Degradation Of High Concentrations Research Articles

Isolation and identification of acetaminophen degrading strain Shinella sp. HZA2

Acetaminophen (APP), frequently used as analgesic and antipyretic drug in our life, is potentially toxic to both animals and humans. A novel acetaminophen degrading strain HZA2, was isolated from the activated sludge, and identified as Shinella sp. based on its 16S rRNA gene sequence analysis, morphological, physiological, and biochemical characterizations. This strain could degrade 100 mg L−1 acetaminophen completely within 12 h, and it was also a very effective strain for the degradation of high concentration of acetaminophen below 3000 mg L−1 under the optimal condition. The optimal degrading conditions of acetaminophen by HZA2 were pH 7.5 and 32.7 °C by the analysis of response surface methodology. Exogenous carbon source could enhance the biodegradation of acetaminophen. During the process, the intermediate metabolites were identified as 4-aminophenol and hydroquinone via gas chromatography-mass spectrometry analysis. The results indicated that strain HZA2 may be a promising bacterium for the bioremediation of acetaminophen pollutions.

Enhanced esterase activity during the degradation of dibutyl phthalate by Fusarium species in liquid fermentation.

Dibutyl phthalate (DBP) is one of the most abundantly produced and used plasticizers and is incorporated into plastic to make it more flexible and malleable. DBP has been found to be an environmental contaminant and reported as an endocrine disruptor. Therefore, it is crucial to develop ecofriendly alternatives to eliminate phthalate pollution. In the present research, the growth of F. culmorum and F. oxysporum in the presence of DBP was studied in liquid fermentation. The esterase activity, specific growth rate, and growth and enzymatic yield parameters were determined in DBP-supplemented media (1,500 or 2,000 mg/L) and in control medium (lacking DBP). These results show that in general, for both Fusarium species, the highest esterase activities, specific growth rates, and yield parameters were observed in media supplemented with DBP. It was observed that 1,500 and 2,000 mg of DBP/L did not inhibit F. culmorum or F. oxysporum growth and that DBP induced esterase production in both fungi. These organisms have much to offer in the mitigation of environmental pollution caused by the endocrine disruptor DBP. This study reports, for the first time, esterase production during the degradation of high concentrations (i.e., 1,500 and 2,000 mg/L) of DBP by F. culmorum F. oxysporum.

Biomimetic preparation of ternary heterogeneous catalyst derived from biopolymer in biological sludge and synergistic effects in Fenton process

Biopolymer (BioP) was extracted from waste activated sludge and the ternary catalyst BioP@PANI@Fe3O4 was prepared by biomimetic method. Control experiments proved the synergistic effects of the components in BioP@PANI@Fe3O4. The degradation of high concentration of model pollutant proved its good performance as the heterogeneous Fenton catalyst.The high utilization efficiency of H2O2 and wide oprational pH range showed the promising application of BioP@PANI@Fe3O4 in the oxidative degradation of organic pollutants. The possible reaction mechanism on the surface of BioP@PANI@Fe3O4 lies in that PANI provide the acidic condition and the initially generated ≡Fe(II) species react with H2O2 to generate •OH, which destroy the organic dyes adsorbed onto catalyst surface. The redox process Fe(III)→Fe(II) take place easily due to convenient electro transfer in PANI and reduction power of functional groups in BioP.

Characterization of the growth on SDS by <i>Enterobacter</i> sp. strain Neni-13

Sodium dodecyl sulphate (SDS) is an anionic surfactant which is mainly utilized in washing detergents and industrial products and solutions. Its toxicity and contamination of the surroundings environment are ubiquitous. In this study, the SDS-degradation capacity of a previously isolated molybdenum-reducing bacterium; Enterobacter sp. Strain Neni-13 is reported. At 1 g/L of SDS as the sole carbon source, the bacterium grew maximally at pH 7.0, the temperature range from 20 to 45 °C support maximal growth and require ammonium sulphate as the best nitrogen source at the optimal concentration of 1 % w/v. Growth on various concentrations of SDS as a carbon source shows that the bacterium can grow maximally in between 800 and 1200 mg/L and was able to grow at the maximum concentration of 1500 mg/L while concentrations higher than this caused the cessation of growth. The heavy metals mercury, silver and copper inhibit growth on SDS. The ability of this bacterium to detoxify dual toxicants, which include the degradation of high concentration of SDS is highly sought.

Degradation of high concentration 2,4-dichlorophenol by simultaneous photocatalytic–enzymatic process using TiO2/UV and laccase

Removal of 2,4-dichlorophenol (2,4-DCP) by TiO2/UV photocatalytic, laccase, and simultaneous photocatalytic–enzymatic treatments were investigated. Coupling of native laccase with TiO2/UV showed a negative synergetic effect due to the rapid inactivation of laccase. Immobilizing laccase covalently to controlled porous glass (CPG) effectively enhanced the stability of laccase against TiO2/UV induced inactivation. By coupling CPG–laccase with the TiO2/UV the degradation efficiency of 2,4-DCP was significantly increased as compared with the results obtained when immobilized laccase or TiO2/UV were separately used. Moreover, the enhancement was more remarkable for the degradation of 2,4-DCP with high concentration, such that for the degradation of 5mM 2,4-DCP, 90% removal percentage was achieved within 2h with the coupled degradation process. While for the TiO2/UV and CPG–laccase process, the removal percentage of 2,4-DCP at 2h were only 26.5% and 78.1%, respectively. The degradation kinetics were analyzed using a intermediate model by taking into account of the intermediates formed during the degradation of 2,4-DCP. The high efficiency of the coupled degradation process therefore provided a novel strategy for degradation of concentrated 2,4-DCP. Furthermore, a thermometric biosensor using the immobilized laccase as biorecognition element was constructed for monitoring the degradation of 2,4-DCP, the result indicated that the biosensor was precise and sensitive.

Formation of chlorinated biphenyls, diphenyl ethers and benzofurans as a result of Fenton-driven oxidation of 2-chlorophenol

Homogeneous catalytic Fenton oxidation proved to be very efficient in the degradation of high concentrations (3.9 mM) of 2-chlorophenol (2-CP) in aqueous matrices. When using [H 2O 2] 0/[2-CP] 0 substoichiometric molar ratios of 4 and 16, the detected aromatic intermediates included mainly chlorinated benzenediols, with the virtual absence of condensation products of higher molecular weight. At even lower substoichiometric ratios of [H 2O 2] 0/[2-CP] 0 (⩽2.2), hydroxylated chlorobiphenyls, hydroxylated chlorodiphenyl ethers and hydroxylated chlorinated dibenzofurans were formed in addition to chlorinated benzenediols. The aromatic intermediates were identified as trimethylsilyl ethers and dimethyl-t-butyl silyl ethers. A reaction scheme was proposed to describe the formation of aromatic intermediates based on coupling reactions of resonance-stabilized 2-CP radicals generated by electrophilic attack of reactive hydroxyl radicals. The pattern of aromatic intermediates identified in the Fenton solutions coincided well with that predicted on the basis of oxidative coupling reactions. In addition to coupling of stabilized radicals, aromatic intermediates can be formed by addition of organoradicals onto neutral analyte molecules. The findings presented in this contribution are considered crucial for the design and optimization of Fenton-based remediation devoted either to wastewater treatment under economically feasible conditions or to in situ groundwater treatment where poorly controlled reaction conditions prevail.

Degradation of high concentrations of cresols by Pseudomonas sp. CP4

Pseudomonas sp. CP4, a potent phenol-degrading laboratory isolate could mineralize all three isomers of cresol. This strain readily utilized up to 1.4, 1.1 and 2.2 g/l of o- m- and p-cresol, respectively as the sole sources of carbon and energy. These are the highest concentrations of cresols reported to be degraded by a bacterial strain. The rates of degradation of the three isomers were in the order: o- > p- > m-cresol. All the isomers of cresol were catabolized through a meta-cleavage pathway. Fairly high catechol 2,3-dioxygenase (C230) activity against catechol was observed in the cell-free extracts of the culture grown on these compounds and were in the order: m- > o- > p-cresol.

Biodegradation of acrylonitrile in soil

AbstractThe aerobic biodegradation of [14Clacrylonitrile at concentrations ranging from 10 to 1,000 ppm was examined in a variety of surface soils. At concentrations up to 100 ppm, complete degradation of the compound occurred in <2 d in a Londo soil. Greater than 50% of the radioactivity was recovered as [14C]carbon dioxide following 6 d of incubation. Because the soil had no known previous exposure to acrylonitrile, dissimilation did not appear to require acclimation of the microorganisms. Transient formation of acrylamide and acrylic acid as intermediates of degradation was also observed. These results appear to be consistent with previously published results of acrylonitrile transformation by axenic microbial cultures. Similar results were obtained in studies conducted with Tappan loam (10, 50, 100 ppm) and sand (10 and 50 ppm). Acclimation of the microorganisms was required before degradation of 100 ppm acrylonitrile in sand. Degradation of higher concentrations (500 and 1,000 ppm in Londo soil) was relatively slow and may be due to inhibitory effects of the parent compound.

Effectiveness ofPseudomonas aeruginosa for detoxification of tetramethylthiuram disulfide (TMTD) from contaminated soil

We have previously reported the effectiveness of Pseudomonas aeruginosa towards the degradation of high concentrations of TMTD in autoclaved soils. Our results, reported here, concern the use of biological assay (plant growth) to measure the ability of P. aeruginosa to detoxify TMTD in soil contamined with to 2500 ppm TMTD