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1.
Ind Eng Chem Res ; 63(13): 5488-5498, 2024 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-38586214

RESUMO

Boron-doped diamond (BDD) electrodes are the most effective and resistant electrodic materials to perform advanced oxidation processes. Having a reactor that can provide adequate hydrodynamic conditions is mandatory to use these electrodes effectively. In this work, the diamond anode electrochemical reactor (E3L-DAER) is designed to fulfill this necessity. Several features are included to improve its efficiency, like conic inlet/outlet, flow enhancers, and a reduced interelectrode gap. The fluid dynamic validation has been performed using computer fluid dynamics (CFD) calculations, residence time distribution (RDT) curves, and mass transfer analysis. The reactor has been made using a three-dimensional (3D) printing stereolithography (SLA) technique, which allows us to build chemical-resistant reactors with nonstandard and tailored features in a cheap and fast way. The obtained results demonstrate that the designed reactor has the required fluid dynamics properties to perform reliable BDD electrode studies and applications. Finally, a BDD electrode was used to test the production of different oxidants such as persulfate, peroxophosphate, and chlorine-derived species.

2.
J Environ Manage ; 345: 118798, 2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-37591101

RESUMO

Pathogenic microorganisms are a major concern in indoor environments, particularly in sensitive facilities such as hospitals, due to their potential to cause nosocomial infections. This study evaluates the concentration of airborne bacteria and fungi in the University Hospital Complex of Albacete (Spain), comparing the results with recent literature. Staphylococcus is identified as the most prevalent bacterial genus with a percentage distribution of 35%, while Aspergillus represents the dominant fungal genus at 34%. The lack of high Technology Readiness Levels (TRL 6, TRL 7) for effective indoor air purification requires research efforts to bridge this knowledge gap. A screening of disinfection technologies for pathogenic airborne microorganisms such as bacteria and fungi is conducted. The integration of filtration, irradiation or and (electro)chemical gas treatment systems in duct flows is discussed to enhance the design of the air-conditioning systems for indoor air purification. Concerns over microbial growth have led to recent studies on coating commercial fibrous air filters with antimicrobial particles (silver nanoparticles, iron oxide nanowires) and polymeric materials (polyaniline, polyvinylidene fluoride). Promising alternatives to traditional short-wave UV-C energy for disinfection include LED and Far-UVC irradiation systems. Additionally, research explores the use of TiO2 and TiO2 doped with metals (Ag, Cu, Pt) in filters with photocatalytic properties, enabling the utilization of visible or solar light. Hybrid photocatalysis, combining TiO2 with polymers, carbon nanomaterials, or MXene nanomaterials, enhances the photocatalytic process. Chemical treatment systems such as aerosolization of biocidal agents (benzalkonium chloride, hydrogen peroxide, chlorine dioxide or ozone) with their possible combination with other technologies such as adsorption, filtration or photocatalysis, are also tested for gas disinfection. However, the limited number of studies on the use of electrochemical technology poses a challenge for further investigation into gas-phase oxidant generation, without the formation of harmful by-products, to raise its TRL for effectively inactivating airborne microorganisms in indoor environments.


Assuntos
Poluição do Ar em Ambientes Fechados , Nanopartículas Metálicas , Humanos , Prata , Raios Ultravioleta , Desinfecção/métodos , Poluição do Ar em Ambientes Fechados/prevenção & controle
3.
Chemosphere ; 333: 138847, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37187374

RESUMO

In this work, it is studied the photolysis, electrolysis, and photo-electrolysis of a mixture of pharmaceutics (sulfadiazine, naproxen, diclofenac, ketoprofen and ibuprofen) contained in two very different types of real water matrices (obtained from surface and porewater reservoirs), trying to clarify the role of the matrix on the degradation of the pollutants. To do this, a new metrological approach was also developed for screening of pharmaceuticals in waters by capillary liquid chromatography mass spectrometry (CLC-MS). This allows the detection at concentrations lower than 10 ng mL-1. Results obtained in the degradation tests demonstrate that inorganic composition of the water matrix directly influences on the efficiency of the drugs removal by the different EAOPs and better degradation results were obtained for experiments carried out with surface water. The most recalcitrant drug studied was ibuprofen for all processes evaluated, while diclofenac and ketoprofen were found to be the easiest drugs for being degraded. Photo-electrolysis was found to be more efficient than photolysis and electrolysis, and the increase in the current density was found to attain a slight improvement in the removal although with an associated huge increase in the energy consumption. The main reaction pathways for each drug and technology were also proposed.


Assuntos
Cetoprofeno , Poluentes Químicos da Água , Diclofenaco/química , Cetoprofeno/análise , Ibuprofeno/análise , Água/química , Poluentes Químicos da Água/análise , Preparações Farmacêuticas
4.
Environ Res ; 216(Pt 1): 114458, 2023 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-36181895

RESUMO

The composition and concentration of airborne microorganisms in hospital indoor air has been reported to contain airborne bacteria and fungi concentrations ranged 101-103 CFU/m3 in inpatients facilities which mostly exceed recommendations from the World Health Organization (WHO). In this work, a deeper knowledge of the performance of airborne microorganisms would allow improving the designs of the air-conditioning installations to restrict hospital-acquired infections (HAIs). A solution containing Escherichia coli (E. coli) as a model of airborne bacteria was nebulized using the Collison nebulizer to simulate bioaerosols in various hospital areas such as patients' rooms or bathrooms. Results showed that the bioaerosol source had a significant influence on the airborne bacteria concentrations since 4.00 102, 6.84 103 and 1.39 104 CFU mL-1 were monitored during the aerosolization for 10 min of urine, saliva and urban wastewater, respectively. These results may be explained considering the quite narrow distribution profile of drop sizes around 1.10-1.29 µm obtained for urban wastewater, with much vaster distribution profiles during the aerosolization of urine or saliva. The airborne bacteria concentration may increase up to 107 CFU mL-1 for longer sampling times and higher aerosolization pressures, causing several cell damages. The cell membrane damage index (ID) can vary from 0 to 1, depending on the genomic DNA releases from bacteria. In fact, the ID of E. coli was more than two times higher (0.33 vs. 0.72) when increasing the pressure of air flow was applied from 1 to 2 bar. Finally, the ventilation air flow also affected the distribution of bioaerosols due to its direct relationship with the relative humidity of indoor air. Specifically, the airborne bacteria concentration diminished almost below 3-logs by applying more than 10 L min-1 during the aerosolization of urine due to their inactivation by an increase in their osmotic pressure.


Assuntos
Microbiologia do Ar , Poluição do Ar em Ambientes Fechados , Humanos , Poluição do Ar em Ambientes Fechados/análise , Águas Residuárias , Escherichia coli , Bactérias/genética , Fungos , Aerossóis/análise , Hospitais , Monitoramento Ambiental
5.
J Hazard Mater ; 426: 128028, 2022 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-34923384

RESUMO

In this work, data obtained from the University Hospital Complex of Albacete (Spain) were selected as a case study to carry out the disinfection experiments. To do this, different configurations of electrochemical reactors were tested for the disinfection of complex urines. Results showed that 4-6 logs bacterial removal were achieved for every bacterium tested when working with a microfluidic flow-through reactor after 180 min (0.423 Ah dm-3). The MIKROZON® cell reached a total disinfection after 60 min (1.212 Ah dm-3), causing severe damages induced in the cell walls observed in SEM images. The concentration profiles of the electrogenerated disinfectants in solution could explain the differences observed. Additionally, a mean decrease in the ARGs concentration ranked as follows: blaKPC (4.18-logs) > blaTEM (3.96-logs) > ermB (3.23-logs) using the MIKROZON® cell. This electro-ozonizer could be considered as a suitable alternative to reduce the risk of antibiotic resistance spread. Hence, this study provides an insight into different electrochemical reactors for the disinfection of complex hospital urine matrices and contributes to reduce the spread of antibiotic resistance through the elimination of ARGs. A topic of great importance nowadays that needs to be further studied.


Assuntos
Antibacterianos , Desinfecção , Antibacterianos/farmacologia , Bactérias/genética , Resistência Microbiana a Medicamentos/genética , Genes Bacterianos , Humanos , Águas Residuárias
6.
Molecules ; 26(22)2021 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-34833906

RESUMO

The inefficiency of conventional biological processes to remove pharmaceutical compounds (PhCs) in wastewater is leading to their accumulation in aquatic environments. These compounds are characterized by high toxicity, high antibiotic activity and low biodegradability, and their presence is causing serious environmental risks. Because much of the PhCs consumed by humans are excreted in the urine, hospital effluents have been considered one of the main routes of entry of PhCs into the environment. In this work, a critical review of the technologies employed for the removal of PhCs in hospital wastewater was carried out. This review provides an overview of the current state of the developed technologies for decreasing the chemical risks associated with the presence of PhCs in hospital wastewater or urine in the last years, including conventional treatments (filtration, adsorption, or biological processes), advanced oxidation processes (AOPs) and electrochemical advanced oxidation processes (EAOPs).


Assuntos
Técnicas Eletroquímicas/métodos , Resíduos de Serviços de Saúde/prevenção & controle , Águas Residuárias/análise , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Antibacterianos/isolamento & purificação , Antibacterianos/urina , Biodegradação Ambiental , Resíduos de Drogas/isolamento & purificação , Hospitais , Humanos , Resíduos de Serviços de Saúde/análise , Eliminação de Resíduos de Serviços de Saúde/métodos , Consórcios Microbianos/fisiologia , Oxirredução , Urina/química , Eliminação de Resíduos Líquidos/métodos
7.
Chemosphere ; 285: 131359, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34246099

RESUMO

In this work, it is evaluated the fixation of carbon dioxide using the alkali generated in the chloralkaline process, as a new way to face the treatment of highly saline wastewater, in which it is aimed not to separate the wastewater into concentrated and diluted streams but to recover value-added products (VAPs) while contributing to minimize the carbon fingerprint of other processes. The electrolytic process is combined with a reactive absorption and with a crystallization, demonstrating the formation of pure nahcolite, hypochlorite (or chlorine) and hydrogen from the waste. Carbon dioxide is captured with a current efficiency over 90% and the energy required is around 0.65 kWh kg-1, which is very promising from the view point of sustainability, considering that the system can be easily powered with green energies.


Assuntos
Dióxido de Carbono , Ácido Hipocloroso , Eletrólise , Salinidade , Águas Residuárias
8.
Sci Total Environ ; 797: 149150, 2021 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-34303979

RESUMO

The occurrence of antibiotic-resistant bacteria (ARB) in water bodies poses a sanitary and environmental risk. These ARB and other mobile genetic elements can be easily spread from hospital facilities, the point in which, for sure, they are more concentrated. For this reason, novel clean and efficient technologies are being developed for allowing to remove these ARB and other mobile genetic elements before their uncontrolled spread. In this paper, a review on the recent knowledge about the state of the art of the main disinfection technologies to control the antibiotic resistance spread from natural water, wastewater, and hospital wastewater (including urine matrices) is reported. These technologies involve not only conventional processes, but also the recent advances on advanced oxidation processes (AOPs), including electrochemical advanced oxidation processes (EAOPs). This review summarizes the state of the art on the applicability of these technologies and also focuses on the description of the disinfection mechanisms by each technology, highlighting the promising impact of EAOPs on the remediation of this important environmental and health problem.


Assuntos
Desinfecção , Purificação da Água , Antagonistas de Receptores de Angiotensina/farmacologia , Inibidores da Enzima Conversora de Angiotensina/farmacologia , Antibacterianos/farmacologia , Bactérias/genética , Resistência Microbiana a Medicamentos/genética , Genes Bacterianos , Tecnologia , Águas Residuárias
9.
PeerJ Comput Sci ; 7: e513, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34084925

RESUMO

Cloud computing has emerged as a cutting-edge technology which is widely used by both private and public institutions, since it eliminates the capital expense of buying, maintaining, and setting up both hardware and software. Clients pay for the services they use, under the so-called Service Level Agreements (SLAs), which are the contracts that establish the terms and costs of the services. In this paper, we propose the CloudCost UML profile, which allows the modeling of cloud architectures and the users' behavior when they interact with the cloud to request resources. We then investigate how to increase the profits of cloud infrastructures by using price schemes. For this purpose, we distinguish between two types of users in the SLAs: regular and high-priority users. Regular users do not require a continuous service, so they can wait to be attended to. In contrast, high-priority users require a constant and immediate service, so they pay a greater price for their services. In addition, a computer-aided design tool, called MSCC (Modeling SLAs Cost Cloud), has been implemented to support the CloudCost profile, which enables the creation of specific cloud scenarios, as well as their edition and validation. Finally, we present a complete case study to illustrate the applicability of the CloudCost profile, thus making it possible to draw conclusions about how to increase the profits of the cloud infrastructures studied by adjusting the different cloud parameters and the resource configuration.

10.
Chemosphere ; 270: 129344, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33395582

RESUMO

The treatment of hospital wastewater is very complex, so treating polluted human urine is a significant challenge. Here, we tested a novel MMO-Ti/RuO2IrO2 electrode to reduce the ecotoxicity risk of hospital urines contaminated with antibiotics. This electrode was used as the anode in electro-Fenton (EF) and photoelectro-Fenton (PhEF) processes. The results were compared with those obtained using the boron-doped diamond (BDD) anode, as well as those obtained by a conventional Fenton oxidation. In order to analyze the performance of the processes, the treatments were evaluated on the subject of Penicilin G (PenG) removal, toxicity (using a standardized method with Vibrio Fisheri), and antibiotic activity (Enterococcus faecalis as the target bacterium). The results reveal that PenG degrades in the following order: Fenton < EF < PhEF. The best results are found for the MMO-PhEF, which completely removed PenG, decreased 96% of toxicity, and completely removed antibiotic activity. Besides, for comparison, tests were performed with BDD, and results point out the higher convenience of the new electrode in terms of acceptable use of energy because the effluents generated can be further degraded in an urban wastewater treatment plant. Because of that, MMO-RuO2-IrO2 emerges as a promising cost-effective material for the pre-treatment of hospital urine effluents.


Assuntos
Titânio , Poluentes Químicos da Água , Antibacterianos/toxicidade , Diamante , Eletrodos , Humanos , Peróxido de Hidrogênio , Oxirredução , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
11.
J Environ Manage ; 277: 111424, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33038673

RESUMO

The aim of this work is to compare three biological strategies for the in situ remediation of a 2,4-dichlorophenoxyacetic acid (2,4-D) polluted clayey soil by coupling electrokinetics (EK) and bioremediation (technology named as electrobioremediation, EBR). The first option (i) is EK-biostimulation, in which the activity of microorganisms already present in soil is enhanced by EK phenomena. The second and third options are EK-bioaugmentation, which consist of addition of microorganisms to soil through the inclusion of permeable biological barriers: (ii) using a microbial fixed biofilm reactor as biobarrier (BB1), and (iii) using a mixture of clean soil and a microbial suspension as biobarrier (BB2). Thus, three batch experiments at bench scale were conducted under a constant electric field of 1 V cm-1, and electrode polarity was periodically reversed every 12 h (2 d-1). The duration of each test was 10 days. Two additional tests using only biodegradation or only EK were performed as auxiliary reference tests. A microbial consortium acclimated to 2,4-D biodegradation was employed. Results showed that EK-biostimulation strategy offered the best pollutant removal efficiency (reaching up almost 100%) while biobarriers offered pollutant removal rates between 75 and 85%. Permeable biobarriers allowed the introduction of microorganism but caused a decrease in the electro-osmotic flow which, in turn, reduced the mobilization and contact between microorganisms and pollutants. These results can contribute to the knowledge and understanding of electrobioremediation of polluted soil and to the feasibility of delivering microorganism to the soil by using biobarriers. Despite biostimulation was found to be the best option, results show that permeable reactive biobarriers may result in a successful alternative for in-situ EK-bioaugmentation when acclimated microbial population is not already present in soil.


Assuntos
Herbicidas , Poluentes do Solo , Ácido 2,4-Diclorofenoxiacético , Biodegradação Ambiental , Solo , Microbiologia do Solo , Poluentes do Solo/análise
12.
Environ Sci Pollut Res Int ; 28(19): 23657-23666, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-32948947

RESUMO

This work focuses on the development of electro-absorption and photoelectro-absorption technologies to treat gases produced by a synthetic waste containing the highly volatile perchloroethylene (PCE). To do this, a packed absorption column coupled with a UV lamp and an undivided electrooxidation cell was used. Firstly, it was confirmed that the absorption in a packed column is a viable method to achieve retention of PCE into an absorbent-electrolyte liquid. It was observed that PCE does not only absorb but it was also transformed into phosgene and other by-products. Later, it was confirmed that the electro-absorption process influenced the PCE degradation, favoring the transformation of phosgene into final products. Opposite to what is expected, carbon dioxide is not the main product obtained, but carbon tetrachloride and trichloroacetic acid. Both species are also hazardous but their higher solubility in water opens possibilities for a successful and more environmental-friendly removal. The coupling with UV-irradiation has a negative impact on the degradation of phosgene. Finally, a reaction mechanism was proposed for the degradation of PCE based on the experimental observations. Results were not as expected during the planning of the experimental work but it is important to take in mind that PCE decomposition occurs in wet conditions, regardless of the applied technology, and this work is a first approach to try to solve the treatment problems associated to PCE gaseous waste flows in a realistic way.


Assuntos
Tetracloroetileno , Tetracloreto de Carbono , Gases , Tetracloroetileno/análise , Raios Ultravioleta
13.
J Hazard Mater ; 410: 124548, 2021 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-33246823

RESUMO

This work focuses on the removal of antibiotic-resistant bacteria (ARB) contained in hospital urines by UV disinfection enhanced by electrochemical oxidation to overcome the limitations of both single processes in the disinfection of this type of effluents. UV disinfection, electrolysis, and photoelectrolysis of synthetic hospital urine intensified with K. pneumoniae were studied. The influence of the current density and the anode material was assessed on the disinfection performance of combined processes and the resulting synergies and/or antagonisms of coupling both technologies were also evaluated. Results show that the population of bacteria contained in hospital urine is only reduced by 3 orders of magnitude during UV disinfection. Electrolysis leads to complete disinfection of hospital urine when working at 50 A m-2 using Boron Doped Diamond (BDD) and Mixed Metal Oxides (MMO) as anodes. The coupling of electrolysis to the UV disinfection process leads to the highest disinfection rates, attaining a complete removal of ARB for all the current densities and anode materials tested. The use of MMO anodes leads to higher synergies than BDD electrodes. Results confirm that UV disinfection can be enhanced by electrolysis for the removal of ARB in urine, considering both technical and economic aspects.


Assuntos
Desinfecção , Poluentes Químicos da Água , Antagonistas de Receptores de Angiotensina , Inibidores da Enzima Conversora de Angiotensina , Diamante , Eletrodos , Eletrólise , Oxirredução , Poluentes Químicos da Água/análise
14.
Sci Total Environ ; 736: 139536, 2020 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-32485374

RESUMO

The objective of this study is to understand the influence of the characteristics of boron-doped diamond anodes on the degradation of Penicillin G contained in urine. Therefore, five commercial BDD anodes with different boron doping levels (100 ppm - 8000 ppm) were studied. These electrodes were characterized by cyclic voltammetry, electrochemical impedance spectroscopy, and electrolysis. The boron doping was found to correlate well with the electrochemical properties of the electrodes, and results indicate a different behavior in drug degradation. The improvement in the toxicity and the reduction of the antibiotic effect of urine were the most innovative inputs monitored. For this, the concentration of Penicillin G, the toxicity toward Vibrio fisheri, and the antibiotic effect in Enterococcus faecalis were monitored. The best results were found for the BDD with a boron content of 200 ppm, capable of removing 100% of the antibiotic, reducing toxicity by 90%, and eradicating the antibiotic effect. These results indicate that low doping levels are more efficient for urine removal by anodic oxidation.


Assuntos
Dopagem Esportivo , Poluentes Químicos da Água/análise , Boro , Diamante , Eletrodos , Oxirredução , Penicilina G
15.
Sci Total Environ ; 725: 138430, 2020 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-32298888

RESUMO

This work focuses on improving the biodegradability of hospital urines polluted with antibiotics by electrochemical advanced oxidation processes (EAOPs). To do this, chloramphenicol (CAP) has been used as a model compound and the influence of anodic material (Boron Doped Diamond (BDD) and Mixed Metal Oxide (MMO)) and current density (1.25-5 mA cm-2) on the toxicity and the biodegradability was evaluated. Results show that a complete CAP removal was attained using BDD anodes, being the process more efficient at the lowest current density tested (1.25 mA cm-2). Conversely, after passing 4 Ah dm-3, only 35% of CAP removal is reached using MMO anodes, regardless of the current density applied. Furthermore, a kinetic study demonstrated that there is a clear competitive oxidation between the target antibiotic and the organic compounds naturally contained in urine, regardless the current density and the anode material used. During the first stages of the electrolysis, acute toxicity is around 1% EC50 but it increases once CAP and its organic intermediates have been degraded. The formation and accumulation of inorganic oxidants may justify the remaining acute toxicity. This also helps to explain the trend observed in the rapid biodegradability assays. Finally, a 60% of standard biodegradability (Zahn-Wellens test) was achieved which suggests that electrochemical oxidation with BDD anodes could be the most appropriate technology to reduce the hazard of hospital urines at the operating conditions tested.


Assuntos
Cloranfenicol , Poluentes Químicos da Água , Diamante , Eletrodos , Eletrólise , Oxirredução
16.
J Environ Manage ; 258: 110015, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31929057

RESUMO

This work focuses on the evaluation of the electrochemical dewatering of sludge obtained in the coagulation of wastes polluted with oxyfluorfen. To do this, sludge samples were treated, aiming not only to reduce the sludge volume, but also to facilitate the degradation of oxyfluorfen contained in the cake via electrolysis with a boron-doped diamond anode. Results show that water can be effectively recovered through three sequential stages. First, a gravity-driven stage, that can recover around 60% of initial volume and where no oxyfluorfen is dragged. Then, a second stage that involves the application of pressure and which accounts for the recuperation of an additional 25% of the total volume of the water removed and in which oxyfluorfen also remained in the cake. Finally, an electrochemical stage, which involves the application of electricity with increasing electric fields (1.0, 2.0, 4.0, and 16.0 V cm-1), accounting for the recovery of the rest of water released and where an electrolytic degradation of oxyfluorfen is obtained, whose extension depends on the electrode configuration used in the electro-dewatering cell. This electrode configuration also influences the retention or loss of oxyfluorfen from the cake, being the optimum choice the placement of the cathode downstream, next to the outlet of the dewatering cell.


Assuntos
Esgotos , Eliminação de Resíduos Líquidos , Floculação , Éteres Difenil Halogenados , Água
17.
Chemosphere ; 238: 124575, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31446274

RESUMO

Significance of surface and ground water contamination by synthetic organic compounds has been pointed out in a very high number of papers worldwide, as well as the need of application of treatment technologies capable to assure their complete removal. Among these processes, the electrochemical advanced oxidation is an interesting option, especially when irradiated with UVC light (photo-electrochemical, P-EC) to promote homolysis of electrogenerated oxidants. In this work, the herbicide glyphosate (GLP) was used as model compound and it was electrochemically treated under UVC irradiation in the presence of NaCl and using a DSA® and BDD anodes. Total organic carbon concentration was measured throughout the electrolysis, as well as the concentration of short chain carboxylic acids and inorganic ions (NO3-, PO43-,ClO-, ClO3- and ClO4-). The synergism of the P-EC was more pronounced when using a DSA® electrode, which led to complete GLP mineralization in 1 h (0.52 A h L-1), as also confirmed by the stoichiometric formation of NO3- and PO43- ions, with an energy consumption as low as 1.25 kW h g-1. Unexpectedly, the concentration evolution of oxyhalides for the P-EC process using both anodes, especially for DSA® at 10 mA cm-2, showed the production of ClO3-, whereas detection of ClO4- species was only found when using BDD at 100 mA cm-2 for the electrochemical process. Finally, small amounts of carboxylic acids were detected, including dichloroacetic acid, especially when using a BDD electrode.


Assuntos
Técnicas Eletroquímicas/métodos , Glicina/análogos & derivados , Água Subterrânea/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Purificação da Água/métodos , Ácidos Carboxílicos/análise , Diamante/química , Eletrodos , Glicina/análise , Oxidantes/química , Oxirredução , Raios Ultravioleta , Glifosato
18.
J Hazard Mater ; 384: 121237, 2020 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-31581020

RESUMO

This paper focuses on the removal of lindane from soil washing effluents (SWEs) using combined electrochemical -biological processes. In particular, it has been evaluated the influence of the anodic material used in the electrolysis of the SWE on the biodegradability and toxicity of the effluents. Four anode materials were tested: Boron Doped Diamond (BDD), Carbon Felt (CF), and Mixed Metal Oxides Anodes with iridium and ruthenium (MMO-Ir and MMO-Ru). These materials were tested at different current densities and electric current charges applied. Lindane, TOC, sulphate, and chlorine species concentrations were monitored during electrochemical experiments, showing important differences in their evolution during the treatment. In spite of reaching a good removal of lindane with all the materials tested, results showed that Boron Doped Diamond working at 15 mA cm-2 achieved the best biodegradability results in the electrolyzed effluents, because the ratio BOD5/COD increased from 0.2 to 0.5, followed by Carbon Felt anode. Regarding toxicity, Carbon Felt decreased toxicity by 80%. Opposite to what it was expected, MMO anodes did not achieve biodegradability improvement and they only showed reduction in toxicity at high electrical charges.


Assuntos
Recuperação e Remediação Ambiental/métodos , Hexaclorocicloexano , Inseticidas , Poluentes do Solo , Poluentes Químicos da Água , Aliivibrio fischeri/efeitos dos fármacos , Boro/química , Carbono/química , Diamante/química , Eletrodos , Eletrólise , Hexaclorocicloexano/química , Hexaclorocicloexano/metabolismo , Hexaclorocicloexano/toxicidade , Inseticidas/química , Inseticidas/metabolismo , Inseticidas/toxicidade , Irídio/química , Óxidos/química , Rutênio/química , Solo , Poluentes do Solo/química , Poluentes do Solo/metabolismo , Poluentes do Solo/toxicidade , Poluentes Químicos da Água/química , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/toxicidade
19.
J Environ Manage ; 255: 109806, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31759201

RESUMO

Electrokinetic-assisted phytoremediation (EKPR) has been recently proposed for the removal of pesticides from polluted soils. In this work, we report the results from an EKPR experiment that was carried out in a mesocosm mock-up of 0.386 m3 using ryegrass (Lolium perenne L.) and a low permeability soil spiked with atrazine. Plants were initially grown for 35 days; then, the soil was spiked with atrazine at a dose of 2 mg kg-1 soil. A DC electrical field of 0.6 V cm-1 was applied 24 h every day, switching polarity daily. Another identical mock-up with the same experimental conditions but without plants was used for comparison purposes. The duration of the EKPR test was 19 days during which some operational parameters were registered (electric current intensity, soil pH and temperature) and soil porewater samples were taken and analysed. Plant tissues and soil samples from the different sections in which the mock-ups were divided, were also collected and analysed at the end of the experiment. 3-D profiles of soil pH, water content and atrazine residues concentration in plants and soil were obtained and discussed. The results of this experiment were compared with others previously reported by us from a similar EKPR pot test. In spite of the difficulties to get an adequate geometric and operational similarity between setups of different scale, the main output parameters of the EKPR process (electric current, specific current charge, overall atrazine removal, specific atrazine removal efficiency, root biomass:soil weight ratio) were discussed. It was shown that, although the processes carried out are essentially the same in both scales, their extent may be quite different; it highlights the limitations of small-scale experiments to predict the results at field conditions.


Assuntos
Atrazina , Poluentes do Solo , Biodegradação Ambiental , Eletrodos , Solo
20.
J Environ Manage ; 255: 109895, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31770704

RESUMO

This work focuses on the partial anodic electro-oxidation of atrazine-polluted soil washing effluents (SWE) in order to reduce its toxicity and to improve its biodegradability. Concretely it has been evaluated the influence of the anodic material used. It is hypothesized that such partial oxidation step could be considered as a pre-treatment for a subsequent biological treatment. At first, atrazine was extracted from a polluted soil by means of a surfactant-aided soil-washing process. Then, four different anodic materials were studied in partial electro-oxidation pre-treatment batch experiments at different electric charges applied: Boron Doped Diamond (BDD), Carbon Felt (CF), and Mixed Metal Oxides Anodes with Iridium and Ruthenium. Atrazine, TOC, surfactant and sulphate species concentrations, as well as changes in toxicity and biodegradability, were monitored during electrochemical experiments, showing important differences in their evolution during the treatment. It was observed that BDD was the most powerful anodic material to completely degrade atrazine. The other materials achieve an atrazine degradation rate about 75%. Regarding mineralization of the organics in SWE, BDD overtakes clearly the rest of anodes tested. CF obtains good atrazine removal but low mineralization results. All the anodes tested slightly reduced the ecotoxicity of the water effluents. About the biodegradability, only the effluent obtained after the pre-treatment with BDD presented a high biodegradability. In this sense, it must be highlighted the mineralization obtained during the BDD pre-treatment was very strong. These results globally indicate that it is necessary to find a compromise between reaching efficient atrazine removal and biodegradability improvement, while also simultaneously avoiding strong mineralization. Additional efforts should be made to find the most adequate working conditions.


Assuntos
Atrazina , Poluentes Químicos da Água , Diamante , Eletrodos , Oxirredução , Solo
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