Energy generation by methanation of persistent wastes

A 15-L anaerobic fixed-film reactor (AFFR) was evaluated for treating a trade effluent containing inhibitory concentrations of persistent branched-chain fatty acids, namely 2-ethylhexanoic acid (2-EHA) and neopentanoic acid (NPA), at a total of 17,000 mg COD/L. The AFFR was packed with fire-expanded clay spheres, and start-up was accomplished in 60 d. The organic load was increased in steps from 1.1 to 8.5 g COD/L/d. Total COD, 2-EHA, and NPA removal efficiencies were maintained above 70, 98, and 75%, respectively. The reactor could recover from a shock load of 150% increase in organic load. Combined mechanisms of organic adsorption and biodegradation rendered the AFFR more stable with shock loads. Mathane gas produced from the process could be used for preheating the effluent.     

Molluscicidal activity of methomyl and cardenolide extracts from Calotropis procera and Adenium arabicum against the land snail Monacha cantiana

In this work, we have evaluated the molluscicidal activity of two cardenolide extracts from Adenium arabicum Balf f. [the benzene (B) and methanol (M) extracts], one cardenolide extract from Calotropis procera (Aiton) W.T. Aiton (extract C), and methomyl against the harmful land snail Monacha cantiana (Montagu). The contact LD?? values for the above mentioned plant extracts were 12.62, 34.63, and 34.35 mg·kg?1 of body weight, respectively, while the LD?? for methomyl was 116.62 mg·kg?1, that is, the plant extracts were 9.24, 3.37, and 3.4 times more toxic than methomyl. In addition, a simple colorimetric method, based on Kedde reagent, was modified to determine cardenolide concentrations in plant extracts. Thin layer chromatography analysis (TLC) showed several cardiac glycosidal compounds in each plant extract. The results proved that cardiac glycosides are promising candidate compounds that could be used to control land snails, or exploited to develop new, effective, and environmentally friendly molluscicides.     

Preparation and binding study of solid-phase microextraction fiber on the basis of ametryn-imprinted polymer: Application to the selective extraction of persistent triazine herbicides in tap water,rice, maize and onion

A monolithic ametryn molecular-imprinted polymer based on a simple polymerization method was fabricated for use as new solid-phase microextraction (SPME) fiber, which can be coupled with GC and GC/MS for selective extraction and analysis of triazine herbicides. Methacrylic acid (MAA), ethylene glycol dimethacrylate (EDMA) and ametryn bear role of functional monomer, cross-linker and template, respectively. In the optimized conditions the fabricated fiber showed better molecular recognition abilities for methylthiotriazine herbicides than chloro-triazine herbicides. By use of bi-Langmuir isotherm model the evaluated equilibrium constants for ametryn were 0.01 and 890.69 μM⁻¹, and the numbers of binding sites were 129.98 and 5.82 nmol g⁻¹, respectively. The high extraction efficiency was obtained for ametryn, prometryn, terbutryn, atrazine, simazine, propazine, and cyanazine, yielding the detection limits of 14, 28, 45, 56, 85, 95 and 74 ng mL⁻¹, respectively by GC with flame ionization detection. The reliability of the prepared fiber for extraction of ametryn and other analogues in real samples has been investigated and proved by using spiked samples such as tap water, rice, maize, and onion.     

Toxicity and biodegradability of olive mill wastewaters in batch anaerobic digestion

The anaerobic biodegradability and toxicity of olive mill waste-waters (OMW) were studied in batch anaerobic digestion experiments. Anaerobic digestion of OMW or the supernatant of its centrifugation, the methane production was achieved at up to 5–15% (V/V) dilution corresponding to only 5–20 g/L COD. The washed suspended solids of OMW were toxic at up to 80 g/L COD; however, the kinetic of biodegradability of OMW or the supernatant was faster than for suspended solids, which are constituted meanly of cellulose and lignin. The darkly colored polyphenols induce the problem of biodegradation of OMW, whereas the long chain fatty acids (LCFA), tannins and simple phenolic compounds are responsible its toxicity for methanogenic bacteria.     

Identification of disinfection by‐products of selected triazines in drinking water by LC‐Q‐ToF‐MS/MS and evaluation of their toxicity

During the development of an on‐line solid phase extraction‐liquid chromatography‐ultraviolet detection (SPE‐LC‐UV) analytical method for determination of eight selected triazines; ametryn, atrazine, cyanazine, metrybuzine, prometryn, propazin, simazine, and terbutryn, in drinking water, it was observed that the retention times of three of them (ametryn, prometryn, and terbutryn) in Milli‐Q water were different from those in chlorinated Milli‐Q water, indicating the formation of new products. The cause of this change was found in the oxidation of the molecules as a result of chlorination with sodium hypochlorite. Experiments performed at varying concentrations of triazines and hypochlorite showed that the extent of the reaction depended on their relative concentrations. At the maximum admissible level of 100 ng/l for individual pesticides in drinking water, no apparent transformation was observed in the absence or at low concentrations (0.05 mg/l) of hypochlorite; however, on increasing the concentration of hypochlorite to the level typically present in drinking water (0.9 mg/l) the transformation was complete. The reaction is quite fast; within 1 h the parent compound is completely degraded and after 22 h the concentrations of the by‐products are constant. Investigation of the by‐products by ultra performance liquid chromatography‐quadrupole‐time of flight‐ tandem mass spectrometry (UPLC‐Q‐ToF‐MS/MS) has shown that all three triazines follow a similar transformation pathway, forming four new molecules whose structure have been elucidated. The acute toxicity of the new products was investigated using a standard method based on the bioluminescence inhibition of Vibrio fischeri, and the by‐products showed a higher toxicity than that of the parent compounds. Copyright © 2008 John Wiley & Sons, Ltd.     

Mixed-level orthogonal array design for the optimization of solid-phase extraction of some pesticides from surface water

An orthogonal array design (OAD), OA32(4(1) x 2(28)), was employed as a chemometric method for the optimization of the solid-phase extraction (SPE) of atrazine, diazinon, ametryn and fenthion in surface water. Seven parameters: the type of eluting solvent, type of sorbent, flow-rate of eluting solvent, sample pH, sample volume, elution volume, addition of modifier and flow-rate of water sample were studied and optimized by a mixed-level OAD. The effects of these factors and some two-variable interactions on the recovery of the pesticides were quantitatively evaluated by the analysis of variance and percentage contribution techniques. The final optimized condition was employed for the SPE of selected micro-organic pollutants from Karoun river water, south of Iran. Atrazine and ametryn were tentatively identified and determined at the 0.7 and 0.9 microg l(-1) level, respectively.     

Molecularly imprinted polymers for triazine herbicides prepared by multi-step swelling and polymerization method. Their application to the determination of methylthiotriazine herbicides in river water

Uniformly-sized, molecularly imprinted polymers (MIPs) for atrazine, ametryn and irgarol were prepared by a multi-step swelling and polymerization method using ethylene glycol dimethacrylate as a cross-linker and methacrylic acid (MAA), 2-(trifluoromethyl) acrylic acid (TFMAA) or 4-vinylpyridine either as a functional monomer or not. The MIP for atrazine prepared using MAA showed good molecular recognition abilities for chlorotriazine herbicides, while the MIPs for ametryn and irgarol prepared using TFMAA showed excellent molecular recognition abilities for methylthiotriazine herbicides. A restricted access media-molecularly imprinted polymer (RAM-MIP) for irgarol was prepared followed by in situ hydrophilic surface modification using glycerol dimethacrylate and glycerol monomethacrylate as hydrophilic monomers. The RAM-MIP was applied to selective pretreatment and enrichment of methylthiotriazine herbicides, simetryn, ametryn and prometryn, in river water, followed by their separation and UV detection via column-switching HPLC. The calibration graphs of these compounds showed good linearity in the range of 50-500 pg/mL (r > 0.999) with a 100 mL loading of a river water sample. The quantitation limits of simetryn, ametryn and prometryn were 50 pg/mL, and the detection limits were 25 pg/mL. The recoveries of simetryn, ametryn and prometryn at 50 pg/mL were 101%, 95.6% and 95.1%, respectively. This method was successfully applied for the simultaneous determination of simetryn, ametryn and prometryn in river water.     

Pesticide toxicity assessment using an electrochemical biosensor with <Emphasis Type="Italic">Pseudomonas putida</Emphasis> and a bioluminescence inhibition assay with <Emphasis Type="Italic">Vibrio fischeri</Emphasis>

Two different toxicity tests, an electrochemical biosensor Cellsense and a bioluminescence inhibition assay ToxAlert were performed in order to establish and compare the acute toxicity responses of different types of raw and spiked water for a selected group of pesticides. The selected compounds were endosulfan, chlorfenvinphos, dimethoate, fenamiphos, ametryn, deltamethrin and alpha-cypermethrin; all of them are used in large quantities for agricultural purposes. In the first step, the study of the toxicity responses for each individual pesticide with Milli-Q water was carried out. Next, the toxic responses of different mixtures of these pesticides in different water matrices, i.e., Milli-Q water, surface water, groundwater and wastewater were studied in order to evaluate (i) device advantages and limitations for the toxicity evaluation of real environmental samples, (ii) antagonistic or synergistic effects and (iii) the influence of the water matrices. The survey of pesticides in real samples was carried out using a combined method involving both chemical analysis and toxicity bioassays. Chemical analysis involved the use of solid-phase micro-extraction (SPME) followed by gas chromatography with electron capture detection (GC/ECD) or thermoionic specific detection (GC/TSD) with mass spectrometric confirmation (GC/MS).     

Biodegradation of polyurethanes and nanocomposites to non-cytotoxic degradation products

Polyurethanes with controllable biodegradable properties have been considered for biomedical applications. However, the potential toxicity of their biodegraded by-products is still a concern. In this study, biodegradable polyurethanes based on poly(?-caprolactone) (PCL) and/or poly(ethylene glycol) as soft segments and biodegradable polyurethanes containing montmorillonite nanoparticles were synthesized and were subjected to in vitro biodegradation for 4 months. The post-degraded polyurethanes and nanocomposites were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and small angle X-ray scattering (SAXS). The toxicity of the biodegradation by-products was evaluated by measuring their effect on the viability of retinal cells. FTIR results indicated that hard segments of the biomaterials were preserved during biodegradation, and suggested that the ester bonds of the PCL incorporated into the soft segments were hydrolytic broken. XRD data indicated also that the soft segments crystallized as a result of the hydrolysis of PCL ester bonds and re-organization of the amorphous phase during annealing at 37 °C. As the biodegradation of the biomaterials induced the formation of soft segment lamella crystals, a complex nanostructure was formed, resulting in the enhancement of the small angle X-ray scattering. The by-products were non-cytotoxic to the retinal cells. These results suggest that the hydrolytic unstable polyurethanes and nanocomposites can be possible candidates for ophthalmological applications.     

Sequential anaerobic/aerobic treatment of dye-containing wastewaters: colour and COD removals, and ecotoxicity tests

Colour and COD removals of the azo dyes Congo Red (CR) and Reactive Black 5 (RB5) were individually evaluated in a sequential anaerobic/aerobic treatment system. Additionally, dye toxicity was assessed by using acute ecotoxicity tests with Daphnia magna as the indicator-organism. The anaerobic reactor was operated at approximately 27 °C and with hydraulic retention times of 12 and 24 h. The aerobic reactor was operated in batch mode with a total cycle of 24 h. During anaerobic step, high colour removals were obtained, 96.3% for CR (400 mg/L) and 75% for RB5 (200 mg/L). During the aerobic phase, COD effluent was considerably reduced, with an average removal efficiency of 52% for CR and 85% for RB5, which resulted in an overall COD removal of 88% for both dyes. Ecotoxicity tests with CR revealed that the anaerobic effluent presented a higher toxicity compared with the influent, and an aerobic post-treatment was not efficient in reducing toxicity. However, the results with RB5 showed that both anaerobic and aerobic steps could decrease dye toxicity, especially the aerobic phase, which removed completely the toxicity in D. magna. Therefore, the anaerobic/aerobic treatment is not always effective in detoxifying dye-containing wastewaters, sometimes even increasing dye toxicity.     

Evaluation of Techniques Used for Parameters Estimation: an Application to Bioremediation of Grease Waste

In the present work, evaluation of different conventional techniques, i.e., chemical oxygen demand (COD), biological oxygen demand, elemental analysis, Fourier transform infrared (FTIR), and gas chromatography used for estimating biodegradation of grease waste was carried out. In this order grease waste was incubated with Penicillium chrysogenum for 7?C30?days and analyzed percentage of degradation. After 15?days of incubation, the percentages of reduction in COD, carbon, hydrogen, and nitrogen content of grease waste were found 28, 53.5, 12.7, and 0, respectively. Further it was analyzed by FTIR and gas chromatography?Cmass spectroscopy (GC-MS) and observed that bifurcated peaks of grease waste at 2,926 and 2,855?cm^?1 had reduced remarkably, which corresponds to aliphatic hydrocarbons, while new broad peaks appeared at 3,400?cm^?1 indicating addition of oxygen molecule to reduced aliphatic hydrocarbon. GC-MS study also supports the results of FTIR, COD, and elemental analysis, but quantification of the percentage of degradation was difficult and limited to volatile organic content, while COD and elemental analysis were found more accurate and more informative. The current study would be helpful in the estimation of biodegradability not only of grease waste but also of other complex nonbiodegradable compounds polluting the environment.     

Biodegradation studies of <Emphasis Type="Italic">N</Emphasis><Superscript>4</Superscript>-acetylsulfapyridine and <Emphasis Type="Italic">N</Emphasis><Superscript>4</Superscript>-acetylsulfamethazine in environmental water by applying mass spectrometry techniques

This work evaluates the biodegradation of N ⁴-acetylsulfapyridine (AcSPY) and N ⁴-acetylsulfamethazine (AcSMZ), metabolites of two of the most commonly used sulfonamides (SAs) in human and veterinary medicine, respectively. Aerobic transformation in effluent wastewater was simulated using aerated fixed-bed bioreactors. No visible changes in concentration were observed in the AcSMZ reactor after 90 days, whereas AcSPY was fully degraded after 32 days of experiment. It was also demonstrated that AcSPY transformed back to its parent compound sulfapyridine (SPY). The environmental presence of these two metabolites in wastewater effluent had been previously investigated and confirmed, together with three more SA acetylated metabolites and their corresponding parent compounds, in 18 different wastewater treatment plants in Hesse (Germany). Sulfamethoxazole (SMX) and SPY were the two SAs detected most frequently (90% and 89% of the samples, respectively) and in the highest concentrations (682 ng L⁻¹ for SMX and 532 ng L⁻¹ for SPY). To conclude, hazard quotients were calculated whenever toxicity data were available. None of the SAs studied posed an environmental risk.     

Biodegradation of poly(lactic acid) powders proposed as the reference test materials for the international standard of biodegradation evaluation methods

The methods for producing reference test materials for biodegradation evaluation tests have been studied. Mechanical crushing at low temperature of polymer pellets using dry ice was selected for the method of producing polymer powder of poly(lactic acid) (PLA). The powders were fractionated using 60 mesh (250 μm) and 120 mesh (125 μm) sieves. The size distributions were then measured. The average diameter of the PLA particles obtained by this method was 214.2 μm. The biodegradation speeds of these PLA polymer powders were evaluated by two methods based on the international standard and one in vitro method based on the enzymatic degradation. First, the degree of biodegradation for this PLA powder was 91% for 35 days in a controlled compost determined by a method based on ISO 14855-1 (JIS K6953) at 58 °C managed by the Mitsui Chemical Analysis and Consulting Service, Inc. (Japan). Second, these polymer powders were measured for biodegradation by the Microbial Oxidative Degradation Analyzer (MODA) in a controlled compost at 58 °C and 70 °C based on ISO/DIS 14855-2 under many conditions. The degree of biodegradation for this PLA powder was approximately 80% for 50 days. In addition, the polymer powders were biodegraded by Proteinase K which is a PLA degradation enzyme. This polymer powder was suitable as a reference material for the evaluation methods of biodegradation.     

Methomyl Detection by Inhibition of Laccase Using a Carbon Ceramic Biosensor

A sol–gel derived carbon ceramic biosensor was used for methomyl determination in vegetable extract samples based on the immobilization of laccase from Aspergillus oryzae. Esculetin was chosen as the substrate for laccase in order to measure inhibition by this pesticide. The analytical curve was linear for methomyl concentrations of 0.5 to 12.2 µM with a detection limit of 0.2 µM. The lifetime of the proposed biosensor was 60 days and the recovery from vegetable extract samples ranged from 98.0 to 104.2 %. The results using the proposed method are in agreement with those using HPLC at the 95 % confidence level.     

Application of multivariate analysis to the screening of molecularly imprinted polymers (MIPs) for ametryn

Among the solid-phase extraction (SPE) techniques, a novel system for a triazine herbicide named ametryn, has been developed based on a molecular imprinted polymer (MIP) phase. Through this method, the synthesis of the complementary to ametryn MIP was accomplished and the factors influencing its efficiency have been optimized. Through the optimization process, the type and the amounts of functional monomer and solvents, template amount, cross-linker, initiator as well as the polymerization temperature were considered to be evaluated. Based on the obtained results, the optimum conditions for the efficient polymerized sorbent, considering the recovery efficiency were solvent: acetonitrile, 6.41 mL; monomer: methacrylic acid, 5.41 mmol; template: 1.204 mmol; cross-linker: 27.070 mmol; initiator: 2.03 mmol; temperature: 40.86 degrees C. The optimum molar ratio among the template, monomer and cross-linker for ametryn was 1:4.49:22.48. The reversed-phase HPLC-UV was used for the ametryn determination, using an isocratic solvent delivery system (acetonitrile: H(2)O, 60:40), flow-rate of 0.8 mL min(-1) and a UV wavelength of 220 nm. In line with the obtained results, using central composite design (CCD) can increase the precision and accuracy of synthesis and optimization of MIP to ametryn and possibly other similar analogues.     

Biodegradabilities of some chain oils in groundwater as determined by the respirometric BOD OxiTop method

The respirometric BOD OxiTop method was used to monitor the biodegradation of different chain oils (mineral, rapeseed and tall oils) over 28 days in groundwater, as well as in standard conditions described by OECD 301 F. The aim of the study was to gather more information about the biodegradability of forestry oils in groundwater, as well as about the suitability of the automatic OxiTop method for biodegradation measurements. The BOD OxiTop method proved to be a precise and reliable technique for determining the biodegradations of different oils. Some comparative studies were also made using a traditional IR method in order to clarify the total oil concentrations. The results show that if biodegradation only is to be monitored, the OxiTop method is preferable. This is due to the influence of other reactions aside from biodegradation on total hydrocarbon concentrations when using the IR method.     

pH-Sensitive surfactants from lysine: assessment of their cytotoxicity and environmental behavior

The toxicity and environmental behavior of new pH-sensitive surfactants from lysine are presented. Three different chemical structures are studied: surfactants with one amino acid and one alkyl chain, surfactants with two amino acids on the polar head and one alkyl chain, and gemini surfactants. The pH sensitivity of these compounds can be tuned by modifying their chemical structures. Cytotoxicity has been evaluated using erythrocytes and fibroblast cells. The toxic effects against these cells depend on the hydrophobicity of the molecules as well as their cationic charge density. The effect of hydrophobicity and cationic charge density on toxicity is different for each type of cells. For erythrocytes, the toxicity increases as hydrophobicity and charge density increases. Nevertheless, for fibroblasts cationic charge density affects cytotoxicity in the opposite way: the higher charge density, the lower the toxicity. The effect of the pH on hemolysis has been evaluated in detail. The aquatic toxicity was established using Daphnia magna . All surfactants yielded EC(50) values considerably higher than that reported for cationic surfactants based on quaternary ammonium groups. Finally, their biodegradability was evaluated using the CO(2) headspace test (ISO 14593). These lysine derivatives showed high levels of biodegradation under aerobic conditions and can be classified as "readily biodegradable compounds".     

Biodegradation and thermal decomposition of poly(lactic acid)-based materials reinforced by hydrophilic fillers

The effect of hydrophilic fillers (starch and wood-flour) on the degradation and decomposition of poly(lactic acid) (PLA) based materials was investigated. Biodegradation was evaluated by composting under controlled conditions in accordance with AS ISO 14855. Thermal decomposition was studied by thermogravimetry (TGA). Morphological variations during biodegradation were investigated by SEM examination. It was found that biodegradation rates of PLA/starch blends and PLA/wood-flour composites were lower than that of pure cellulose but higher than that of pure PLA. The biodegradation rate was increased from about 60% to 80% when the starch content was increased from 10% to 40% after 80 days. Both starch and wood-flour accelerated thermal decomposition of PLA, and starch exhibited a relatively stronger affect then wood-flour. The decomposition temperature of PLA was decreased about 40 °C when the filler content was increased to 40%. Small polar molecules released during thermal decomposition of starch and wood-flour were attributed to the thermal decomposition behaviours of the PLA based blends and composites and their role is further discussed in this paper.     

气相色谱-质谱法同时测定蔗汁中的莠去津与莠灭净残留量

建立了气相色谱-质谱法(GC-MS/SIM)同时测定蔗汁样品中莠去津和莠灭净的方法,并优化了样品前处理和色谱条件.在优化条件下,两种除草剂在0.00-0.60 mg/L范围内线性关系良好,方法的检出限(S/N=3)均为0.001 mg/L.在加标水平为0.050-0.100 mg/L时,两种除草剂的回收率在93%-10...     

气相色谱法检测七种动物源食品中莠灭净残留量

本研究建立了动物源食品中莠灭净残留量的气相色谱检测法。样品以乙腈为提取溶剂,提取液以酸性氧化铝柱净化,乙腈-甲苯(7∶2,V/V)洗脱,以气相色谱火焰光度检测器(GC-FPD,S型滤光片)检测,外标法定量。方法的准确度与精密度较好,检出限为0.005mg/kg,平均添加回收率在88.1%～102.8%之间,相对标准偏差(RSD)为3.07%～8.29%,满足农药残留分析的要求。