Removal of phosphorus by modified bentonite:polyvinylidene fluoride membrane-study of adsorption performance and mechanism.

Enhanced phosphorus management, geared towards sustainability, is imperative due to its indispensability for all life forms and its close association with water bodies' eutrophication, primarily stemming from anthropogenic activities. In response to this concern, innovative technologies rooted in the circular economy are emerging, to remove and recover this vital nutrient to global food production. This research undertakes an evaluation of the dead-end filtration performance of a mixed matrix membrane composed of modified bentonite (MB) and polyvinylidene fluoride (PVDF) for efficient phosphorus removal from water media. The MB:PVDF membrane exhibited higher permeability and surface roughness compared to the pristine membrane, showcasing an adsorption capacity (Q) of 23.2 mgP·m-2. Increasing the adsorbent concentration resulted in a higher removal capacity (from 16.9 to 23.2 mgP·m-2) and increased solution flux (from 0.5 to 16.5 L·m-2·h-1) through the membrane. The initial phosphorus concentration demonstrates a positive correlation with the adsorption capacity of the material, while the system pressure positively influences the observed flux. Conversely, the presence of humic acid exerts an adverse impact on both factors. Additionally, the primary mechanism involved in the adsorption process is identified as the formation of inner-sphere complexes.

Source apportionment and health impact assessment of atmospheric particulate matter in the city of São Carlos, Brazil.

In this study, positive matrix factorization method was used for source apportionment of PM10 in the city of São Carlos from 2015 to 2018. The annual mean concentrations of PM10, 15 PAHs, 4 oxy-PAHs, 6 nitro-PAHs, 21 saccharides, and 17 ions in these samples were in the ranges 18.1 ± 6.99 to 25.0 ± 11.3 µg m-3 for PM10, 9.80 × 10-1 ± 2.06 to 2.03 ± 8.54 × 10-1 ng m-3 for ΣPAHs, 83.9 ± 35.7 to 683 ± 521 pg m-3 for Σoxy-PAHs, 1.79 × 10-2 ± 1.23 × 10-1 to 7.12 ± 4.90 ng m-3 for Σnitro-PAHs, 83.3 ± 44.7 to 142 ± 85.9 ng m-3 for Σsaccharides, and 3.80 ± 1.54 to 5.66 ± 4.52 µg m-3 for Σions. For most species, the concentrations were higher in the dry season than in the rainy. This was related not only to the low rainfall and relative humidity characteristic of the dry season but also to an increase in fire spots recorded in the region between April and September every year from 2015 to 2018. A 4-factor solution provided the best description of the dataset, with the four identified sources of PM10 being soil resuspension (28%), biogenic emissions (27%), biomass burning (27%), and vehicle exhaust together with secondary PM (18%). Although the PM10 concentrations were not above the limit established by local legislation, the epidemiological study showed that by reducing PM2.5 concentrations to the level recommended by the WHO, approximately 35 premature deaths per 100,000 population could be avoided annually. The results revealed that biomass burning continues to be one of the main anthropic sources of emissions to the atmosphere in the region, so it needs to be incorporated into the existing guidelines and policies to reduce the concentration of particulate matter to within the limits recommended by the WHO, in order to avoid premature deaths.

Toxicity of the sawdust used for phosphorus recovery in a eutrophic reservoir: experiments with Lactuca sativa and Allium cepa.

Eutrophication is one of the environmental problems arising from the increase of essential nutrient concentrations, mainly phosphorus and nitrogen. In contrast to excess phosphorus, the depletion of phosphate rock deposits used for the production of fertilizers compromises the food supply. Therefore, the development of technologies that propose the recovery of the phosphorus contained in eutrophic environments for its later use for agricultural fertilization purposes is very important to ensure global food security. This work aimed to evaluate the toxic potential of the sawdust (biosorbent previously used for phosphorus adsorption) in order to enable its application in agriculture. For this, toxicity experiments with Lactuca sativa (lettuce) and Allium cepa (onion) seeds were performed. The phytotoxic potential was assessed by means of the seed germination index and physiological parameters such as radicle and hypocotyl growth. Cytotoxicity, genotoxicity, and mutagenicity tests were also performed on onion seeds. From statistical tests, it was possible to affirm that the sawdust did not promote inhibition of seed germination and radicle and hypocotyl growth. No genotoxicity, cytotoxicity and, mutagenicity were observed, which allowed to state that the sawdust is not toxic to the onion species, which reinforces the possibility of application of the biosorbent for soil fertilization purposes. Therefore, the use of sawdust for phosphorus biosorption with the subsequent agricultural application is promising and quite important from a global food security point of view.

Development of a simple method to quantify fipronil and its intermediates in soil.

A simple and reproducible method was developed and validated for simultaneous quantification of the pesticide fipronil and its intermediates fipronil desulfinyl, fipronil sulfone and fipronil sulfide, in soil. The analytes were extracted by ultrasonic bath and the ratio of solvents (hexane/acetone), number and time of cycles were optimized by Box-Behnken design with a triplicate central point. The optimal extraction conditions were achieved through a response surface analysis. The clean-up step was conducted by cartridges of solid phase extraction (SPE) containing silica (Florisil®) and aluminum oxide. Gas chromatography with electron capture detection (GC-ECD) was employed for separating fipronil and its intermediates with a suitable resolution and runtime of 20 minutes. The best quantification was achieved with 1 : 1 (v/v) acetone/hexane and 2 ultrasound cycles of 15 minutes each. The recovery values were between 81 to 108%, with relative standard deviation (RSD) lower than 6%, with no effect of the used matrix. Analytical curves presented regression coefficients values above 0.9908 for a concentration range from 0.005 to 0.6 µg g-1. Limits of detection (LOD) from 0.002 to 0.006 µg g-1 and limits of quantification (LOQ) from 0.006 to 0.020 µg g-1 were reached for all analytes. This method can be used to monitor and quantify fipronil and its intermediates in soil.

Equilibrium and kinetic studies of the adsorption of antibiotics from aqueous solutions onto powdered zeolites.

The performances of two FAU-type zeolites with different SiO2/Al2O3 ratios were evaluated for the removal of antibiotics of three different classes, namely azithromycin, ofloxacin, and sulfamethoxazole, from aqueous solutions. Commercial zeolites were used, without any previous treatment. Use of a small adsorbent dosage resulted in fast antibiotic adsorption that followed pseudo-second order kinetics. The removals of azithromycin and sulfamethoxazole were highly pH-dependent, with low removal percentages observed under acid (pH 2.5-4.5) and basic (pH 8.5-10.5) conditions, respectively. The Freundlich isotherm model provided the best fits to the adsorption data. The adsorption mechanisms appeared to involve both electrostatic and H-bonding interactions. Using an antibiotics mixture, percentage removals of azithromycin and ofloxacin onto the zeolites of up to 79% were obtained. Both materials presented good adsorption (>50%) of azithromycin and ofloxacin from a real sample of effluent wastewater. The results showed that zeolites with FAU structure can be used as effective adsorbents for the removal of antibiotics with different physicochemical properties, including molecules with large volumes, such as azithromycin.

Spatio-temporal evaluation of emerging contaminants and their partitioning along a Brazilian watershed.

The occurrence, partitioning, and spatio-temporal distribution of seven pharmaceuticals for human use, three steroid hormones and one personal care product were determined in surface water, suspended particulate matter (SPM), and sediment of Piraí Creek and Jundiaí River (Jundiaí River Basin, São Paulo, Brazil). The maximum average detected concentrations of the compounds in the Piraí River samples were < 30 ng L-1, except for caffeine (222 ng L-1). In Jundiaí River samples, most of the compounds were frequently detected, wherein caffeine had the highest concentration, with maximum average concentrations of 14,050 ng L-1, followed by atenolol (431 ng L-1), ibuprofen (268 ng L-1) and diclofenac (214 ng L-1). Atenolol, propranolol, estrone, and triclosan were the contaminants most frequently detected in sediment and SPM samples. Triclosan had the highest average proportion of SPM as opposed to in the aqueous phase (> 75%). Contaminants with acid functional groups showed, in general, a lower tendency to bind to particulate matter and sediments. In addition, hydrophobicity had an important effect on their environmental partitioning. The spatial distribution of contaminants along the Jundiaí River was mainly affected by the higher concentration of contaminants in water samples collected downstream from a sewage treatment plant (STP). The results obtained here clearly showed the importance of the analysis of some contaminants in the whole water, meaning both dissolved and particulate compartments in the water, and that the partitioning is ruled by a set of parameters associated to the physicochemical characteristics of contaminants and the matrix properties of the studied, which need be considered in an integrated approach to understand the fate of emerging chemical contaminants in aquatic environments.

Multivariate analyses of the effect of an urban wastewater treatment plant on spatial and temporal variation of water quality and nutrient distribution of a tropical mid-order river.

Freshwater resources are increasingly scarce due to human activities, and the understanding of water quality variations at different spatial and temporal scales is necessary for adequate management. Here, we analyze the hypotheses that (1) the presence of a wastewater treatment plant (WWTP) and (2) a polluted tributary that drains downstream from the WWTP change the spatial patterns of physicochemical variables (pH, turbidity, dissolved oxygen, and electrical conductivity) and nutrient concentrations (reactive soluble phosphorus, total phosphorus, nitrogen series, total nitrogen, and total dissolved carbon) along a mid-order river in SE Brazil and that these effects depend on rainfall regime. Six study sites were sampled along almost 4 years to evaluate the impacts of human activities, including sites upstream (1-3) and downstream (5-6) from the WWTP. The impacts were observed presenting an increasing trend from the source (site 1) towards Água Quente stream (site 4, the polluted tributary), with signs of attenuation at site 5 (downstream from both WWTP and site 4) and the river mouth (site 6). Input of nutrients by rural and urban runoff was observed mainly at sites 2 and 3, respectively. At sites 4 and 5, the inputs of both untreated and treated wastewaters increased nutrient concentrations and changed physicochemical variables, with significant impacts to Monjolinho River. Seasonal variations in the measured values were also observed, in agreement with the pluviometric indexes of the region. Univariate analyses suggested no effect of the WWTP for most variables, with continued impacts at sites downstream, but non-parametric multivariate analysis indicated that these sites were recovering to chemical characteristics similar to upstream sites, apparently due to autodepuration. Therefore, multivariate methods that allow rigorous tests of multifactor hypotheses can greatly contribute to determine effects of both point and non-point sources in river systems, thus contributing to freshwater monitoring and management.

Ion Imprinted Polymer for Preconcentration and Determination of Ultra-Trace Cadmium, Employing Flow Injection Analysis with Thermo Spray Flame Furnace Atomic Absorption Spectrometry.

This work proposes a preconcentration method using an ion imprinted polymer (IIP) for determination of cadmium, in several samples, employing a mini-column filled with the polymer coupled into a flow injection analysis system with detection by thermospray flame furnace atomic absorption spectrometry (FIA-TS-FF-AAS). The polymer was synthesized via bulk using methacrylic acid and vinylimidazole as a functional monomer. For the FIA system initial assessment, the variables: pH, eluent concentration and buffer concentration were studied, employing a 23 full factorial design. To obtain the optimum values for each significant variable, a Doehlert matrix was employed. After the optimization conditions as: pH 5.8, eluent (HNO3) concentration of 0.48 mol L-1 and buffer concentration of 0.01 mol L-1, were adopted. The proposed method showed a linear response in the range of 0.081-10.0 µg L-1, limits detection and quantification of 0.024 and 0.081 µg L-1, respectively; preconcentration factor of 165, consumptive index of 0.06 mL, concentration efficiency 132 min-1, and frequency of readings equal to 26 readings h-1 The accuracy was checked by analysis of certified reference materials for trace metals and recovery tests. The obtained results were in agreement with 95% confidence level (t-test). The method was adequate to apply in samples of: jewelry (earrings) (2.38 ± 0.28 µg kg-1), black tea (1.09 ± 0.15 µg kg-1), green tea (3.85 ± 0.13 µg kg-1), cigarette tobacco (38.27 ± 0.22 µg kg-1), and hair (0.35 ± 0.02 µg kg-1).

Ultrasound-assisted extraction method for the simultaneous determination of emerging contaminants in freshwater sediments.

Sediments are the fate of several emerging organic contaminants, such as pharmaceuticals, personal care products and hormones, and therefore an important subject in environmental monitoring studies. In the present work, a simple and sensitive method was developed, validated and applied for the simultaneous extraction of atenolol, caffeine, carbamazepine, diclofenac, ibuprofen, naproxen, propranolol, triclosan, estrone, 17-ß-estradiol and 17-α-ethinylestradiol using ultrasound-assisted extraction from freshwater sediment samples followed by solid-phase extraction clean-up and liquid chromatography with tandem mass spectrometry detection. The solvent type and extraction pH were evaluated to obtain the highest recoveries of the compounds. The best method shows absolute recoveries between 54.0 and 94.4% at 50 ng/g concentration. The method exhibits good precision with relative standard deviation ranging from 1.0-16%. The detection and quantification limits ranged from 0.006-0.067 and 0.016-0.336 ng/g, respectively. The developed method was successfully applied to freshwater sediment samples collected from different sites in Jundiaí River basin of São Paulo State, Brazil. The compounds atenolol, caffeine, propranolol and triclosan were detected in all the sampling sites with concentrations of 13.8, 41.0, 28.5 and 176 ng/g, respectively.

Electrical conductivity and emerging contaminant as markers of surface freshwater contamination by wastewater.

The use of chemical markers of undoubted anthropogenic sources for surface freshwater contamination by wastewaters was evaluated employing correlations observed between measured physico-chemical parameters as the electrical conductivity and the concentration of different emerging organic compounds. During the period from April/2011 to April/2012 spatial-temporal variations and contamination patterns of two rivers (Piraí and Jundiaí rivers), São Paulo state, Brazil were evaluated. Seven physico-chemical parameters and concentrations of different classes of emerging contaminants were determined in samples collected in seven field campaigns. The high linear correlation coefficients obtained for the compounds diclofenac (r=0.9085), propanolol (r=0.8994), ibuprofen (r=0.8720) and atenolol (r=0.7811) with electrical conductivity, also corroborated by principal component analysis (PCA), point to the potential use of these compounds as markers of investigated surface water contamination by wastewaters. Due to specific inputs, these environmental markers showed very good effectiveness for the identification and differentiation of water body contamination by discharges of treated and untreated urban sewage.

Desnitrificacao em um sistema simplificado de tratamento de esgoto / Denitrification in a simple wastewater treatment system

Nesta pesquisa, foram operados três filtros anaeróbios com tempo de detenção hidráulica nominal de nove horas, sendo o efluente gerado disposto nos leitos de quatro filtros de areia em distintas taxas de aplicações. No primeiro filtro de areia, foram aplicados 50 L.m-2 uma vez por dia. No segundo, terceiro e quarto filtros, essa mesma carga foi disposta em 2, 3 e 4 horários, com aplicações espaçadas entre as 9h e as 16h, correspondendo às taxas de 100, 150 e 200 L.m-2.dia-1. Após a passagem pelo leito de areia, o efluente era encaminhado para reatores de desnitrificação preenchidos com brita 1. Os filtros de areia apresentaram uma grande capacidade de nitrificação e, após a adição da fonte externa de carbono, o reator de desnitrificação que recebia uma única disposição diária de 50 L.m-2 propiciou uma diminuição na concentração de N-total de 43,5%.

In this research, three anaerobic filters were operated with a 9 hour hydraulic detention time, and its effluent was disposed on four sand filters' bed in different application rates. On the first sand filter, 50 L.m-2 were disposed once a day. On the second, the third and the fourth filters, the same load was disposed in twice, three and four times a day, distributed between 9 am and 4 pm, corresponding to rates of 100, 150 and 200 L.m-2.d-1. After the sand filter, the effluent was conducted to the denitrification reactors filled up with grit. As result, the sand filters have shown a great nitrification capacity and, after the external carbon adding, the denitrification reactor, where 50 L.m-2 was disposed a day, showed a decrease of 43.5% in N-total concentration.

Determination of selenium using atomically imprinted polymer (AIP) and hydride generation atomic absorption spectrometry.

This paper describes selenium determination based on Se(0) preconcentration in the imprinted polymer (synthesized with 2.25mmol SeO2, 4-vinylpyridine and 1-vinylimidazole) with subsequent detection on-line in HG-FAAS. During the synthesis, SeO2 is reduced to Se (0). Therefore, there are no MIP neither IIP in the present work, thus we denominated: AIP, i.e., atomically imprinted polymers. For the optimization of analytical parameters Doehlert design was used. The method presented limit of detection and limit of quantification of 53 and 177ngL(-1), respectively, and linear range from 0.17 up to 6µgL(-1) (r=0.9936). The preconcentration factor (PF), consumptive index (CI) and concentration efficiency (CE) were 232; 0.06mL and 58min(-1) respectively. The proposed method was successfully applied to determine Se in Brazil nuts (0.33±0.03mgkg(-1)), apricot (0.46±0.02mgkg(-1)), white bean (0.47±0.03mgkg(-1)), rice flour (0.47±0.02mgkg(-1)) and milk powder (0.22±0.01mgkg(-1)) samples. It was possible to do 12 analyzes per hour. Accuracy was checked and confirmed by analyzing certified reference material (DORM-2, dogfish muscle), and samples precision was satisfactory with RSD lower than 10%.

Degradation of formaldehyde by advanced oxidation processes.

The degradation of formaldehyde in an aqueous solution (400 mg L(-1)) was studied using photolysis, peroxidation and advanced oxidation processes (UV/H(2)O(2), Fenton and photo-Fenton). Photolysis was the only process tested that did not reduce formaldehyde concentration; however, only advanced oxidation processes (AOPs) significantly decreased dissolved organic carbon (DOC). UV/H(2)O(2) and photo-Fenton AOPs were used to degrade formaldehyde at the highest concentrations (1200-12,000 mg L(-1)); the processes were able to reduce CH(2)O by 98% and DOC by 65%. Peroxidation with ultraviolet light (UV/H(2)O(2)) improved the efficiency of treatment of effluent from an anatomy laboratory. The effluent's CH(2)O content was reduced by 91%, DOC by 48%, COD by 46% and BOD by 53% in 420 min of testing.

Ozonização em meio básico para redução de cor do licor negro de indústria de celulose de algodão / Color reduction of black liquor from cotton cellulose industry using ozonation in an alkaline medium

As indústrias de papel e celulose descartam no ambiente um grande volume de efluente contendo grande quantidade da substância lignina, que atribui coloração e apresenta considerável potencial de toxicidade. Neste trabalho, foi avaliada a ozonização em meio básico para a redução de cor do licor negro gerado por uma indústria de celulose de algodão. Face aos resultados, foi possível observar que, para menores concentrações iniciais de ozônio (0,4 gO3 L-1 h-1), foi necessário um tempo mais longo de ozonização para se obter a redução desejada de 80 por cento da cor. O consumo específico de ozônio, entretanto, em comparação a experimentos com dosagens mais elevadas (4,3 gO3 L-1 h-1) foi menor. Sugere-se que o oxigênio molecular desempenhe, também, um importante papel na oxidação dos compostos, participando do mecanismo de oxidação iniciado por radical hidroxila, •OH, formado na ozonização em meio básico.

Pulp and paper mills discharge large amounts of wastewater containing high concentrations of lignin, a coloring substance that is dangerous and presents high toxicity to the environment. In this study, ozonation in alkaline ambience was evaluated for color reduction in black liquor, generated in a cotton linter mill. It was observed that the ozonation time to reach 80 percent color reduction was higher at a lower initial ozone dose (0,4 gO3 L-1 h-1) in comparison to a higher initial ozone dose (4,3 gO3 L-1 h-1). On the other hand, the amount of consumed oxidant was lower at the lower ozone dose. It is suggested that molecular oxygen participates in the oxidation mechanism of colored compounds, which is initiated by hydroxyl radicals (•OH) formed during ozonation in alkaline ambience.

Elemental gaseous mercury flux at the water/air interface over the Negro River basin, Amazon, Brazil.

The amount of dissolved gaseous mercury (DGM) released annually into the atmosphere by water bodies in each of the 18 major sub-basins of the Negro River tributaries has been estimated for the wet season and adopted for the entire year. Using Remote Sensors (RS) and the Geographic Information System (GIS), an estimate was made for the total flooded area during the period of the wet season (May-July), which corresponds to around 10% of the total basin area. The estimates of DGM evasive flux values were made during four scientific campaigns and ranged from 0.09 to 14 mug m(-2) y(-1). Mercury wet deposition to the same area was estimated using average values of the metal concentration in the rainwater (9.8 ng L(-1)), which varies from 17 to 27 microg m(-2) year(-1). Considering the flooded area of the Negro River Basin as 69,000 km(2), the total amount of mercury emitted by all bodies of water reaches nearly 0.26 ton year(-1), which represents not more than 2% of the total mercury found in wet deposition in this same area.