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Treatment of biodigested coffee processing wastewater using Fenton’s oxidation and coagulation/flocculation
2020
Gomes de Barros, Valciney | Rodrigues, Carmen S.D. | Botello-Suárez, Wilmar Alirio | Duda, Rose Maria | Alves de Oliveira, Roberto | da Silva, Eliana S. | Faria, Joaquim L. | Boaventura, Rui A.R. | Madeira, Luis M.
Biodigested coffee processing wastewater (CPW) presents a high organic load and does not meet the limits imposed by legislation (namely in Brazil) for discharge into water bodies. Anaerobic digestion generally cannot provide a satisfactory organic matter reduction in CPW as a significant fraction of recalcitrant compounds still persists in the treated effluent. So, this study aims to find alternative ways to remove refractory organic compounds from this wastewater in order to improve the biodegradability and reduce the toxicity, which will allow its recirculation back into the anaerobic digester. Three treatment approaches (Fenton’s oxidation - Approach 1, Coagulation/flocculation (C/F) - Approach 2, and the combination of C/F with Fenton’s process - Approach 3) were selected to be applied to the biodigested CPW in order to achieve that objective.The application of the Fenton process under the optimal operating conditions (initial pH = 5.0; T = 55 °C, [Fe³⁺] = 1.8 g L⁻¹ and [H₂O₂] = 9.0 g L⁻¹) increased the biodegradability (the BOD₅:COD ratio raised from 0.34 ± 0.02 in biodigested CPW to 0.44 ± 0.01 after treatment) and eliminated the toxicity (0.0% of Vibrio fischeri inhibition) along with moderate removals of organic matter (51.3%, 55.7% and 39.7% for total organic carbon – TOC, chemical oxygen demand – COD and biochemical oxygen demand - BOD₅, respectively). The implementation of a coagulation/flocculation process upstream from Fenton’s oxidation, under the best operating conditions (pH 10–11 and [Fe³⁺] = 250 mg L⁻¹), also allowed to slightly increase the biodegradability (from 0.34 to 0.47) and reduce the toxicity, whereas providing a higher removal of organic matter (TOC = 76.2%, COD = 76.5 and BOD₅ = 66.3% for both processes together). Approach 1 and Approach 3 showed to be the best ones, implying similar operating costs (∼74 R$ m⁻³/∼17 € m⁻³) and constitute an attractive option for managing biodigested CPW.
Afficher plus [+] Moins [-]Co-effect of minerals and Cd(II) promoted the formation of bacterial biofilm and consequently enhanced the sorption of Cd(II)
2020
Xu, Shaozu | Xing, Yonghui | Liu, Song | Luo, Xuesong | Chen, Wenli | Huang, Qiaoyun
Heavy metal pollution is very common in soils. Soils are complex systems including minerals, bacteria, and various other substances. In Cd(II) contaminated soil, the combined effects of clay minerals and heavy metals on bacterial biofilm and Cd(II) adsorption are unappreciated. Our study showed that the combination of clay minerals (goethite, kaolinite, and montmorillonite) and heavy metals promoted Serratia marcescens S14 biofilm development significantly more than clay minerals or Cd(II) alone. The amount of biofilm after binary treatment with clay minerals and Cd(II) was 2.3–7.3 times than that in control. Mineral-induced cell death and the expression of the fimA, bsmA, and eps were key players in biofilm formation. Binary treatment with montmorillonite and Cd(II) significantly enhanced biofilm development and consequently increased the adsorption of Cd(II). Cd(II) removal is the result of co-adsorption of bacteria and minerals. Bacterial biofilm played an important role in Cd(II) adsorption. FTIR spectroscopy showed the components of biofilm were not affected by minerals and revealed the functional groups –OH, –NH, –CH₂, –SH, –COO participated in Cd(II) immobilization. Our findings are of fundamental significance for understanding how minerals and Cd(II) affect biofilms and thereby enhance Cd(II) adsorption and predicting the mobility and fate of heavy metals in heavy metal-contaminated soil.
Afficher plus [+] Moins [-]Polycyclic aromatic hydrocarbons exposure and their joint effects with age, smoking, and TCL1A variants on mosaic loss of chromosome Y among coke-oven workers
2020
Liu, Yuhang | Bai, Yansen | Wu, Xiulong | Li, Guyanan | Wei, Wei | Fu, Wenshan | Wang, Gege | Feng, Yue | Meng, Hua | Li, Hang | Li, Mengying | Guan, Xin | Zhang, Xiaomin | He, Meian | Wu, Tangchun | Kwok, Woon
Mosaic loss of chromosome Y (mLOY) is the most common structure somatic event that related to increased risks of various diseases and mortality. Environmental pollution and genetic susceptibility were important contributors to mLOY. We aimed to explore the associations of polycyclic aromatic hydrocarbons (PAHs) exposure, as well as their joint effects with age, smoking, and genetic variants on peripheral blood mLOY. A total of 1005 male coke-oven workers were included in this study and their internal PAHs exposure levels of 10 urinary PAH metabolites and plasma benzo[a]pyrene-r-7,t-8,t-9,c-10-tetrahydotetrol-albumin (BPDE-Alb) adducts were measured. mLOY was defined by the median log R ratio(mLRR) of 1480 probes in male-specific region of chromosome-Y from genotyping array. We found that the PAHs exposure levels were linearly associated with mLOY. A 10-fold increase in urinary 1-hydroxynaphthalene (1-OHNa), 1-hydroxyphenanthrene (1-OHPh), 2-OHPh, 1-hydroxypyrene (1-OHP), ΣOH-PAHs, and plasma BPDE-Alb adducts could generate 0.0111, 0.0085, 0.0069, 0.0103, 0.0134, and 0.0152 decrease in mLRR-Y, respectively. Additionally, mLOY accelerated with age, smoking pack-years, and TCL1A rs1122138-C allele, and we observed the most severe mLOY among subjects carrying more than 3 of the above risk factors. Our results revealed the linear dose-effect associations between PAHs exposure and mLOY. Elder male smokers carrying rs1122138CC genotype were the most susceptible subpopulations to mLOY, who should be given protections for PAHs exposure induced chromosome-Y aberration.
Afficher plus [+] Moins [-]Mechanistic study for stibnite oxidative dissolution and sequestration on pyrite
2020
Yan, Li | Chan, Tingshan | Jing, Chuanyong
Stibnite (Sb₂S₃) dissolution and transformation on mineral surfaces are the fundamental steps controlling the fate of antimony (Sb) in the environment. The molecular-level understanding of Sb₂S₃-mineral-water interfacial reactions is of great importance. Herein, Sb₂S₃ oxidative dissolution and sequestration on pyrite (FeS₂) were explored. The results show that FeS₂ accelerated the rate of Sb₂S₃ oxidative dissolution by a factor of 11.4-fold under sunlight due to heterogeneous electron transfer. The electron transfer from Sb₂S₃ to FeS₂ separated photogenerated hole (h⁺) and electron (e⁻) pairs, facilitating the generation of hydroxyl radicals (OH) on Sb₂S₃ and FeS₂, and superoxide radicals (O₂⁻) on FeS₂. Surface O₂⁻ was the dominant oxidant for Sb(III) oxidation with 91% contribution, as evidenced by radical trapping experiments. OH was preferentially adsorbed on Sb₂S₃, but was released with Sb₂S₃ dissolution, and subsequently contributable to Sb(III) oxidation in solution. The Sb(III) oxidation and sequestration on FeS₂ surface coupled Fe²⁺/Fe³⁺ cycling and inhibited FeS₂ dissolution, as evidenced by X-ray absorption near edge structure and X-ray photoelectron spectroscopy. The insights gained from this study further our understanding of Sb₂S₃ transformation and transport at the environmental mineral-water interfaces.
Afficher plus [+] Moins [-]The role of Hipk2-p53 pathways in arsenic-induced autistic behaviors: A translational study from rats to humans
2020
Zhou, Hao | Lin, Yan | Zhao, Weiqing | Teng, Yanbo | Cui, Yuxia | Wang, Tianqi | Li, Chunpei | Jiang, Yong-hui | Zhang, Junfeng (Jim) | Wang, Yi
Previous studies have associated the risk of autism spectrum disorder (ASD) with increased exposures to metals and metalloids such as arsenic. In this study, we used an animal-to-human translational strategy to identify key molecular changes that potentially mediated the effects of arsenic exposures on ASD development. In a previously established rat model, we have induced autistic behaviors in rat pups with gestational arsenic exposures (10 and 45 μg/L As₂O₃ in drinking water). Neuronal apoptosis and the associated epigenetic dysregulations in frontal cortex were assayed to screen potential mediating pathways, which were subsequently validated with qPCR, western blotting, and immunohistochemistry analyses. Furthermore, the identified pathway, along with serum levels of 26 elements including arsenic, were characterized in a case-control study with 21 ASD children and 21 age-matched healthy controls. In animals, we found that arsenic exposures caused difficulties of social interaction and increased stereotypic behaviors in a dose-dependent manner, accompanied by increased neuronal apoptosis and upregulation of Hipk2-p53 pathway in the frontal cortex. In humans, we found that serum levels of Hipk2 and p53 were 24.7 (95%CI: 8.5 to 43.4) % and 23.7 (95%CI: 10.5 to 38.5) % higher in ASD children than in healthy controls. ASD children had significantly higher serum levels of 15 elements, among which arsenic, silicon, strontium, and vanadium were positively associated with both Hipk2 and p53. Results from both the rat arsenic exposure and human case-control studies suggest a likely role of Hipk2-p53 pathway in ASD development induced by exposures to environmental pollutants such as arsenic.
Afficher plus [+] Moins [-]Characterization of plastic micro particles in the Atlantic Ocean seashore of Cape Town, South Africa and mass spectrometry analysis of pyrolyzate products
2020
Vilakati, Bongekile | Sivasankar, V. | Mamba, Bhekie B. | Omine, Kiyoshi | Msagati, Titus A.M.
The microplastic particles with 29 pyrolyzate compounds of marine water samples from the seashore locations in Cape Town, South Africa were analysed using Pyrolysis- GC-TOF-MS. The mass spectra data documented the presence of various chemical groups that include alkanes, alkenes, dienes, fatty acids and esters, biphenyl and benzene (along with derivatives). Out of 16 identified polymers in the study area, polythene (PE) was the dominant in six out of seven locations with 87.5% followed by polyethylene terephthalate (PET) and polyvinylchloride (PVC) in five (71.4%) and four (57.1%) out of seven locations respectively. The other constituent polymers of microplastics identified through pyrolyzates were polystyrene (PS), polyamide 12 (PA-12) polyacrylic acid (PAA) and ethyl vinyl acetate (EVA) copolymer. The microplastic samples contained six additives predominantly in the family of fatty acid esters and nine plasticizers from alcohols, carboxylic esters and acids. The base peaks of m/z 41, 43, 55, 57, 69, 73, 91, 102, 105, 127 and 154 were characterized respectively with the fragmented species of C₃H₅⁺, C₃H₇⁺, C₄H₇⁺, C₄H₉⁺, C₅H₉⁺, C₃H₅O₂⁺, C₇H₇⁺, C₃H₁₀O₂⁺(McLafferty ion), C₈H₉⁺, C₈H₁₅O⁺ and C₁₂H₁₀⁺. Accordingly to Globally Harmonized System (GHS) of hazard classification, about 27.4% of pyrolyzates are Irritants, 31.4% of pyrolyzates found to be Irritants along with other hazards such as Flammable, Compressed Gas, Environmental Hazard, Corrosive, Health Hazard, Acute Toxicity and Allergy. About 41.2% of the pyrolyzates are not classified under the Irritant category. Characterizations of the plastic microparticles from the seven seashore locations such as FTIR, SEM with EDX and TGA were also done and discussed to understand the functional groups, surface morphology with elemental composition and stability respectively of the polymeric microparticles.
Afficher plus [+] Moins [-]Pennisetum giganteum: An emerging salt accumulating/tolerant non-conventional crop for sustainable saline agriculture and simultaneous phytoremediation
2020
Hayat, Kashif | Zhou, Yuanfei | Menhas, Saiqa | Bundschuh, Jochen | Hayat, Sikandar | Ullah, Abid | Wang, Juncai | Chen, Xunfeng | Zhang, Dan | Zhou, Pei
Soil salinity is a global threat to the environmental sustainability, in particular to the developing countries due to their limited resources for soil reclamation. In a greenhouse pot experiment, Pennisetum giganteum, was investigated for its tolerance to salt stress and simultaneous phytoremediation capability. 4 weeks post-germination, NaCl (10, 50, 150, 250, 350, 450 and 550 mM) and tap water (control) was applied after every 2 consecutive days for two weeks in a completely randomized design and their effects were established in the growth and physico-chemical aspects of these plants. Our results indicated that P. giganteum withstood high salt stress (with 550 mM NaCl tolerance threshold level). Interestingly, the plants grown under saline conditions had higher biomass yield when compared to the control. Furthermore, the antioxidant activity and proline content of plants under saline conditions were significantly (p < 0.05) higher than those of control plants, indicating their adaptability to high salt stress. Biochemical analysis such as chlorophyll contents, total soluble sugar, total phenol and protein contents revealed considerable differences between plants grown under higher NaCl stress compared to the control conditions. Additionally, significantly different ionic flux along with high K⁺/Na⁺ ratio was observed in plants grown under a range of saline conditions. The results obtained are therefore of value to indicate P. giganteum an eco-friendly alternate source for the phytoremediation of saline soils and may be used as base for future research on this plant. Effective strategies need to be adopted with this plant to reclaim saline-degraded as well as marginal soils.
Afficher plus [+] Moins [-]Effect of different air pollution control devices on the gas/solid-phase distribution of PCDD/F in a full-scale municipal solid waste incinerator
2020
Lin, Xiaoqing | Ma, Yunfeng | Chen, Zhiliang | Li, Xiaodong | Lu, Shengyong | Yan, Jianhua
The emission of polychlorinated dibenzo-p-dioxins and -furans (PCDD/F) from full-scale municipal solid waste incinerators (MSWI) is harmful to human and environmental health. This study analyzes the effect of different units of an air pollution control devices (APCDs), i.e. the semi-dry scrubber, fabric filter (FF), selective catalytic reduction (SCR), and wet scrubber (WS), on the removal characteristics and gas- and solid-phase distributions of PCDD/F in MSWI flue gas. APCDs reduce PCDD/F concentrations from 24.9 ng Nm⁻³ to 0.979 ng Nm⁻³ (2.16 ng I-TEQ Nm⁻³ to 0.0607 ng I-TEQ Nm⁻³), with a total removal efficiency (RE) of 96.1% (97.2% I-TEQ). Specifically, APCDs remove more than 95% of both gas- and solid-phase PCDD/F. The FF coupled with active carbon injection (FF + ACI) substantially reduces both gas- and solid-phase PCDD/F concentrations with an RE of 97.2% (98.7% I-TEQ). Additionally, FF + ACI exhibits a better RE of PCDF (98.9%) than PCDD (94.6%) and leads to PCDD congeners dominating the gas-phase. Both desorption and destruction of PCDD/F occur in the SCR, which favors removal of gas-phase PCDD/F but increases solid-phase PCDD/F. Therefore, SCR only decreases PCDD/F with a low RE of 27.6% (16.9% I-TEQ). However, SCR reduces NOₓ with a high RE of 82.3%, which could inhibit the RE of PCDD/F because of their different reaction mechanisms. WS increases PCDD/F in both the gas and solid-phase by 1.95 times (2.57 times for I-TEQ) due to the memory effect, which typically increases the total mass concentration of PCDD/F and the proportions of lower-chlorinated gas-phase PCDD/F. Migration of gas- and solid-phase PCDD/F are also analyzed according to temperature. The results of this study can contribute to the optimized design of industrial APCDs for controlling PCDD/F emissions from MSWI.
Afficher plus [+] Moins [-]Relative contributions of a major international airport activities and other urban sources to the particle number concentrations (PNCs) at a nearby monitoring site
2020
Pirhadi, Milad | Mousavi, Amirhosein | Sowlat, Mohammad H. | Janssen, Nicole A.H. | Cassee, Flemming R. | Sioutas, Constantinos
In this study, the positive matrix factorization (PMF) source apportionment model was employed to quantify the contributions of airport activities to particle number concentrations (PNCs) at Amsterdam Schiphol. Time-resolved particle number size distributions in parallel with the concentrations of auxiliary variables, including gaseous pollutants (NOₓ and CO), black carbon, PM₂.₅ mass, and number of arrivals/departures were measured for 32 sampling days over a 6-month period near Schiphol airport to be used in the model. PMF results revealed that airport activities, cumulatively, accounted for around 79.3% of PNCs and our model segregated them into three major groups: (i) aircraft departures, (ii) aircraft arrivals, and (iii) ground service equipment (GSE) (with some contributions of local road traffic, mostly from airport parking lots). Aircraft departures and aircraft arrivals showed mode diameters <20 nm and contributed, respectively, to 46.1% and 26.7% of PNCs. The factor GSE/local road traffic, with a mode diameter of around 60–80 nm, accounted for 6.5% of the PNCs. Road traffic related mainly to the surrounding freeways was characterized with a mode diameter of 30–40 nm; this factor contributed to 18.0% of PNCs although its absolute PNCs was comparable with that of areas heavily impacted by traffic emissions. Lastly, urban background with a mode diameter at 150–225 nm, had a minimal contribution (2.7%) to PNCs while dominating the particle volume/mass concentrations with a contribution of 58.2%. These findings illustrate the dominant role of the airport activities in ambient PNCs in the surrounding areas. More importantly, the quantification of the contributions of different airport activities to PNCs is a useful tool to better control and limit the increased PNCs near the airports that could adversely impact the health of the adjacent urban communities.
Afficher plus [+] Moins [-]Details of plastic ingestion and fibre contamination in North Sea fishes
2020
Kuhn, Susanne | van Franeker, Jan A. | O’Donoghue, Anastasia M. | Swiers, Ailynn | Starkenburg, Marrit | van Werven, Bernike | Foekema, Edwin | Hermsen, Enya | Egelkraut-Holtus, Marion | Lindeboom, Han
This study combines published datasets with unpublished data on plastic ingestion in several North Sea fish species. The combined dataset of 4389 individuals from 15 species allows the analysis of spatial distribution and temporal variability of plastic uptake in fish. Airborne fibre contamination was observed to be the main contributor to fibres encountered in the samples. The number of fibres in samples was strongly related to the time needed to process a sample, not to the number of individual fishes in the sample. Accurate correction for secondary fibre contamination was not possible, but corrections required would be similar to fibre numbers observed in the samples. Consequently, all fibres were omitted from further analysis. The frequency of occurrence and the average number of plastics in fish is generally low (1.8% and 0.022 pieces per organism respectively), with only cod having a higher prevalence (12.3%). While latitude of catch locations influences plastic uptake in fish, no correlation with the distance to the coast was found. Slightly less plastics were ingested in winter, and a decrease in plastics ingested was observed between 2009 and 2018. These factors should be considered when fish species, catch location and time are discussed as indicators for plastic pollution in the European Marine Strategy Framework Directive. We recommend considering demersal cod and pelagic sprat as two species suitable for monitoring plastic ingestion in biota, both on the seafloor and in the water column.
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