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1.
Sci Total Environ ; 819: 153152, 2022 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-35041954

RESUMO

This work deals with microcontaminants (MCs) removal by natural solar zero-valent iron (ZVI) process at natural pH in actual matrices. Commercial ZVI microspheres were selected as ZVI source and hydrogen peroxide and persulfate were used as oxidant agents. The experimental plan comprised the evaluation of sulphates and carbonates/bicarbonates effect on process performance, the possibility of adding an iron chelate (EDDS) to take advantage of leached iron and the treatment of MCs in actual MWWTP secondary effluent. The presence of sulphates and EDDS addition did not lead to significant changes in the process efficiency, while the carbonates naturally present in natural water (458 mg/L) diminished the treatment time need to reach the decontamination goal. Finally, the treatment of a MCs mixture consisting of Atrazine, Carbendazim, Imidacloprid, and Thiamethoxam in the range of µg/L in actual MWWTP secondary effluent by solar/msZVI/H2O2 and solar/msZVI/S2O82- obtained 7 and 22% of total removal after 180 min, respectively, which indicated a moderate competitiveness of these processes with respect to other advanced oxidation processes.


Assuntos
Ferro , Poluentes Químicos da Água , Peróxido de Hidrogênio , Concentração de Íons de Hidrogênio , Oxidantes , Oxirredução , Água , Poluentes Químicos da Água/análise
2.
Chemosphere ; 286(Pt 1): 131557, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34293562

RESUMO

Solar zerovalent iron (ZVI) was studied at circumneutral pH in combination with hydrogen peroxide and persulfate for removal of imidacloprid as a model contaminant in natural water. Three commercial ZVI sources, steel wool (ZVI-SW) and two iron micro-powders (ZVI-MS and ZVI-S) were independently evaluated. First, different ZVI corrosion conditions were tested in contact with air, exposed to natural solar radiation and with addition of oxidants, such as H2O2 and S2O82-, demonstrating the importance of released iron. Then, the technical feasibilities of solar/H2O2/ZVI and solar/S2O82-/ZVI were assessed for the elimination of 1 mg/L of imidacloprid. In general, H2O2 concentrations and treatment times were high. Only ZVI-MS (1 mM) reached 80% imidacloprid degradation after 157 min and 3 mM (102 mg/L) of H2O2. Solar/S2O82-/ZVI performance was better, reaching >80% imidacloprid degradation in <60 min with 1 mM (192 mg/L) S2O82- for all ZVI sources. Efficiency was highest with ZVI-MS, which was therefore selected for feasibility testing of a microcontaminant (MC) mixture containing 100 µg/L each of atrazine, carbendazim, imidacloprid and thiamethoxam with both solar/oxidizing agents/ZVI. H2O2 took 180 min to achieve 76% degradation of the sum of MCs, while 80% total degradation was reached after 69 min by adding S2O82-, confirming its higher efficiency. Finally, this study showed that ZVI in combination with solar radiation does not enhance significantly the photocatalytic cycle.


Assuntos
Energia Solar , Poluentes Químicos da Água , Peróxido de Hidrogênio , Concentração de Íons de Hidrogênio , Ferro , Água , Poluentes Químicos da Água/análise
3.
Chemosphere ; 279: 130560, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34134406

RESUMO

The application of electrochemical processes for wastewater treatment has increase significantly in the last two decades. However, most of the works are focused on lab-scale systems testing in saline simulated solutions spiked with a reference organic compound, evidencing the scarcity of studies on actual wastewaters through a more realistic practical approach. The aim of the present work is assessing the performance of electrochemical treatments in actual matrices, considering the formation of different oxidants species, apart from hydroxyl radicals, from dissolved ions contained in target effluents as well as both, the regeneration of Fe2+ and their combination with a light irradiation source. The degradation of a mix of microcontaminants in water matrices with different complexity by solar photoelectron-Fenton at natural pH and at pilot scale has been carried out at Plataforma Solar de Almería. Higher degradation rates were obtained when focusing on the more complex and saline matrices. In addition, complex industrial wastewaters mineralization was also studied by means of solar assisted electro-oxidation, showing the crucial role of ammonium concentration in the effluent, since it acts as a competitor for active chlorine species and so reducing the mineralization rate.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Peróxido de Hidrogênio , Ferro , Oxirredução , Águas Residuárias
4.
Chemosphere ; 275: 129962, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33652284

RESUMO

Autopsy of carbon-PTFE cathodes was performed by addressing their degradation in a commercial plate-and-frame cell equipped with a Nb-BDD anode. Cell is arranged within an electrochemical pilot plant designed for treating wastewaters by electrochemical Fenton-like processes, thus an efficient electrocatalytic production of H2O2 is necessary to guarantee Fenton's reaction. Significant decrease in H2O2 electrogeneration occurred during pilot plant operation, hindering the efficient performance of Fenton-like processes. Two cathodes were studied, first was operated at pH 3 and second at neutral pH by using EDDS as complexing agent to maintain iron in solution. Electrogenerated H2O2 decreased from 43 mg L-1 to 16 mg L-1 in the first cathode after 50 h of operation and from 49 mg L-1 to 24 mg L-1 in the second one after 26 h of operation. Both were cleaned with 30% (v/v) solution of HCl/water for 24 h and H2O2 production was recovered only in the second cathode (able to generate 39 mg L-1). Autopsy of the cathodes was tackled by scanning electron microscopy (SEM) and X-ray energy dispersive (EDX), evidencing a strong degradation of first cathode surface and iron oxide inlays in second one due to the decomposition of Fe3+:EDDS and consequent iron precipitation at neutral pH.


Assuntos
Peróxido de Hidrogênio , Poluentes Químicos da Água , Carbono , Eletrodos , Oxirredução
5.
J Hazard Mater ; 384: 121372, 2020 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-31610347

RESUMO

Conventional wastewater treatments are not usually effective in the remediation of specific landfill leachates due to their high content in toxic and recalcitrant compounds. Advanced and intensive treatments are needed for the decontamination and possible recycling of these effluents. Here, the combination of advanced oxidation processes (solar photo-Fenton) and an aerobic biological reactor have been applied to treat urban landfill leachates. The effectiveness of the proposed treatment line was also evaluated considering the removal of organic microcontaminants (OMCs) identified in the different phases, which is an innovative practice. The analytical strategy included: (i) a target approach (115 analytes) by liquid chromatography-mass spectrometry (LC-MS/MS); and two suspect approaches using (ii) LC-high-resolution MS (database with >1300 compounds) and (iii) gas-chromatography-MS (database with >900 compounds). OMCs on the treated landfill leachate was reduced up to 94% of the initial concentration. 8 target compounds (mainly pharmaceuticals) out of 115 target analytes represented 85% of the OMC concentration in the raw leachate: cotinine, diclofenac, gabapentin, ketoprofen, lidocaine, mecoprop, nicotine and trigonelline. 3 non-previously reported OMCs were confirmed: di-n-nonyl phthalate, o-phenylphenol and tonalide. Leachate partially oxidized by solar photo-Fenton process can be successfully incorporated to biological systems to complete the treatment by means of specifically adapted biomass.

6.
Sci Total Environ ; 705: 135831, 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-31818565

RESUMO

Industrial wastewaters characterized by its high content in organics and conductivity entails a challenge for conventional treatments due to its low biodegradability. Electro-oxidative processes have been successfully applied for the treatment of this kind of wastewaters achieving high organics and ammonia removal. The degradation process is executed mainly by electrochemically generated active chlorine species, as HClO and ClO- with E0 = 1.49 V; and E0 = 0.89 V, respectively. Under solar radiation, specifically at 313 nm, the formation of Cl (E0 = 2.4 V) from ClO- is promoted, improving the oxidizing capacity of the process. In this work the combination of an electrochemical device with a solar photo-reactor has been evaluated aiming to increase the degradation rate per kWh-1. Two different complex industrial wastewaters were tested, achieving higher organics degradation when electrochemical treatment was assisted by solar light. Toxicity reduction was also assessed and biodegradability enhanced and allowing its ulterior lower-cost biological treatment.

7.
Sci Total Environ ; 687: 567-576, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31216510

RESUMO

This paper contains a multidisciplinary approach that will contribute to design and properly evaluate a treatment line for complex biorecalcitrant wastewaters. To demonstrate this approach a specific industrial wastewater (cork boiling wastewater, CBW) was used. A treatment line based on a coagulation-flocculation step followed by an Advanced Oxidation Process (AOP) (solar photo-Fenton) and combined with an aerobic biological system was evaluated. Applied microbiological techniques: optical microscopy, plate count, DNA extraction and qPCR, indicated that some communities disappeared after the activated sludge adaptation period to the partially treated wastewater, while communities that did not disappear were damaged: 2-log reduction of total heterotrophic bacteria (THB) and a decrease in DNA concentration from 200 ng/µL to 65 ng/µL were observed. Therefore, chemical and microbiological results obtained along the set of experiments, suggested the inefficiency of the combined treatment option between solar photo-Fenton and advanced aerobic biological systems for CBW. This led to the necessity of applying solar photo-Fenton without combining with biotreatment and with the objective of improving the effluent quality enough for being reused in the own industry. Toxicity tests, based on different organisms (after coagulation-flocculation followed by solar photo-Fenton), showed increase on acute toxicity (from 46% to 71% by respirometric assays) and the development of chronic toxicity (from 21-29% to 83-90% also measured by respirometric assays), made evident the incompatibility of this type of wastewater with a biological treatment even after the application of an AOP.


Assuntos
Resíduos Industriais/análise , Eliminação de Resíduos Líquidos/métodos , Floculação , Esgotos , Águas Residuárias/química , Poluentes Químicos da Água/análise
8.
J Hazard Mater ; 372: 137-144, 2019 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-29567303

RESUMO

The aim of this work was to investigate the treatment of the artificial sweetener saccharin (SAC) in a solar compound parabolic collector pilot plant by means of the photo-Fenton process at pH 2.8. Olive mill wastewater (OMW) was used as iron chelating agent to avoid acidification of water at pH 2.8. For comparative purposes, Ethylenediamine-N, N-disuccinic acid (EDDS), a well-studied iron chelator, was also employed at circumneutral pH. Degradation products formed along treatment were identified by LC-QTOF-MS analysis. Their degradation was associated with toxicity removal, evaluated by monitoring changes in the bioluminescence of Vibrio fischeri bacteria. Results showed that conventional photo-Fenton at pH 2.8 could easily degrade SAC and its intermediates yielding k, apparent reaction rate constant, in the range of 0.64-0.82 L kJ-1, as well as, eliminate effluent's chronic toxicity. Both OMW and EDDS formed iron-complexes able to catalyse H2O2 decomposition and generate HO. OMW yielded lower SAC oxidation rates (k = 0.05-0.1 L kJ-1) than EDDS (k = 2.21-7.88 L kJ-1) possibly due to its higher TOC contribution. However, the degradation rates were improved (k = 0.13 L kJ-1) by increasing OMW dilution in the reactant mixture. All in all, encouraging results were obtained by using OMW as iron chelating agent, thus rendering this approach promising towards the increase of process sustainability.


Assuntos
Peróxido de Hidrogênio/química , Quelantes de Ferro/análise , Ferro/química , Sacarina/análise , Luz Solar , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Etilenodiaminas/química , Olea , Projetos Piloto , Succinatos/química , Eliminação de Resíduos Líquidos/métodos
9.
J Hazard Mater ; 372: 129-136, 2019 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-29588104

RESUMO

The main purpose of this pilot plant study was to compare degradation of five microcontaminants (MCs) (antipyrine, carbamazepine, caffeine, ciprofloxacin and sulfamethoxazole at 100 µg/L) by solar photo-Fenton mediated by EDDS and solar/Fe:EDDS/S2O82-. The effects of the Fe:EDDS ratio (1:1 and 1:2), initial iron species (Fe(II) or Fe(III) at 0.1 mM) and oxidizing agent (S2O82- or H2O2 at 0.25-1.5 mM) were evaluated. The higher the S2O82- concentration, the faster MC degradation was, with S2O82- consumption always below 0.6 mM and similar degradation rates with Fe(II) and Fe(III). Under the best conditions (Fe 0.1 mM, Fe:EDDS 1:1, S2O82- 1 mM) antipyrine, carbamazepine, caffeine, ciprofloxacin and sulfamethoxazole at 100 µg/L where 90% eliminated applying a solar energy of 2 kJ/L (13 min at 30 W/m2 solar radiation <400 nm). Therefore, S2O82- promotes lower consumption of EDDS as Fe:EDDS 1:1 was better than Fe:EDDS 1:2. In photo-Fenton-like processes at circumneutral pH, EDDS with S2O82- is an alternative to H2O2 as an oxidizing agent.

10.
Ecotoxicol Environ Saf ; 166: 123-131, 2018 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-30265875

RESUMO

In cork industry, the operation of boiling raw cork generates large volumes of wastewater named Cork Boiling Wastewater (CBW). The main characteristics are the low biodegradability and medium to low acute toxicity, resulting in the necessity of designing advanced biological treatments by possible conventional activated sludge adaptation. In order to evaluate the variation of bacterial population along that process, a study based on optical microscopy, plate count, DNA extraction, qPCR and massive sequencing techniques was performed. Results showed a diminution of the total and volatile solids (TSS and VSS), jointly with a decrease in DNA concentration, general bacteria (16 S) and ammonia-oxidizing bacteria (AOB). After a few hours of testing, diverse microbiological species died while others showed a possible adaptation of the biological system, accompained by a dissolved organic carbon (DOC) reduction. In addition, toxicity tests based on activated sludge showed the development of chronic toxicity through the contact time. Combination of classical and advanced microbiological techniques, such as quantitative real time Polymerase Chain Reaction (qPCR) and metagenomics, was essential to predict the variation of species during the experiment and to conclude if effective biological adaptation could be finally attained for the target complex wastewater.


Assuntos
Biodegradação Ambiental , Eliminação de Resíduos Líquidos/métodos , Bactérias/genética , Bactérias/metabolismo , Metagenômica/métodos , Oxirredução , Reação em Cadeia da Polimerase em Tempo Real/métodos , Esgotos/microbiologia , Águas Residuárias/química , Águas Residuárias/microbiologia
11.
Sci Total Environ ; 633: 508-517, 2018 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-29579662

RESUMO

Cork boiling wastewater is a very complex mixture of naturally occurring compounds leached and partially oxidized during the boiling cycles. The effluent generated is recalcitrant and could cause a significant environmental impact. Moreover, if this untreated industrial wastewater enters a municipal wastewater treatment plant it could hamper or reduce the efficiency of most activated sludge degradation processes. Despite the efforts to treat the cork boiling wastewater for reusing purposes, is still not well-known how safe these compounds (original compounds and oxidation by-products) will be. The purpose of this work was to apply an HPLC-high resolution mass spectrometry method and subsequent non-target screening using a multivariate analysis method (PCA), to explore relationships between samples (treatments) and spectral features (masses or compounds) that could indicate changes in formation, degradation or polarity, during coagulation/flocculation (C/F) and photo-Fenton (PhF). Although, most of the signal intensities were reduced after the treatment line, 16 and 4 new peaks were detected to be formed after C/F and PhF processes respectively. The use of this non-target approach showed to be an effective strategy to explore, classify and detect transformation products during the treatment of an unknown complex mixture.

12.
J Hazard Mater ; 323(Pt A): 442-451, 2017 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-26988902

RESUMO

The purpose of this work was to study the ozonation of nanofiltration (NF) retentates of real municipal wastewater treatment plant (MWTP) effluents for removal of microcontaminants (MCs) and toxicity. MCs present in these effluents were monitored using LC-MS/MS. Acute and chronic toxicity was addressed with Daphnia magna, Vibrio fischeri and Selenastrum capricornutum. Up to 40 MCs were found, most of them in concentrations over 100ng/L. 90% degradation of the sum of MCs was the critical point of comparison. When the NF membrane system was applied to MWTP effluents, treatment of NF rejection needed 2.75-4.5g O3/m3,4.5g O3/m3, which is less than 50% of the ozone needed for direct treatment of MWTP effluent. Treatment time (lower than 11min) was not influenced by MCs concentration, at least in the range tested (25-190µg/L). It has been demonstrated that consumption of ozone increased with organic load and inorganic content of different real effluents. MCs were eliminated by ozonation but acute toxicity (against V. fischeri and D. magna) increased. Chronic toxicity results were different and contrary in D. magna and S. capricornutum, due to the generation of new transformation products more toxic to D. magna than the parent contaminants. S. capricornutum inhibition percentage decreased in all cases after ozonation treatment. According to these results, before ozonation is implemented in MWTPs for the removal of MCs, the transformation products must first be examined and the treatment time or ozone doses should be extended to complete degradation if necessary.


Assuntos
Recuperação e Remediação Ambiental/métodos , Ozônio/química , Ultrafiltração/métodos , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/toxicidade , Aliivibrio fischeri/efeitos dos fármacos , Animais , Clorófitas/efeitos dos fármacos , Daphnia/efeitos dos fármacos , Membranas Artificiais , Purificação da Água
13.
Environ Sci Pollut Res Int ; 24(7): 6317-6328, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27519899

RESUMO

Industrial preparation of cork consists of its immersion for approximately 1 hour in boiling water. The use of herbicides and pesticides in oak tree forests leads to absorption of these compounds by cork; thus, after boiling process, they are present in wastewater. Cork boiling wastewater shows low biodegradability and high acute toxicity involving partial inhibition of their biodegradation when conventional biological treatment is applied. In this work, a treatment line strategy based on the combination of advanced physicochemical technologies is proposed. The final objective is the reuse of wastewater in the cork boiling process; thus, reducing consumption of fresh water in the industrial process itself. Coagulation pre-treatment with 0.5 g/L of FeCl3 attained the highest turbidity elimination (86 %) and 29 % of DOC elimination. Similar DOC removal was attained when using 1 g/L of ECOTAN BIO (selected for ozonation tests), accompanied of 64 % of turbidity removal. Ozonation treatments showed less efficiency in the complete oxidation of cork boiling wastewater, compared to solar photo-Fenton process, under the studied conditions. Nanofiltration system was successfully employed as a final purification step with the aim of obtaining a high-quality reusable permeate stream. Monitoring of unknown compounds by LC-QTOF-MS allowed the qualitative evaluation of the whole process. Acute and chronic toxicity as well as biodegradability assays were performed throughout the whole proposed treatment line.


Assuntos
Resíduos Industriais , Reciclagem/métodos , Águas Residuárias/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Cloretos/química , Compostos Férricos/química , Peróxido de Hidrogênio/química , Oxirredução , Ozônio/química , Poluentes Químicos da Água/toxicidade
14.
Environ Sci Pollut Res Int ; 22(2): 846-55, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24756680

RESUMO

In view of the inefficient elimination of micro-pollutants by today's conventional biological treatments and new legislation requiring elimination of at least 80 % of their concentration, the application of an advanced tertiary treatment must be studied. A good option would be advanced oxidation processes (AOPs), which have very often been combined with physicochemical pre-treatSments to increase efficiency or reduce operating costs. This study focused on the combination of membrane nanofiltration and solar photo-Fenton for the main purpose of removing five pharmaceuticals (sulfamethoxazole, ibuprofen, ofloxacin, carbamazepine and flumequine) from real MWTP effluents under realistic conditions (µg L(-1)). This research also included tests performed with modified photo-Fenton using a low iron concentration at circumneutral pH and a low hydrogen peroxide dose, in an attempt to reduce major treatment costs. Over 80 % of dissolved organic carbon, chemical oxygen demand and turbidity were also retained during nanofiltration, making pharmaceutical removal less efficient in terms of concentrate treatment time than direct treatment, i.e. the concentrate illumination time was around 150 min while direct treatment was around 40 min. Nevertheless, it should be highlighted that, although no savings in installation costs was observed for the combined system (nanofiltration/solar photo-Fenton), the reaction rate improved and so, there was a savings in reagent costs (mainly hydrogen peroxide and sulfuric acid).


Assuntos
Peróxido de Hidrogênio/química , Ferro/química , Preparações Farmacêuticas/química , Fotólise , Poluentes Químicos da Água/química , Purificação da Água/métodos , Análise da Demanda Biológica de Oxigênio , Concentração de Íons de Hidrogênio , Luz , Ofloxacino/química , Oxirredução , Preparações Farmacêuticas/efeitos da radiação , Sulfametoxazol/química , Luz Solar , Ultrafiltração , Poluentes Químicos da Água/efeitos da radiação , Purificação da Água/economia
15.
Water Res ; 64: 23-31, 2014 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-25025178

RESUMO

In recent years, membrane technologies (nanofiltration (NF)/reverse osmosis (RO)) have received much attention for micropollutant separation from Municipal Wastewater Treatment Plant (MWTP) effluents. Practically all micropollutants are retained in the concentrate stream, which must be treated. Advanced Oxidation Processes (AOPs) have been demonstrated to be a good option for the removal of microcontaminants from water systems. However, these processes are expensive, and therefore, are usually combined with other techniques (such as membrane systems) in an attempt at cost reduction. One of the main costs in solar photo-Fenton comes from reagent consumption, mainly hydrogen peroxide and chemicals for pH adjustment. Thus, in this study, solar photo-Fenton was used to treat a real MWTP effluent with low initial iron (less than 0.2 mM) and hydrogen peroxide (less than 2 mM) concentrations. In order to work at neutral pH, iron complexing agents (EDDS and citrate) were used in the two cases studied: direct treatment of the MWTP effluent and treatment of the concentrate stream generated by NF. The degradation of five pharmaceuticals (carbamazepine, flumequine, ibuprofen, ofloxacin and sulfamethoxazole) spiked in the effluent at low initial concentrations (µg L(-1)) was monitored as the main variable in the pilot-plant-scale photo-Fenton experiments. In both effluents, pharmaceuticals were efficiently removed (>90%), requiring low accumulated solar energy (2 kJUV L(-1), key parameter in scaling up the CPC photoreactor) and low iron and hydrogen peroxide concentrations (reagent costs, 0.1 and 1.5 mM, respectively). NF provided a clean effluent, and the concentrate was positively treated by solar photo-Fenton with no significant differences between the direct MWTP effluent and NF concentrate treatments.


Assuntos
Complexos de Coordenação/química , Peróxido de Hidrogênio/química , Ferro/química , Preparações Farmacêuticas/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Concentração de Íons de Hidrogênio , Oxirredução , Preparações Farmacêuticas/efeitos da radiação , Luz Solar , Ultrafiltração , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/efeitos da radiação
16.
Environ Sci Pollut Res Int ; 21(21): 12182-9, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24809495

RESUMO

Solar photo-Fenton process has been extensively reported to be highly efficient in the remediation of complex industrial wastewater containing several families of pollutants such as pharmaceuticals, dyes, pesticides, derivatives of wine, etc. Moreover, solar photo-Fenton mathematical modelling regarded as a powerful tool for scaling-up and process control purposes is hindered by the complexity and variability of its reaction mechanism which depends on the particular wastewater under study. In this work, non-biodegradable cork boiling wastewater has been selected as a case study for solar photo-Fenton dynamic modelling by using MATLAB® software. First of all physic-chemical pretreatment was applied attaining chemical oxygen demand (COD) reductions between 43 and 70 % and total suspended solid (TSS) reductions between 23 % and 59 %. After solar photo-Fenton treatment, COD decreased between 45 and 90 % after consumptions of H2O2 varying around 1.9 and 2.4 g/L. Individual calibration of the semi-empirical model by using experimental results made it possible to perfectly predict hydrogen peroxide variations throughout the treatment. It must be highlighted that slight deviations between predictions and experimental data must be attributed to important changes in wastewater characteristics.


Assuntos
Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/química , Análise da Demanda Biológica de Oxigênio , Peróxido de Hidrogênio , Resíduos Industriais/análise , Projetos Piloto , Luz Solar
17.
J Dent Res ; 93(7 Suppl): 80S-85S, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24621670

RESUMO

In this study, we analyzed the influence of prosthetic abutment height on marginal bone loss (MBL) around implants in the posterior maxilla. In this retrospective cohort study, the radiographically determined MBL was related to the height of the abutments of internal conical connection implants at 6 and 18 months post-loading. Data were gathered on age, sex, bone substratum, smoking habit, history of periodontitis, and prosthetic features, among other variables. A linear mixed model was used for statistical analysis. The study included 131 patients receiving 315 implants. MBL rates at 6 and 18 months were mainly affected by the abutment height but were also significantly influenced by the bone substratum, periodontitis, and smoking habit. MBL rates were higher for prosthetic abutment < 2 mm vs. ≥ 2 mm, for periodontal vs. non-periodontal patients, for grafted vs. pristine bone, and for a heavier smoking habit. The abutment height is a key factor in MBL. MBL rates followed a non-linear trend, with a greater MBL rate during the first 6 months post-loading than during the next 12 months.


Assuntos
Dente Suporte , Projeto do Implante Dentário-Pivô , Peri-Implantite/etiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Densidade Óssea/fisiologia , Transplante Ósseo/métodos , Estudos de Coortes , Prótese Dentária Fixada por Implante , Feminino , Seguimentos , Humanos , Masculino , Maxila/cirurgia , Pessoa de Meia-Idade , Perda da Inserção Periodontal/classificação , Periodontite/classificação , Radiografia Panorâmica , Estudos Retrospectivos , Fumar , Propriedades de Superfície , Adulto Jovem
18.
Water Res ; 47(4): 1521-8, 2013 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-23332646

RESUMO

Conventional municipal wastewater treatment plants are not able to entirely degrade some organic pollutants that end up in the environment. Within this group of contaminants, Emerging Contaminants are mostly unregulated compounds that may be candidates for future regulation. In this work, different advanced technologies: solar heterogeneous photocatalysis with TiO(2), solar photo-Fenton and ozonation, are studied as tertiary treatments for the remediation of micropollutants present in real municipal wastewater treatment plants effluents at pilot plant scale. Contaminants elimination was followed by Liquid Chromatography/Quadrupole ion trap Mass Spectrometry analysis after a pre-concentration 100:1 by automatic solid phase extraction. 66 target micropollutants were identified and quantified. 16 of those contaminants at initial concentrations over 1000 ng L(-1), made up over 88% of the initial total effluent pollutant load. The order of micropollutants elimination efficiency under the experimental conditions evaluated was solar photo-Fenton > ozonation > solar heterogeneous photocatalysis with TiO(2). Toxicity analyses by Vibrio fischeri and respirometric tests showed no significant changes in the effluent toxicity after the three tertiary treatments application. Solar photo-Fenton and ozonation treatments were also compared from an economical point of view.


Assuntos
Ozônio/química , Fotoquímica/métodos , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Aliivibrio fischeri/efeitos dos fármacos , Cromatografia Líquida/métodos , Peróxido de Hidrogênio/química , Espectrometria de Massas/métodos , Fotoquímica/instrumentação , Luz Solar , Titânio/química , Testes de Toxicidade , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
19.
J Hazard Mater ; 211-212: 131-7, 2012 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-21943922

RESUMO

The optimal photocatalyst concentration for industrial wastewater treatment in current photoreactor designs is several hundreds of milligrams per liter. However, the elimination of emerging contaminants (ECs), which are present at extremely low concentrations in waste water treatment plants (WWTP) effluents might be accomplished at much lower catalyst (TiO(2)) concentrations. One of the main drawbacks of reducing catalyst loading below the optimum is the loss of useful photons which instead are transmitted through the TiO(2) suspension without being absorbed by the catalyst. Accordingly, in this work, laboratory and solar pilot-scale experiments were performed with real WWTP effluents to evaluate the kinetics of photocatalytic degradation of 52 emerging contaminants under realistic (ppb) concentrations. The analysis of the samples was accomplished by solid phase extraction (SPE) followed by liquid chromatography-mass spectrometry (LC-MS). In view of the results, low concentrations of TiO(2) of the order of tens of milligrams per liter were found to be insufficient for the degradation of the ECs in photoreactors with a short light-path length (29 cm). However, it was established that solar reactors of diameters of several hundreds of millimetres could be used for the efficient removal of ECs from WWTP effluents. The results presented show a general methodology for selecting the most efficient reactor diameter on the basis of the desired catalyst concentration.


Assuntos
Luz Solar , Titânio/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Catálise , Fotólise , Poluentes Químicos da Água/efeitos da radiação
20.
Photochem Photobiol Sci ; 10(3): 381-8, 2011 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-20859602

RESUMO

Our previous contribution showed that Fusarium solani spores are inactivated by low amounts of hydrogen peroxide (lower than 50 mg L(-1)) together with solar irradiation in bottles. The purpose of the current study was to evaluate the effectiveness of solar H(2)O(2)/UV-Vis in distilled water and simulated municipal wastewater treatment plant effluent (SE) contaminated with chlamydospores of Fusarium equiseti in a 60 L solar CPC photo-reactor under solar irradiation. This study showed that F. equiseti chlamydospores in distilled and simulated municipal wastewater effluent were inactivated with 10 mg L(-1) of H(2)O(2) in a 60 L CPC photoreactor. F. equiseti chlamysdospore concentration decreased from 325 (±70) CFU mL(-1) to below the detection limit (DL=2 CFU mL(-1)) within five hours of solar exposure in a solar bottle reactor and from 180 (±53) CFU mL(-1) to below the detection limit in distilled water within two hours of solar irradiation in the solar CPC reactor. These results demonstrate that the use of low concentrations of hydrogen peroxide and CPC systems may be a good alternative for disinfection of resistant microorganisms in water.


Assuntos
Desinfecção/métodos , Fusarium/efeitos da radiação , Peróxido de Hidrogênio/toxicidade , Esporos Fúngicos/efeitos da radiação , Luz Solar , Microbiologia da Água , Fusarium/efeitos dos fármacos , Fusarium/isolamento & purificação , Limite de Detecção , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/isolamento & purificação , Raios Ultravioleta , Eliminação de Resíduos Líquidos/métodos
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