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Occurrence and point-of-use treatment of contaminants of emerging concern in groundwater of the Nzoia River basin, Kenya
2022
K'oreje, Kenneth | Okoth, Maurice | Langenhove, Herman Van | Demeestere, Kristof
Groundwater constitutes a major source of fresh water globally. However, it faces serious quality challenges from both conventional pollutants and contaminants of emerging concern (CECs) such as pharmaceutically active compounds (PhACs), personal care products (PCPs) and pesticides. There exists a significant knowledge gap regarding the occurrence of CECs in groundwater, especially in Africa. This study presents unique data on the concentration of fourteen PhACs, five PCPs and nine pesticides in groundwater wells in Nzoia River basin, Kenya. Generally, PCPs were the most dominant class with concentrations up to 10 μg/L (methylparaben). Anti(retro)virals, being important in the treatment of HIV/AIDS, were more prevalent among the PhACs as compared to the developed world, with concentrations up to 700 ng/L (nevirapine). In contrast, pesticides were measured at lower concentrations, the maximum being 42 ng/L (metolachlor). A basic risk assessment shows that – among the detected CECs – carbamazepine may pose medium human health risk and requires further investigation among infants and children. Point-of-use (POU) technologies are being increasingly promoted especially in the developing nations to provide drinking water solutions at the household level, but very little data is available on their performance towards CECs removal. Therefore, besides measuring CECs in groundwater, we investigated ceramic filters and solar disinfection (SODIS) as possible POU treatment options. Both techniques show potential to treat CECs in groundwater, with removal efficiencies higher than 90% obtained for 41 and 22 compounds in ceramic filters and SODIS, respectively. Moreover, for the more recalcitrant compounds (e.g. sulfadoxin), the performance is improved by up to three orders of magnitude when using TiO₂ as a photocatalyst in SODIS.
Показать больше [+] Меньше [-]Field-based measurements of major air pollutant emissions from typical porcelain kiln in China
2021
Du, Wei | Wang, Jinze | Chen, Yuanchen | Zhuo, Shaojie | Wu, Shuiping | Liu, Weijian | Lin, Nan | Shen, Guofeng | Tao, Shu
China has been famous for its porcelains for millennia, and the combustion processes of porcelain production emit substantial amounts of air pollutants, which have not been well understood. This study provided firsthand data of air pollutant emissions from biomass porcelain kilns. The emission factor of PM₂.₅ was 0.95 ± 1.23 g/kg during the entire combustion cycle, lower than that of biomass burning in residential stoves and coal burning in brick kilns, attributed to the removal effects of the long-distance transport in dragon kilns. The temporal trend of particle pollutants, including particulate matters (PMs) and particulate polycyclic aromatic hydrocarbons (PAHs) (low at ignition phase and high at the end) again indicated the removal effects of the special structure, while gaseous pollutants, such as gaseous PAHs, exhibited the opposite result. The GWC₁₀₀ was estimated as 1.4 × 10⁶ and 0.5 × 10⁶ kg CO₂e/yr for the scenarios in which 50% and 100% of the wood was renewable, respectively. The GWC₁₀₀ of dragon kilns is nearly equal to that of 745 households using wood-fueled stoves. These results indicate the necessity of pollution controls for biomass porcelain kilns to estimate the emission inventory and climate change.
Показать больше [+] Меньше [-]Developing water and nitrogen budgets of a wheat-maize rotation system using auto-weighing lysimeters: Effects of blended application of controlled-release and un-coated urea
2020
Zheng, Wenkui | Wan, Yongshan | Li, Yuncong | Liu, Zhiguang | Chen, Jianqiu | Zhou, Hongyin | Gao, Yongxiang | Chen, Baocheng | Zhang, Min
Evaluation of the effectiveness of best management practices for reducing nitrate leaching in agricultural systems requires detailed water and nitrogen (N) budgets. A 3-year field experiment using 15 auto-weighing lysimeters was set up to quantify nitrate leaching, crop evapotranspiration (ET), and N and water use efficiencies within an intensive wheat-maize rotation system in the Northern China Plain. The lysimeter consists mainly of the following: (1) high-resolution weighing cells; (2) ceramic solution samplers for soil solutions collection; and (3) circular stainless steel leaching trays for collecting seepage water. Two N fertilizer types were applied at two rates (150 and 225 kg N hm⁻² for each crop) with no-N applied as the control. The N fertilizer types were monotypic un-coated urea and a blend product with controlled-release urea (CRU) and un-coated urea. The results indicate that when compared with un-coated urea at the same application rate, the blend product greatly improved water and N use efficiencies with significant increase in yields and crop ET as well as reduction of nitrate accumulation and leaching in the soil profile (p < 0.05). This was mostly because the blend product consistently supplied N to meet crop demands over the entire growth season. The study implied that effective best management practices to control nitrate leaching should be based on technically sound fertilization and irrigation schemes in terms of timing, rate, and fertilizer type to suit site specific conditions.
Показать больше [+] Меньше [-]Design and optimization of a new reactor based on biofilm-ceramic for industrial wastewater treatment
2019
Beni, Ali Aghababai | Esmaeili, Akbar
A biofilm reactor was designed with flat ceramic substrates to remove Co(II), Ni(II) and Zn(II) from industrial wastewater. The ceramics were made of clay and nano-rubber with high mechanical resistance. The surface of the ceramic substrate was modified with neutral fiber and nano-hydroxyapatite. A uniform and stable biofilm mass of 320 g with 2 mm of thickness was produced on the modified ceramic after 3 d. The micro-organisms were identified in the biofilm by polymerase chain reaction (PCR) method. Functional groups of biofilms were identified with a Fourier transform infrared spectrometer (FT-IR). Experiments were designed by central composite design (CCD) using the responsive surface method (RSM). The biosorption process was optimized at pH = 5.8, temperature = 22 °C, feed flux of heavy metal wastewater = 225 ml, substrate flow = 30 ml, and retention time = 7.825 h. The kinetic data was analyzed by pseudo first-order and pseudo second-order kinetic models. Isotherm models and thermodynamic parameters were applied to describe the biosorption equilibrium data of the metal ions on the biofilm-ceramic. The maximum biosorption efficiency and capacity of heavy metal ions were about 72% and 57.21 mg, respectively.
Показать больше [+] Меньше [-]Performance of ceramic disk filter coated with nano ZnO for removing Escherichia coli from water in small rural and remote communities of developing regions
2018
Huang, Jing | Huang, Guohe | An, Chunjiang | He, Yuan | Yao, Yao | Zhang, Peng | Shen, Jian
Global water safety is facing great challenges due to increased population and demand. There is an urgent need to develop suitable water treatment strategy for small rural and remote communities in low-income developing countries. In order to find a low-cost solution, the reduction of E. coli using ceramic water disk coated with nano ZnO was investigated in this study. The performance of modified ceramic disk filters was influenced by several factors in the filter production process. Based on the factorial analysis, the pore size of the disk filters was the most significant factor for influencing E. coli removal efficiency and the clay content was the most significant one for influencing flow rate of modified disk filters. The coating of nano ZnO led to the change of disk filter surface and porosity. The reduction of E. coli could be attributed to both filter retention and photocatalytic antibacterial activity of nano ZnO. The effects of filter operation factors including initial E. coli concentration, illumination time and lamp power on E. coli removal effectiveness were also revealed. The results can help find a safe and cost-effective approach to solve drinking water problems in small rural and remote communities of developing regions.
Показать больше [+] Меньше [-]One-century sedimentary record of heavy metal pollution in western Taihu Lake, China
2018
Li, Yan | Zhou, Shenglu | Zhu, Qing | Li, Baojie | Wang, Junxiao | Wang, Chunhui | Chen, Lian | Wu, Shaohua
Long-term trends of sediment compositions are important for assessing the impact of human activities on the sediment and protecting the sediment environment. In this study, based on the contents of heavy metals and the Pb isotope ratios in lake sediments, atmospheric dustfall and soil in Yixing, China, the representative heavy metals (Zn, Pb, Cr and Cd) in lake sediments from western Taihu Lake were studied. The evolution history of heavy metals in the local environment was constructed for the past 100 years. From 1892 to the 1990s, the anthropogenic fluxes of the representative heavy metals were negligible, indicating minimal anthropogenic emissions of heavy metals. Since the 1990s, anthropogenic fluxes of the representative heavy metals began to increase, concurrent with the economic growth and development in the western Taihu Lake Basin after the Chinese economic reform. The maximum flux percentage of the heavy metals in the sediments, caused by human activities, is 23.0% for Zn, 31.6% for Pb, 39.5% for Cr and 85.3% for Cd, indicating that most of the Cd comes from human activities. The Cd content in the western Taihu Lake Basin was significantly higher than that in the other areas, and the rapid development of the industry in the western Taihu Lake Basin and ceramics in Yixing led to the enrichment of heavy metals in local sediments. Since the 21st century, measures have been taken to control the pollution of heavy metals, including the increase in local government attention and the deployment of environmental monitoring technology. However, heavy metal content remains high, and the Pb content is still increasing. The ratios of Pb isotopes show that the main sources of heavy metals in the western Taihu Lake sediments, the local soil of Yixing and the atmospheric dustfall are coal combustion, leaded gasoline combustion, industrial wastewater and domestic sewage.
Показать больше [+] Меньше [-]Ovarian cancer mortality and industrial pollution
2015
García-Pérez, Javier | Lope, Virginia | López-Abente, Gonzalo | González Sánchez, Mario | Fernández-Navarro, Pablo
We investigated whether there might be excess ovarian cancer mortality among women residing near Spanish industries, according to different categories of industrial groups and toxic substances. An ecologic study was designed to examine ovarian cancer mortality at a municipal level (period 1997–2006). Population exposure to pollution was estimated by means of distance from town to facility. Using Poisson regression models, we assessed the relative risk of dying from ovarian cancer in zones around installations, and analyzed the effect of industrial groups and pollutant substances. Excess ovarian cancer mortality was detected in the vicinity of all sectors combined, and, principally, near refineries, fertilizers plants, glass production, paper production, food/beverage sector, waste treatment plants, pharmaceutical industry and ceramic. Insofar as substances were concerned, statistically significant associations were observed for installations releasing metals and polycyclic aromatic chemicals. These results support that residing near industries could be a risk factor for ovarian cancer mortality.
Показать больше [+] Меньше [-]A method using porous media to deliver gas-phase phthalates rapidly and at a constant concentration: Effects of temperature and media
2020
Chen, Zhuo | Afshari, Alireza | Mo, Jinhan
Phthalates are widely used as additives to consumer products. Many diseases have been shown to be related to the uptake of phthalates. To achieve equilibrium constant phthalate generation for mass transfer and exposure experiments, the present study developed a porous media based method using Teflon generators connected to the media with stainless steel connectors. Carbon sponges with the porosities of 20 ppi (pores per inch), 30 ppi, 40 ppi and honeycomb ceramics of 14 ppi were used as porous media fillers to evaluate the effect of temperature-controlled states, materials, and pore sizes on the generating performance of phthalates. The results showed that 30 ppi carbon sponge fillers at 25.0 ± 0.4 °C performed satisfactorily. DMP, DiBP and DEHP were used as examined phthalates and were generated at 12,800 ± 740 μg/m³, 330 ± 13 μg/m³ and 2.37 ± 0.15 μg/m³, respectively. The times to reach stable concentrations were 4.5 h, 18.5 h and 89.5 h, respectively. The reproducibility of DiBP and DEHP delivery deviated by less than 2.4%. Long-term generating experiments should be performed in the future. The porous media based method could stably deliver gaseous PAEs and tends to be widely used in the research of the adsorption of PAEs on surfaces (airborne particles, settled dust and indoor surfaces) and exposure experiments.
Показать больше [+] Меньше [-]Preparation of immobilized coating Fenton-like catalyst for high efficient degradation of phenol
2017
Wang, Jiankang | Yao, Zhongping | Wang, Yajing | Xia, Qixing | Chu, Huiya | Jiang, Zhaohua
In this study, solid acid amorphous Fe3O4/SiO2 ceramic coating decorated with sulfur on Q235 carbon steel as Fenton-like catalyst for phenol degradation was successfully prepared by plasma electrolytic oxidation (PEO) in silicate electrolyte containing Na2S2O8 as sulfur source. The surface morphology and phase composition were characterized by SEM, EDS, XRD and XPS analyses. NH3-TPD was used to evaluate surface acidity of PEO coating. The results indicated that sulfur decorated amorphous Fe3O4/SiO2 ceramic coatings with porous structure and higher acid strength had the similar pore size and the surface became more and more uneven with the increase of Na2S2O8 in the silicate electrolyte. The Fenton-like catalytic activity of sulfur decorated PEO coatings was also evaluated. In contrast to negligible catalytic activity of sulfur undecorated PEO coating, catalytic activity of sulfur decorated PEO coating was excellent and PEO coating prepared with 3.0 g Na2S2O8 had the highest catalytic activity which could degrade 99% of phenol within 8 min under circumneutral pH. The outstanding performance of sulfur decorated PEO coating was attributed to strong acidic microenvironment and more Fe²⁺ on the surface. The strong acid sites played a key factor in determining catalytic activity of catalyst. In conclusion, rapid phenol removal under circumneutral pH and easier separation endowed it potential application in wastewater treatment. In addition, this strategy of preparing immobilized solid acid coating could provide guidance for designing Fenton-like catalyst with excellent catalytic activity and easier separation.
Показать больше [+] Меньше [-]Breast and prostate cancer mortality and industrial pollution
2016
García-Pérez, Javier | Pérez-Abad, Natalia | Lope, Virginia | Castelló, Adela | Pollán, Marina | González Sánchez, Mario | Valencia, Jose Luis | López-Abente, Gonzalo | Fernández-Navarro, Pablo
We investigated whether there might be an excess of breast and prostate cancer mortality among the population residing near Spanish industries, according to different categories of industrial groups. An ecologic study was designed to examine breast and prostate cancer mortality at a municipal level (period 1997–2006). Population exposure to pollution was estimated by means of distance from town of residence to industrial facilities. Using Besag-York-Mollié regression models with Integrated Nested Laplace approximations for Bayesian inference, we assessed the relative risk of dying from these tumors in 2-, 3-, 4-, and 5-km zones around installations, and analyzed the effect of category of industrial group. For all sectors combined, no excess risk was detected. However, excess risk of breast cancer mortality (relative risk, 95% credible interval) was detected near mines (1.10, 1.00–1.21 at 4 km), ceramic industries (1.05, 1.00–1.09 at 5 km), and ship building (1.12, 1.00–1.26 at 5 km), and excess risk of prostate cancer was detected near aquaculture for all distances analyzed (from 2.42, 1.53–3.63 at 2 km to 1.63, 1.07–2.36 at 5 km). Our findings do not support that residing in the vicinity of pollutant industries as a whole (all industrial sectors combined) is a risk factor for breast and prostate cancer mortality. However, isolated statistical associations found in our study with respect to specific industrial groups warrant further investigation.
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