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Study on sandstorm PM10 exposure assessment in the large-scale region: a case study in Inner Mongolia Full text
2018
Wang, Hongmei | Lv, Shihai | Diao, Zhaoyan | Wang, Baolu | Zhang, Han | Yu, Caihong
The current exposure-effect curves describing sandstorm PM₁₀ exposure and the health effects are drawn roughly by the outdoor concentration (OC), which ignored the exposure levels of people’s practical activity sites. The main objective of this work is to develop a novel approach to quantify human PM₁₀ exposure by their socio-categorized micro-environment activities-time weighed (SCMEATW) in strong sandstorm period, which can be used to assess the exposure profiles in the large-scale region. Types of people’s SCMEATW were obtained by questionnaire investigation. Different types of representatives were trackly recorded during the big sandstorm. The average exposure levels were estimated by SCMEATW. Furthermore, the geographic information system (GIS) technique was taken not only to simulate the outdoor concentration spatially but also to create human exposure outlines in a visualized map simultaneously, which could help to understand the risk to different types of people. Additionally, exposure-response curves describing the acute outpatient rate odds by sandstorm were formed by SCMEATW, and the differences between SCMEATW and OC were compared. Results indicated that acute outpatient rate odds had relationships with PM₁₀ exposure from SCMEATW, with a level less than that of OC. Some types of people, such as herdsmen and those people walking outdoors during a strong sandstorm, have more risk than office men. Our findings provide more understanding of human practical activities on their exposure levels; they especially provide a tool to understand sandstorm PM₁₀ exposure in large scale spatially, which might help to perform the different categories population’s risk assessment regionally.
Show more [+] Less [-]Status of electronic waste recycling techniques: a review Full text
2018
Abdelbasir, Sabah M. | Hassan, S. S. M. | Kamel, Ayman H. | El-Nasr, Rania Seif
The increasing use of electrical and electronic equipment leads to a huge generation of electronic waste (e-waste). It is the fastest growing waste stream in the world. Almost all electrical and electronic equipment contain printed circuit boards as an essential part. Improper handling of these electronic wastes could bring serious risk to human health and the environment. On the other hand, proper handling of this waste requires a sound management strategy for awareness, collection, recycling, and reuse. Nowadays, the effective recycling of this type of waste has been considered as a main challenge for any society. Printed circuit boards (PCBs), which are the base of many electronic industries, are rich in valuable heavy metals and toxic halogenated organic substances. In this review, the composition of different PCBs and their harmful effects are discussed. Various techniques in common use for recycling the most important metals from the metallic fractions of e-waste are illustrated. The recovery of metals from e-waste material after physical separation through pyrometallurgical, hydrometallurgical, or biohydrometallurgical routes is also discussed, along with alternative uses of non-metallic fraction. The data are explained and compared with the current e-waste management efforts done in Egypt. Future perspectives and challenges facing Egypt for proper e-waste recycling are also discussed.
Show more [+] Less [-]Hydrothermal synthesized magnetically separable mesostructured H2Ti3O7/γ-Fe2O3 nanocomposite for organic dye removal via adsorption and its regeneration/reuse through synergistic non-radiation driven H2O2 activation Full text
2018
Narayani, Harsha | Jōs, Manu | Sriram, K. | Shukla, Satyajit
Hydrogen titanate (H₂Ti₃O₇) nanotubes/nanosheets (HTN) are emerging class of adsorbent material which possess unique property of activating hydrogen peroxide (H₂O₂) to generate the reactive oxygen species (ROS), such as superoxide radical ions (O₂.⁻) and hydroxyl radicals (·OH), effective in the decomposition of surface-adsorbed dye. However, HTN are non-magnetic which create hurdle in their effective separation from the treated aqueous solution. To overcome this issue, magnetic nanocomposites (HTNF) composed of HTN and maghemite (γ-Fe₂O₃) nanoparticles have been processed by subjecting the core–shell magnetic photocatalyst consisting of γ-Fe₂O₃/silica (SiO₂)/titania (TiO₂), having varying amounts of TiO₂ in the shell to the hydrothermal conditions. HTNF-5 magnetic nanocomposite consisting of 31 wt% H₂Ti₃O₇, typically having nanotube morphology with the highest specific surface area (133 m² g⁻¹) and pore-volume (0.22 cm³ g⁻¹), exhibits the highest capacity (74 mg g⁻¹) for the adsorption of cationic methylene blue (MB) dye from an aqueous solution involving the electrostatic attraction mechanism and pseudo-second-order kinetics. Very fast magnetic separation followed by regeneration of HTNF-5 magnetic nanocomposite has been demonstrated via non-radiation driven H₂O₂ activation. It has been ascertained for the first time that the underlying mechanism of dye decomposition involves the synergy effect between the constituents of HTNF magnetic nanocomposite.
Show more [+] Less [-]Whole genome analysis of six organophosphate-degrading rhizobacteria reveals putative agrochemical degradation enzymes with broad substrate specificity Full text
2018
Iyer, Rupa | Iken, Brian | Damania, Ashish | Krieger, Jerry
Six organophosphate-degrading bacterial strains collected from farm and ranch soil rhizospheres across the Houston-metropolitan area were identified as strains of Pseudomonas putida (CBF10-2), Pseudomonas stutzeri (ODKF13), Ochrobactrum anthropi (FRAF13), Stenotrophomonas maltophilia (CBF10-1), Achromobacter xylosoxidans (ADAF13), and Rhizobium radiobacter (GHKF11). Whole genome sequencing data was assessed for relevant genes, proteins, and pathways involved in the breakdown of agrochemicals. For comparative purposes, this analysis was expanded to also include data from deposited strains in the National Center for Biotechnology Information’s (NCBI) database. This study revealed Zn-dependent metallo-β-lactamase (MBL)-fold proteins similar to OPHC2 first identified in P. pseudoalcaligenes as the likely agents of organophosphate (OP) hydrolysis in A. xylosoxidans ADAF13, S. maltophilia CBF10-1, O. anthropi FRAF13, and R. radiobacter GHKF11. A search of similar proteins within NCBI identified over 200 hits for bacterial genera and species with a similar OPHC2 domain. Taken together, we conclude from this data that intrinsic low-level OP hydrolytic activity is likely prevalent across the rhizosphere stemming from widespread OPHC2-like metalloenzymes. In addition, P. stutzeri ODKF13, P. putida CBF10-2, O. anthropi FRAF13, and R. radiobacter GHKF11 were found to harbor glycine oxidase (GO) enzymes that putatively possess low-level activity against the herbicide glyphosate. These bacterial GOs are reported to catalyze the degradation of glyphosate to α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and suggest a possible link to AMPA that can be found in glyphosate-contaminated agricultural soil. The presence of aromatic degradation proteins were also detected in five of six study strains, but are attributed primarily to components of the widely distributed β-ketoadipate pathway found in many soil bacteria.
Show more [+] Less [-]The microbial community structure change of an anaerobic ammonia oxidation reactor in response to decreasing temperatures Full text
2018
Wang, Weigang | Yan, Yuan | Song, Chengkang | Pan, Mianli | Wang, Yayi
In anaerobic ammonium oxidation (anammox) systems, temperature may regulate the activity of functional bacteria (e.g., anammox bacteria) and the composition of the microbial population, ultimately determining the performance of the anammox reactor. Knowledge of the dynamic changes in nitrogen removal rates and the microbial anammox community at low and/or ambient temperature is still limited. This study explored the response of an anammox sequencing batch reactor (SBR) to a gradient of decreasing temperature (33, 25, 20, 15, 10 °C), followed by recovery to 22 °C, over 360 days. Particularly, the specific anammox activity (SAA) and microbial community were assessed. The anammox reaction in the SBR remained stable and efficient at 20–33 °C, with a total nitrogen removal load of 0.4 g-N L⁻¹ day⁻¹ and an SAA of > 0.32 g-N g-VSS⁻¹ day⁻¹; 10 °C was the turning point for the anammox bacterial metabolic activity, at which the SAA decreased by 91% compared with that at 33 °C. After the temperature was returned to 22 °C, the anammox activity recovered to 0.24 g-N g-VSS⁻¹ day⁻¹. The apparent activation energy for the anammox reaction was 68.4 kJ mol⁻¹ at 10–33 °C and 152.9 kJ mol⁻¹ at 10–20 °C. High-throughput sequencing results revealed that Kuenenia was the dominant species of anammox bacteria, and Kuenenia had a higher tolerance to low temperature than Candidatus Brocadia and Candidatus Jettenia. This study clearly shows the effectiveness of anammox bioreactors for treatment of wastewater at ambient temperatures of 15–33 °C.
Show more [+] Less [-]Geochemical characteristics of n-alkanes and isoprenoids in coal seams from Zhuji coal mine, Huainan coalfield, China, and their relationship with coal-forming environment Full text
2018
Wang, Shanshan | Liu, Guijian | Liu, Jingjing
Ten coal seams in Upper Shihezi Formation, Lower Shihezi Formation, and Shanxi Formation from the Zhuji mine, Huainan coalfield, China, were analyzed for n-alkanes and isoprenoids (pristine and phytane) using gas chromatography-mass spectrometry (GC-MS), with an aim of reconstructing the coal-forming plants and depositional environments along with organic carbon isotope analyses. The total n-alkane concentrations ranged from 34.1 to 481 mg/kg. Values of organic carbon isotope (δ¹³Cₒᵣg) ranged from − 24.6 to − 23.7‰. The calorific value (Qb,d), maximum vitrinite reflectance (Roₘₐₓ), proximate, and ultimate analysis were also determined but showed no correlation with n-alkane concentrations. Carbon Preference Index (CPI) values ranged from 0.945 to 1.30, suggesting no obvious odd/even predominance of n-alkane. The predominance of C₁₁ and C₁₇ n-alkanes implied that the coal may be deposited in the fresh and mildly brackish environment. According to the contrary changing trend of pristine/phytane (Pr/Ph) ratio and boron concentrations, Pr/Ph can be used as an indicator to reconstruct the marine transgression-regression in sedimentary environment of coal formation. The influence of marine transgression may lead to the enrichment of pyrite sulfur in the coal seam 4-2. C3 plants (− 32 to − 21‰) and marine algae (− 23 to − 16‰) were probably the main coal-forming plants in the studied coal seams. No correlation of the n-alkane concentration and redox condition of the depositional environment with organic carbon isotope composition were found.
Show more [+] Less [-]Effect of intermittent operation model on the function of soil infiltration system Full text
2018
Hou, Lizhu | Hu, BillX. | He, Mengmeng | Xu, Xue | Zhang, Wenjing
To enhance denitrification in a process of solute infiltration through a soil, a two-section mixed-medium soil infiltration system (TMSIS) for urban non-point pollution was developed. The artificial aerobic respiration and nitrification took place in the upper aerobic section (AES), while grass powders and sawdust were mixed in the bottom anaerobic section (ANS) to supply organic carbon source for denitrification bacteria, and the reduction was increased by iron addition in the ANS. Measured resident concentrations from the bottom of each ANS column were assumed to represent mean values averaged over the column cross-sectional area. The TMSIS with hydraulic loading rates (HLR) of 0.32, 0.24, and 0.16 m³ m⁻² day⁻¹ and with wetting–drying ratio (RWD) of 1.0 showed remarkable removal efficiencies for chemical oxygen demand (COD), NH₄⁺-N, and TP, respectively. The hydraulic loading rate of 0.32 m³ m⁻² day⁻¹ was selected as the optimal HLR due to the high contaminated runoff treatment efficiency. When RWD was 1.0, 0.5, or 0.2 with hydraulic loading rate of 0.32 m³ m⁻² day⁻¹, the TMSIS could treat synthetic urban runoff contaminants very well. The corresponding effluent water met the China’s national quality standard for class V surface water. The wetting–drying ratio of 0.5 with hydraulic loading of 0.32 m³ m⁻² day⁻¹ was selected as the optimal operation conditions for the TMSIS. Aerobic respiration and nitrification mainly took place in the upper AES, in which most of the COD and the NH₄⁺-N were removed. Mixed sawdust and grass powders used as a carbon source and heterotrophic denitrification were put at the bottom of the ANS. The developed TMSIS has the potential to be applied for urban non-point pollution removal.
Show more [+] Less [-]The basic roles of indoor plants in human health and comfort Full text
2018
Deng, Linjing | Deng, Qihong
Humans have a close relationship with nature, and so integrating the nature world into indoor space could effectively increase people’s engagement with nature, and this in turn may benefit their health and comfort. Since people spend 80–90% of their time indoors, the indoor environment is very important for their health. Indoor plants are part of natural indoor environment, but their effect on the indoor environment and on humans has not been quantified. This review provides a comprehensive summary of the role and importance of indoor plants in human health and comfort according to the following four criteria: photosynthesis; transpiration; psychological effects; and purification. Photosynthesis and transpiration are important mechanisms for plants, and the basic functions maintaining the carbon and oxygen cycles in nature. Above all have potential inspiration to human’s activities that people often ignored, for example, the application of solar panel, artificial photosynthesis, and green roof/facades were motivated by those functions. Indoor plants have also been shown to have indirect unconscious psychological effect on task performance, health, and levels of stress. Indoor plants can act as indoor air purifiers, they are an effective way to reduce pollutants indoor to reduce human exposure, and have been widely studied in this regard. Indoor plants have potential applications in other fields, including sensing, solar energy, acoustic, and people’s health and comfort. Making full use of various effects in plants benefit human health and comfort.
Show more [+] Less [-]Investigating the sorption behavior of cadmium from aqueous solution by potassium permanganate-modified biochar: quantify mechanism and evaluate the modification method Full text
2018
Fan, Zixi | Zhang, Qian | Li, Meng | Niu, Dongyuan | Sang, Wenjiao | Verpoort, Francis
In this work, a KMnO₄-modified-biochar-based composite material with manganese oxide produced at 600 °C was fabricated to investigate the sorption mechanism of Cd(II) and to comprehensively evaluate the effect of the modification on biochar properties. Cd(II) adsorption mechanisms were mainly controlled by interaction with minerals, complexation with oxygen-containing functional groups, and cation-π interaction. The sorption capacity was significantly reduced after a deash treatment of biochar, almost shrunk by 3 and 3.5 times for pristine biochar (PBC) and modified biochar (MBC). For deashed PBC, oxygen-containing functional groups were the main contributor toward Cd(II) adsorption while interaction with minerals was significantly compromised and became negligible. The sorption capacity was also apparently decreased after the deash treatment of MBC; however, for deashed MBC, interaction with minerals still was the main contributor to the sorption ability, which could be attributed to the mechanism of interaction of Cd(II) with loaded MnOₓ on biochar. Cation-π interaction in MBC was notably enhanced compared to PBC due to the oxidation of KMnO₄ on biomass. Also, sorption performance by oxygen-containing functional groups was also enhanced. Hence, the modification by KMnO₄ has a significant effect on the Cd(II) sorption performance of biochar.
Show more [+] Less [-]Antimonate uptake by calcined and uncalcined layered double hydroxides: effect of cationic composition and M2+/M3+ molar ratio Full text
2018
Dore, Elisabetta | Frau, Franco
This study gives a contribution to assess the efficacy of some LDHs (layered double hydroxides) in Sb(V) uptake and understand the mechanisms involved in the removal process. Uncalcined nitrate Mg/Al LDHs and the mixed Mg-Al oxides derived from calcined carbonate Mg/Al LDHs mainly remove Sb(OH)₆⁻ from aqueous solution through the formation of a brandholzite-like phase (a non-LDH compound with general formula Mg[Sb(OH)₆]₂·6H₂O), although with a different efficiency (< 50 and 90–100% of Sb(V) removed, respectively). The formation of a brandholzite-like compound highlights the fundamental role of Mg in the removal process. The Sb(OH)₆⁻ removal capacity of uncalcined nitrate Mg/Al LDHs increases from 22 to 46% as the Mg/Al molar ratio decreases from 4 to 2 thanks to the increasing excess of positive charge of brucite-like sheets and the expanding interlayer thickness due to the different spatial orientations of nitrate groups (flat for Mg/Al = 4, perpendicular for Mg/Al = 2). The presence of Fe³⁺ in the trivalent cationic site of carbonate LDHs (Mg/(Al + Fe) = 3/(0.5 + 0.5)) improves the Sb(OH)₆⁻ removal capacity of their calcined products. When Mg is replaced by Zn in the divalent cationic site of carbonate LDHs and the sorption experiments are performed using the mixed Zn-Al oxides derived from calcination, Sb(OH)₆⁻ is mainly removed from the solution through the reconstruction of an antimonate LDH structure (i.e., a zincalstibite-like compound with general formula Zn₂Al(OH)₆[Sb(OH)₆]). The removal efficiency of calcined carbonate Zn/Al LDHs is high and comparable to that of calcined carbonate Mg/Al LDHs; however, the mechanisms involved in the removal process are substantially different: entrance of Sb(OH)₆⁻ in the interlayer in the first case, adsorption of Sb(OH)₆⁻ onto the surface and formation of a new phase (a brandholzite-like compound) in the second case. In both cases, the removal processes are described with the pseudo-second-order kinetic model; the theoretical maximum adsorption capacity determined with the Langmuir isotherm results to be 4.54 and 4.37 mmol g⁻¹ for calcined carbonate Mg/AlFe and Zn/Al LDHs, respectively.
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