Refinar búsqueda
Resultados 1-10 de 124
Anaerobic treatment of wastewaters from alcohol and yeast factories
1999
Klasnja, M. | Sciban, M. (Univerzitet u Novom Sadu, Novi Sad (Yugoslavia). Tehnoloski fakultet)
Alcohol and yeast production is the most important part of the biotechnological production in Yugoslavia, with annual production of 13 667 867 liters of absolute alcohol and of 20 947 490 kg of yeast in the year 1998. Large environmental load is produced by wastewaters from alcohol and yeast factories (512 000 P.E.), especially by alcohol stillage (BOD 40 000 - 50 000 mg/L). Anaerobic treatment is suitable process for treatment of alcohol stillage, and of yeast factory wastewater. In this paper, effects of treatment process (organic load reduction, energy of produced biogas) are discussed; and potential of anaerobic treatment os wastewaters from Yugoslavia's alcohol and yeast factories is reviewed.
Mostrar más [+] Menos [-]Short-term ambient particulate air pollution exposure, microRNAs, blood pressure and lung function Texto completo
2022
Cong, Xiaowei | Zhang, Juan | Sun, Rongli | Pu, Yuepu
Ambient particulate air pollution is a risk factor for cardiovascular and respiratory disease, yet the biological mechanisms underlying this association are not well understood. The current study aimed to investigate the mediation role of microRNAs on the association between personal PM₂.₅ exposure and blood pressure and lung function. One hundred and twenty adults (60 truck drivers and 60 office workers) aged 18–46 years were assessed on the June 15, 2008 and at follow-up (1- to 2-weeks later). MicroRNAs were extracted from the peripheral blood samples. Compared to truck drivers, there is a significant increase in FEF₂₅₋₇₅, FEV₁, and FEV₁/FVC and a decrease in PM₂.₅ in office workers (all p < 0.05). According to the Bonferroni corrected threshold p-value < 6.81 × 10⁻⁵ (0.05/734) used, personal PM₂.₅ data showed a significant positive association with miR-644 after the adjustment for age, BMI, smoking status, and habitual alcohol use. The mediation effect of miR-644 on the association between personal PM₂.₅ exposure and FEF₂₅₋₇₅ [B (95%CI) = −1.342 (−2.810, −0.113)], PEF [B (95%CI) = -1.793 (−3.926, −0.195)], and FEV₁/FVC [B (95%CI) = −0.119‰ (−0.224‰, −0.026‰)] was significant only for truck drivers after the adjustment for covariates. There were no similar associations with blood pressure. These results demonstrate microRNAs to potentially mediate association of PM₂.₅ with lung function. Subsequent studies are needed to further elucidate the potential mechanisms of action by which the mediation effect of microRNAs is achieved with this process.
Mostrar más [+] Menos [-]Emerging and legacy per- and polyfluoroalkyl substances in water, sediment, and air of the Bohai Sea and its surrounding rivers Texto completo
2020
Zhao, Zhen | Cheng, Xianghui | Hua, Xia | Jiang, Bin | Tian, Chongguo | Tang, Jianhui | Li, Qilu | Sun, Hongwen | Lin, Tian | Liao, Yuhong | Zhang, Gan
Per- and polyfluoroalkyl substances (PFASs) contamination in the Bohai Sea and its surrounding rivers has attracted considerable attention in recent years. However, few studies have been conducted regarding the distribution of PFASs in multiple environmental media and their distributions between the suspended particles and dissolved phases. In this study, surface water, surface sediment, and air samples were collected at the Bohai Sea to investigate the concentration and distribution of 39 targeted PFASs. Moreover, river water samples from 35 river estuaries were collected to estimate PFAS discharge fluxes to the Bohai Sea. The results showed that total ionic compound (Σi-PFASs) concentrations ranged from 19.3 to 967 ng/L (mean 125 ± 152 ng/L) in the water and 0.70–4.13 ng/g dw (1.78 ± 0.76 ng/g) in surface sediment of the Bohai Sea, respectively. In the estuaries, Σi-PFAS concentrations were ranged from 10.5 to 13500 ng/L (882 ± 2410 ng/L). In the air, ΣPFAS (Σi-PFASs + Σn-PFASs) concentrations ranged from 199 to 678 pg/m³ (462 ± 166 pg/m³). Perfluorooctanoic acid (PFOA) was the predominant compound in the seawater, sediment, and river water; in the air, 8:2 fluorotelomer alcohol was predominant. Xiaoqing River discharged the largest Σi-PFAS flux to the Bohai Sea, which was estimated as 12,100 kg/y. Some alternatives, i.e., 6:2 fluorotelomer sulfonate acid (6:2 FTSA), hexafluoropropylene oxide dimer acid (HFPO-DA), and chlorinated 6:2 polyfluorinated ether sulfonic acid (Cl-6:2 PFESA), showed higher levels than or comparable concentrations to those of the C8 legacy PFASs in some sampling sites. The particle-derived distribution coefficient in seawater was higher than that in the river water. Using high resolution mass spectrometry, 29 nontarget emerging PFASs were found in 3 river water and 3 seawater samples. Further studies should be conducted to clarify the sources and ecotoxicological effects of these emerging PFASs in the Bohai Sea area.
Mostrar más [+] Menos [-]3D printer waste, a new source of nanoplastic pollutants Texto completo
2020
Rodríguez-Hernández, A.G. | Chiodoni, Angelica | Bocchini, Sergio | Vazquez-Duhalt, Rafael
Plastics pollution has been recognized as a serious environmental problem. Nevertheless, new plastic uses, and applications are still increasing. Among these new applications, three-dimensional resin printers have increased their use and popularity around the world showing a vertiginous annual-sales growth. However, this technology is also the origin of residues generation from the alcohol cleaning procedure at the end of each printing. This alcohol/resin mixture can originate unintentionally very small plastic particles that usually are not correctly disposed, and as consequence, could be easily released to the environment. In this work, the nanoparticle generation from 3D printer’s cleaning procedure and their physicochemical characterization is reported. Nano-sized plastic particles are easily formed when the resin residues are dissolved in alcohol and placed under UV radiation from sunlight. These nanoparticles can agglomerate in seawater showing an average hydrodynamic diameter around 1 μm, whereas the same nanoparticles remain dispersed in ultrapure water, showing a hydrodynamic diameter of ≈300 nm. The formed nanoparticles showed an isoelectric point close to pH 2, which can facilitate their interaction with other positively charged pollutants. Thus, these unexpected plastic nanoparticles can become an environmental issue and public health risk.
Mostrar más [+] Menos [-]Photochemical degradation kinetics and mechanism of short-chain chlorinated paraffins in aqueous solution: A case of 1-chlorodecane Texto completo
2019
Zhang, Wanlan | Gao, Yanpeng | Qin, Yaxin | Wang, Mei | Wu, Junji | Li, Guiying | An, Taicheng
Short chain chlorinated paraffins (SCCPs) have attracted worldwide attention in recent years, due to their high production volume, persistent, bioaccumulative and toxic properties. In this study, 1-chlorodecane (CD) was selected as a model of SCCPs to explore its photochemical degradation behavior under UV irradiation. The results found that CD could be completely photochemical degradation within 120 min, and the •OH was found to be the main reactive species from both quenching experiments and electron paramagnetic resonance (EPR) results. However, the contribution of triple excited state of CD (³CD*) was still nonnegligible from the results with the absorption peak at 480 nm obtained by laser flash photolysis. Based on the identified intermediates as well as the data from theoretical chemical calculation, the detailed photochemical degradation mechanism of CD was tentatively proposed that CD firstly was excited and photo-ionized under UV irradiation, and the released Cl• in water could result in generating •OH. Then •OH initiates CD degradation mainly through the H-abstraction pathway, leading to the generation of several dehydrogenation radicals, which further generated alcohols or long chain intermediates through radical-radical reactions. The results will provide a comprehensive understanding of the degradation mechanism and environmental fates of SCCPs in water under UV irradiation.
Mostrar más [+] Menos [-]A multi-year study of VOC emissions at a chemical waste disposal facility using mobile APCI-MS and LPCI-MS instruments Texto completo
2018
Healy, Robert M. | Chen, Qingfeng | Bennett, Julie | Karellas, Nicholas S.
Real-time analysis of volatile organic compounds (VOCs) in air is useful both for source identification and emissions compliance applications. In this work, two complementary triple quadrupole mass spectrometers, fitted with an atmospheric pressure chemical ionization (APCI) and a low pressure chemical ionization (LPCI) source, respectively, were deployed simultaneously to investigate emissions of VOCs associated with an Ontario-based chemical waste disposal facility. Mobile measurements performed upwind and downwind of the facility enabled selection of the best locations for stationary sampling. Seven separate field studies were undertaken between 2000 and 2016 to assess how emissions of VOCs have changed at the site as a function of time. Up to twenty-nine VOCs were successfully identified and quantified using MS/MS in each study. Simultaneous deployment of the two mass spectrometers enabled the detection of polar VOCs including alcohols, esters, amines and ketones as well as non-polar aromatic VOCs including benzene and naphthalene in real time. Concentrations of VOCs were found to decrease significantly in the vicinity of the facility over the sixteen year period, in particular since 2007. Concentration values for each year are compared with odour thresholds and provincial guidelines and implications of future expansion of on-site solid waste landfill volumes are also discussed.
Mostrar más [+] Menos [-]Comparative adsorption of Pb2+ and Cd2+ by cow manure and its vermicompost Texto completo
2017
Zhu, Weiqin | Du, Wenhui | Shen, Xuyang | Zhang, Hangjun | Ding, Ying
Organic waste has great potential for use as an amendment to immobilize heavy metals in the environment. Therefore, this study investigates various properties of cow manure (CM) and its derived vermicompost (CV), including the pH, cationic exchangeable capacity (CEC), elemental composition and surface structure, to determine the potential of these waste products to remove Pb2+ and Cd2+ from solution. The results demonstrate that CV has a much higher pH, CEC and more irregular pores than CM and is enriched with minerals and ash content but has a lower C, H, O and N content. Adsorption isotherms studies shows that the adsorption of Pb2+ and Cd2+ onto either CM or CV follows a Langmuir model and presents maximum Pb2+ and Cd2+ adsorption capacities of 102.77 mg g−1 and 38.11 mg g−1 onto CM and 170.65 and 43.01 mg g−1 onto CV, respectively. Kinetic studies show that the adsorption of Pb2+ onto CM and CV fits an Elovich model, whereas the adsorption of Cd2+ onto CM and CV fits a pseudo-second-order model. Desorption studies indicate that CV is more effective than CM in removing Pb2+ and Cd2+. FTIR analysis demonstrates that the adsorption of Pb2+ and Cd2+ onto CM mainly depends on existed aliphatic alcohol, aromatic acid as well as new produced carbonates, whereas that onto CV may be contributed by the existed aliphatic alcohol, aromatic acids as well as some carbonates and phosphates. Thus, vermicomposting disposal of cow manure with destination mineral addition may broaden the way of its recycle and environmental usage.
Mostrar más [+] Menos [-]High throughput screening of photocatalytic conversion of pharmaceutical contaminants in water Texto completo
2017
Romão, Joana | Barata, David | Ribeiro, Nelson | Habibovic, Pamela | Fernandes, Hugo | Mul, Guido
The susceptibility for photon-induced degradation of over 800 pharmaceutical compounds present in the LOPAC1280 library, was analyzed by UV/Vis spectroscopy in the absence or presence of TiO2 P25 in water. In general, few compounds were effectively degraded in the absence of the TiO2 photocatalyst (3% of all compounds tested), while in the presence of TiO2, the majority of compounds was converted, often to a large degree. Differences in degree of degradation are evaluated on the basis of molecular weight, as well as the chemical nature of the drug compounds (functional groups and pharmacological classes). In general, if the molecular weight increases, the degradation efficacy decreases. Relatively high degrees of conversion can be achieved for (relatively small) molecules with functional groups such as aldehydes, alcohols, ketones and nitriles. A low degree of conversion was observed for compounds composed of conjugated aromatic systems. Trends in degradation efficacy on the basis of pharmacological class, e.g. comparing hormones and opioids, are not obvious.
Mostrar más [+] Menos [-]Perfluoroalkyl acids and their precursors in indoor air sampled in children's bedrooms Texto completo
2017
Winkens, Kerstin | Koponen, Jani | Schuster, Jasmin | Shoeib, Mahiba | Vestergren, Robin | Berger, Urs | Karvonen, Anne M. | Pekkanen, Juha | Kiviranta, Hannu | Cousins, Ian T.
The contamination levels and patterns of perfluoroalkyl acids (PFAAs) and their precursors in indoor air of children's bedrooms in Finland, Northern Europe, were investigated. Our study is among the most comprehensive indoor air monitoring studies (n = 57) and to our knowledge the first one to analyse air in children's bedrooms for PFASs (17 PFAAs and 9 precursors, including two acrylates, 6:2 FTAC and 6:2 FTMAC). The most frequently detected compound was 8:2 fluorotelomer alcohol (8:2 FTOH) with the highest median concentration (3570 pg/m3). FTOH concentrations were generally similar to previous studies, indicating that in 2014/2015 the impact of the industrial transition had been minor on FTOH levels in indoor air. However, in contrast to earlier studies (with one exception), median concentrations of 6:2 FTOH were higher than 10:2 FTOH. The C8 PFAAs are still the most abundant acids, even though they have now been phased out by major manufacturers. The mean concentrations of FOSE/As, especially MeFOSE (89.9 pg/m3), were at least an order of magnitude lower compared to previous studies. Collectively the comparison of FTOHs, PFAAs and FOSE/FOSAs with previous studies indicates that indoor air levels of PFASs display a time lag to changes in production of several years. This is the first indoor air study investigating 6:2 FTMAC, which was frequently detected (58%) and displayed some of the highest maximum concentrations (13 000 pg/m3). There were several statistically significant correlations between particular house and room characteristics and PFAS concentrations, most interestingly higher EtFOSE air concentrations in rooms with plastic floors compared to wood or laminate.
Mostrar más [+] Menos [-]Neutral polyfluoroalkyl substances in the atmosphere over the northern South China Sea Texto completo
2016
Lai, Senchao | Song, Junwei | Song, Tianli | Huang, Zhijiong | Zhang, Yingyi | Zhao, Yan | Liu, Guicheng | Zheng, Junyu | Mi, Wenying | Tang, Jianhui | Zou, Shichun | Ebinghaus, Ralf | Xie, Zhiyong
Neutral Polyfluoroalkyl substances (PFASs) in the atmosphere were measured during a cruise campaign over the northern South China Sea (SCS) from September to October 2013. Four groups of PFASs, i.e., fluorotelomer alcohols (FTOHs), fluorotelomer acrylates (FTAs), fluorooctane sulfonamides (FOSAs) and fluorooctane sulfonamidoethanols (FASEs), were detected in gas samples. FTOHs was the predominant PFAS group, accounting for 95.2–99.3% of total PFASs (ΣPFASs), while the other PFASs accounted for a small fraction of ΣPFASs. The concentrations of ΣPFASs ranged from 18.0 to 109.9 pg m−3 with an average of 54.5 pg m−3. The concentrations are comparable to those reported in other marine atmosphere. Higher concentrations of ΣPFASs were observed in the continental-influenced samples than those in other samples, pointing to the substantial contribution of anthropogenic sources. Long-range transport is suggested to be a major pathway for introducing gaseous PFASs into the atmosphere over the northern SCS. In order to further understand the fate of gaseous PFASs during transport, the atmospheric decay of neutral PFASs under the influence of reaction with OH radicals and atmospheric physical processes were estimated. Concentrations of 8:2 FTOH, 6:2 FTOH and MeFBSE from selected source region to the atmosphere over the SCS after long-range transport were predicted and compared with the observed concentrations. It suggests that the reaction with OH radicals may play an important role in the atmospheric decay of PFAS during long-range transport, especially for shorted-lived species. Moreover, the influence of atmospheric physical processes on the decay of PFAS should be further considered.
Mostrar más [+] Menos [-]