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261.
262.
The protozoan parasites such as Cryptosporidiumparvum and Giardialamblia have been recognized as a frequent cause of recent waterborne disease outbreaks because of their strong resistance against chlorine disinfection. In this study, ozone and Fe(VI) (i.e., FeO(4)(2-)) were compared in terms of inactivation efficiency for Bacillus subtilis spores which are commonly utilized as an indicator of protozoan pathogens. Both oxidants highly depended on water pH and temperature in the spore inactivation. Since redox potential of Fe(VI) is almost the same as that of ozone, spore inactivation efficiency of Fe(VI) was expected to be similar with that of ozone. However, it was found that ozone was definitely superior over Fe(VI): at pH 7 and 20°C, ozone with the product of concentration×contact time (CˉT) of 10mgL(-1)min inactivate the spores more than 99.9% within 10min, while Fe(VI) with CˉT of 30mgL(-1) min could inactivate 90% spores. The large difference between ozone and Fe(VI) in spore inactivation was attributed mainly to Fe(III) produced from Fe(VI) decomposition at the spore coat layer which might coagulate spores and make it difficult for free Fe(VI) to attack live spores. 相似文献
263.
Naile JE Khim JS Wang T Wan Y Luo W Hu W Jiao W Park J Ryu J Hong S Jones PD Lu Y Giesy JP 《Environmental pollution (Barking, Essex : 1987)》2011,159(4):907-917
Polychlorinated-dibenzo-p-dioxins and -dibenzofurans (PCDD/Fs) were measured in soils and sediments from the Yellow Sea region. Korean soils and sediments mostly contained detectable PCDD/Fs and showed a widespread distribution among locations. Soil and sedimentary PCDD/Fs from China were comparable to or less than those in Korea. The patterns of relative concentrations of individual congeners in soils were different between the two countries, but similar in sediments. Sources of PCDD/Fs in China and Korea were found to be independent of each other and their distributions reflected matrix-dependent accumulation. Spatial distribution indicated some point sources in Korea while Chinese sources were more widespread and diffuse. PCDD/Fs measured in the coastal areas of the Yellow Sea were comparable to or less than those previously reported in for eastern Asia. However, ∑TEQs in soils and sediments were near to or, in some cases exceeded environmental quality guidelines. 相似文献
264.
Construction and demolition waste has been dramatically increased in the last decade, and social and environmental concerns on the recycling have consequently been increased. Recent technology has greatly improved the recycling process for waste concrete. This study investigates the fundamental characteristics of concrete using recycled concrete aggregate (RCA) for its application to structural concrete members. The specimens used 100% coarse RCA, various replacement levels of natural aggregate with fine RCA, and several levels of fly ash addition. Compressive strength of mortar and concrete which used RCA gradually decreased as the amount of the recycled materials increased. Regardless of curing conditions and fly ash addition, the 28 days strength of the recycled aggregate concrete was greater than the design strength, 40 MPa, with a complete replacement of coarse aggregate and a replacement level of natural fine aggregate by fine RCA up to 60%. The recycled aggregate concrete achieved sufficient resistance to the chloride ion penetration. The measured carbonation depth did not indicate a clear relationship to the fine RCA replacement ratio but the recycled aggregate concrete could also attain adequate carbonation resistance. Based on the results from the experimental investigations, it is believed that the recycled aggregate concrete can be successfully applied to structural concrete members. 相似文献
265.
Seok-Pyo Hong Jong-In Dong Sang-Ku Yeo In-Hee Park Moon-Sik Chung Doo-Il Kim Young-Kwon Park 《Journal of Material Cycles and Waste Management》2011,13(3):186-189
Solid-fuel conversion or gasification study of sewage sludge and energy recovery has become increasingly important because
energy recovery and climate change are emerging issues. Various types of catalysts, such as dolomite, steel slag and calcium
oxide, were tested for tar reduction during the sewage sludge gasification process. For the experiments on sewage sludge gasification
reactions and tar reduction using the catalysts, a fixed bed of laboratory-scale experimental apparatus was set up. The reactor
was made of quartz glass using an electric muffle furnace. The sewage sludge samples used had moisture contents less than
6%. The experimental conditions were as follows: sample weight was 20 g and reaction time was 10 min, gasification reaction
temperature was from 600 to 800°C, and the equivalence ratio was 0.2. The quantity of catalysts was 2–6 g, and temperatures
of catalyst layers were 500–700°C. As the reaction temperature increased up to 800°C, the yields of gaseous products and liquid
products increased, whereas char and tar products decreased, showing effects on gas product compositions. These results were
considered to be due to the increase of the water-gas reaction and Boudouard reaction. In the case of experiments with catalysts,
dolomite (4 g), steel slag (6 g) and calcium oxide (6 g) were used. When the temperature of catalysts increased, the weight
of the tar produced decreased with different cracking performances by different catalysts. Reforming reactions were considered
to occur on the surface of dolomite, steel slag and calcium oxide, causing cracking of the hydrocarbon structure, which eventually
showed reduced tar generation. 相似文献
266.
The extent of impervious cover in a watershed has been linked to the quality of an urban aquatic environment. The Kyeongan watershed in South Korea was investigated to evaluate the relationship between the total impervious area (TIA) and the aquatic ecosystem of the watershed, including water quality and aquatic life using a relatively high-resolution (0.4 m) image. The TIA was found to be approximately 12% of the watershed, which indicates that the quality of its environment was being adversely affected by it. For water quality, Pearson correlation analyses showed that all water quality parameters studied were found to be positively correlated with TIA at p < 0.01, except for nitrate (NO3-). In addition, the zone with a higher TIA was found to have worse water quality. Some water quality parameters, such as nitrite (NO2-), total phosphorus, and phosphate (PO4(3-)) were highly affected by discharges from wastewater treatment plants. Water quality data suggest that TIA could be used to predict the water quality of streams. For ecological parameters, the diatom index for organic pollution and trophic diatom index were found to be highly correlated with TIA, whereas physical habitat and benthic macroinvertebrates were poorly correlated with TIA. However, the results indicate that the extent of impervious cover can be a useful indicator for predicting the status of specific ecosystem of streams. 相似文献
267.
Jin-San Kim Tara Sankar Pathak Jung-Ho Yun Ki-Pal Kim Tae-Joon Park Yongae Kim Ki-Jung Paeng 《Journal of Polymers and the Environment》2013,21(1):224-232
Alginate polyurethane hybrid materials are prepared by varying mole ratio of 2, 4-TDI as a di-isocyanate and alginic acid as a polyol in presence of dimethyl sulfoxide (DMSO) as a solvent. FT-IR and 13C one-dimensional (1D) solid state NMR (SSNMR) spectroscopy indicates that alginic acid is converted into alginate-polyurethane hybrid material via urethane linkage. Surface morphology of alginate-polyurethane hybrids changes by varying alginic acid: TDI ratio. The peak at near 221 °C in DSC thermogram of alginic acid (Alg) is shifted to higher temperature in alginate-polyurethane hybrid (Algpu1 and Algpu2). TGA study shows that alginate-polyurethane hybrid prepared using alginic acid: TDI = 1:1 (Algpu2) is more stable than alginic acid: TDI = 1:0.5 (Algpu1) at 300 °C. Kinetic analysis was performed to fit with TGA data, where the entire degradation process has been considered as three consecutive 1st order reactions. This study shows that thermal stability of alginate-polyurethane hybrid material was increased by adjusting mole ratio of 2, 4-TDI and alginic acid. 相似文献
268.
Yun Hui Lim Khanh Quoc Ngo Young Koo Park 《Journal of the Air & Waste Management Association (1995)》2013,63(8):924-931
Capturing of odorous compounds such as toluene vapor by a particulate-activated carbon adsorbent was investigated in a gas-solid cyclone, which is one type of mobile beds. The test cyclone was early modified with the post cyclone (PoC) and a spiral flow guide to the vortex finder. The proposed process may contribute to the reduction of gases and dust from industrial exhausts, especially when dealing with a low concentration of odorous elements and a large volume of dust flow. In this device, the toluene capturing efficiency at a 400 ppm concentration rose up to 77.4% when using activated carbon (AC) particles with a median size of 27.03 μm. A maximum 96% of AC particles could be collected for reuse depending on the size and flow rate. The AC regenerated via thermal treatment showed an adsorption potential up to 66.7% throughout repeated tests.
Implications: VOCs and particles have been of interest both in industrial field and public indoor spaces. In this study, a post cyclone (PoC) that utilizes a residual vortex from the mother cyclone was modified by inserting a flow guide and was applied to capture toluene vapor. The device of modified post-cyclone system can be used effectively in simultaneous treatment of gas-solid flow. 相似文献
269.
Dae-Young Kim Hong-Youl Ryu Seung-Hyun Kim Kyoung-Tae Park Seong-Seock Cho Moon-Hee Han 《International Journal of Green Energy》2016,13(6):573-579
A novel on-board hydrogen generation concept using Al coil with NaOH was investigated. The reaction rate was successfully controlled by introducing a pumping system for the NaOH solution. The time for the flow to develop fully was mainly dependent on the solution temperature, and the fastest start time recorded was 60 sec at a solution temperature of 70°C. The maximum H2 generation rate was 200 L min–1 with a prototype design of the on-board hydrogen generation system 1/8 times the size of a full-size reactor. The H2 generation process coupled with the solution pumping system was simulated with three-dimensional fluid dynamic software, and the calculated H2 flow and temperature rise of the system were validated with experimental data. 相似文献
270.
Ok-Kyung Koo Christopher A. Baker Hyun-Jung Kim Si Hong Park 《Journal of environmental science and health. Part. B》2016,51(9):622-627
The purpose of this study was to characterize the microbial community in ground pork using molecular approaches. Forty six ground pork products were purchased from local stores in the north central area of South Korea. Aerobic plate counts varied 4.23 ± 5.14 × 105 CFU/g with the range between 5.00 × 103 and 1.85 × 106 CFU/g for ground pork samples. Four ground meat samples were further processed for metagenomic analysis. Pseudomonas species was the most relative abundant with a wide range occurring (1.72 to 77.7%) as part of the microbial genera in ground pork. Bacteria such as Carnobacterium, Yersinia, Photobacterium were also identified in ground pork. Despite the prominence of certain genera across all samples there was still extensive microbial diversity among ground pork products that originated from different slaughter houses and were processed in different markets. Such diversity indicates that designing interventions to extend shelf life may be hampered by the extensive variability in the microbial consortia associated with pork products. However, this diversity may be useful for developing microbial traceability signatures unique to a slaughter house or a particular market. 相似文献