presented excellent performance in the removal of chromium under acidic conditions, with the advantage that it could be regenerated and reused.

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The growth of maritime transport and oil exploitation activities may increase the risk of oil spills. Thus, plans and actions to prevent or mitigate impacts are needed to minimize the effects caused by oil. However, tools used worldwide to support contingency plans have not been integrated, thus leading to failure in establishing priority areas. This investigation aimed to develop indices of environmental vulnerability to oil (IEVO), by combining information about environmental sensibility to oil and results of numerical modeling of spilled oil. To achieve that, a case study concerning to oil spills scenarios in a subtropical coastal area was designed, and IEVOs were calculated and presented in maps, in order to make the information about the areas' vulnerability more easily visualized. For summer, the extension of coastline potentially affected by oil was approximately 150 km, and most of the coastline presented medium to high vulnerability. For winter, 230 km coastline would be affected, from which 75% were classified as medium to high vulnerability. Thus, IEVO maps allowed a rapid and clearer interpretation of the vulnerability of the mapped region, facilitating the planning process and the actions in response to an oil spill.

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In this work, an adsorbent coal was characterized and its sorption properties for the removal of iron and manganese from aqueous solutions were determined. Energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD) identified the presence of quartz, magnetite and manganese oxide in the adsorbent coal. The results of the adsorption isotherms verified the adsorption of iron and manganese by adsorbent coal showing a linear behaviour and indicated that chemisorption and physisorption occurred. The kinetic results were best adjusted to the pseudo-second order model with a 0.999 correlation coefficient. The results showed that the adsorbent coal could be used efficiently for the removal of iron and manganese from aqueous solutions.

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The effectiveness of photolysis (UV), peroxidation (H(2)O(2)), peroxidation combined with UV light (UV/H(2)O(2)), Fenton reagent (H(2)O(2)/Fe(2+)), and the photo-Fenton process (H(2)O(2)/Fe(2+)/UV) at degrading the textile dye Reactive Blue 19 was evaluated. The efficiency of the photo-Fenton process for degrading raw textiles and biologically pre-treated effluents was also evaluated. H(2)O(2) (100-800 mg L(-1)) and UV light did not degrade dye when used separately. The UV/H(2)O(2) process was effective but slow: 91% of dye degraded within 3 h of reaction at a concentration of 500 mg L(-1) H(2)O(2). Fenton reagent reduced dissolved organic carbon by 36.8% and color was reduced by >98% within a few minutes of reaction. The photo-Fenton process was the most efficient, reducing 94.5% of dissolved organic carbon and 99.4% of color. The combination of a biological system and the photo-Fenton process degraded a high level of textile effluent degradation, reducing dissolved organic carbon by 88%, color by 85%, chemical oxygen demand by 80%, and biochemical oxygen demand by 93%.

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Since 1998 the highly polluted Havana Bay ecosystem has been the subject of a mitigation program. In order to determine whether pollution-reduction strategies were effective, we have evaluated the historical trends of pollution recorded in sediments of the Bay. A sediment core was dated radiometrically using natural and artificial fallout radionuclides. An irregularity in the (210)Pb record was caused by an episode of accelerated sedimentation. This episode was dated to occur in 1982, a year coincident with the heaviest rains reported in Havana over the XX century. Peaks of mass accumulation rates (MAR) were associated with hurricanes and intensive rains. In the past 60 years, these maxima are related to strong El Niño periods, which are known to increase rainfall in the north Caribbean region. We observed a steady increase of pollution (mainly Pb, Zn, Sn, and Hg) since the beginning of the century to the mid 90 s, with enrichment factors as high as 6. MAR and pollution decreased rapidly after the mid 90 s, although some trace metal levels remain high. This reduction was due to the integrated coastal zone management program introduced in the late 90 s, which dismissed catchment erosion and pollution.

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Determining reference concentrations in rivers and streams is an important tool for environmental management. Reference conditions for eutrophication-related water variables are unavailable for Brazilian freshwaters. We aimed to establish reference baselines for São Paulo State tropical rivers and streams for total phosphorus (TP) and nitrogen (TN), nitrogen-ammonia (NH(4) (+)) and Biochemical Oxygen Demand (BOD) through the best professional judgment and the trisection methods. Data from 319 sites monitored by the São Paulo State Environmental Company (2005 to 2009) and from the 22 Water Resources Management Units in São Paulo State were assessed (N = 27,131). We verified that data from different management units dominated by similar land cover could be analyzed together (Analysis of Variance, P = 0.504). Cumulative frequency diagrams showed that industrialized management units were characterized by the worst water quality (e.g. average TP of 0.51 mg/L), followed by agricultural watersheds. TN and NH(4) (+) were associated with urban percentages and population density (Spearman Rank Correlation Test, P < 0.05). Best professional judgment and trisection (median of lower third of all sites) methods for determining reference concentrations showed agreement: 0.03 & 0.04 mg/L (TP), 0.31 & 0.34 mg/L (TN), 0.06 & 0.10 mg-N/L (NH(4) (+)) and 2 & 2 mg/L (BOD), respectively. Our reference concentrations were similar to TP and TN reference values proposed for temperate water bodies. These baselines can help with water management in São Paulo State, as well as providing some of the first such information for tropical ecosystems.

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PURPOSE: Metal bioavailability-based sediment quality analysis, inferred from geochemical partitioning data, may contribute to improve sediment management policies. This is important because decision-making processes should not give similar priorities to sediments offering contrasting environmental risks associated to metal bioavailability. However, current uses of Sediment Quality Guidelines (SQGs) as interpretive tools to support decisions about dredging-related activities have not considered the changes in metal bioavailability upon sediment resuspension. METHODS: Sediments from a Cu-contaminated site in Guanabara Bay (Brazil) were submitted to 16-h resuspension experiments in estuarine water to assess the susceptibility of Cu mobilization to the dissolved phase and alteration in the solid phase partitioning between a potentially bioavailable (1 mol/l HCl-extractable) phase and concentrated HNO(3)-extractable phase. RESULTS: After sediment resuspensions, dissolved Cu levels became slightly lower (in a surface water-resuspension treatment) or slightly higher (in a bottom water-resuspension treatment). In both treatments, the 1 mol/l HCl-extractable solid phase concentrations changed from seven times lower to two times higher values than an SQG adopted in Brazilian legislation. This change was explained by a transition from concentrated HNO(3)-extractable phases to reactive HCl-extractable phases upon resuspension. CONCLUSIONS: An evaluation of metal susceptibility to present geochemical partitioning changes, as can be inferred from HCl-extractable fraction analyses before and after resuspension experiments, is recommended as an additional criterion to assess environmental risks of sediment dredging in relation to resuspension-sensitive metals, such as Cu.

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Intensive land development as a result of the rapidly growing tourism industry in the "Riviera Maya" region of the Yucatan Peninsula, Mexico may result in contamination of groundwater resources that eventually discharge into Caribbean coastal ecosystems. We deployed two types of passive sampling devices into groundwater flowing through cave systems below two communities to evaluate concentrations of contaminants and to indicate the possible sources. Pharmaceuticals and personal care products accumulated in the samplers could only have originated from domestic sewage. PAHs indicated contamination by runoff from highways and other impermeable surfaces and chlorophenoxy herbicides accumulated in samplers deployed near a golf course indicated that pesticide applications to turf are a source of contamination. Prevention and mitigation measures are needed to ensure that expanding development does not impact the marine environment and human health, thus damaging the tourism-based economy of the region.

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In 2008, the hypoxic zone in the Gulf of Mexico, measuring 20 720 km2, was one of the two largest reported since measurement of the zone began in 1985. The extent of the hypoxic zone is related to nitrogen and phosphorous loadings originating on agricultural fields in the upper Midwest. This study combines the tools of evolutionary computation with a water quality model and cost data to develop a trade-off frontier for the Upper Mississippi River Basin specifying the least cost of achieving nutrient reductions and the location of the agricultural conservation practices needed. The frontier allows policymakers and stakeholders to explicitly see the trade-offs between cost and nutrient reductions. For example, the cost of reducing annual nitrate-N loadings by 30% is estimated to be US$1.4 billion/year, with a concomitant 36% reduction in P and the cost of reducing annual P loadings by 30% is estimated to be US$370 million/year, with a concomitant 9% reduction in nitrate-N.

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An evaluation of the efficiency of bacterial biomass augmentation was performed at lab-scale for the pollution treatment of the Derby-Tacaruna canal. The canal is located at the central area of Great Recife, alongside an important urban corridor. The characterization of the canal water in different tidal conditions showed that the actual pollution is organic and inorganic (heavy metals). Degradation experiments of water from the canal and rain-off system polluted by synthetic wastewater were performed, using activated sludge and an industrial bioadditive. Continuous reactors under two different conditions were evaluated: with diffuse aeration and without aeration. The channel reactor was operated under steady state conditions at a flow rate of 2.5 L h(-1) and with an average residence time of 22 h without aeration and 17 h with aeration. The organic matter removal was in the range of 60% for the system inoculated with the bioadditive and 85% with activated sludge. It was concluded that the water of the Derby-Tacaruna canal may be treated by activated sludge without being affected by its salt content, while the bioaugmentation technique was not satisfactory due to inhibition by inorganics.

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The potential of the H2O2/UV process for improving quality of an industrial textile effluent before biological treatment was evaluated in the laboratory using a multivariate experimental design to determine the effects of pH, H2O2 dose and reaction time on colour, COD and toxicity removal efficiencies. Increasing reaction time (from 10 to 120 min) and H2O2 dose (from 0 to 5 mmol L(-1)) significantly improved removal efficiencies, while increasing pH (from 4 to 10) had a negative effect on colour and toxicity removals. Laboratory H2O2/UV treatment of the mill effluent under optimum conditions (pH 7, 5 mmol L(-1) H2O2, 120 min) resulted in decreases in colour (70%), COD (21%) and toxicity (67%), without lowering BOD. H2O2 was consumed within the first 30-60 min, while the effluent average oxidation state stabilized after 60 min. Decreasing reaction time to 60 min resulted in similar colour (63%) and COD (20%) removals but lower toxicity removal (44%). Spectrophotometric monitoring of the optimized reaction indicated partial destruction of residual aromatic azo dyes. H2O2 and residual peroxide and average oxidation state of the effluent Effluent biodegradability (BOD/COD) increased by 28% after the H2O2/UV treatment. Improvements observed in effluent quality are expected to enhance combined AOP-biological treatment efficiency of the mill effluent.

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The determination of the optimal conditions for using electrocoagulation as a treatment for landfill leachate was carried out using surface response methodology. A central composite design was applied to investigate the effect of four control factors, namely current density, pH, time and fluid conductivity, as well as the interaction among (between) them to get an optimal turbidity removal. The independent variables were each coded at three levels and their values were selected on the basis of preliminary experimental results. The central composite design consisted of 29 experimental points with five replications at the centre point. A second order polynomial model was used for predicting the response. Regression analysis showed that more than 95% of the variation was explained by the model wherein current density with a 60.1% contribution turned out to be the factor with the most significant influence. Analysis of variance showed that time, pH, current density and the interaction time/current density had a significant influence on the turbidity removal, The optimal conditions obtained for the removal of turbidity were time 38.8 min, pH 7.6, current density 109.9 A m(-2) and NaCl 2.9 g L(- 1). Experimental results showed that for a 96.9% turbidity removal, similar reduction in Al (97.0%) and Fe (99.5%) concentrations; as well as 66% total Kjeldahl nitrogen removal were obtained. Furthermore, the sludge formed exhibited a good floc size, which separated in less than 10 min by classical sedimentation. The results analysis provided evidence of reduction of chemical pollutants, although the electrocoagulated leachate could not satisfy regulations for the maximum Total Kjeldahl nitrogen leachate discharge level to public wastewater collection systems in the town of Freire, Chile.

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