ABSTRACT
RESUMO O ácido 2,4-diclorofenoxiacético (2,4-D) é o segundo herbicida mais consumido no Brasil e seus efeitos na contaminação dos recursos hídricos e consequente risco sanitário para abastecimento público são conhecidos. O 2,4-D e seu principal produto de degradação, o 2,4-diclorofenol (2,4-DCP), apresentam potencial de desregulação endócrina, e o ácido 2,4,5-triclorofenoxiacético (2,4,5-T) é tóxico e persistente no meio ambiente. A inexistência de uma metodologia para quantificação simultânea desses compostos motivou o desenvolvimento e a validação do método de extração e concentração de amostras ambientais e a quantificação em cromatografia líquida de alta eficiência com detector de arranjo de diodos (CLAE-DAD) para análise de 2,4-D, 2,4-DCP e 2,4,5-T em água filtrada produzida em estação de tratamento de água e água de manancial superficial. Os resultados de extração em fase sólida e a concentração da amostra demonstraram recuperação de 89 a 119%, e desvio padrão entre 0,9 e 11,4%. Para os ensaios de identificação e quantificação, os limites de detecção variaram entre 0,17 e 0,51 µg.L-1 e limite de quantificação de 1,0 µg.L-1. Os resultados mostraram que é possível empregar esse método na quantificação do 2,4-D, do 2,4-DCP e do 2,4,5-T em monitoramento ambiental e em sistemas de abastecimento de água atendendo às legislações brasileiras.
ABSTRACT The 2,4-dichlorophenoxyacetic acid (2,4-D) is the second most consumed herbicide in Brazil and their effects in the contamination of the water resources and consequent sanitary risk for public supply are known. The 2,4-D and its main degradation product, 2,4-dichlorophenol (2,4-DCP), have the potential for endocrine disruption and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) is toxic and persistent in the environment. The absence of a methodology that simultaneously determines these compounds led to the development and validation of the solid phase extraction method, environmental samples concentrations, identification and quantification in HPLC-DAD for 2,4-D, 2,4-DCP and 2,4,5-T analysisin filtered water, produced at water treatment plants, and surface water. The extraction essay and samples concentration showed recovery from 85 to 119%, standard deviation between 0.9 and 11.4%. For identification and quantification essays, detection limits ranged between 0.17 and 0.51 µg.L-1 and the quantification limit was 1.0 µg.L-1. The results showed that it is possible to employ this method for the quantification of 2,4-D, 2,4-DCP and 2,4,5-T in environmental monitoring and in water supply systems taking account of Brazilian regulatory agencies
ABSTRACT
This work aimed to investigate the capacity of Pleurotus ostreatus DSM 1833 to degrade 2,4-dichlorophenol, important pollutant found in the wastewaters of the paper and cellulose industry. Using a factorial design 2², the concentrations of glucose and 2,4-dichlorophenol varied between 0 and 10g.L-1 and 5 and 30mg.L-1, respectively. The best global biodegradation rate was obtained using 30 mg.L-1 of 2,4- dichlorophenol in the absence of glucose. This culture medium was used for scaling up the process, resulting in a global biodegradation rate of 0.47mg.L-1.h-1. A comparative test between an inoculated medium and an abiotic control demonstrated that 54.1 percent of 2,4- dichlorophenol degradation could be attributed to the presence of P. ostreatus.
A indústria de papel e celulose contribui para a contaminação ambiental devido aos resíduos gerados, especialmente, no processo de branqueamento da polpa Kraft, realizada com cloro. Basideomicetos saprófitas têm a capacidade de degradar compostos organoclorados como cloroligninas e clorofenóis. Este trabalho teve como objetivo investigar a capacidade de Pleurotus ostreatus DSM 1833 em degradar 2,4-diclorofenol, importante poluente encontrado nos efluentes da indústria de papel e celulose. Utilizando um planejamento fatorial 2², as concentrações de glicose e de 2,4-diclorofenol variaram entre 0 e 10 g.L-1 e 5 e 30 mg.L-1, respectivamente. A melhor taxa global de degradação foi obtida usando-se 30 mg.L-1 de 2,4-diclorofenol na ausência de glicose. Este meio de cultura foi utilizado para a ampliação da escala do processo, resultando em uma taxa global de biodegradação de 0,47 mg.L-1.h-1. Um teste comparativo entre o meio inoculado e o controle abiótico demonstrou que 54,1 por cento da degradação do 2,4-diclorofenol pode ser atribuída à presença de Pleurotus ostreatus.
ABSTRACT
A test was conducted to examine the effect of several electron donors such as glucose, sodium acetate, Fe0, Fe0+glucose and Fe0+sodium acetate on reductive dechlorination of 2,4-dichlorophenol (2,4-DCP) through inoculating the unacclimated anaerobic mixed bacteria. The optimum condition and sus-tainability of Fe0 as electron donor was also been discussed. The results showed that, Fe0+glucose enhanced the dechlorination of contaminant effectively compared to glucose. Sodium acetate, Fe0 and Fe0+sodium acetate were all effective electron donors and Fe0 was the optimum, the optimum initial pH was 8.0 and quantity of added Fe0 was 2.0 g/L. 4-CP was the mainly intermediate product for 2,4-DCP dechlorination. Fe0 could support the electron for reductive dechlorination of 2,4-DCP continuously. In contrast, when so-dium acetate as electron donor, the effect of dechlorination was inferior to Fe0 with the consumption of sodium acetate.
ABSTRACT
A 2,4 -dichlorophenol degrading Pseudomonas strain GI241-1 was isolated from a soil sample. The dienelactone hydrolase gene, designated as dcpD which encodes dienelactone hydrolase involved in transforming cis-2-chloro-dienelactone into 2-chloromaleylacetic acid, was cloned from this bacterium strain. The gene cloning strategy was to construct genomic library after location of its neighbouring gene by Southem blot and to screen the aim transformant by dot blotting. Sequencing results showed that length of dcpD is 702bp. The sequence of dcpD and the deduced amino acid are different from the relative sequences registered in the GenBank.
ABSTRACT
A batch laboratory test was conducted to examine the effect of biological reductive dechlorination of 2,4-Dichlorophenol(2,4-DCP) by the addition of zero-valent iron(Fe0) in the anaerobic system, through inoculating the anaerobic mixed microorganism acclimated for two months. Meanwhile, several factors that affected "Fe0+ microbe" system were also being discussed. The results showed that, "Fe0+ microbe" system accelerated the biological dechlorination of 2,4-DCP effectively compared to the individual use. The opti-mum quantity of added Fe0 and inoculation was 0.5 g/L and 376.2 mgVSS/L in the combined system respec-tively. It showed the most effective transformation efficiency for 2,4-DCP when initial pH=8.0, whereas it become weaker when initial pH are keeping in acid condition. There existed a proportion between quantity of added Fe0 and inoculation. It enhanced degradable effect of 2,4-dichlorophenol when increased the quan-tity of inoculation at suitable ranges, which generated more enzyme or enzymatic series degraded pollutant.