Concentrations and composition profiles of benzotriazole UV stabilizers in municipal sewage sludge in China

The environmental contamination and fate of benzotriazole UV stabilizers (BZTs) have received increasing attention due to their large production volume and wide usage in various consumer and industrial products. In the present work, 60 municipal sewage sludge samples from wastewater treatment plants (WWTPs) in 33 cities in China were collected to investigate the occurrence and distribution of 9 frequently used BZTs. The most dominant analogue was 2-[3,5-bis(1-methyl-1-phenylethyl)-2-hydroxyphenyl]benzotriazole (UV-234) at a median concentration of 116 ng/g (dry weight) and accounted on average for 27.2% of total BZTs. The abundance was successively followed by 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole (UV-329, average 24.3%), 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole (UV-326, average 22.2%), 2-(3,5-di-tert-amyl-2-hydroxyphenyl)benzotriazole (UV-328, average 17.7%), and 2-(2-hydroxy-5-methylphenyl)benzotriazole (UV-P, average 6.6%), with median concentrations of 66.8, 67.8, 57.3, and 20.6 ng/g, respectively. 5-Chloro-2-(3,5-di-tert-butyl-2-hydroxyphenyl)benzotriazole (UV-327) and 2-(3-sec-butyl-5-tert-butyl-2-hydroxyphenyl)benzotriazole (UV-350) had low detection frequency, while 2-(3,5-di-tert-butyl-2-hydroxyphenyl)benzotriazole (UV-320) and 2-(5-tert-butyl-2-hydroxyphenyl)benzotriazole (UV-PS) were not detectable in any sample. To our knowledge, this is the first study reporting the occurrence of UV-234, UV-329, and UV-350 in sewage sludge in China. Significant correlations were found among the BZT concentrations and also with a WWTP characteristic (daily treatment volume). Furthermore, results from degradation prediction and multimedia fate simulation based on a quantitative structure-property relationship (QSPR) model at screening level also implied that the commercial BZT chemicals and their plausible transformation products might be persistent in the environment.     

Co-detoxification of transformer oil-contained PCBs and heavy metals in medical waste incinerator fly ash under sub- and supercritical water

The simultaneous detoxification processes of transformer oil-contained PCBs and heavy metals in medical waste incinerator (MWI) fly ash were developed under sub- and supercritical water. The addition of MWI fly ash to transformer oil-contained PCBs was found to increase the destruction efficiency of PCBs, at the same time, it facilitated reducing the leaching concentration of toxic metals from residues (obtained after reaction) for harmless disposal. In this study, we elucidated primarily the catalysis possibility of heavy metals in raw MWI fly ash for PCBs degradation by adopting the sequential extraction procedure. For both MWI fly ashes, more than 90% destruction efficiency of PCBs was achieved at ≥375 °C for 30 min, and trichlorobenzene (TCB) existing in the transformer oil was also completely decomposed. The correlation of catalytic performance to PCBs degradation was discussed based on structural characteristics and dechlorinated products. Likewise, such process rendered residues innocuous through supercritical water treatment for reuse or disposal in landfill.     

Anammox bacterial abundance, activity, and contribution in riparian sediments of the pearl river estuary

The hypothesis of an anammox hotspot in river riparian zones was put forward based on our investigation on freshwater ecotones for over 25 years and previous anammox research. Here we used a complementary array of methods including isotope-pairing technique, quantitative PCR assays, and 16S rRNA and hydrazine synthase gene (hzsB) clone libraries to document the spatiotemporal evidence for a high abundance zone of anammox bacteria in river riparian sediment with observed abundance of 1.3-12 × 10(6) (summer) and 1.4-20 × 10(8) (winter) hydrazine synthase gene copies g(-1), which is the highest abundance in natural environments recorded so far. Meanwhile high anammox bacterial biodiversity were detected with 'Brocadia' and 'Kuenenia' dominating. However, the high anammox bacterial abundances were not related with high activities and contributions for nitrogen gas generation. The anammox activities ranged from 0.07 to 0.15 nmol N cm(-3) h(-1) (summer) to 1.0-2.6 nmol N cm(-3) h(-1) (winter) with high temporal heterogeneity. The retrieval of archaeal and bacterial amoA sequences indicated that nitrifying microbes might be the major source of nitrite for anammox bacteria in winter, while in summer the anaerobic nitrate reduction is more likely the main source. On the basis of (15)N tracing technology, it was estimated that a total loss of 0.67-9.62 g N m(-2) yr(-1) is linked to anammox in the riparian zone while denitrification contributed 96.2-170.3 g N m(-2) yr(-1) in Pearl River riparian sediments.     

生活污水的一体化反应器同步脱氮除磷研究

根据污水生物脱氮除磷原理设计了一套一体化反应器,并在其中分别投加普通生物悬浮载体和双室悬浮载体,以研究两者对生活污水同步脱氮除磷的效果。结果表明,在相同HRT下、温度控制在20～30℃和pH为6.5～7.8时,双室悬浮载体对污水总氮的平均去除率比普通生物悬浮载体的高近10%;但是两者对总磷及COD的去除效果相近,且对COD的去除效果较好,平均去除率在90%以上;Grau模型计算表明,HRT为12 h时,反应器中投加双室悬浮载体后的污水底物降解常数最大(2.18)。因此,把双室悬浮载体及其一体化反应器用于污水的同步脱氮除磷是一种高效的生活污水处理方法。     

Changes in physicochemical properties and bactericidal efficiency of acidic electrolyzed water ice and available chlorine decay kinetics during storage

Acidic electrolyzed water ice (AEW ice) is a new kind of bactericide used in preservation or cold sterilization of food products. The aim of this study was to investigate changes in the physicochemical properties (oxidation reduction potential (ORP), pH value and available chlorine concentration (ACC)), bactericidal efficiency, and decay kinetics of available chlorine in AEW ice during 10 h of storage time. Results indicated that pH changes of AEW ice did not have a significant difference (p > 0.05) during the first 6-h storage, after 6 h, the pH of AEW ice prepared with ≤1 g/l NaCl solution changed more slowly than that of AEW ice prepared with >1 g/l NaCl solution. Both ORP and ACC decreased with storage time. The ACC of AEW ices prepared from >1.5 g/l NaCl solutions decreased faster and in a greater extent than those prepared from ≤1.5 g/l NaCl solutions. According to the correlation analysis, the correlation coefficients between pH, ORP, and ACC and Vibrio parahaemolyticus inactivation were −0.831, 0.787 and 0.944, respectively, and those between the above parameters and Listeria monocytogenes inactivation were −0.814, 0.701 and 0.97, respectively. Based on the kinetic study, the decay of ACC fitted the first order kinetics.     

Gas-particle partitioning of polychlorinated dibenzo-p-dioxins and dibenzofurans in the sintering process

The distribution of seventeen gaseous and particle-bound 2,3,7,8-substituted chlorinated PCDD/Fs in the flue gas of different windboxes of the sintering machine was analyzed.The influence of temperature change on the PCDD/Fs emission from the sintering process and the formation mechanism of PCDD/Fs were discussed.The result has shown that among the seventeen gaseous and particle-bound PCDD/Fs in the flue gas of different windboxes,furans occupied the major place.The proportion of the gaseous PCDD/Fs in most windboxes is from 40% to 60%.The change tendencies of the concentration of both the gaseous and particle-bound PCDD/Fs were similar,with a higher level at the end of the sintering bed.The PCDD/Fs concentration’s change tendency in the windbox was very consistent with the change of temperature of the flue gas in the windboxes.More than 60% PCDD/Fs of the total PCDD/Fs emission amount was emitted at the end of the sintering bed.Only this part of the waste gas accounted for 12% of the total waste gas volume.     

Quantitative structure-activity relationship models for prediction of the toxicity of polybrominated diphenyl ether congeners

Levels of polybrominated diphenyl ethers (PBDEs) are increasing in the environment and may cause long-term health problems in humans. The similarity in the chemical structures of PBDEs and other halogenated aromatic pollutants hints on the possibility that they might share similar toxicological effects. In this work, three-dimensional quantitative structure activity relationships (3-D-QSAR) models, using comparative molecular field analysis (CoMFA) and comparative similarity indices analysis (CoMSIA), were built based on calculated structural indices and a reported experimental toxicology index (aryl hydrocarbon receptor relative binding affinities, RBA) of 18 PBDEs congeners, to determine the factors required for the RBA of these PBDEs. After performing leave-one-out cross-validation, satisfactory results were obtained with cross-validation O2 and R2 values of 0.580 and 0.995 by the CoMFA model and 0.680 and 0.982 by the CoMSIA model, respectively. The results showed clearly that the nonplanar conformations of PBDEs result in the lowest energy level and that the electrostatic index was the main factor reflecting the RBA of PBDEs. The two QSAR models were then used to predict the RBA value of 46 PBDEs for which experimental values are unavailable at present.     

Distribution and trophic transfer of short-chain chlorinated paraffins in an aquatic ecosystem receiving effluents from a sewage treatment plant

Short-chain chlorinated paraffins (SCCPs) are an extremely complex group of industrial chemicals and found to be potential persistent organic pollutants (POPs), and thus have attracted extensive concern worldwide. In this study, influent, effluent, and sludge were collected from a large sewage treatment plant (STP) in Beijing, China. Water, sediment, and aquatic species were also collected from a recipient lake that receives effluents discharged from the STP. These samples were then analyzed to investigate the effect of STP effluent on distribution and trophic transfer of SCCPs in the local aquatic ecosystem. Concentrations of total SCCPs (ΣSCCPs) in lake water and surface sediments were found in the range 162-176 ng/L and 1.1-8.7 μg/g (dry weight, dw), respectively. Vertical concentration profiles of sediment cores showed ΣSCCPs decreased exponentially with increasing depth. Specific congener composition analysis in sediment layers indicated possible in situ biodegradation might be occurring. High bioaccumulation of SCCPs was observed in the sampled aquatic species. The bioaccumulation factor (BAF) generally increased with the number of chlorines in the SCCP congeners. A significantly positive correlation between lipid-normalized ΣSCCPs concentration and trophic levels (R(2) = 0.65, p < 0.05) indicate that SCCPs can biomagnify through the food chain in the effluent-receiving aquatic ecosystem.     

Search for the contamination source of butyltin compounds in wine: agglomerated cork stoppers

A possible butyltin contamination source in wine was studied in this paper. Agglomerated cork stoppers, which were produced in Portugal, Spain, and Italy, used in wine bottles were examined. The domestic cork products, cork granules, and mucus used for cork products were also analyzed. The levels of mono- and dibutyltin compounds in corks were found in the range from <0.0024 to 3.3 and from <0.0029 to 6.7 microg of Sn/g, respectively. A low level of tributyltin contamination was also found in 2 of 31 tested samples. The presence of butyltin compounds in agglomerated cork stoppers was confirmed by GC-MS. Experimental results indicated that all overseas agglomerated cork stoppers studied contained mono- and/or dibutyltins. Butyltins were not detected in cork granules, mucus, most of the natural cork stoppers, and domestic agglomerated cork products. The concentrations of mono- and dibutyltins increased with the time in a 30-day experiment, showing that butyltin compounds can leach from agglomerated cork to the wine. When the butyltin concentrations in wine samples were compared with their levels in the corresponding agglomerated cork stoppers, a correlation was found. The potential harm of such food contamination was evaluated by the toxic research of butyltin compounds using Daphnia sp. as the experimental model.     

Arsenate adsorption on an Fe-Ce bimetal oxide adsorbent: role of surface properties

An Fe-Ce bimetal adsorbent was investigated with X-ray powder diffraction (XRD), transmission electron micrograph (TEM), Fourier transform infrared spectra (FTIR), and X-ray photoelectron spectroscopy (XPS) methods for a better understanding of the effect of surface properties on arsenate (As(V)) adsorption. In the adsorption test, the bimetal oxide adsorbent showed a significantly higher As(V) adsorption capacity than the referenced Ce and Fe oxides (CeO2 and Fe3O4) prepared by the same procedure and some other arsenate adsorbents reported recently. XRD measurement of the adsorbent demonstrated that the phase of magnetite (Fe3O4) disappears gradually with the increasing dosage of Ce4+ ions until reaching a molar ratio of Ce4+ to Fe3+ and Fe2+ of 0.08:0.2:0.1 (Fe-CeO8 refers to the adsorbent prepared at this ratio), and the phase of CeO2 begins to appear following a further increase of the Ce dose. Combined with the results of TEM observation, it was assumed that a solid solution of Fe-Ce is formed following the disappearance of the magnetite phase. Occurrence of a characteristic surface hydroxyl group (MOH, metal surface hydroxyl, 1126 cm(-1)), which showed the highest band intensity in the solid solution state, was confirmed on the bimetal oxide adsorbent by FTIR. Quantificational calculation from the XPS narrow scan results of O(1s) spectra also indicated that the formation of the bimetal Fe-CeO8 was composed of more hydroxyl (30.8%) than was the formation of CeO2 and Fe3O4 (12.6% and 19.6%). The results of adsorption tests on Fe-CeO8 at differentAs(V) concentrations indicated that both the integral area of the As-O band at 836 cm(-1) and the As(V) adsorption capacity increased almost linearly with the decrease of the integral area of M-OH bands at 1126 cm(-1), proving that the adsorption of As(V) by Fe-CeO8 is mainly realized through the mechanism of quantitative ligand exchange. The atomic ratio of Fe on Fe-CeOB decreased from 20.1% to 7.7% with the increase of the As atom ratio from 0 to 16% after As(V) adsorption, suggesting that As(V) adsorption might be realized through the replacement of the M-OH group of Fe (Fe-OH) with arsenate. The well splitting of three v3 bands at As-O band (836 cm(-1)) of FTIR and the hydroxyl ratio (1.7) of Fe-CeO8 calculated from the XPS results suggested that the diprotonated monodentate complex (SOAsO(OH)2) is possibly dominant on the surface of Fe-CeO8.