Fixed-bed adsorption performance of oil palm shell-based activated carbon for removal of 2,4,6-trichlorophenol

This study investigated the adsorption potential of oil palm shell-based activated carbon to remove 2,4,6-trichlorophenol from aqueous solution using fixed-bed adsorption column. The effects of 2,4,6-trichlorophenol inlet concentration, feed flow rate and activated carbon bed height on the breakthrough characteristics of the adsorption system were determined. The regeneration efficiency of the oil palm shell-based activated carbon was evaluated using ethanol desorption technique. Through ethanol desorption, 96.25% of the adsorption sites could be recovered from the regenerated activated carbon.     

硝酸盐还原条件下Fe0/厌氧微生物联合体系降解2,4,6-三氯酚

本文采用间歇试验,对硝酸盐还原条件下Fe0/厌氧微生物联合体系降解2,4,6-三氯酚(2,4,6-TCP)进行了研究。考察了不同硝酸盐浓度下,体系中pH、硝酸盐浓度以及硝酸盐还原活性的变化情况。结果表明:当2,4,6-TCP初始浓度为20mg/L时,硝酸盐对Fe0/厌氧微生物联合体系降解2,4,6-三氯酚具有明显的抑制作用;且随着硝酸盐浓度的升高,2,4,6-TCP的去除率降低,硝酸盐还原活性升高;体系先发生硝酸盐还原再进行2,4,6-TCP还原脱氯。     

Degradation of Chlorophenols by Alcaligenes eutrophus JMP134(pJP4) in Bleached Kraft Mill Effluent

The ability of Alcaligenes eutrophus JMP134(pJP4) to degrade 2,4-dichlorophenoxyacetic acid, 2,4,6-trichlorophenol, and other chlorophenols in a bleached kraft mill effluent was studied. The efficiency of degradation and the survival of strain JMP134 and indigenous microorganisms in short-term batch or long-term semicontinuous incubations performed in microcosms were assessed. After 6 days of incubation, 2,4-dichlorophenoxyacetate (400 ppm) or 2,4,6-trichlorophenol (40 to 100 ppm) were extensively degraded (70 to 100%). In short-term batch incubations, indigenous microorganisms were unable to degrade such of compounds. Degradation of 2,4,6-trichlorophenol by strain JMP134 was significantly lower at 200 to 400 ppm of compound. This strain was also able to degrade 2,4-dichlorophenoxyacetate, 2,4,6-trichlorophenol, 4-chlorophenol, and 2,4,5-trichlorophenol when bleached Kraft mill effluent was amended with mixtures of these compounds. On the other hand, the chlorophenol concentration and the indigenous microorganisms inhibited the growth and survival of the strain in short-term incubations. In long-term (>1-month) incubations, strain JMP134 was unable to maintain a large, stable population, although extensive 2,4,6-trichlorophenol degradation was still observed. The latter is probably due to acclimation of the indigenous microorganisms to degrade 2,4,6-trichlorophenol. Acclimation was observed only in long-term, semicontinuous microcosms.     

Utilization of d-carnitine by Pseudomonas sp. AK 1

Abstract The degradation of chlorophenols by Alcaligenes eutrophus JMP134 (pJP4) was studied. The strain grew on 2,4,6-trichlorophenol or 2,4,6-tribromophenol as the sole carbon and energy source. Complete degradation of 2,4,6-trichlorophenol was confirmed by chloride release and gas chromatography analysis of supernatants from growth cultures. The 2,3,5-, 2,3,4-, 2,3,6-and 2,4,5-isomers of trichlorophenol did not support growth. However, up to 40% of 2,4,5-trichlorophenol was mineralized during growth of A. eutrophus on chemostats fed with either phenol (0.4 mM) or 2,4,6-trichlorophenol (0.4 mM) plus 2,4,5-trichlorophenol (0.1 mM). Growth on 2,4,6-trihalophenols was also observed in A. Eutrophus JMP222, the strain lacking pJP4, suggesting that this new degradative ability reported for A. eutrophus is not related to pJP4 encoded catabolic functions.     

Reductive dechlorination of chlorophenols by a pentachlorophenol- acclimated methanogenic consortium.

Anaerobic digester sludge fed 5,300 mg of acetate per liter, 3.4 microM pentachlorophenol, and nutrients for 10 days biotransformed pentachlorophenol by sequential ortho dechlorinations to produce 2,3,4,5-tetrachlorophenol and 3,4,5-trichlorophenol. Upon acclimation to 3.4 microM pentachlorophenol for 6 months, the methanogenic consortium removed chlorines from the ortho, meta, and para positions of pentachlorophenol and its reductive dechlorination products. Pentachlorophenol was degraded to produce 2,3,4,5-tetrachlorophenol, 2,3,4,6-tetrachlorophenol, and 2,3,5,6-tetrachlorophenol. Dechlorination of 2,3,4,5-tetrachlorophenol produced 3,4,5-trichlorophenol, which was subsequently degraded to produce 3,4-dichlorophenol and 3,5-dichlorophenol. 2,3,4,6-Tetrachlorophenol was dechlorinated at the ortho and meta positions to produce 2,4,6-trichlorophenol and 2,4,5-trichlorophenol. 2,3,5,6-Tetrachlorophenol yielded 2,3,5-trichlorophenol, followed by production of 3,5-dichlorophenol. 2,4,6-Trichlorophenol was degraded to form 2,4-dichlorophenol, and 2,4,5-trichlorophenol was dechlorinated at two positions to form 2,4-dichlorophenol and 3,4-dichlorophenol. Of the three dichlorophenols produced (2,4-dichlorophenol, 3,4-dichlorophenol, and 3,5-dichlorophenol), only 2,4-dichlorophenol was degraded significantly within 3 weeks, to produce 4-chlorophenol.     

Reductive dechlorination of chlorophenols by a pentachlorophenol- acclimated methanogenic consortium.

Anaerobic digester sludge fed 5,300 mg of acetate per liter, 3.4 microM pentachlorophenol, and nutrients for 10 days biotransformed pentachlorophenol by sequential ortho dechlorinations to produce 2,3,4,5-tetrachlorophenol and 3,4,5-trichlorophenol. Upon acclimation to 3.4 microM pentachlorophenol for 6 months, the methanogenic consortium removed chlorines from the ortho, meta, and para positions of pentachlorophenol and its reductive dechlorination products. Pentachlorophenol was degraded to produce 2,3,4,5-tetrachlorophenol, 2,3,4,6-tetrachlorophenol, and 2,3,5,6-tetrachlorophenol. Dechlorination of 2,3,4,5-tetrachlorophenol produced 3,4,5-trichlorophenol, which was subsequently degraded to produce 3,4-dichlorophenol and 3,5-dichlorophenol. 2,3,4,6-Tetrachlorophenol was dechlorinated at the ortho and meta positions to produce 2,4,6-trichlorophenol and 2,4,5-trichlorophenol. 2,3,5,6-Tetrachlorophenol yielded 2,3,5-trichlorophenol, followed by production of 3,5-dichlorophenol. 2,4,6-Trichlorophenol was degraded to form 2,4-dichlorophenol, and 2,4,5-trichlorophenol was dechlorinated at two positions to form 2,4-dichlorophenol and 3,4-dichlorophenol. Of the three dichlorophenols produced (2,4-dichlorophenol, 3,4-dichlorophenol, and 3,5-dichlorophenol), only 2,4-dichlorophenol was degraded significantly within 3 weeks, to produce 4-chlorophenol.     

Removal of chlorophenols from synthetic solutions using Phanerochaete chrysosporium

The potential use of the fungus Phanerochaete chrysosporium to remove chlorophenols (phenol, o-chlorophenol, p-chlorophenol and 2,4,6-trichlorophenol) from aqueous solutions was evaluated. The kinetics of both adsorption and desorption of phenolic compounds was rapid for all adsorbates. The maximum adsorptions of phenol and chlorophenols onto the Phanerochaete chrysosporium were 1.23 mmol/g for phenol, 1.49 mmol/g for o-chlorophenol, 1.78 mmol/g for p-chlorophenol and 2.14 mmol/g for 2,4,6-trichlorophenol. The affinity order was as follows: 2,4,6-trichlorophenol > p-chlorophenol > o-chlorophenol > phenol. Phenol and chlorophenols binding with Phanerochaete chrysosporium were clearly pH dependent. The adsorption of phenol and chlorophenols increased as pH increased. Desorption of phenol or chlorophenols was achieved using methanol solution (30% (v/v)). Phanerochaete chrysosporium is suitable for reuse for more than ten cycles without noticeable loss of adsorption capacity.     

Conversion of polychlorophenols by laccases with 1-hydroxybenzotriazole as a mediator

The action of purified laccase from the basidial fungi Cerrena unicolor and Trametes sp. on 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP) was studied, including reactions involving I-hydroxybenzotriazole as a mediator. Oxidation of 2,4,6-TCP by laccase without the mediator yielded 2,6-dichlorobenzoquinone as a primary conversion product, whereas PCP was not oxidized. Products of further conversion of 2,4,6-TCP and PCP formed with the presence of the mediator.     

Removal of chlorophenols from aquatic systems using the dried and dead fungus Pleurotus sajor caju

In this study, the potential use of the fungus Pleurotus sajor caju to remove phenols (i.e., phenol, o-chlorophenol, p-chlorophenol and 2,4,6-trichlorophenol) from aqueous solutions was evaluated. Biosorption of phenol or chlorophenols reached equilibrium in 4 h. The maximum adsorptions of phenol and chlorophenols onto the Pleurotus sajor caju were 0.95 mmol/g for phenol, 1.24 mmol/g for o-chlorophenol, 1.47 mmol/g for p-chlorophenol and 1.89 mmol/g for 2,4,6-trichlorophenol. The affinity order was as follows: 2,4,6-trichlorophenol> p-chlorophenol> o-chlorophenol>phenol. Phenol and chlorophenols bindings onto Pleurotus sajor caju were clearly pH dependent. The adsorption of phenol and chlorophenols increased with increasing pH. Desorption was achieved using methanol solution (30%, v/v). Pleurotus sajor caju biomass is suitable for reuse for more than five cycles without noticeable loss of adsorption capacity.     

Biodegradation of phenol and chlorophenols with defined mixed culture in shake-flasks and a packed bed reactor

Pseudomonas testosteroni CPW301 degraded phenol and 4-chlorophenol simultaneously, but degradation rates of these compounds were affected by 4-chlorophenol. Phenol increased the cell concentration and therefore the degradation efficiency of 4-chlorophenol was improved. Pseudomonas solanacearum TCP114 could degrade only 2,4,6-trichlorophenol. A defined mixed culture of P. testosteroni CPW301 and P. solanacearum TCP114 could treat phenol, 4-chlorophenol, and 2,4,6-trichlorophenol completely and overcome the inhibition of substrates to other microorganisms. The degradation capacity of the packed bed reactor (PBR) was higher than that of the continuous stirred tank reactor, but the PBR was unsuitable for oxygen-sensitive microorganisms.     

Conversion of polychlorophenols by laccases with 1-hydroxybenzotriazole as a mediator

The action of purified laccase from the basidial fungi Cerrena unicolor and Trametes sp. on 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP) was studied, including reactions involving 1-hydroxybenzotriazole as a mediator. Oxidation of 2,4,6-TCP by laccase without the mediator yielded 2,6-dichlorobenzoquinone as a primary conversion product, whereas PCP was not oxidized. Products of further conversion of 2,4,6-TCP and PCP formed with the presence of the mediator.     

Degradation of polychlorinated phenols by Rhodococcus chlorophenolicus

Summary An actinomycete, Rhodococcus chlorophenolicus, isolated from a pentachlorophenol-degrading mixed bacterial culture is a polychlorophenol degrader. It was shown to oxidize pentachlorophenol into carbon dioxide and to metabolize also 2,3,4,5-,2,3,4,6-, and 2,3,5,6-tetrachlorophenol, 2,3,4-, 2,3,5-, 2,3,6-, 2,4,6-, and 2,4,5-trichlorophenol, 2,5-, and 2,6-dichlorophenol and tetrachloro-p-hydroquinone in an inducible manner. Pentachlorophenol set on the synthesis of enzymes required for the metabolism of all these chlorophenols and of tetrachloro-p-hydroquinone. 2,4,5-, and 2,4,6-trichlorophenol and 2,5-, and 2,6-dichlorophenol were degraded by R. chlorophenolicus cells only if these had previous contact to pentachlorophenol. Other chlorophenols mentioned were able to set on the synthesis of enzymes for their own degradation. 2,3,4,5-, and 2,3,4,6-tetrachlorophenol, and 2,3,5-, 2,4,5-, and 3,4,5-trichlorophenol were more toxic to R. chlorophenolicus than the other chlorophenols, but nevertheless 2,3,4,5-, and 2,3,4,6-tetrachlorophenol and 2,3,5-trichlorophenol were readily degraded by the bacteria.Abbreviations DCP dichlorophenol - TCP trichlorophenol - TeCP tetrachlorophenol - PCP pentachlorophenol - TeCH tetrachloro-p-hydroquinone An example of numeration: 2345-TeCP, 2,3,4,5-tetrachlorophenol     

Rapid dehalogenation of 2,4,6-trichlorophenol at alkaline pH by an anaerobic enrichment culture

An enrichment culture, derived from the anaerobic stage of a two-step sequential anaerobic-aerobic reactor system which mineralized 2,4,6-trichlorophenol, stoichiometrically converted 2,4,6-trichlorophenol to 4-chlorophenol. Dehalogenation occurred only in alkaline media (pH 8–9) at concentrations of substrate up to 1 mmol 1¹. Formate plus acetate or trypticase could serve as electron donors. Neither vitamins nor trace elements were required in a chloride-free defined medium. The dehalogenating organism was oxygen-resistant, but was not active in media which were oxidized with respect to resazurin indicator dye. Most probable number counts of the dehalogenating cultures showed that the dehalogenating organisms were present in very small numbers, yet catalysed dehalogenation at rates considerably faster than other dehalogenating organisms described in the literature.     

Biodegradation of 2,4,6-tribromophenol by Ochrobactrum sp. strain TB01

A bacterium that utilizes 2,4,6-tribromophenol (2,4,6-TBP) as sole carbon and energy source was isolated from soil contaminated with brominated pollutants. This bacterium, designated strain TB01, was identified as an Ochrobactrum species. The organism degraded 100 microM of 2,4,6-TBP within 36 h in a growing culture. In addition, it released 3 mol of bromine ions from 1 mol of 2,4,6-TBP during the complete degradation of 2,4,6-TBP in a resting cell assay. Moreover, cells grown on 2,4,6-TBP degraded 2,6-dibromophenol (2,6-DBP), 4-bromophenol (4-BP), 2,4,6-trichlorophenol (2,4,6-TCP) and phenol. Metabolic intermediates were detected in the reaction mixture of an in vitro assay for 2,4,6-TBP, and they were identified as 2,4-DBP and 2-BP. NADH was required for the debromination of 2,4,6-TBP. These results suggest that 2,4,6-TBP is converted to phenol through sequential reductive debromination reactions via 2,4-DBP and 2-BP by this strain.     

Enzymatic dehalogenation of pentachlorophenol by extracts from Arthrobacter sp. strain ATCC 33790.

Arthrobacter sp. strain ATCC 33790 was grown with pentachlorophenol (PCP) as the sole source of carbon and energy. Crude extracts, which were prepared by disruption of the bacteria with a French pressure cell, showed no dehalogenating activity with PCP as the substrate. After sucrose density ultracentrifugation of the crude extract at 145,000 x g, various layers were found in the gradient. One yellow layer showed enzymatic conversion of PCP. One chloride ion was released per molecule of PCP. The product of the enzymatic conversion was tetrachlorohydroquinone. NADPH and oxygen were essential for this reaction. EDTA stimulated the enzymatic activity by 67%. The optimum pH for the enzyme activity was 7.5, and the temperature optimum was 25 degrees C. Enzymatic activity was also detected with 2,4,5-trichlorophenol, 2,3,4-trichlorophenol, 2,4,6-trichlorophenol, and 2,3,4,5-tetrachlorophenol as substrates, whereas 3,4,5-trichlorophenol, 2,4-dichlorophenol, 3,4-dichlorophenol, and 4-chlorophenol did not serve as substrates.     

Isolation of Pseudomonas pickettii strains that degrade 2,4,6-trichlorophenol and their dechlorination of chlorophenols.

Three strains of Pseudomonas pickettii that can grow with 2,4,6-trichlorophenol (2,4,6-TCP) as the sole source of carbon and energy were isolated from different mixed cultures of soil bacterial populations that had been acclimatized to 2,4,6-TCP. These strains released 3 mol of chloride ion from 1 mol of 2,4,6-TCP during the complete degradation of the TCP. Of these strains, P. pickettii DTP0602 in high-cell-density suspension cultures dechlorinated various chlorophenols (CPs). Cells that were preincubated with 2,4,6-TCP converted isomers of 4-CP to the corresponding chloro-p-hydroquinones, but those preincubated with 4-CP converted CPs lacking a chlorine atom(s) at the o position to isomers of chlorocatechol. The ability of DTP0602 to dechlorinate 2,4,6-TCP was induced by 2,6-dichlorophenol, 2,3,6- and 2,4,6-TCP, and 2,3,4,6-tetrachlorophenol and was repressed in the presence of succinate or glucose.     

Isolation of Pseudomonas pickettii strains that degrade 2,4,6-trichlorophenol and their dechlorination of chlorophenols.

Three strains of Pseudomonas pickettii that can grow with 2,4,6-trichlorophenol (2,4,6-TCP) as the sole source of carbon and energy were isolated from different mixed cultures of soil bacterial populations that had been acclimatized to 2,4,6-TCP. These strains released 3 mol of chloride ion from 1 mol of 2,4,6-TCP during the complete degradation of the TCP. Of these strains, P. pickettii DTP0602 in high-cell-density suspension cultures dechlorinated various chlorophenols (CPs). Cells that were preincubated with 2,4,6-TCP converted isomers of 4-CP to the corresponding chloro-p-hydroquinones, but those preincubated with 4-CP converted CPs lacking a chlorine atom(s) at the o position to isomers of chlorocatechol. The ability of DTP0602 to dechlorinate 2,4,6-TCP was induced by 2,6-dichlorophenol, 2,3,6- and 2,4,6-TCP, and 2,3,4,6-tetrachlorophenol and was repressed in the presence of succinate or glucose.     

Monitoring of an Alkaline 2,4,6-Trichlorophenol-Degrading Enrichment Culture by DNA Fingerprinting Methods and Isolation of the Responsible Organism, Haloalkaliphilic Nocardioides sp. Strain M6

A site situated near Alkali Lake (Oregon) and highly contaminated by chloroaromatic compounds was chosen for isolation of alkaliphilic chlorophenol-degrading bacteria. Prolonged cultivation of an enrichment culture followed by successive transfers resulted in a strong increase in the 2,4,6-trichlorophenol (2,4,6-TCP) degradation rate. Repetitive extragenic palindromic PCR and amplified ribosomal DNA restriction analysis were applied to distinguish members of the enrichment culture and monitor them during the enrichment procedure. Comparison of the fingerprints of the isolates obtained from the enrichment culture and its total DNA fingerprint indicated the presence of an unidentified bacterium in the enrichment culture, assisting in its isolation. The 2,4,6-TCP-degrading isolate, M6, was tentatively identified as a Nocardioides sp. strain based on its partial 16S RNA sequence and fatty acid profile. Strain M6 was capable of utilizing up to 1.6 g of 2,4,6-TCP per liter as a sole carbon and energy source and could also grow on 2,4-dichlorophenol and 2,4,5-trichlorophenol. A high-cell-density suspension of this strain degraded a wide range of chlorinated phenols from di- to pentachlorophenol while showing a clear preference for phenols containing chlorine substituents in positions 2 plus 4. Based on its optimal pH (9.0 to 9.4) and sodium ion concentration (0.2 to 0.4 M) for growth, Nocardioides sp. strain M6 is a slightly halophilic alkaliphile.     

Degradation of 2,4,6-tribromophenol and 2,4,6-trichlorophenol by aerobic heterotrophic bacteria present in psychrophilic lakes

Halogenated compounds have been incorporated into the environment, principally through industrial activities. Nonetheless, microorganisms able to degrade halophenols have been isolated from neither industrial nor urban environments. In this work, the ability of bacterial communities from oligotrophic psychrophilic lakes to degrade 2,4,6-tribromophenol and 2,4,6-trichlorophenol, and the presence of the genes tcpA and tcpC described for 2,4,6-trichlorophenol degradation were investigated. After 10 days at 4°C, the microcosms showed the ability to degrade both halophenols. Nonetheless, bacterial strains isolated from the microcosms did not degrade any of the halophenols, suggesting that the degradation was done by a bacterial consortium. Genes tcpA and tcpC were not detected. Results demonstrated that the bacterial communities present in oligotrophic psycrophilic lakes have the ability to degrade halophenolic compounds at 4°C and the enzymes involved in their degradation could be codified in genes different to those described for bacteria isolated from environments contaminated by industrial activities.     

Role of Chrysonilia sitophila in the quality of cork stoppers for sealing wine bottles

The contribution of Chrysonilia sitophila in cork stopper manufacture was studied and a simulation of the industrial processing of cork stoppers was performed. Stoppers cut from slabs where mold development was inhibited were compared with others cut from slabs colonized by C. sitophila alone or with several molds, in terms of physical properties and chemical taints. C. sitophila does not produce 2,4,6-trichloroanisole, guaiacol, or 1-octene-3-ol on cork slabs incubated for 66 days. Since some chlorophenol-related compounds contaminate cork slabs during the production processes, metabolic tests were performed to investigate the capability of molds to produce 2,4,6-trichloroanisole by methylation of 2,4,6-trichlorophenol. Degradation of 2,4,6-trichlorophenol by C. sitophila resulted in a very high level of degradation without production of 2,4,6-trichloroanisole. C. sitophila restricted growth of other molds on maturing slabs for at least 30 days. These results show that C. sitophila can be exploited by industrial producers of cork stoppers since it is able to inhibit the development of other molds and it does not produce the compounds responsible for ‘cork-taint’, even in the presence of chlorophenols. Journal of Industrial Microbiology & Biotechnology (2000) 24, 256–261. Received 28 July 1999/ Accepted in revised form 05 January 2000