Time filter

Source Type

Deng S.,CAS Research Center for Eco Environmental Sciences | Deng S.,University of Chinese Academy of Sciences | Kang S.,BCEG Environmental Remediation Co. | Feng N.,CAS Research Center for Eco Environmental Sciences | And 6 more authors.
Journal of Hazardous Materials | Year: 2017

Recent researches indicate that mechanochemical treatment (MCT) is a promising method to degrade the environmental hazards, especially in the area of persistent organic pollutants (POPs) disposal. However, the mechanochemical dechlorination mechanism of POPs still needs to be further verified. In this mechanochemical process, hexachlorobenzene (HCB) was chosen as a model pollutant with aluminum and alumina (Al + Al2O3) powders as the co-milling regents. Both of the intermediate analysis and quantum chemical calculations were adopted to elucidate the free radical dechlorination mechanism of HCB. The solid residues were characterized by electron spin-resonance (ESR) spectroscopy, Fourier transform infrared (FTIR) spectra and X-ray photoelectron (XPS) spectra, which proposed that the radicals formed in the mechanochemical process were chlorinated phenoxyl radicals (CB-O[rad]). Four quantum chemical descriptors were selected in predicting the intermediates and reaction pathway: (i) atomic charge, (ii) electrostatic potential (ESP), (iii) frontier molecular orbitals (FMO) theory and (iv) dual descriptor. Then, a stepwise dechlorination mechanism based on CB-O[rad] was proposed. It was found that the intermediates and radical-related reactions in the mechanochemical dechlorination of HCB are quite different from that happen in a typical photocatalytic dechlorination process. Impacts of different radical reactions on the dechlorination of HCB were also compared at last. © 2017 Elsevier B.V.


Yu R.,Nanjing Southeast University | Yu R.,University of Connecticut | Smets B.F.,Technical University of Denmark | Gan P.,University of Connecticut | And 3 more authors.
Canadian Journal of Microbiology | Year: 2014

We investigated the seasonal and spatial variation in activity and density of the metabolically active in situ microbial community (AIMC) at a landfill leachate-impacted groundwater - surface water interface (GSI). A series of AIMC traps were designed and implemented for AIMC sampling and microbial activity and density examinations. Measurements were made not only at the level of bacterial domain but also at the levels of alphaproteobacterial Rhizobiales order and gammaproteobacterial Pseudomonas genus, both of which included a large number of iron-oxidizing bacteria as revealed from previous analysis. Consistently higher microbial activities with less variation in depth were measured in the AIMC traps than in the ambient sediments. Flood disturbance appeared to control AIMC activity distributions at the gradually elevated GSI. The highest AIMC activities were generally obtained from locations closest to the free surface water boundary except during the dry season when microbial activities were similar across the entire GSI. A clone library of AIMC 16S rRNA genes was constructed, and it confirmed the predominant role of the targeted alphaproteobacterial group in AIMC activity and composition. This taxon constituted 2%-14% of all bacteria with similar activity distribution profiles. The Pseudomonas group occupied only 0.1‰-0.5‰ of the total bacterial density, but its activity was 27 times higher than the bacterial average. Of the 16S rRNA sequences in the AIMC clone library, 7.5% were phylogenetically related to putative IOB, supporting the occurrence and persistence of active microbial iron oxidation across the studied iron-rich GSI ecosystem.


Du P.,Chinese Research Academy of Environmental Sciences | Wang S.-J.,Beijing Municipal Research Institute of Environmental Protection | Zhao H.-H.,Chinese Research Academy of Environmental Sciences | Wu B.,Chinese Research Academy of Environmental Sciences | And 5 more authors.
Huanjing Kexue/Environmental Science | Year: 2013

The influencing factors of benzene diffusion fluxes from sand and black soil to atmosphere were investigated using a flux chamber (30.0 cm×17.5 cm×29.0 cm). In this study, the benzene diffusion fluxes were estimated by measuring the benzene concentrations both in the headspace of the chamber and in the soils of different layers. The results indicated that the soil water content played an important role in benzene diffusion fluxes. The diffusion flux showed positive correlation with the initial benzene concentration and the benzene dissolution concentration for both soil types. The changes of air flow rate from 300 to 900 mL·min-1 and temperature from 20°C to 40°C resulted in increases of the benzene diffusion flux. Our study of benzene diffusion fluxes from contaminated soils will be beneficial for the predicting model, and emergency management and precautions.


Zhang X.,Nanjing Agricultural University | Zhang X.,BCEG Environmental Remediation Co. | Liang X.,Nanjing Agricultural University | Zhan X.,Nanjing Agricultural University | And 2 more authors.
Chinese Journal of Environmental Engineering | Year: 2013

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous, environmental organic pollutants. They have been of particular concern because some of them are highly carcinogenic and mutagenic for human and animals. The aim of this paper was to investigate the intercropping remediation of ryegrass and clover in phenanthrene-contaminated soil through pot experiments. Results indicated that ryegrass and clover grew well in the phenanthrene range of 0~50 mg/kg. Intercropping between ryegrass and clover enhanced phenanthrene uptake by ryegrass and clover roots, and root concentration factor in intercropping system was much higher than that in single-cropping system. Phenanthrene in soil decreased significantly over the incubation period because of biodecomposition and plant absorption. The effectiveness of intercropping remediation was better than that of single cropping remediation in heavily contaminated soil with a highest removal rate of 90.53%. Therefore, it is suggested that ryegrass and clover intercropping is a feasible technique for phytoremediating heavily PAH-contaminated soils.


Fang Z.-Q.,China University of Mining and Technology | Gan P.,BCEG Environmental Remediation Co. | Yang L.,China University of Mining and Technology | Dai Z.-Y.,China University of Mining and Technology | And 3 more authors.
Huanjing Kexue/Environmental Science | Year: 2013

The dissipative concentration test of VOCs in the remediation process of a typical contaminated site was operated, and three routes of exposure were set up for health risk assessment in the repair process. Analysis showed that carbon tetrachloride was the single pollutant with highest multi-route cumulative non-carcinogenic index, which was as high as 8.86E+01, and its contribution rate to the integrated non-carcinogenic effects was 74.45%. Respiratory exposure was the exposure route with highest multi-pollutant hazard index, which was 1.01E+02, accounting for 84.87% of the comprehensive risk index, and the index of integrated non-carcinogenic damage was 1.19E+02. 1, 2-dichloroethane was the single pollutant with highest multi-route cumulative carcinogenic index, which was as high as 3.08E-02, and its contribution rate to the integrated carcinogenic effects was 69.53%. Respiratory exposure was the exposure route with highest multi-pollutant hazard index, which was 3.96E-02, accounting for 89.39% of the comprehensive risk index, and the index of integrated carcinogenic damage was 4.43E-02.


Gan P.,BCEG Environmental Remediation Co. | Yang Y.-W.,BCEG Environmental Remediation Co. | Fang Z.-Q.,BCEG Environmental Remediation Co. | Guo S.-Q.,BCEG Environmental Remediation Co. | And 2 more authors.
Huanjing Kexue/Environmental Science | Year: 2013

Volatile and semi-volatile organic compounds (VOCs/SVOCs) are commonly identified contaminants in industrial contaminated sites in China. VOCs migrate easily in the environment due to their relatively high volatilities. When disturbed during excavation, for example, VOCs in the soil release to the air in high concentrations within relatively short period of time, joepodizing the health of the sorrounding population, if not appropriately protected. In this study, distribution of gas phase VOCs was monitored during excavation of a site remediation project, using a combined method of field testing instrument and gas phase sampling tubes. Monitoring results indicated that gas phase concentration decreased with distance, exhibiting an alternating peak-and-valley pattern in the down-wind direction. The monitoring results could be stimulated using Gaussian Puff Model. Remediation site health and safety zoning method was developed combining appropriate workplace health and safety air limits and site monitoring results. Personal protection measures deemed appropriated for each safety zone were proposed.


Huang Y.,Shandong Academy of Sciences | Xu M.,Shandong Academy of Sciences | Li S.,BCEG Environmental Remediation Co. | Guo L.,BCEG Environmental Remediation Co. | And 5 more authors.
Chinese Journal of Environmental Engineering | Year: 2015

Pilot scale treatability studies were conducted to evaluate the remediation of hexavalent chromium [Cr(VI)] in soil at a former dump site of chromite ore processing residue (COPR). Our results showed that approximately 93.9% of Cr(VI) was reduced by molasses after a curing period of 45 days, whereas the average reduction percentage of Cr(VI) to Cr(III) was more than 99% in soil treated with DARAMEND-M, ferrous sulfate(FeSO4)and calcium polysulfide(CPS), respectively. The amount of easily soluble chromium (the water soluble + exchangeable fractions) decreased from 21.77% in the untreated subsoil to 6.26% and 2.95% in the soils subjected to molasses and DARAMEND-M, respectively, while the amount of easily soluble chromium (the water soluble + exchangeable fractions) decreased from 22.12% in the untreated surface soil to 4.58% and 2.94% in the soils subjected to FeSO4 and CPS, respectively. The sequential extraction suggested that chromium was effectively stabilized. The pH of the treated soil increased with CPS addition, whereas treatment with molasses, DARAMEND-M and FeSO4, respectively resulted in decrease in soil pH. Then, the addition of molasses or DARAMEND-M increased the microbial biomass C. It is concluded that, DARAMEND-M has more favorable properties for Cr(VI) treatment in soils with low Cr(VI) content compared to molasses; FeSO4 and CPS are extremely effective in reduction and stabilization of Cr(VI) in soils with high Cr(VI) content. ©, 2015, Science Press. All right reserved.


Ren Y.,CAS Research Center for Eco Environmental Sciences | Kang S.,BCEG Environmental Remediation Co. | Zhu J.,CAS Research Center for Eco Environmental Sciences
Journal of Material Cycles and Waste Management | Year: 2015

In the present work, we investigate the destruction efficiency of hexachlorobenzene (HCB) by milling with various reagents in a planetary ball mill under different milling conditions. Under the same conditions of mill rotary rate and charge ratio, the mixture of magnesium powder and aluminum oxide (Mg/Al2O3) was found best in promoting the destruction of HCB, which can be completed destroyed after 90 min grinding at a charge ratio of 20:1 (reagent/HCB, m/m), a ball mass/reagent mass ration of 30:1 and a mill rotation speed of 550 rpm. The ground samples were characterized and analyzed by X-ray fluorescence, gas chromatography (GC), X-ray diffraction and ion chromatography. The intermediate products, such as pentachlorobenzene, tetrachlorobenzene, trichlorobenzene isomers, dichlorobenzene and monochlorobenzene were detected by GC. Then the main dechlorination path way for HCB was proposed. With a series of verification experiments, the final degradation products of HCB were amorphous carbon and inorganic chlorine. Based on this study, Mg/Al2O3 has the potential to complete the innocuous treatment of chlorinated compounds. © 2015 Springer Japan

Loading BCEG Environmental Remediation Co. collaborators
Loading BCEG Environmental Remediation Co. collaborators