Degradation of carbamazepine by Trametes versicolor in an air pulsed fluidized bed bioreactor and identification of intermediates

The paper describes the aerobic degradation of carbamazepine (CBZ), an anti-epileptic drug widely found in aquatic environment, from Erlenmeyer flask to bioreactor by the white-rot fungus Trametes versicolor. In Erlenmeyer flask, CBZ at approximately 9 mg L⁻¹ was almost completely eliminated (94%) after 6 d, while at near environmentally relevant concentrations of 50 μg L⁻¹, 61% of the contaminant was degraded in 7 d. Acridone, acridine, 10,11-dihydro-10,11-dihydroxy-CBZ, and 10, 11-epoxy-CBZ were identified as major metabolites, confirming the degradation of CBZ. The degradation process was then carried out in an air pulsed fluidized bioreactor operated in batch and continuous mode. Around 96% of CBZ was removed after 2 days in batch mode operation, and 10,11-dihydro-10,11-epoxycarbamazepine was found as unique metabolite. In bioreactor operated in continuous mode with a hydraulic retention time of 3 d, 54% of the inflow concentration (approx. 200 μg L⁻¹) was reduced at the steady state (25 d) with a CBZ degradation rate of 11.9 μg CBZ g⁻¹ dry weight d⁻¹. No metabolite was detected in the culture broth. Acute toxicity tests (Microtox) indicated that the final culture broth in both batch and continuous mode operation were non toxic, with 15 min EC50 values of 24% and 77%, respectively.     

Degradation and byproduct formation of parathion in aqueous solutions by UV and UV/H(2)O(2) treatment

The photodegradation of parathion in aqueous solutions by UV and UV/H(2)O(2) processes was evaluated. Direct photolysis of parathion both by LP (low pressure) and MP (medium pressure) lamps at pH 7 was very slow with quantum yields of 6.67+/-0.33x10(-4) and 6.00+/-1.06x10(-4)molE(-1), respectively. Hydrogen peroxide enhanced the photodegradation of parathion through the reaction between UV generated hydroxyl radical and parathion with a second-order reaction rate constant of 9.70+/-0.45x10(9)M(-1)s(-1). An optimum molar ratio between hydrogen peroxide and parathion was determined to be between 300 and 400. Photodegradation of parathion yielded several organic byproducts, of which the paraoxon, 4-nitrophenol, O,O,O-triethyl thiophosphate and O,O-diethyl-methyl thiophosphate were quantified and their occurrence during UV/H(2)O(2) processes were discussed. NO(2)(-), PO(4)(3-), NO(3)(-) and SO(4)(2-) were the major anionic byproducts of parathion photodegradation and their recover ratios were also discussed. A photodegradation scheme suggesting three simultaneous pathways was proposed in the study.     

Biological assessments of a mixture of endocrine disruptors at environmentally relevant concentrations in water following UV/H2O2 oxidation

Numerous studies have investigated degradation of individual endocrine disrupting compounds (EDCs) in lab or natural waters. However, natural variations in water matrices and mixtures of EDCs in the environment may confound analysis of the treatment efficiency. Because chemical based analytical methods cannot represent the combined or synergistic activities between water quality parameters and/or the EDC mixtures at environmentally relevant concentrations (microg L(-1)-ng L(-1)), bioanalytical assessments of residual estrogenic activity in treated water were used to evaluate the performance of the UV based advanced oxidation process for estrogenic contaminants in water. Four EDCs including estradiol (E(2)), ethinyl estradiol (EE(2)), bisphenol-A (BPA) and nonylphenol (NP) were spiked individually or as a mixture at mug L(-1)-ng L(-1) in laboratory or natural river water. The removal rates of estrogenic activity were quantitatively evaluated by in vitro yeast estrogen screen (YES) and in vivo Vitellogenin (VTG) assays with Japanese medaka fish (Oryzias latipes). UV in combination with 10 ppm H(2)O(2) as an oxidation process was capable of decreasing in vitro and in vivo estrogenic activity, however, in vivo estrogenic activity of the EDC mixture in natural water was not completely removed at UV fluence up to 2000 mJ cm(-2). The removal rates of in vitro estrogenic activity of the EDC mixtures were lower than those observed for single compounds, and slower in natural waters, likely due to lower steady-state concentrations of hydroxyl radicals (*OH) in the presence of *OH scavengers from the water matrix and EDC mixture.     

Degradation of sulfamethoxazole in water by solar photo-Fenton. Chemical and toxicological evaluation

In this work, the photocatalytic degradation of the antibiotic sulfamethoxazole (SMX) by solar photo-Fenton at pilot plant scale was evaluated in distilled water (DW) and in seawater (SW). Degradation and mineralization of SMX were strongly hindered in SW compared to DW. The influence of H₂O₂ and iron concentration on the efficiency of the photocatalytic process was evaluated. An increase in iron concentration from 2.6 to 10.4 mg L⁻¹ showed only a slight improvement in SMX degradation and mineralization. However, an increase in H₂O₂ concentration up to 120 mg L⁻¹ during photo-Fenton in DW decreased SMX solution toxicity from 85% to 20%, according to results of Daphnia magna bioassays. The same behaviour was not observed after photo-Fenton treatment in SW. Despite 45% mineralization in SW, toxicity increased from 16% to 86% as shown by Vibrio fischeri bioassays, which suggests that the intermediates generated in SW are different from those in DW. A SMX degradation pathway during the photo-Fenton treatment in DW is proposed.     

Delayed effects of environmentally relevant concentrations of 3,3',4,4'-tetrachlorobiphenyl (PCB-77) and non-polar sediment extracts detected in the prolonged-FETAX

In the prolonged-FETAX (prolonged-Frog Embryo Teratogenic Assay-Xenopus) tadpoles are allowed to develop until metamorphosis after an initial 4 day early life-stage exposure (FETAX). PCB 77 (3,4,3',4'-tetrachlorobiphenyl) and sediment extracts were used in the presented experiments. Concentrations of PCB 77 (0.03 nM=8.55 ng/L; 3 nM=855 ng/L; 300 nM=85.5 microg/L, 30,000 nM=8.55 mg/L) were derived on the basis of dioxin-like toxic equivalency concentrations known to be present in pore-water. The results were compared to those obtained with the standard FETAX. In the prolonged-FETAX the percentage of animals passing metamorphosis within 115 days was significantly decreased in the groups exposed to 300 or 30,000 nM PCB 77. Significantly increased percentages of tadpoles were halted in thyroid hormone dependent early metamorphic NF stages 相似文献   

电化学/过硫酸盐耦合体系降解水中有机药物卡马西平

采用电化学/过硫酸盐耦合体系(E-PS过程)降解水中的有机药物卡马西平(CBZ)。实验采用了分批模式进行,研究了温度、过硫酸钠浓度、初始pH值、电压等因素对E-PS过程降解CBZ的影响。反应100min后,单独过硫酸钠、电解和E-PS过程对卡马西平的降解率分别为25.5%、59.3%、78.1%,TOC去除率分别为8.25%、23.48%、26.68%。升高温度可以有效提高CBZ的降解率。反应100min后,在288K,CBZ降解率为60.2%;在298K,CBZ降解率达到78.1%;而在308K,CBZ降解率为90.1%。CBZ的降解率随着过硫酸盐浓度的增加而提高。当过硫酸盐浓度为40g/L时,反应100min,CBZ降解率达94.7%。初始pH值对CBZ降解率的影响为pH 3.0pH 5.0pH 7.0;电压对CBZ降解率的影响为6V5V4V。     

Degradation of monomethylmercury chloride by hydroxyl radicals in simulated natural waters

The degradation of methylmercury chloride by hydroxyl radicals (*OH) has been investigated using nitrate photolysis from 285 to 800 nm with a 450 W Xenon lamp as the (*OH source. The identified products are Hg(2+), Hg(0), CHCl(3) and formaldehyde. The second-order rate constant at pH of 5 at room temperature was determined to be 9.83(+-0.66)x10(9) M(-1) x s(-1)using benzoic acid as the *OH scavenger. The effects of chloride concentration and methylmercury speciation have also been investigated. A mechanism of the CH(3)HgCl-*OH reaction has been proposed. The calculated methylmercury degradation rates in natural waters using the above rate constant were comparable to the in situ photodegradation rates reported previously, indicating that degradation by (*)OH may be one of the important pathways of methylmercury degradation in sunlit surface waters.     

Oxidation of atenolol, propranolol, carbamazepine and clofibric acid by a biological Fenton-like system mediated by the white-rot fungus Trametes versicolor

Biological advanced oxidation of the pharmaceuticals clofibric acid (CA), carbamazepine (CBZP), atenolol (ATL) and propranolol (PPL) is reported for the first time. Extracellular oxidizing species were produced through a quinone redox cycling mechanism catalyzed by an intracellular quinone reductase and any of the ligninolytic enzymes of Trametes versicolor after addition of the lignin-derived quinone 2,6-dimethoxy-1,4-benzoquinone (DBQ) and Fe³⁺-oxalate in the medium. Time-course experiments with approximately 10 mg L⁻¹ of initial pharmaceutical concentration resulted in percent degradations above 80% after 6 h of incubation. Oxidation of pharmaceuticals was only observed under DBQ redox cycling conditions. A similar degradation pattern was observed when CBZP was added at the environmentally relevant concentration of 50 μg L⁻¹. Depletion of DBQ due to the attack of oxidizing agents was assumed to be the main limiting factor of pharmaceutical degradation. The main degradation products, that resulted to be pharmaceutical hydroxylated derivatives, were structurally elucidated. The detected 4- and 7-hydroxycarbamazepine intermediates of CBZP degradation were not reported to date. Total disappearance of intermediates was observed in all the experiments at the end of the incubation period.     

Degradation of H-acid and its derivative in aqueous solution by ionising radiation

The mechanism of high-energy radiation induced degradation of H-acid (4-amino-5-hydroxynaphthalene-2,7-disulphonic acid, (I)) and its derivative, 4-hydroxynaphthalene-2,7-disulphonic acid (II) (central parts of a large number of azo dyes), was investigated in aqueous solutions. These compounds can be efficiently destroyed by the (*)OH and hydrated electron intermediates produced during water radiolysis. As the first step of degradation mainly cyclohexadienyl-type radicals form, however, with I H-atom elimination from the NH(2) group is also observed yielding anilino-type radicals. Both the cyclohexadienyl and the anilino-type radicals decay on the millisecond timescale. In the (*)OH reactions as stable products hydroxylated molecules and quinone-type compounds form. These molecules by further decomposition of the ring structure transform to open chain molecules. In the case of hydrated electron, the primarily formed products have absorption spectra shifted to the low-wavelength region indicating the destruction of at least one of the aromatic rings.     

Degradation of the antibiotic amoxicillin by photo-Fenton process--chemical and toxicological assessment

The influence of iron species on amoxicillin (AMX) degradation, intermediate products generated and toxicity during the photo-Fenton process using a solar simulator were evaluated in this work. The AMX degradation was favored in the presence of the potassium ferrioxalate complex (FeOx) when compared to FeSO₄. Total oxidation of AMX in the presence of FeOx was obtained after 5 min, while 15 min were necessary using FeSO₄. The results obtained with Daphnia magna biossays showed that the toxicity decreased from 65 to 5% after 90 min of irradiation in the presence of FeSO₄. However, it increased again to a maximum of 100% after 150 min, what indicates the generation of more toxic intermediates than AMX, reaching 45% after 240 min. However, using FeOx, the inhibition of mobility varied between 100 and 70% during treatment, probably due to the presence of oxalate, which is toxic to the neonates. After 240 min, between 73 and 81% TOC removal was observed. Different pathways of AMX degradation were suggested including the opening of the four-membered β-lactamic ring and further oxidations of the methyl group to aldehyde and/or hydroxylation of the benzoic ring, generating other intermediates after bound cleavage between different atoms and further oxidation to carboxylates such acetate, oxalate and propionate, besides the generation of nitrate and ammonium.     

Degradation of antibiotics in water by non-thermal plasma treatment

The decomposition of three β-lactam antibiotics (amoxicillin, oxacillin and ampicillin) in aqueous solution was investigated using a dielectric barrier discharge (DBD) in coaxial configuration. Solutions of concentration 100 mg/L were made to flow as a film over the surface of the inner electrode of the plasma reactor, so the discharge was generated at the gas-liquid interface. The electrical discharge was operated in pulsed regime, at room temperature and atmospheric pressure, in oxygen. Amoxicillin was degraded after 10 min plasma treatment, while the other two antibiotics required about 30 min for decomposition. The evolution of the degradation process was continuously followed using liquid chromatography-mass spectrometry (LC-MS), total organic carbon (TOC) and chemical oxygen demand (COD) analyses.     

Degradation of the emerging contaminant ibuprofen in water by photo-Fenton

In this study the degradation of the worldwide Non-Steroidal Anti-Inflammatory Drug (NSAID) ibuprofen (IBP) by photo-Fenton reaction by use of solar artificial irradiation was carried out. Non-photocatalytic experiments (complex formation, photolysis and UV/Vis-H₂O₂ oxidation) were executed to evaluate the isolated effects and additional differentiated degradation pathways of IBP. The solar photolysis cleavage of H₂O₂ generates hydroxylated-IBP byproducts without mineralization. Fenton reaction, however promotes hydroxylation with a 10% contamination in form of a mineralization. In contrast photo-Fenton in addition promotes the decarboxylation of IBP and its total depletion is observed. In absence of H₂O₂ a decrease of IBP was observed in the Fe(II)/UV-Vis process due to the complex formation between iron and the IBP-carboxylic moiety. The degradation pathway can be described as an interconnected and successive principal decarboxylation and hydroxylation steps. TOC depletion of 40% was observed in photo-Fenton degradation. The iron-IBP binding was the key-point of the decarboxylation pathway. Both decarboxylation and hydroxylation mechanisms, as individual or parallel process are responsible for IBP removal in Fenton and photo-Fenton systems. An increase in the biodegradability of the final effluent after photo-Fenton treatment was observed. Final BOD₅ of 25 mg L⁻¹ was reached in contrast to the initial BOD₅ shown by the untreated IBP solution (BOD₅ < 1 mg L⁻¹). The increase in the biodegradability of the photo-Fenton degradation byproducts opens the possibility for a complete remediation with a final post-biological treatment.     

Degradation of sodium dodecylbenzene sulfonate in water by ultrasonic irradiation

The potential of using ultrasonic irradiation for the removal of sodium dodecylbenzene sulfonate (SDBS) from aqueous solutions has been investigated. Experiments were performed at initial concentrations of 15, 30 and 100 mgl(-1), ultrasonic frequencies of 20 and 80 kHz, applied power values of 45, 75 and 150 W and liquid bulk temperatures of 20, 40 and 60 degrees C. At the conditions in question, SDBS conversion was found to decrease with increasing temperature and initial solute concentration and decreasing power and frequency. Investigations using the radical scavengers 1-butanol and KBr revealed that SDBS degradation proceeds through radical reactions occurring predominately at the bubble-liquid interface and, to a lesser extent, in the liquid bulk. Addition of NaCl or H(2)O(2) had little or even an adverse effect on SDBS conversion. Conversely, addition of Fe(2+) either alone or in conjunction with H(2)O(2) (Fenton reagent) had a positive effect on degradation. Finally, shake flask tests with activated sludge were performed to assess the aerobic biodegradability before and after sonochemical treatment. At the conditions under consideration, the use of ultrasound enhanced the aerobic degradability of the substrate in question.     

Degradation of plasmid and plant DNA in water microcosms monitored by natural transformation and real-time polymerase chain reaction (PCR)

Extracellular DNA exists in the environment and can be taken up by competent bacterial cells, leading to horizontal gene transfer. The persistence of extracellular plasmid and plant DNA in water microcosms was monitored in this study. Water samples were two groundwater (GW1 and GW2) and one river water (RW) samples. Three treatments included: (1) intact, (2) 0.22 microm filter-sterilized, and (3) autoclaved water. DNA from a plasmid (pNS1) and a transgenic Bt (Bacillus thuringiensis) corn line, both carrying a neomycin phosphotransferase gene (nptII gene) conferring kanamycin and neomycin resistance, was inoculated into the microcosms at 0.4 and 0.8 microg/ml, respectively. By monitoring its ability to transform a competent Pseudomonas stutzeri strain harboring plasmid pMR7 (P. stutzeri pMR7), plasmid DNA was degraded to undetectable levels in the intact and/or filter-sterilized water treatments within 48-96 h in GW1, GW2, and RW. Meanwhile, plasmid DNA persisted in the autoclaved treatment throughout the entire incubation period. For plant DNA, a highly sensitive real-time PCR method using SYBR Green I was developed to monitor the degradation dynamics of the nptII gene carried by the transgenic corn line in the microcosms. The results showed that the concentration of plant DNA was reduced by two orders of magnitude (from 0.8-0.008 microg/ml) within 96 h in the intact and filter-sterilized treatments of GW1, GW2, and RW, in contrast to its persistence in the autoclaved treatment. In addition, no kanamycin resistant (Km R) transformants were detected from in situ transformation of P. stutzeri pMR7 with plasmid pNS1 DNA.     

Degradation of reactive dyes in wastewater from the textile industry by ozone: Analysis of the products by accurate masses

The present work describes the use of ozone to degrade selected reactive dyes from the textile industry and the analysis of the resulting complex mixture by liquid chromatography/mass spectrometry (LC-MS). To allow certain identification of the substances detected in the wastewater, the original dyes were also investigated either separately or in a synthetic mixture of three dyes (trichromie). Since the reactive dyes are hydrolyzed during the dyeing process, procedures for the hydrolysis were worked out first for the individual dyes. The ozonated solutions were concentrated by solid-phase extraction, which separated very polar or ionic substances from moderately polar degradation products. The latter, which are the primary degradation products, were investigated by liquid chromatography/mass spectrometry with a tandem quadrupole time-of-flight mass analyzer. Accurate masses, which in most cases could be determined with a deviation of ≤5 ppm from the exact value, were also measured. In addition, a diode-array detector was placed before the mass analyzer to provide UV-vis spectra of the products in the same run. With retention times, mass spectra, accurate masses, UV-vis spectra and, of course, knowledge of the structures of the original dyes, plausible structures could be proposed for most of the components of the moderately polar fraction. These structures were confirmed by ¹H NMR in cases where it was practical to isolate the degradation products by preparative HPLC.     

Degradation of phenolic compounds with hydrogen peroxide catalyzed by enzyme from Serratia marcescens AB 90027

In this paper, the degradation of phenolic compounds using hydrogen peroxide as oxidizer and the enzyme extract from Serratia marcescens AB 90027 as catalyst was reported. With such an enzyme/H2O2 combination treatment, a high chemical oxygen demand (COD) removal efficiency was achieved, e.g., degradation of hydroquinone exceeded 96%. From UV-visible and IR spectra, the degradation mechanisms were judged as a process of phenyl ring cleavage. HPLC analysis shows that in the degradation p-benzoquinone, maleic acid and oxalic acid were formed as intermediates and that they were ultimately converted to CO2 and H2O. With the enzyme/H2O2 treatment, vanillin, hydroquinone, catechol, o-aminophenol, p-aminophenol, phloroglucinol and p-hydroxybenzaldehyde were readily degraded, whereas the degradation of phenol, salicylic acid, resorcinol, p-cholorophenol and p-nitrophenol were limited. Their degradability was closely related to the properties and positions of their side chain groups. Electron-donating groups, such as -OH, -NH2 and -OCH3 enhanced the degradation, whereas electron-withdrawing groups, such as -NO2, -Cl and -COOH, had a negative effect on the degradation of these compounds in the presence of enzyme/H2O2. Compounds with -OH at ortho and para positions were more readily degraded than those with -OH at meta positions.     

Degradation of pharmaceuticals in non-sterile urban wastewater by Trametes versicolor in a fluidized bed bioreactor

The constant detection of pharmaceuticals (PhACs) in the environment demonstrates the inefficiency of conventional wastewater treatment plants to completely remove them from wastewaters. So far, many studies have shown the feasibility of using white rot fungi to remove these contaminants. However, none of them have studied the degradation of several PhACs in real urban wastewater under non-sterile conditions, where mixtures of contaminants presents at low concentrations (ng L⁻¹ to μg L⁻¹) as well as other active microorganisms are present. In this work, a batch fluidized bed bioreactor was used to study, for the first time, the degradation of PhACs present in urban wastewaters at their pre-existent concentrations under non-sterile conditions. Glucose and ammonium tartrate were continuously supplied as carbon and nitrogen source, respectively, and pH was maintained at 4.5. Complete removal of 7 out of the 10 initially detected PhACs was achieved in non-sterile treatment, while only 2 were partially removed and 1 of the PhACs analyzed increased its concentration. In addition, Microtox test showed an important reduction of toxicity in the wastewater after the treatment.     

Degradation of pharmaceutical compound pentoxifylline in water by non-thermal plasma treatment

The decomposition of a model pharmaceutical compound, pentoxifylline, in aqueous solution was investigated using a dielectric barrier discharge (DBD) in coaxial configuration, operated in pulsed regime, at atmospheric pressure and room temperature. The solution was made to flow as a film over the surface of the inner electrode of the plasma reactor, so the discharge was generated at the gas-liquid interface. Oxygen was introduced with a flow rate of 600 sccm. After 60 min plasma treatment 92.5% removal of pentoxifylline was achieved and the corresponding decomposition yield was 16 g/kWh. It was found that pentoxifylline degradation depended on the initial concentration of the compound, being faster for lower concentrations. Faster decomposition of pentoxifylline could be also achieved by increasing the pulse repetition rate, and implicitly the power introduced in the discharge, however, this had little effect on the decomposition yield. The degradation products were investigated by liquid chromatography-mass spectrometry technique (LC-MS). The evolution of the intermediates during plasma treatment showed a fast increase in the first 30 min, followed by a slower decrease, so that these products are almost completely removed after 120 min treatment time.     

改进型涡凹气浮工艺浓缩剩余活性污泥试验研究

为了考察改进型涡凹气浮设备MCAF-10浓缩剩余活性污泥的性能,在朝阳洲污水处理厂对MCAF-10浓缩剩余污泥进行了试验研究,结果表明：絮凝剂采用FO4440SH,最佳投加量为1.0 kg/tDS,表面活性剂采用1 227,最佳投加量0.2 kg/tDS,最佳固体负荷和水力负荷分别为270 kgMLSS/m^2.d1、10 m^3/m^2.d,出水SS为100～150 mg/L,与CAF-5浓缩剩余活性污泥时最佳固体负荷和水力负荷分别为230 kgMLSS/m^2.d9、0 m^3/m^2.d,出水SS为200～250 mg/L相比,提高了涡凹气浮污泥浓缩工艺的处理能力,降低了出水SS浓度,MCAF工艺比CAF工艺更适合于剩余活性污泥的浓缩。