Improved liquid chromatographic determination of nine currently used (fluoro)quinolones with fluorescence and mass spectrometric detection for environmental samples

An HPLC method using C18-modified silica as stationary phase has been developed for environmental trace analysis of nine (fluoro)quinolones. Detection is done by fluorescence measurement or MS using the modes of SIM and selected reaction monitoring (SRM). Best separation is achieved with a gradient consisting of 50 mM formic acid and methanol, which is fully compatible with MS coupling. LOQs (S/N of 10) for fluorescence detection are between 10 and 60 microg/L, depending on the analyte. MS detection (SIM and SRM) yields LOQs that are better by a factor of at least an order of magnitude. Sample preconcentration and sample clean-up is accomplished by SPE (preconcentration factor of 1000), leading to LOQs in the low ng/L range. Recoveries of the preconcentration procedure are better than 80% for all analytes. The suitability for real samples has been demonstrated by analyzing surface waters, municipal waste waters, sewage treatment plant effluents, sewage sludge, and sediment taken from rivers and fish ponds. The method should also be useful for determination of residues of (fluoro)quinolones in food or other matrices. The degradation of the (fluoro)quinolones has been examined over 5 days in order to get information about the decomposition rate and the degradation products eventually occurring in the environment.     

Optimisation of caffeine and antidepressants extraction from sediments and sewage sludge using experimental designs

This study proposes a microwave-assisted method for the simultaneous extraction of highly prescribed antidepressants (citalopram, venlafaxine, fluoxetine, sertraline and amitriptyline) and caffeine from sediments and sewage sludge for subsequent HPLC-PDA analysis. Because the sludge and sediment matrices have high contents of organic material, they strongly interact with the analytes and hinder extraction. Thus, a carefully optimised analytical methodology is required for quantitative extraction. A simplex-centroid design was applied to optimise the solvent composition, and a three-factor central composite rotational design was used to optimise the extraction protocol with regards to pH, amount of solvent and processing time. Samples (in triplicates) were fortified with a standard mixed solution of all the analytes and extracted according to the experimental design in each study. The extraction steps included: 30 s vortexing, 20 s microwave heating at 10 W, cooling to room temperature (25°C) in an ultrasonic bath for 60 s, 2 min centrifugation at 2000 rpm, and filtration. Analysis of variance and lack-of-fit tests were used to assess the significance of data fitting at 95% confidence. The desirability function was the optimisation tool used to obtain the ideal extraction conditions. As a result, a binary mixture of methanol and acetonitrile in 45:55 and 53:47 (v/v) ratios was indicated as the optimum solvent composition for the simultaneous extraction of all the target drugs from the sludge and sediment, respectively. The optimised extraction conditions were: 3 extraction cycles with 4 mL of solvent at pH 3 for sewage sludge extraction and 4 extraction cycles with 3 mL of solvent at pH 11 for sediment extraction. Further, low recoveries were obtained for extractions from sediment as compared to sludge indicating strong interaction of antidepressants and caffeine with the acidic organic components of sediments. It was found that the optimisation of pH of the extraction phase was crucial for the efficient extraction of the analytes from these environmental matrices.     

Bio-adsorption of dyes from aqueous solution by powdered excess sludge (PES): Kinetic,isotherm, and thermodynamic study

Over 30 million tons of excess sludge is discharged from rural municipal sewage plants annually in China and it is predicted that this figure will keep increasing. However, most of the excess sludge is dumped in landfills except for minor applications. In this study, based on low-cost and recycling waste, the excess sludge was used to adsorb organic dyes from aqueous solution after being directly dewatered. The powdered excess sludge (PES) presents selective adsorption property to cationic dyes. Statics batch adsorption experiments of malachite green (MG) on PES were performed to evaluate the effects of pH, adsorbent dosage, and initial MG concentration. Results revealed that the bio-adsorption equilibrium of MG on the PES can be quickly achieved at 30 min with maximum percentage adsorption of 84% at pH 7, initial dye concentration of 20 mg L^?1, and adsorbent dosage of 1.5 g L^?1. Moreover, the adsorption kinetics follows a pseudo-second-order pathway, and the equilibrium adsorption data could be described well by the Langmuir isotherm equation. Intra-particle diffusion is not the only rate-controlling step in the entire adsorption process. The adsorption process is endothermic, spontaneous, and random. PES can be used as a low-cost adsorbent for refractory cationic organic dye in effluent.     

污水污泥流化床气化焦油的化学组成分析

以空气为气化剂、并通过GC-MS分析,研究了污水污泥流化床气化时气化温度（650、750和850 ℃）和污泥性质对污泥气化焦油产率及其化学组成的影响。结果表明,污泥气化焦油产率随气化温度的升高而降低,且厌氧消化污泥气化焦油的产率比未消化污泥的低。污泥气化焦油中的化学组成可分为五类：脂肪族化合物、脂环化合物、芳香烃、芳香烃衍生物和杂环化合物。随气化温度的升高,A²/O工艺的未消化污泥气化生成的焦油中脂肪族化合物和脂环化合物的产率均明显降低,芳香烃衍生物的产率则有显著地提高,而芳香烃和杂环化合物的产率均先增加后减少。气化温度为650 ℃时,活性污泥法消化污泥气化焦油中五类有机物的产率均低于未消化污泥的,而A²/O工艺消化污泥气化焦油中芳香烃产率高于未消化污泥的,其他四种有机物的产率则均低于未消化污泥的。     

O2/CO2气氛下污泥/煤混燃中半挥发性重金属的释放特性

在固定床焚烧实验装置上,采用正交实验法研究了焚烧温度(t_c)、污泥掺混比(X_s)、O_2体积分数(φ_(O2))、初始含水率(φ_(H2O))、焚烧时间(τ)和含氯量(φ_(Cl))六个因素对O_2/CO_2气氛下污泥/煤混燃中半挥发性重金属(Zn、Pb、Cd、Cu、Ni和Cr)释放特性的影响。结果表明,六种因素对重金属释放率影响程度排序为t_cX_sφ_(H2O)φ_(O2)≈τφ_(Cl)。相同焚烧工况下,Zn释放率最大,Pb和Cd次之,Cu、Ni和Cr较小。提高温度会促进重金属释放,且高温(1000-1100℃)对重金属释放的影响显著强于低温(700-900℃)。随着温度由700℃升高至1100℃,Zn和Pb释放率分别由36.1%和12.2%上升至70.9%和63.5%,Cd在900℃下达到40.0%的最大释放率,而Cu、Ni和Cr释放率大都维持在20.0%以下,温度对重金属释放率影响程度排序为PbZnCdCuCrNi。重金属释放率随着污泥掺混比增加逐渐下降,却随着初始含水率增加呈现波浪式变化趋势,且在30%O_2体积分数下重金属释放率取得最小值。焚烧时间和含氯量对Pb释放的影响程度显著强于其他五种重金属。O_2/CO_2气氛下污泥/煤混燃的最佳工况为:焚烧温度为900-1000℃、污泥掺混比为25%左右、O_2体积分数为30%、初始含水率小于10%,并尽可能的缩短焚烧时间。     

Status and prospect of oil recovery from oily sludge:A review

Oily sludge is a kind of solid emulsified waste produced by the petroleum industry. It is generally composed of water, crude oil, and solid particulate matter. Because it contains large amounts of cycloalkanes, benzene series, polycyclic aromatic hydrocarbons, and other toxic and harmful substances, it poses a substantial threat to human health and the surrounding environment; therefore, it must be treated to reduce its toxicity. However, a large component of oily sludge is crude oil, which has great recycling value. Therefore, various crude oil recovery technologies, such as solvent extraction, pyrolysis, centrifugation, ultrasonic treatment, electronal treatment, flotation, supercritical treatment, and combined processes, have been developed for the treatment of oily sludge. The main purpose of this review is to discuss the development of these recycling technologies and to summarize and compare their advantages, disadvantages, and mechanisms of action. On this basis, the future development direction of recycling technology is prospected.     

水性漆污泥中钛元素的赋存状态研究

工业固体废弃物中金属元素的赋存状态是判别废弃物种类的重要指标。采用现代分析测试手段对水性漆污泥样品中钛的赋存状态进行了研究。实验表明,该污泥样品中钛元素赋存于氧化钛和钙钛矿中,其中95.82%存在于氧化钛中,4.18%存在于钙钛矿中,未检测出水溶性钛。在自然环境中,该样品中的钛元素以较稳定形式存在,不会对环境产生影响。     

高效液相色谱-质谱联用法同步测定城市污水处理厂活性污泥中的多类抗生素残留

采用超声萃取、固相萃取及高效液相色谱-质谱联用技术(LC-MS),建立了活性污泥中3类共9种抗生素(包括5种磺胺类、3种四环素类及1种大环内酯类)的同时分析方法.样品经甲醇-Na2,EDTA/Mcllvaine缓冲液(1∶1,体积比)超声萃取,HLB固相萃取柱净化富集后,以Symmetry C18反相柱为分析柱,0.2...     

Magnetic resonance microscopy of iron transport in methanogenic granules

Interactions between anaerobic biofilms and heavy metals such as iron, cobalt or nickel are largely unknown. Magnetic resonance imaging (MRI) is a non-invasive method that allows in situ studies of metal transport within biofilm matrixes. The present study investigates quantitatively the penetration of iron (1.75 mM) bound to ethylenediaminetetraacetate (EDTA) into the methanogenic granules (spherical biofilm). A spatial resolution of 109 × 109 × 218 μm³ and a temporal resolution of 11 min are achieved with 3D Turbo Spin Echo (TSE) measurements. The longitudinal relaxivity, i.e. the slope the dependence of the relaxation rate (1/T₁) on the concentration of paramagnetic metal ions, was used to measure temporal changes in iron concentration in the methanogenic granules. It took up to 300 min for the iron–EDTA complex ([FeEDTA]²⁻) to penetrate into the methanogenic granules (3–4 mm in diameter). The diffusion was equally fast in all directions with irregularities such as diffusion-facilitating channels and diffusion-resistant zones. Despite these irregularities, the overall process could be modeled using Fick’s equations for diffusion in a sphere, because immobilization of [FeEDTA]²⁻ in the granular matrix (or the presence of a reactive barrier) was not observed. The effective diffusion coefficient (D_ejf) of [FeEDTA]²⁻ was found to be 2.8 × 10⁻¹¹ m² s⁻¹, i.e. approximately 4% of D_ejf of [FeEDTA]²⁻ in water. The Fickian model did not correspond to the processes taking place in the core of the granule (3–5% of the total volume of the granule), where up to 25% over-saturation by iron (compare to the concentration in the bulk solution) occurred.     

Effects of Ca and Na acetates on nitrogen transformation during sewage sludge pyrolysis

The study reports the effects of Ca and Na acetates on the transformation of nitrogen species during sewage sludge pyrolysis. Sludge samples, with or without acetates, were pyrolysed in a fix-bed reactor at 150–550 °C, and the nitrogen species in the pyrolysis products (char, tar, and gas) were characterised and quantified. Ca and Na acetates distinctly affect nitrogen transformation during sludge pyrolysis, which is ascribable to their different catalytic activities for the decomposition of nitrogen species in sludge. The addition of Ca acetate is found to increase nitrogen retention in char and reduce the formation of nitrogen species in tar, which is mainly due to the suppressed decomposition of protein-N as well as the promoted formation of stable nitrogen species in char. On the other hand, the addition of Na acetate enhances the decomposition of nitrogen species in sludge, such as protein- and inorganic-N. The levels of both Ca and Na acetates are significantly reduced in the nitrogen-containing gas emissions because acetone is produced when acetates are heated, and acetone readily reacts with NH₃ to produce binary clusters or amines. Our results show that acetate addition is an important strategy for the reduction of NH₃ emission during sludge pyrolysis.