Degradation of phenol by coal-based carbon membrane integrating sulfate radicals-based advanced oxidation processes.

Phenol, as a representative organic pollutant in aquatic environments, has posed a serious threat to humans and ecosystem. In this work, a novel integration system combined coal-based carbon membrane with sulfate radicals-based advanced oxidation processes (SR-AOPs) was designed for degradation of phenol. The integrated system achieved 100% removal efficiency under the optimal condition (peroxydisulfate dosage is 0.2 g/L, at alkaline condition with 2 mL/min flow velocity). The quenching experiments revealed that the efficient removal of phenol by the integrated system were attributed to the co-existence of radical and nonradical mechanisms. This study proposes a green and efficient technique for the removal of phenol.

Implications of hydrogen peroxide on bromate depression during seawater ozonation.

The presence of hydrogen peroxide (H2O2) in ozonation process can resist the formation of carcinogenic bromate (BrO3¯) efficiently, and the bromate depression is closely related with background water qualities, especially in high bromide-containing seawater. In this study, the freshwater and seawater were selected to investigate the effects of H2O2 on ozone (O3) decomposition kinetics, bromide transformation and bromate depression, and the evolutions of BrO3¯ under different scavengers were explored to speculate the primary bromate formation pathways. The results showed that the initial O3 half-live period (t1/2-O3) in seawater was only one-sixth of that in freshwater, and its attenuation rate increased analogously with the increase of H2O2 concentration in both freshwater and seawater. The H2O2 could promote the formation of BrO3¯ via hydroxyl radical (•OH) based bromate pathways, nevertheless higher concentration of H2O2 facilitated the reduction of HOBr/OBr¯ back to Br¯, resulting in 87.0% and 73.2% of BrO3¯ retardment in freshwater and seawater, respectively. The suppression ratios of BrO3¯ were up to 48.4% and 35.3% in freshwater with the addition of •OH and •O2¯ scavengers, and the corresponding depressions in seawater decreased to 35.3% and 12.7%, indicating that •OH was dominant on bromate formation when the concentration of residual ozone was adequate to generate some bromine intermediates, meanwhile H2O2 and •O2¯ functioned as the key reductants for bromate depression. Based on these results, the Br¯ transformation mechanisms via O3, •OH, H2O2, and •O2¯ reactions were speculated, and the feasibility of H2O2-ozonation was verified for the treatment of high Br¯-containing seawater.

Enhanced Treatment Ability of Membrane Technology by Integrating an Electric Field for Dye Wastewater Treatment: A Review.

The increasing environmental awareness and stricter regulations have prompted the developments of various treatment technologies for dye wastewater. Membrane separation receives extensive attention as a promising technology because of many advantages. However, higher removal performance requirements and membrane fouling issues make a single separation method inadequate for the removal of dyes from industrial wastewater. Exerting an electric field on membrane separation system for dye wastewater treatment has already been proposed and newly developed in recent years because each technology complements the advantages and overcomes the challenges of the other. Although the amount of literature in this field is limited, this integrated technology has exhibited good performance on dye removal and is believed to have a bright prospect. This review mapped out the previous studies and current trends as well as provided a prospective outlook for advances in various membrane-combining technologies with an electric field, especially with the electric advanced oxidation processes. The different combination patterns, performance evaluations, removal mechanisms, and treatment parameters are gathered and discussed.

Trophic magnification of polybrominated diphenyl ethers in the marine food web from coastal area of Bohai Bay, North China.

Trophic transfer of polybrominated diphenyl ethers (PBDEs) in aquatic ecosystems is an important criterion for assessing their environmental risk. This study analyzed 13 PBDEs in marine organisms collected from coastal area of Bohai Bay, China. The concentrations of total PBDEs (Σ13PBDEs) ranged from 12 ± 1.1 ng/g wet weight (ww) to 230 ± 54 ng/g ww depending on species. BDE-47 was the predominant compound, with a mean abundance of 20.21 ± 12.97% of total PBDEs. Stable isotopic ratios of carbon (δ(13)C) and nitrogen (δ(15)N) were analyzed to determine the food web structure and trophic level respectively. Trophic magnification factors (TMFs) of PBDEs were assessed as the slope of lipid equivalent concentrations regressed against trophic levels. Significant positive relationships were found for Σ13PBDEs and eight PBDE congeners (BDE-28, BDE-47, BDE-49, BDE-66, BDE-85, BDE-99, BDE-100 and BDE-154). Monte-Carlo simulations showed that the probabilities of TMF >1 were 100% for Σ13PBDEs, BDE-47, BDE-85, BDE-99 and BDE-100, 99% for DE-28, BDE-49, BDE-66 and BDE-154, 94% for BDE-153, and 35% for BDE-17.

Occurrence and distribution of perfluoroalkyl substances (PFASs) in surface water and bottom water of the Shuangtaizi Estuary, China.

Perfluoroalkyl substances (PFASs) have been recognized as emerging environmental pollutants. However, there is limited information on the contamination level and spatial distribution of PFASs in the Shuangtaizi Estuary, where the Shuangtaizi Hekou Nature Reserve is located. In the present study, the contamination level and spatial distribution of PFASs in surface water (approximately 0.5 m below the surface) and bottom water (about 0.5 m above the bottom) of the Shuangtaizi Estuary were investigated. The data indicated that the Shuangtaizi Estuary was commonly contaminated by PFASs. The total concentration of PFASs in surface and bottom water of the Shuangtaizi Estuary ranged from 66.2 to 185 ng L(-1) and from 44.8 to 209 ng L(-1), respectively. The predominant PFASs were perfluorobutanoic acid (PFBA), perfluoropentanoic acid, perfluorooctanoic acid, perfluorohexanoic acid and perfluorobutane sulfonate (PFBS). In general, PFAS concentrations in surface water samples were lower than those in bottom water samples. The spatial distribution of PFASs in the Shuangtaizi Estuary was mainly affected by particular landform, tide and residual currents in Liaodong Bay. The total mass flux of 15 PFASs from the Shuangtaizi River to Liaodong Bay was estimated to be 352 kg year(-1), which was lower than the total flux from the Daling River and the Daliao River. As short-chain PFASs, such as PFBS and PFBA, have been the prevalent compounds in some places and are continuously produced and used, long-term monitoring and effective pollution controls are suggested.

Toxicity and DNA methylation changes induced by perfluorooctane sulfonate (PFOS) in sea urchin Glyptocidaris crenularis.

Perfluorooctane sulfonate (PFOS) is an ubiquitous persistent organic pollutant, which can be bioaccumulated and cause adverse effects on organisms. However, there is very limited information about the toxic effects of PFOS to marine organisms and its mechanisms. Therefore, in the present study, adult sea urchins Glyptocidaris crenularis were exposed to PFOS for 21 d, followed by a 7-d depuration period, in order to investigate the toxicity of PFOS to sea urchin and its potential epigenetic mechanisms. Sea urchins dropped spines, and lowered down the motor ability and feeding ability after the PFOS exposure. Superoxide dismutase activities in supernatant of coelomic fluid of sea urchin increased firstly and then dropped down, while the change of the catalase activity took an opposite trend during the exposure period. They both approached to the corresponding activity of the control after the depuration period. The DNA methylation polymorphism, methylation rate and demethylation rate in sea urchin gonad all increased following the prolonged exposure time, and then decreased after the depuration period. The demethylation rates were lower than the corresponding methylation rates, therefore methylation events were dominant during the whole experimental period. This might suggest that sea urchin have strong self-protection mechanisms and can survive from the PFOS exposure presented in this study. Further efforts are needed to more precisely investigate the DNA methylation effects of PFOS and the self-protection mechanism of sea urchin.

Spatial distribution and risk assessment of heavy metals in sediments of Shuangtaizi estuary, China.

In order to evaluate the spatial distribution and potential ecological risk of Pb, Cu, Zn, Cd, and Hg, the surface sediments were collected from 18 sites in the Shuangtaizi estuary. The concentrations of Pb, Cu, Zn, Cd, and Hg were analyzed by atomic absorption spectrophotometry and atomic fluorescence spectrometry after digestion. The particle sizes of the sediments were analyzed using a laser diffraction particle size analyzer. The results show that the heavy metal contents in the sediments are observed in the following order: Zn (18.25-126.75mg/kg)>Pb (4.38-9.65mg/kg)>Cu (1.80-17.68mg/kg)>Cd (0.241-0.764mg/kg)>Hg (0.007-0.021mg/kg). In comparison with the concentrations of heavy metals in other regions, the concentrations of Pb, Cu, and Zn in the Shuangtaizi estuary are generally low, and the Cd concentrations are close to those reported in other regions. Both the potential ecological risk index and the geoaccumulation index reveal that the heavy metal pollution in Shuangtaizi estuary is mainly dominated by Cd.