| 1. |
- Arriaga, S, et al.
(författare)
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Gaseous hexane biodegradation by Fusarium solani in two liquid phase packed-bed and stirred-tank bioreactors
- 2006
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 40:7, s. 2390-2395
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Tidskriftsartikel (refereegranskat)abstract
- Biofiltration of hydrophobic volatile pollutants is intrinsically limited by poor transfer of the pollutants from the gaseous to the liquid biotic phase, where biodegradation occurs. This study was conducted to evaluate the potential of silicone oil for enhancing the transport and subsequent biodegradation of hexane by the fungus Fusarium solani in various bioreactor configurations. Silicone oil was first selected among various solvents for its biocompatibility, nonbiodegradability, and good partitioning properties toward hexane. In batch tests, the use of silicone oil improved hexane specific biodegradation by approximately 60%. Subsequent biodegradation experiments were conducted in stirred-tank (1.5 L) and packed-bed (2.5 L) bioreactors fed with a constant gaseous hexane load of 180 g center dot m(reactor)(-3)center dot h(-1) and operated for 12 and 40 days, respectively. In the stirred reactors, the maximum hexane elimination capacity (EC) increased from 50 g center dot m(reactor)(-3)center dot h(-1) (removal efficiency, RE of 28%) in the control not supplied with silicone oil to 120 g center dot m(reactor)(-3)center dot h(-1) in the biphasic system (67% RE). In the packed-bed bioreactors, the maximum EC ranged from 110 (50% RE) to 180 g center dot m(reactor)(-3)center dot h(-1) (>90% RE) in the control and two-liquid-phase systems, respectively. These results represent, to the best of our knowledge, the first reported case of fungi use in a two-liquid-phase bioreactor and the highest hexane removal capacities so far reported in biofilters.
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| 2. |
- Blanquez, Paqui, et al.
(författare)
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Continuous biodegradation of 17 beta-estradiol and 17 alpha-ethynylestradiol by Trametes versicolor
- 2008
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 1873-3336 .- 0304-3894. ; 150:2, s. 459-462
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Tidskriftsartikel (refereegranskat)abstract
- The feasibility of 17 beta-estradiol (E2) and 17 alpha-ethynylestradiol (EE2) removal by Trametes versicolor was demonstrated in batch and continuous cultures. In batch, E2 and EE2 initially supplied at 10 mg l(-1) were removed by more than 97% in 24 h, which corresponded to volumetric removal rates of 0.43 and 0.44 mg l(-1) h(-1), respectively. A bioreactor inoculated with T versicolor pellets was then continuously operated during 26 days at a hydraulic retention time of 120 h. E2 and EE2 were completely removed at volumetric removal rates of 0.16 and 0.09 mg l(-1) h(-1), respectively, when fed at 18.8 and 7.3 mg l(-1), respectively. Evidence was found that removal was caused by laccase. This study demonstrates the technical feasibility of fungal treatment of estrogens using continuous bioreactor with suspended fungal biomass.
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| 3. |
- Borde, X, et al.
(författare)
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Synergistic relationships in algal-bacterial microcosms for the treatment of aromatic pollutants.
- 2003
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Ingår i: Bioresource Technology. - 1873-2976. ; 86:3, s. 293-300
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Tidskriftsartikel (refereegranskat)abstract
- The potential of algal–bacterial microcosms was studied for the biodegradation of salicylate, phenol and phenanthrene. The isolation and characterization of aerobic bacterial strains capable of mineralizing each pollutant were first conducted. Ralstonia basilensis was isolated for salicylate degradation, Acinetobacter haemolyticus for phenol and Pseudomonas migulae and Sphingomonas yanoikuyae for phenanthrene. The green alga Chlorella sorokiniana was then cultivated in the presence of the pollutants at different concentrations, showing increasing inhibitory effects in the following order: salicylate85%) was recorded only in the systems inoculated with both algae and bacteria and incubated under continuous lighting. This study presents, to our knowledge, the first reported case of photosynthesis-enhanced biodegradation of toxic aromatic pollutants by algal–bacterial microcosms in a one-stage treatment.
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| 4. |
- Essam, Tamer, et al.
(författare)
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Biological treatment of industrial wastes in a photobioreactor
- 2006
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 53:11, s. 117-125
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Tidskriftsartikel (refereegranskat)abstract
- An algal-bacterial consortium was tested for the treatment from a coke factory. A Chlorella vulgaris strain and a phenol-degrading Alcaligenes sp. were first isolated from the wastewater treatment plant to serve as inocula in the subsequent biodegradation tests. Batch tests were then conducted with samples from the real wastewater or using a synthetic wastewater containing 325 mg phenol/l and 500 mg NH4+/l as target pollutants. Direct biological treatment of-the real wastewater was not possible due to the toxicity of organic compounds. Activated carbon adsorption and UV(A-B)-irradiation were efficient in detoxifying the effluent for subsequent biological treatment as inoculation of pretreated samples with the algal-bacterial consortium was followed by complete phenol removal and NH4+ removal of 45%. Complete phenol removal and 33% NH4+ removal were achieved during the fed-batch treatment of artificial wastewater. at 6 d hydraulic retention time (HRT). Under continuous feeding at 3.6 d HRT, phenol and NH4+ removal dropped to 58 and 18%, respectively. However, complete phenol removal and 29% NH4+ removal were achieved when 8 g NaHCO3/1 was added to the artificial wastewater to enhance algal growth. This study confirms the potential of solar-based industrial wastewater treatment based on solar-based UV pretreatment followed by algal-bacterial biodegradation.
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| 5. |
- Essam, Tamer, et al.
(författare)
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Kinetics and metabolic versatility of highly tolerant phenol degrading Alcaligenes strain TW1.
- 2010
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 1873-3336 .- 0304-3894. ; 173, s. 783-788
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Tidskriftsartikel (refereegranskat)abstract
- A bacterium that could completely metabolize phenol in batch culture supplied with up to 1200mg phenoll(-1) at room temperature (25 degrees C) was isolated from the activated sludge of the industrial wastewater treatment plant of a Coke company (Cairo, Egypt). Morphological and physiological characterization showed strain TW1 was a motile, strictly aerobic, gram negative and short-rod occurring singly or in clusters. Partial 16S rRNA gene sequence analysis revealed strain TW1 belonged to the beta group of Proteobacteria, showing 100% identity to Alcaligenes SCTI. Strain TW1 aerobically grew on a number of monocyclic aromatic compounds (hydroquinone, catechol and o-cresol) as well as polycyclic aromatic compounds (pyrene, phenanthrene and naphthalene). The growth of Alcaligenes TW1 on phenol as sole carbon and energy source (25 degrees C) was well described by the Haldane kinetics model with a maximal specific growth rate of 0.58h(-1), a half-saturation constant of 10mgl(-1), and a substrate inhibition constant of 152-550mgl(-1). The biomass yield coefficient ranged from 0.55 to 0.64mg dry cell mass/mg phenol. Due to its high tolerance to phenol and high metabolic versatility, Alcaligenes sp. TW1 is considered an excellent candidate for the biotreatment of high strength phenol-laden industrial wastewaters.
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| 6. |
- Essam, Tamer, et al.
(författare)
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Sequential photochemical-biological degradation of chlorophenols
- 2007
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Ingår i: Chemosphere. - : Elsevier BV. - 1879-1298 .- 0045-6535. ; 66:11, s. 2201-2209
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Tidskriftsartikel (refereegranskat)abstract
- UV/TiO2/H2O2, UV/TiO2 and UV/H2O2 were compared as pre-treatment processes for the detoxification of mixtures of 4-chlorophenol (4CP), 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP) prior to their biological treatment. When each chlorophenol was initially supplied at 50mg l(-1),UV/TiO2/H2O2 treatment supported the highest pollutant removal, COD removal, and dechlorination efficiencies followed by UV/TiO2 and UV/H2O2. The remaining toxicity to Lipediurn sativurn was similar after all pre-treatments. Chlorophenol photodegradation was always well described by a first order model kinetic (r(2) > 0.94) and the shortest 4CP, DCP, TCP and PCP half-lives of 8.7, 7.1, 4.5 and 3.3 h, respectively, were achieved during UV/TiO2/H2O2 treatment. No pollutant removal was observed in the controls conducted with H2O2 or TiO2 only. Inoculation of all the photochemically pre-treated mixtures with activated sludge microflora was followed by complete removal of the remaining pollutants. Combined UV/TiO2/H2O2-biological supported the highest detoxification, dechlorination (99%) and COD removal (88%) efficiencies. Similar results were achieved when each chlorophenol was supplied at 100 mg l(-1). COD and Cl mass balances indicated UV, UV/H2O2, and UV/TiO2 treatments lead to the formation of recalcitrant photoproducts, some of which were chlorinated. (c) 2006 Elsevier Ltd. All rights reserved.
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| 7. |
- Essam, Tamer, et al.
(författare)
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Sequential UV–biological degradation of chlorophenols
- 2006
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Ingår i: Chemosphere. - : Elsevier BV. - 1879-1298 .- 0045-6535. ; 63:2, s. 277-284
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Tidskriftsartikel (refereegranskat)abstract
- The sequential UV–biological degradation of a mixture of 4-chlorophenol (CP), 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP), and pentachlorophenol (PCP) was first tested with each pollutant supplied at an initial concentration of 50 mg l−1. Under these conditions, the chlorophenols were photodegraded in the following order of removal rate: PCP > TCP > DCP > CP with only CP and DCP remaining after 40 h of irradiation. The remaining CP (41 mg l−1) and DCP (13 mg l−1) were then completely removed by biological treatment with an activated sludge mixed culture. Biodegradation did not occur in similar tests conducted with a non-irradiated mixture due to the high microbial toxicity of the solution. UV treatment lead to a significant reduction of the phytotoxicity to Lipedium sativum but no further reduction of phytotoxicity was observed after biological treatment. Evidence was found that the pollutants were partially photodegraded into toxic and non-biodegradable products. When the pollutants were tested individually (initial concentration of 50 mg l−1), PCP, TCP, DCP, 4-CP were photodegraded according to first order kinetic model (r2 > 99) with half-lives of 2.2, 3.3, 5.7, and 54 h, respectively. The photoproducts were subsequently biodegraded. This study illustrates the potential of UV as pre-treatment for biological treatment in order to remove toxicity and enhance the biodegradability of organic contaminants. However, it also shows that UV treatment must be carefully optimized to avoid the formation of toxic and/or recalcitrant photoproducts and results from studies conducted on single contaminants cannot be extrapolated to mixtures.
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| 8. |
- Essam, Tamer, et al.
(författare)
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Solar-based detoxification of phenol and p-nitrophenol by sequential TiO2 photocatalysis and photosynthetically aerated biological treatment
- 2007
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Ingår i: Water Research. - : Elsevier BV. - 1879-2448 .- 0043-1354. ; 41:8, s. 1697-1704
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Tidskriftsartikel (refereegranskat)abstract
- Simulated solar UV/TiO2 photocatalysis was efficient to detoxify a mixture of 100 mg phenol l(-1) and 50 mgp-nitrophenol (PNP) l(-1) and allow the subsequent biodegradation of the remaining pollutants and their photocatalytic products under photosynthetic aeration with Chlorella vulgaris. Photocatalytic degradation of phenol and PNP was well described by pseudo-first order kinetics (r(2) >0.98) with removal rate constants of 1.9 x 10(-4) and 2.8 x 10(-4) min(-1), respectively, when the pollutants were provided together and 5.7 x 10(-4) and 9.7 x 10(-1) min(-1), respectively, when they were provided individually. Photocatalytic pre-treatment of the mixture during 60 h removed 50 +/- 1% and 62 +/- 2% of the phenol and PNP initially present but only 11 +/- 3% of the initial COD. Hydroquinone, nitrate and catechol were identified as PNP photocatalytic products and catechol and hydroquinone as phenol photocatalytic products. Subsequent biological treatment of the pre-treated samples removed the remaining contaminants and their photocatalytic products as well as 81-83% of the initial COD, allowing complete detoxification of the mixture to C. vulgaris. Similar detoxification efficiencies were recorded after biological treatment of the irradiated mixture with activated sludge microflora or with an acclimated consortia composed of a phenol-degrading Alcaligenes sp. and a PNP-degrading Arthrobacter sp., although the acclimated strains biodegraded the remaining pollutants faster. Biological treatment of the non-irradiated mixture was inefficient due to C. vulgaris inhibition. (c) 2007 Elsevier Ltd. All rights reserved.
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| 9. |
- Fernández-Álvarez, Paula, et al.
(författare)
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Removal and destruction of endocrine disrupting contaminants by adsorption with molecularly imprinted polymers followed by simultaneous extraction and phototreatment.
- 2009
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 1873-3336 .- 0304-3894. ; 163, s. 1107-1112
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Tidskriftsartikel (refereegranskat)abstract
- This study presents a method to regenerate molecularly imprinted polymers (MIPs) used for the selective removal of endocrine disrupting compounds from aqueous effluents. Regeneration was based on solvent extraction under UV irradiation to regenerate the polymer and the solvent while destroying the contaminants. Acetone was selected as the best solvent for irradiation of estrone (E1), 17beta-estradiol (E2) and ethinylestradiol (EE2) using either UVC (254nm) or UV-vis. A MIP synthesized with E2 as template was then tested for the extraction of this compound from a 2mug/L loaded aqueous solution. E2 was recovered by 73+/-11% and 46+/-13% from the MIPs and a non-imprinted control polymer synthesized under the same conditions, respectively, after a single step elution with acetone. The irradiated polymers and acetone were reused for an additional extraction-regeneration cycle and showed no capacity decrease.
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| 10. |
- Guieysse, Benoit, et al.
(författare)
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Biodegradation of phenol at low temperature using two-phase partitioning bioreactors
- 2005
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Ingår i: Water Science and Technology. - 0273-1223. ; 52:10-11, s. 97-105
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Tidskriftsartikel (refereegranskat)abstract
- Two-phase partitioning bioreactors offer many advantages for the removal of toxic pollutants. In particular, such systems can be loaded with very large quantities of pollutants without risks of microbial inhibition, they are self-regulated and they prevent the risks of hazardous pollutant volatilisation during aerobic treatment. However, their potential has never been tested at low temperatures. Phenol biodegradation by a cold adapted Pseudomonas strain was therefore tested at 14 or 4 degrees C using 2-undecanone, diethyl sebacate or 2-decanone as organic phases in a two-phase partitioning bioreactor. The three solvents were biocompatible at 14 degrees C but evidence was found that diethyl sebacate was biodegraded by the bacteria and this solvent was not tested further. Although only 2-decanone was suitable at 4 degrees C, phenol biodegradation was more efficient in 2-undecanone at WC, reaching a maximum volumetric rate (based on the volume of aqueous phase) of approximately 1.94 g/L-day after 47 h of cultivation. In 2-clecanone at 14 degrees C, evidence was found that phenol degradation was limited by the release of biosurfactants, which increased the solubility and toxicity of the solvent in the aqueous phase inhibiting microbial activity. This study therefore shows that pollutant removal at low temperature is feasible but that the production of biosurfactants can have a negative impact on the process and must be taken into consideration when selecting the organic solvent. Future work should therefore focus on the selection of solvents suitable for use at temperatures below 14 degrees C.
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