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Carbon nanotubes as catalysts for catalytic wet peroxide oxidation of highly concentrated phenol solutions: towards process intensification

Pinho, Maria; Gomes, Helder; Ribeiro, Rui; Faria, Joaquim; Silva, Adrián
Fonte: Instituto Politécnico de Bragança Publicador: Instituto Politécnico de Bragança
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37%
Commercial multi-walled carbon nanotubes with different properties (two samples from Sigma-Aldrich,SA1 and SA2; one sample from Nanocyl, NC; and two samples from Shenzhen Nanotech, SZ and LSZ),and SA2 modified by hydrothermal treatment with concentrated sulfuric acid (SA2-H), were tested ascatalysts in wet peroxide oxidation. Phenol was selected as model compound since it represents a classof noxious compounds for human health and for the environment and, due to this, phenol is typically considered in wastewater treatment studies. The experiments were carried out under the following inten-sified conditions: phenol concentration = 4.5 g L−1, hydrogen peroxide concentration = 25 g L−1, catalystload = 2.5 g L−1, pH 3.5, T = 353 K and 24 h.The results demonstrated that phenol is poorly adsorbed in this type of carbon materials (11% as max-imum when using the NC sample). However, in the catalytic experiments, complete removal of phenol isachieved when using some of the carbon nanotubes (SA1, NC and SA2), together with a remarkable total organic carbon removal (77, 69 and 67%, respectively). These materials have the less pronounced acidiccharacter, which is often considered favorable for oxidation reactions in advanced oxidation processesand may explain the higher performance of SA1...

Phenol And Para-Substituted Phenols Electrochemical Oxidation Pathways

Enache, Teodor Adrian; Oliveira-Brett, Ana Maria
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37%
The electrochemical behaviour of phenol, catechol, hydroquinone, resorcinol, dopamine, and para-substituted phenolic compounds, 4-ethylphenol, tyrosine, and tyramine, was studied over a wide pH range using a glassy carbon electrode. The oxidation of phenol is pH dependent and irreversible, occurring in one step, and followed by hydrolyse in ortho- and para- positions, leading to two oxidation products, catechol and hydroquinone. The oxidation of phenol oxidation products, ortho-phenol and para-phenol, is reversible and pH dependent. The oxidation potential of parasubstituted phenols varies slightly due to their substituent group in position C4, and occurs in one oxidation step corresponding to the oxidation of phenol. The oxidation products of this group of para-substituted phenols are reversibly oxidised and adsorb on the electrode surface.

Investigation of the mass transfer processes during the desalination of water containing phenol and sodium chloride by electrodialysis

BORGES, F. J.; BALMANN, H. Roux-de; GUARDANI, R.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.03%
Oxidation processes are used in wastewater treatment when conventional processes are not effective due to the presence of recalcitrant organic contaminants, like phenol. However, the presence of ionic compounds associated with organic pollutants may retard the oxidation. In this work the transport of species contained in an aqueous solution of phenol containing sodium chloride was evaluated in an electrodialysis (ED) system. An experimental study was carried out in which the influence of the process variables on the phenol loss and sodium chloride removal was investigated. Experiments were also performed without current, in order to determine the phenol transfer due to diffusion. The phenol and salt concentration variations in the ED compartments were measured over time, using dedicated procedures and an experimental design to determine the global characteristic parameters. A phenomenological approach was used to relate the phenol, salt and water fluxes with the driving forces (concentration and electric potential gradients). Under ED conditions, two contributions were pointed out for the phenol transport, i.e. diffusion and convection, this latter coming from the water flux due to electroosmosis related to the migration of salts. The fitting of the parameters of the transport equations resulted in good agreement with the experimental results over the range of conditions investigated. (c) 2008 Elsevier B.V. All rights reserved.; Brazilian Federal Agency CAPES

Characterization of the Phenol Monooxygenase Gene from Chromobacterium violaceum: Potential Use for Phenol Biodegradation

PERPETUO, Elen Aquino; MARQUES, Regina Celia Pereira; MENDES, Maria Anita; LIMA, Wanessa Cristina de; MENCK, Carlos Frederico Martins; NASCIMENTO, Claudio Augusto Oller do
Fonte: KOREAN SOC BIOTECHNOLOGY & BIOENGINEERING Publicador: KOREAN SOC BIOTECHNOLOGY & BIOENGINEERING
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.09%
In this work, the biodegradation mechanism of phenol and sub products (such as catechol and hydroquinone) in Chromobacterium violaceum was investigated by cloning and molecular characterization of a phenol monooxygenase gene in Escherichia coli. This gene (Cvmp) is very similar (74 and 59% of similarity and identity, respectively) to the ortholog from Ralstonia eutropha, bacteria capable of utilizing phenol as the sole carbon source. The phenol biodegradation ability of E. coli recombinant strains was tested by cell-growth in a minimal medium containing phenol as the sole source of carbon and release of intermediary metabolites (catechol and hydroquinone). Interestingly, during the growth of these strains on phenol, catechol, and hydroquinone accumulated transiently in the medium. These metabolites were further analyzed by HPLC. These results indicated that phenol can be initially orto or para hydroxylated to produce cathecol or hydroquinone, respectively, followed by meta-cleavage of aromatic rings. To verify this information, the metabolites obtained from HPLC were submitted to LC/MS to confirm their chemical structure, thereby indicating that the recombinant strains utilize two different routes simultaneously, leading to different ring-fission substrates for the metabolism of phenol. (C) KSBB; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); CNPq (Brasilia...

Phenol degradation in an anaerobic fluidized bed reactor packed with low density support materials

Sancinetti, Giselle Patricia; Sader, L. T.; Varesche, Maria Bernadete Amâncio; Amorim, Eduardo Lucena Cavalcante de; Omena, Sylvia Paes Farias de; Silva, E. L.
Fonte: BRAZILIAN SOC CHEMICAL ENG; SAO PAULO Publicador: BRAZILIAN SOC CHEMICAL ENG; SAO PAULO
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37%
The objective of this research was to study phenol degradation in anaerobic fluidized bed reactors (AFBR) packed with polymeric particulate supports (polystyrene - PS, polyethylene terephthalate - PET, and polyvinyl chloride - PVC). The reactors were operated with a hydraulic retention time (HRT) of 24 h. The influent phenol concentration in the AFBR varied from 100 to 400 mg L-1, resulting in phenol removal efficiencies of similar to 100%. The formation of extracellular polymeric substances yielded better results with the PVC particles; however, deformations in these particles proved detrimental to reactor operation. PS was found to be the best support for biomass attachment in an AFBR for phenol removal. The AFBR loaded with PS was operated to analyze the performance and stability for phenol removal at feed concentrations ranging from 50 to 500 mg L-1. The phenol removal efficiency ranged from 90-100%.; FAPESP; CAPES; CNPq

Estudo da remoção biológica de nitrogênio via nitrito utilizando fenol como fonte de carbono operando um reator em bateladas seqüenciais (SBR) em escala piloto.; Study of nitrogen biological removal via nitrite using phenol as carbon source operating a pilot scale sequence batch reactor (SBR).

Queiroz, Luciano Matos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/11/2006 PT
Relevância na Pesquisa
37.07%
A presente pesquisa propôs avaliar a remoção biológica do nitrogênio pela via simplificada (nitritação) utilizando fenol como fonte de carbono na etapa anóxica (desnitritação) em um sistema de lodos ativados com biomassa em suspensão. Para tanto operou-se um reator piloto (volume útil de 20 litros) em bateladas seqüenciais alimentado com 5 (cinco) litros de água residuária sintética. A investigação foi caracterizada pela utilização do fenol (1.000 mg C6H5OH/L) e pelo aumento gradual da concentração de nitrogênio amoniacal no despejo líquido sintético (200; 300 e 500 mg N/L) buscando as condições que permitissem a predominância do N-NO2 - ao final da fase aeróbia dos ciclos de tratamento e utilização do fenol pelos microrganismos heterotróficos para redução do nitrogênio oxidado durante a fase anóxica. Para a presente pesquisa as condições para predominância do N-NO2 - na massa líquida do reator ao final da etapa aeróbia foram: pH @ 8,3 associado à extensão do período aeróbio do ciclo de tratamento que garantisse uma concentração mínima de amônia livre (> 0,3 mg NH3/L) no conteúdo do reator piloto. Com estas condições, a relação N NO2 - / (N-NO2 - + N-NO3 -) variou entre 89 e 99%. Mantendo uma concentração de 1...

Remoção de fenol em reator anaeróbio de leito fluidificado sob condições desnitrificantes; Phenol removal an anaerobic fluidized bed reactor under denitrifying conditions.

Omena, Sylvia Paes Farias de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 29/04/2008 PT
Relevância na Pesquisa
37.03%
Este trabalho teve como objetivo geral a caracterização de um sistema de tratamento biológico de remoção de fenol em reator anaeróbio de leito fluidificado utilizando o nitrato como aceptor final de elétrons. O reator foi construído em acrílico transparente, com dimensões equivalentes a 190 cm de altura e 5,3 cm de diâmetro interno, totalizando um volume de 4192 cm³, dos quais cerca de 44% (1831 cm³) foram ocupados pelo meio suporte, na situação de leito fixo. Para imobilização da biomassa foram utilizadas partículas de poliestireno, que foram previamente ativadas através de ataque ácido, com o intuito de aumentar a rugosidade e a porosidade da superfície do material, facilitando a aderência da biomassa ao meio suporte. O reator foi inoculado com lodo proveniente de reator UASB, responsável pelo tratamento de despejos de suinocultura. A realização do experimento foi dividida em cinco fases, que foram alteradas de acordo com o desempenho e a estabilidade do sistema diante do aumento das concentrações de fenol e nitrato. As concentrações médias de fenol afluente estudadas foram de 52, 107, 201, 335 e 518 mg/L, de maneira que não foi detectada presença de fenol no efluente para concentrações de até 335 mg/L. A eficiência de remoção reduziu-se para aproximadamente 70%...

Aspectos oxidativos e de biotransformação do poluente fenol na microalga Minutocellus polymorphus; Oxidative aspects and phenol biotransformation in the microalga Minutocellus polymorphus

Campos, Sara Cristina Gonçalves
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 20/01/2009 PT
Relevância na Pesquisa
37.14%
Minutocellus polymorphus é uma microalga marinha cosmopolita, encontrada em diversas áreas. É sensível a vários tipos de toxicantes e por isso foi escolhida para investigar a metabolização do fenol, assim como os efeitos de estresse oxidativo induzido por este poluente. Na exposição de M. polymorphus ao fenol foi observado um aumento na atividade da enzima superóxido dismutase (143,5±46,9 U mg-1 para o grupo tratado e 27,1±12,7 U mg-1 para o grupo controle) e na atividade de catalase (9,79 ± 1,32 µmol min-1 mg-1 no grupo fenol e 7,00 ± 1,03 µmol min-1 mg-1 no grupo controle). As enzimas ascorbato peroxidase, deidroascorbato redutase, glutationa redutase e glutationa peroxidase não foram afetadas pelo tratamento com fenol. Fenol foi ainda capaz de provocar uma depressão dos níveis de glutationa em M. polymorphus, o decréscimo da razão de GSH/GSSG foi de aproximadamente 80%. O fenol também provocou uma diminuição nos níveis de clorofila a, no entanto, não alterou outros pigmentos. Os níveis de malondialdéido, importante produto de lipoperoxidação, não foram alterados nas células expostas induzidos a este poluente orgânico. A remoção de fenol por M. polymorphus foi verificada no meio de cultura ao longo do tempo...

Analytical Methods in Photoelectrochemical Treatment of Phenol

Lopes, Paulo R. M.; Montagnolli, Renato N.; Bidoia, Ederio Dino
Fonte: Soc Brasileira Quimica Publicador: Soc Brasileira Quimica
Tipo: Artigo de Revista Científica Formato: 1758-1764
ENG
Relevância na Pesquisa
37%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); The aim of the study was to propose a treatment of simulated wastewater containing phenol by photocatalytic and photolytic processes and analyze the toxicity of these phenolic solutions. Two treatment systems were performed with UV radiation, solid electrodes and electric potential. In the first system (S1) phenol concentration was determined by UV direct spectrophotometry (269 nm) and in the second (S2) by direct photometric method (4-aminoantipyrine). Toxicological tests were carried out using two microorganisms: Escherichia coli and Saccharomyces cerevisiae. S1 results showed that erroneous conclusions can be drawn by absorbance values increase at phenol peak. Nevertheless, direct photometric method was able to identify phenol reduction in S2 and the proposed treatments degraded phenol in solution. Also, in treatment using high energy ultraviolet radiation (UVC), the phenol degradation was mainly due to the photolytic process.

Redução da concentração de fenol presente em águas residuárias utilizando sistema anaeróbio-aeróbio : desempenho e toxicidade residual; Phenol concentration reduction in wastewater using anaerobic-aerobic system : performance and residual toxicity

Luciana Vechi de Carvalho
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/08/2012 PT
Relevância na Pesquisa
37.1%
A grande utilização de compostos tóxicos e o descarte dos mesmos sem o devido tratamento fizeram com que o ecossistema aquático recebesse grande quantidade de contaminantes, os quais, com o passar do tempo, tendem a estar presentes em maiores concentrações no sedimento dos rios e mananciais que recebem o efluente in natura. O fenol é um dos compostos que tem sido utilizado de forma descontrolada tanto pelas indústrias como também para fins domésticos, aumentando ainda mais a concentração deste nos efluentes sanitários. Desta forma, estudou-se a capacidade de um sistema de tratamento biológico combinado, anaeróbio/aeróbio, em reduzir a concentração de fenol presente em efluentes sanitários. O sistema foi composto por um filtro anaeróbio (FA) seguido por um biofiltro aerado submerso (BAS), monitorado por meio de análises físicas, químicas e ensaios ecotoxicológicos. Para os ensaios ecotoxicológicos foi iniciado o cultivo de dois novos organismos - Chironomus xanthus e Eisenia sp. - viventes no sedimento, para avaliação da resposta de ambos ao fenol, sendo esta a parte dos rios em que há o maior acúmulo de contaminantes Também foi utilizado Daphnia similis. A pesquisa foi realizada em três etapas: Fase de adaptação...

Analytical methods in photoelectrochemical treatment of phenol

Lopes,Paulo R. M; Montagnolli,Renato N; Bidoia,Ederio D
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2011 EN
Relevância na Pesquisa
37%
The aim of the study was to propose a treatment of simulated wastewater containing phenol by photocatalytic and photolytic processes and analyze the toxicity of these phenolic solutions. Two treatment systems were performed with UV radiation, solid electrodes and electric potential. In the first system (S1) phenol concentration was determined by UV direct spectrophotometry (269 nm) and in the second (S2) by direct photometric method (4-aminoantipyrine). Toxicological tests were carried out using two microorganisms: Escherichia coli and Saccharomyces cerevisiae. S1 results showed that erroneous conclusions can be drawn by absorbance values increase at phenol peak. Nevertheless, direct photometric method was able to identify phenol reduction in S2 and the proposed treatments degraded phenol in solution. Also, in treatment using high energy ultraviolet radiation (UVC), the phenol degradation was mainly due to the photolytic process

Phenol removal through combined biological and enzymatic treatments

Bevilaqua,J.V.; Cammarota,M.C.; Freire,D.M.G.; Sant’Anna Jr.,G.L.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2002 EN
Relevância na Pesquisa
37.03%
This work studies the use of biological and combined biological/enzymatic treatments in phenol degradation. The systems studied were conventional batch aerobic biological followed or preceded by enzymatic treatment. Tyrosinase extracted from the mushroom Agaricus bispora was employed. Biological treatment efficiently degraded effluents containing up to 420 mg.L-1 of phenol, removing 97% of the COD and 99% of the phenol in 48-hour batches. Alterations in phenol concentration intake reduced treatment efficiency significantly. Enzymatic polishing of biotreated effluent removed up to 75% of the remaining phenol in a four-hour reaction with 46 U.mL-1 of tyrosinase and 50 mg.L-1 of chitosan (used as coagulant). Enzymatic pretreatment with 20 U.mL-1 of tyrosinase reduced the phenol concentration by 25 % after 2 hours of reaction, although initial COD increased up to 58%. The subsequent biological treatment of that enzymatic pretreated effluent reduced COD to 151 mgO2.L-1 and phenol concentration to 1 mg.L-1 in 24-hours batches.

Effect of phenol on the biological treatment of wastewaters from a resin producing industry

Eiroa, M.; Vilar, A.; Kennes, Christian; Veiga, María C.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.09%
The effect of phenol on the biological treatment of wastewaters from a resin producing industry was analyzed in a pre-denitrification system. First, the effect of phenol overloads on the removal of organic matter and nitrogen compounds was studied. During the overloads (from 250 to 4000 mg/L), phenol was detected in the effluent of the anoxic reactor but the system recovered fast after stopping the overloads. The total organic carbon (TOC) removal remained unchanged during phenol addition (91.9% at 0.20 kg TOC/m3 d), except for the highest overload. With regard to total Kjeldahl nitrogen (TKN), its mean removal (87.9% at 0.08 kg TKN/m3 d) was not affected by the phenol overloads. Afterwards, the effect of different phenol concentrations on the biological treatment of these wastewaters was analyzed. Phenol concentrations from 250 to 4000 mg/L were added to the feed. Phenol was completely removed despite the presence of other carbon sources in the wastewater. In spite of the presence of phenol, a TOC removal around 91.3% was achieved at an average organic loading rate of 0.11 kg TOC/m3 d. The mean applied nitrogen loading rates were 0.05 and 0.08 kg TKN/m3 d, obtaining TKN removals around 85.8% and 87.1%, respectively. Therefore, the biological treatment of wastewaters from a resin producing industry in a pre-denitrification system was not affected by the presence of phenol.

Biodegradation and effect of formaldehyde and phenol on the denitrification process

Eiroa, M.; Vilar, A.; Amor, L.; Kennes, Christian; Veiga, María C.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.1%
Formaldehyde and phenol biodegradation during the denitrification process was studied at lab-scale, first in anoxic batch assays and then in a continuous anoxic reactor. The biodegradation of formaldehyde (260 mg l−1) as single carbon source and at phenol concentrations ranging from 30 to 580 mg l−1 was investigated in batch assays, obtaining an initial biodegradation rate around 0.5 g CH2O g VSS−1 d−1. With regard to phenol, its complete biodegradation was only observed at initial concentrations of 30 and 180 mg l−1. The denitrification process was inhibited at phenol concentrations higher than 360 mg l−1. Studies were also done using a continuous anoxic upflow sludge blanket reactor in which formaldehyde removal efficiencies above 99.5% were obtained at all the applied formaldehyde loading rates, between 0.89 and 0.14 g COD (CH2O) l−1 d−1. The phenol loading rate was increased from 0.03 to 1.3 g COD (C6H6O) l−1 d−1. Phenol removal efficiencies above 90.6% were obtained at phenol concentrations in the influent between 27 and 755 mg l−1. However, when the phenol concentration was increased to 1010 mg l−1, its removal efficiency decreased. Denitrification percentages around 98.4% were obtained with phenol concentrations in the influent up to 755 mg l−1. After increasing phenol concentration to 1010 mg l−1...

Phenol biodegradation and its effect on the nitrification process

Amor, L.; Eiroa, M.; Kennes, Christian; Veiga, María C.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.05%
Phenol biodegradation under aerobic conditions and its effect on the nitrification process were studied, first in batch assays and then in an activated sludge reactor. In batch assays, phenol was completely biodegraded at concentrations ranging from 100 to 2500 mg l−1. Phenol was inhibitory to the nitrification process, showing more inhibition at higher initial phenol concentrations. At initial phenol concentrations above 1000 mg l−1, the level of nitrification decreased. In the activated sludge reactor, the applied ammonium loading rate was maintained at 140 mg N–NH4+ l−1 d−1 (350 mg N–NH4+ l−1) during the operation time. However, the applied organic loading rate was increased stepwise from 30 to 2700 mg COD l−1 d−1 by increasing the phenol concentration from 35 up to 2800 mg l−1. High phenol removal efficiencies, above 99.9%, were maintained at all the applied organic loading rates. Ammonium removal was also very high during the operation period, around 99.8%, indicating that there was no inhibition of nitrification by phenol.

Uso de reatores biológicos com fungos para remoção de fenol de água residuária sintética ; The use of biological reactors containing fungi to remove phenol from synthetic wastewater

Rodrigues, Kelly de Araújo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 08/05/2006 PT
Relevância na Pesquisa
37.12%
Os compostos fenólicos estão presentes em grande número de efluentes industriais, cujos lançamentos inadequados podem acarretar em riscos ao meio ambiente e à saúde humana. O uso de fungos em reatores biológicos é uma alternativa de tratamento de despejos que possuem compostos persistentes, como fenóis. O objetivo deste trabalho foi estudar a viabilidade do uso de Aspergillus niger em reator biológico para o tratamento de água residuária sintética contendo fenol. O trabalho foi realizado com dois tipos de reatores: em batelada e reatores contínuos com escoamento ascendente. No experimento em batelada, foram utilizados 5 reatores de controle (RC), 5 com fungos (RF) e 5 com fungos e glicose (RFG), verificando-se o uso de glicose (5 g/L), como substrato primário, e a remoção do fenol pelos fungos. Estes apresentaram maior desenvolvimento nos reatores contendo glicose (RFG), alcançando-se remoção de 100% de fenol, no quinto e último dia de experimento. Nestes reatores, a velocidade média de consumo de fenol foi quase o dobro da desenvolvida nos reatores sem glicose (RF). A remoção de matéria orgânica, medida como DQO, foi superior nos reatores contendo glicose (RFG) e atingiu 93%, no quinto dia. Não houve remoção significativa de fenol nos reatores de controle. Nos RF...

Estructura y dinámica de comunidades bacterianas en sistemas de barros activados que degradan fenol; Structure and dynamics of bacterial communities in phenol-degrading activated sludge

Basile, Laura Ana
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2009 SPA
Relevância na Pesquisa
37.12%
La forma en la que las comunidades responden a las alteraciones suelen manifestarse a través de cambios en la composición o en la abundancia relativa de las especies. Frecuentemente estos cambios pueden ser atribuídos a caracteres funcionales o adaptativos. La búsqueda de modelos que expliquen los patrones de composición de especies y la coexistencia de especies similares dentro de comunidades ecológicas, pueden aportar datos sobre los mecanismos subyacentes que regulan la biodiversidad y su relación con el funcionamiento del ecosistema. En este trabajo se estudió la dinámica de las comunidades bacterianas, a nivel taxonómico y funcional, y el funcionamiento de sistemas de barros activados especializados en la degradación de fenol. Se evaluó en primer lugar la dinámica de las comunidades bacterianas en función del tiempo de aclimatación al fenol, operando bioreactores a escala de laboratorio bajo condiciones constantes a lo largo de 9 meses. En una segunda etapa se analizó el modo en que las comunidades bacterianas respondían a un aumento escalonado en la concentración de fenol. El funcionamiento de los reactores se analizó por mediciones de biomasa, niveles de turbidez y de fenol en el sobrenadante y velocidades de degradación de fenol. La estructura de la comunidad bacteriana se estudió por medio de geles de gradiente desnaturalizantes (DGGEs) del dominio variable V3 del ADN ribosomal 16S. La estructura a nivel funcional se determinó mediante la cuantificación por ensayos de PCR en tiempo real de las distintas variantes del gen de la subunidad mayor de la enzima fenol hidroxilasa multicomponente (LmPH)...

Biodegradation of phenol in static cultures by Penicillium chrysogenum ERK1: catalytic abilities and residual phototoxicity

Wolskm,Erika A; Barrera,Viviana; Castellari,Claudia; González,Jorge F
Fonte: Revista argentina de microbiología Publicador: Revista argentina de microbiología
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2012 EN
Relevância na Pesquisa
37.09%
A phenol-degrading fungus was isolated from crop soils. Molecular characterization (using internal transcribed spacer, translation elongation factor and beta-tubulin gene sequences) and biochemical characterization allowed to identify the fungal strain as Penicillium chrysogenum Thorn ERK1. Phenol degradation was tested at 25 °C under resting mycelium conditions at 6, 30, 60, 200, 350 and 400 mg/l of phenol as the only source of carbon and energy. The time required for complete phenol degradation increased at different initial phenol concentrations. Maximum specific degradation rate (0.89978 mg of phenol/day/mg of dry weight) was obtained at 200 mg/l. Biomass yield decreased at initial phenol concentrations above 60 mg/l. Catechol was identified as an intermediate metabolite by HPLC analysis and catechol dioxygenase activity was detected in plate assays, suggesting that phenol metabolism could occur via ortho fission of catechol. Wheat seeds were used as phototoxicity indicators of phenol degradation products. It was found that these products were not phytotoxic for wheat but highly phytotoxic for phenol. The high specific degradation rates obtained under resting mycelium conditions are considered relevant for practical applications of this fungus in soil decontamination processes.

Response of low-strength phenol-acclimated activated sludge to shock loading of high phenol concentrations

Lim,Jun-Wei; Seng,Chye-Eng; Lim,Poh-Eng; Ng,Si-Ling; Tan,Kui-Chew; Kew,Sook-Ling
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
Relevância na Pesquisa
37.15%
The objectives of this study were to: (i) evaluate the growth of low-strength phenol-acclimated activated sludge, (ii) investigate the degradation pathways and (iii) model the growth and biodegradation kinetics, all under the condition of increasingly higher phenol concentrations (step-up shock loading). With the use of activated sludge acclimated to phenol concentration of 140 mg.ℓ-1 (low-strength phenol-acclimated activated sludge), complete degradation of phenol with a COD removal efficiency of more than 95% was achieved up to 1 050 mg.ℓ-1 of initial phenol concentration. At low initial phenol concentrations, the experimental results were indicative of the meta-cleavage pathway for phenol degradation. When the initial phenol concentration was above 630 mg.ℓ-1, the degradation results were indicative of both meta- and ortho-cleavage pathways. The values of the Haldane kinetic parameters indicated a low degree of inhibition exerted by the presence of increasing phenol concentration. This was substantiated by the observation that the rate constant of phenol removal decreased by only 33% even though the initial phenol concentration was increased by 15 times from 70 to 1 050 mg.ℓ-1. Thus, the activated sludge acclimated to only 140 mg.ℓ-1 of phenol could successfully treat up to 1 050 mg.ℓ-1 of phenol without experiencing complete inhibition during the degradation process.

Modelling the change in the oxidation coefficient during the aerobic degradation of phenol by acclimated activated sludge

Lobo,Cintia C; Bertola,Nora C; Contreras,Edgardo M
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
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In this work the aerobic degradation of phenol by acclimated activated sludge was studied. Results demonstrate that while the phenol removal rate by acclimated activated sludge follows the Monod model, the oxygen uptake rate obeys a Haldane-type equation. The phenol oxidation coefficient obtained at different intial phenol concentrations ranged from 1.9 to 2.6 mol O2 · mol-1 phenol. A mathematical model based on a simplified version of the catalytic mechanism of the enzyme phenol 2-monooxygenase was developed to predict transient phenol concentrations and oxygen requirements by phenol-acclimated activated sludge in batch reactors under different initial phenol concentrations. The proposed model not only adequately represents the experimental results of the present paper, but also those reported by other authors. Particular cases of the proposed model are discussed.