A laboratory-scale experiment is conducted to remove nitrogen from nitrogen-rich wastewater using a down-flow hanging sponge (DHS) reactor. Effluent from an anaerobic–aerobic system for treating ...synthetic natural rubber wastewater, which still contains high levels of ammonia, was used as nitrogen-rich wastewater. Experimental period was divided into four phases based whether a carbon source was fed to the DHS reactor. The highest nitrogen removal efficiency (59.5 ± 5.4%) was achieved during phase 4, when a sodium acetate solution was fed into bottom section of the DHS reactor. In the DHS reactor, the nitrification occurred in the upper and middle sections. Then, after adding the sodium acetate solution, denitrification occurred. The final chemical oxygen demand, ammonia, and total inorganic nitrogen concentrations in the DHS reactor effluent were 37 ± 24 mg/L, 34 ± 5 mgN/L, and 42 ± 8 mgN/L, respectively. These concentrations were sufficient to meet the effluent standards of the Vietnamese natural rubber industry, which are the strictest in South-East Asia. The dominant bacteria in the sludge retained by the reactor's sponge media were the nitrifying bacteria Nitrosovibrio (0.2%) and Nitrospira (0.2–0.3%), the denitrifying bacteria Hylemonella (1.0–13.7%), Pseudoxanthomonas (1.2–2.1%), and Amaricoccus (2.4–3.5%), and the anammox bacterium Candidatus Brocadia (0.1–0.2%). Significant amounts of the nitrogen-fixing bacterium Xanthobacter (11.2–14.8%) and the rubber-degrading bacterium Gordonia (11.0–28.6%) were also found in the DHS reactor. These bacteria were thus considered to be the key microbes for nitrogen removal in a DHS reactor fed with a carbon source for denitrification.
•Nitrogen removal was conducted by the down-flow hanging sponge (DHS) reactor.•59.5% of total nitrogen was removed by the DHS without aeration.•Nitrification and denitrification were separately occurred in the DHS.•Nitrifying, denitrifying, nitrogen-fixing bacteria contributed to nitrogen removal.
We investigated the influence of two fillers-CB (carbon black) and silica-on the Hsub.2 permeation of EPDM polymers crosslinked with sulfur in the pressure ranges 1.2-90 MPa. Hsub.2 uptake in the ...CB-blended EPDM revealed dual sorption (Henry's law and Langmuir model) when exposed to pressure. This phenomenon indicates that Hsub.2 uptake is determined by the polymer chain and filler-surface absorption characteristics. Moreover, single sorption characteristics for neat and silica-blended EPDM specimens obey Henry's law, indicating that Hsub.2 uptake is dominated by polymer chain absorption. The pressure-dependent diffusivity for the CB-filled EPDM is explained by Knudsen and bulk diffusion, divided at the critical pressure region. The neat and silica-blended EPDM specimens revealed that bulk diffusion behaviors decrease with decreasing pressure. The Hsub.2 diffusivities in CB-filled EPDM composites decrease because the impermeable filler increases the tortuosity in the polymer and causes filler-polymer interactions; the linear decrease in diffusivity in silica-blended EPDM was attributed to an increase in the tortuosity. Good correlations of permeability with density and tensile strength were observed. From the investigated relationships, it is possible to select EPDM candidates with the lowest Hsub.2-permeation properties as seal materials to prevent gas leakage under high pressure in Hsub.2-refueling stations.
In this paper an analysis of energy use and energy conservation in the Malaysian rubber producing industries is presented. It has been found that rubber industries consume a substantial amount of ...energy. Excessive use of energy is usually associated with many industrial plants worldwide, and rubber plants are no exception. This study is based on the realization that enormous potential exists for cost-effective improvements in the existing energy-using equipment. Through the method of a walkthrough energy audit, power rating, operation time of energy-consuming equipment/machineries and power factor were collected. The data were then analyzed to investigate the breakdown of end-use equipment/machineries energy use. The results of the energy audit in the Malaysian rubber and rubber producing industries showed that the electric motor accounts for a major fraction of total energy consumption followed by pumps, heaters, cooling systems and lighting. Since the electric motor takes up a substantial amount of the total energy used in rubber industries, energy-savings strategies such as the use of high efficient motors, and variable speed drive (VSD) have been used to reduce energy consumption of motors used in rubber industries. Energy-savings strategies for compressed-air systems, boilers, and chillers have also been applied to estimate energy and cost savings. It has been found that significant amount of energy and; utility bills can be saved along with the reduction of emission by applying the foretold strategies for energy using machineries in the rubber industries.
The most significant industrial utilization of carbon disulfide (CS2) has been in the manufacture of cellulose rayon, cellophane, and rubber industry. CS2 prompts expanded recurrence of chromosomal ...variations in laborers occupationally exposed to CS2.
In the current study, the DNA analysis was carried out from exfoliated buccal epithelial cells from rubber industry workers exposed to CS2 and an equal number of healthy control subjects. Both the control and experimental subjects were categorized by their smoking habits such as smokers (S) and non-smokers (NS). Furthermore, experimental subjects were further separated based on their exposure period. Students t-test statistical tools were used to analyze the final results.
The present analysis identified a high frequency of DNA damage in rubber industry workers (16.55±0.43) than control subjects (9.8±0.21). Also, maximum number of DNA damage detected in smoking experimental group (18.27±0.02) than non-smoking experimental (15.02±0.01) and smoking control groups (10.25±0.04 ).
Smoking habits synergistically increased the DNA damage in the rubber industry workers exposed to CS2.
Chronicling the dramatic history of the Brazilian Amazon during the Second World War, Seth Garfield provides fresh perspectives on contemporary environmental debates. His multifaceted analysis ...explains how the Amazon became the object of geopolitical rivalries, state planning, media coverage, popular fascination, and social conflict. In need of rubber, a vital war material, the United States spent millions of dollars to revive the Amazon's rubber trade. In the name of development and national security, Brazilian officials implemented public programs to engineer the hinterland's transformation. Migrants from Brazil's drought-stricken Northeast flocked to the Amazon in search of work. In defense of traditional ways of life, longtime Amazon residents sought to temper outside intervention. Garfield's environmental history offers an integrated analysis of the struggles among distinct social groups over resources and power in the Amazon, as well as the repercussions of those wartime conflicts in the decades to come.
Owing to its remarkable electrical, mechanical and thermal properties, graphene has been considered the most promising reinforcing filler for the development of rubber nanocomposites. In this work, a ...novel interfacial structure consisting of reduced graphene oxide (rGO)/N-tert-butyl-2-benzothiazole sulfonamide (NS)/natural rubber (NR) (NR/NS-rGO) with covalent bond connections was fabricated using one-step modification and coprecipitation methods. When the filler loading of NS-rGO is 0.42 vol.%, not only the thermal conductivity of the rubber composite increases to 0.237 Wm
−1
K
−1
, which is 21.5% higher than that of pure NR; meanwhile, the internal heat generation decreases to 2.6 °C, which is 45.8% lower than that of reduced graphene oxide (rGO)/ascorbic acid (VC)/natural rubber (NR) (NR/VC-rGO), and the mechanical properties have been greatly improved. The results demonstrated that the covalent bond connections greatly reduced interfacial thermal resistance at the filler/matrix interface. Furthermore, the enhanced interfacial interaction reduced frictional heat generation at the filler/matrix interface. More importantly, this strategy provided creative insights into the high application potential of graphene in the rubber industry.
Taraxacum kok-saghyz (TKS) is a model plant and a potential rubber-producing crop for the study of natural rubber (NR) biosynthesis. The precise analysis of the NR biosynthesis mechanism is an ...important theoretical basis for improving rubber yield. The small rubber particle protein (SRPP) and rubber elongation factor (REF) are located in the membrane of rubber particles and play crucial roles in rubber biosynthesis. However, the specific functions of the SRPP/REF gene family in the rubber biosynthesis mechanism have not been fully resolved. In this study, we performed a genome-wide identification of the 10 TkSRPP and 2 TkREF genes’ family members of Russian dandelion and a comprehensive investigation on the evolution of the ethylene/methyl jasmonate-induced expression of the SRPP/REF gene family in TKS. Based on phylogenetic analysis, 12 TkSRPP/REFs proteins were divided into five subclades. Our study revealed one functional domain and 10 motifs in these proteins. The SRPP/REF protein sequences all contain typical REF structural domains and belong to the same superfamily. Members of this family are most closely related to the orthologous species T. mongolicum and share the same distribution pattern of SRPP/REF genes in T. mongolicum and L. sativa, both of which belong to the family Asteraceae. Collinearity analysis showed that segmental duplication events played a key role in the expansion of the TkSRPP/REFs gene family. The expression levels of most TkSRPP/REF members were significantly increased in different tissues of T. kok-saghyz after induction with ethylene and methyl jasmonate. These results will provide a theoretical basis for the selection of candidate genes for the molecular breeding of T. kok-saghyz and the precise resolution of the mechanism of natural rubber production.
![H[sub.2] Uptake and Diffusi...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/2073-4360/small "H[sub.2] Uptake and Diffusion Characteristics in Sulfur-Crosslinked Ethylene Propylene Diene Monomer Polymer Composites with Carbon Black and Silica Fillers after High-Pressure Hydrogen Exposure Reaching 90 MPa")
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