Effect of mixing ratio on sewage sludge and septage co-digestion

Journal of Material Cycles and Waste Management - Septage, which is made up of liquid and solid materials pumped from septic tanks, can be a potential co-digestion resource for sewage sludge. This...     

Effects of climatic factors on the prevalence of influenza virus infection in Cheonan,Korea

Environmental Science and Pollution Research - Big data can be used to correlate diseases and climatic factors. The prevalence of influenza (flu) virus, accounting for a large proportion of...     

Pyrolysis kinetics of waste PVC pipe.

The pyrolysis kinetics of waste PVC pipe was investigated with a thermal gravimetric analysis system at heating rates of 5, 10, and 30 degrees C/min in a nitrogen atmosphere. Freeman-Carroll method was employed to evaluate kinetic parameters. Two dominant peaks were observed on derivative gravimetric curves, hypothetically suggesting a two-stage apparent reaction model. The first-stage reaction was likely to be represented by stoichiometric reaction to yield volatiles (mainly HCl) and intermediates. The second-stage reaction might be described by thermal degradation of intermediates competitively into gas, liquid, and solid by-products. Quasi-isothermal operations were introduced to verify the reaction types of the first and second reaction. The generation reaction of intermediates achieved at lower temperatures was carried out independently with their decomposition reaction at higher temperatures. The effects of additives on the pyrolysis kinetics of waste PVC pipe seem to be significant, especially on the first-stage reaction. The first-stage reaction was retarded. A merged peak at low temperatures was observed on the derivative thermogravimetry (DTG) curve instead of two peaks usually observed for that of pure PVC resin. The first peak on the DTG curve of pure PVC resin may shift more, resulting in the complete overlap of two peaks. The quantity of evolved HCl was likely to decrease because of interaction of metal components of stabilizers with either HCl or active chlorine atom or both. The final residual fraction increased as a result of pyrolysis of organic forms of additives to yield extra char. On the other hand, the second-stage reaction kinetics demonstrates a similar pattern to that of pure PVC resin, implying that the effects of additives may be less significant in comparison with that at the first-stage reaction.     

Seasonal flux of nonylphenol in Han River, Korea

In order to understand the behavior of nonylphenol (NP) in Han River, water, suspended particle and sediment samples were analyzed during summer, autumn and winter. Concentrations of nonylphenol in water ranged from 23.2 to 187.6 ng/l, in suspended particle from 6.8 to 190.8 ng/l and in sediment from 25.4 to 932.0 ng/gdrywt. An increasing trend in the concentration is noticed in all matrices along down the river. In case of water and suspended particle, concentrations were higher in warmer season than in colder season. Percentage of nonylphenol in the suspended particle phase decreased from 67% to 28% with decreasing temperature in water. A reasonable correlation (R2 = 0.63) was obtained for water and suspended particle. The partition coefficient Log Kp is 4.8. No seasonal variation of the concentration in sediment is noticed in this study.     

Monitoring of air pollution by polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans of pine needles in Korea

The atmospheric contamination levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were evaluated from the analysis of pine needles in South Korea. Pine needles were collected from 30 sampling points at five main cities in South Korea (Busan, Daegu, Gwangju, Changwon and Jeju island). The highest concentrations of PCDDs/DFs (2.19–26.88 pg I-TEQ/g of dry weight) were measured at Busan, where is the city of the highest population density and traffic volume among five cities. The lowest concentration was detected at Jeju with 0.62 pg I-TEQ/g dry weight, suggesting Jeju could be an environmental background area in Korea. The dominant homologues of PCDDs/DFs in pine needles were the lower chlorine-substituted compounds such as tetra CDDs and CDFs, and the distribution ratios of PCDDs/DFs decreased with increase of the number of chlorine substituents. Homologue profiles of pine needle samples were similar to PCDDs/DFs profiles of the vapor phase in the ambient air, and thus the pine needles absorbed the vapor phase of PCDDs/DFs from air. Results suggested that pine needles could be used as an indicator of the atmospheric contamination for PCDDs/DFs in Korea.     

Kinetics of low frequency sonodegradation of linear alkylbenzene sulfonate solutions

The decomposition of sodium dodecylbenzene sulfonate (SDBS) in water by means of ultrasound irradiation at 20kHz was investigated. Experiments were conducted at surfactant concentrations of 175, 260 and 350 mg l(-1), liquid volumes of 120, 170 and 220 ml, temperatures of 20, 30 and 45 degrees C and applied power of 40, 80 and 125 W. The extent of degradation was followed monitoring substrate and organic carbon concentrations, while hydrogen peroxide concentration was also measured; the latter is a product of water sonolysis due to hydroxyl radical recombination. 80% SDBS conversion was achieved after 120 min of sonication at 125 W and 30 degrees C; nonetheless, SDBS and its degradation intermediates proved difficult to oxidise as only about 20-25% of the initial carbon content was transformed to carbon dioxide. At the initial stages of the reaction, degradation rate appears to be only weakly dependent on the substrate concentration with the rate increasing from 3.1 to 4 mg l(-1)min(-1) with increasing concentration from 175 to 350 mg l(-1). Degradation appears to occur at the bubble-liquid interface through hydroxyl radical-mediated reactions whose role was established by performing experiments in the presence of radical scavengers, namely potassium bromide and sodium benzoate. Degradation rates increased with increasing power and decreasing temperature and volume.     

Development of a sandwich enzyme-linked immunosorbant assay for the quantification of vitellogeinin in Bullfrog (Rana catesbeiana)

A sandwich enzyme-linked immunosorbant assay (ELISA) was developed to quantitatively detect Bullfrog (Rana catesbeiana) vitellogenin (VTG) levels. This procedure involved a sandwich ELISA using monoclonal antibodies of BVmA1 and BVmA2 against Bullfrog-VTG, and BVmA1 conjugated to horseradish peroxidase as the detection antibody. The assay range was between 9.4 ng/ml and 1200 ng/ml and the recovery of the VTG added to Bullfrog control male serum was 92.0-108.8%. Male Bullfrog was induced by injection 17beta-estradiol (E2) for four weeks and Bullfrog-VTG levels were measured each week. Histological analysis was performed for investigating the correlation of the effect to male reproduction and Bullfrog-VTG level variation depending on E2 dose. After two weeks of E2 exposure, the induced Bullfrog-VTG level was significantly higher than Bullfrog control female (p<0.05). After four weeks of E2 exposure, the rupture and fusion of seminiferous tubule in the testes of male Bullfrog were shown and provided direct evidence that the reproduction of male Bullfrog was affected by estrogenic compounds. Bullfrog-VTG bioassay, using the sandwich ELISA, could be a sensitive and useful tool for quantification of estrogenic principles in aquatic environments.     

Effect of soil chemical properties on the remediation of phenanthrene-contaminated soil by electrokinetic-Fenton process

The electrokinetic-Fenton (EK-Fenton) remediation of soil contaminated with phenanthrene was studied. Two different soils were chosen to investigate the effects of chemical properties, such as Fe oxide contents and acid soil buffer capacity. The H(2)O(2) concentrations in pore water, the electrical potential distributions and the electrical currents were monitored to assess the electrochemical effect in relation to the soil properties. Hadong caly had high acid buffer capacity, and thus the amount of electroosmotic flow was lager in the experiment with Hadong clay than with EPK kaolin. The major mechanism of phenanthrene removal was a degradation in the experiment with EPK Kaolin, while it was a simple transport away from the system in experiment with Hadong clay. It was mainly because of the lower acid buffering capacity and better H(2)O(2) stability in case with EPK Kaolin than with Hadong clay.     

Size removal on polyester fabrics by plasma source ion implantation device

Plasma treatment was evaluated as an alternative clean desizing technology in this work. As indicated by weight loss, O2 plasma treatment efficiently removed sizing agents such as polyvintyl alcohol (PVA), polyacrylic acid esters and their mixture (MIX) on polyethylene terephthalate (PET) fabrics. SEM pictures of the plasma treated samples directly proved the disappearance of the sizing agents. XPS analysis showed apparent changes in chemical composition and functional groups of the PET surface after O2 plasma treatment. Carbon content decreased due to the removal of sizing agents while oxygen content increased. O2 plasma treatment also increased hydrophilic functional groups of sizing agents, which is confirmed by C1s and O1s deconvolution analyses. After O2 plasma treatment, the PET fabric was subjected to conventional desizing process at different temperatures. Except for the PET fabric sized with PVA, plasma-treated fabrics showed more efficient desizing results when compared with untreated fabrics. Furthermore, the desizing effluent from the treated fabric gave lower TOC, COD and BOD values.     

Leaching characteristics of polybrominated diphenyl ethers (PBDEs) from flame-retardant plastics

To investigate the effect of leachant on the leachability of polybrominated diphenyl ethers (PBDEs), we determined the leaching concentrations of PBDEs from flame-retardant plastic samples (TV housings and raw materials before molding processing) that are regarded as a source of PBDEs in landfill sites. The leachants used were distilled water, 20% methanol solution, and dissolved humic solution (DHS) of 1000 mg/l based on organic carbon. The leaching test conditions were a liquid-to-solid ratio of 100:1, and a contact period of five days, with twice-daily agitation in a temperature-controlled room of 30 degrees C without pH or ionic strength control. The leaching concentrations of PBDEs increased with increased content, and were found to be remarkably enhanced when methanol and DHS were used instead of distilled water. The enhancement of leachability in the presence of the latter was attributed to the cosolvency effect, and complex formations between the PBDEs and dissolved humic matter (DHM). PBDE concentrations in the leachate obtained from the leaching test and an actual landfill site revealed a significant presence of congeners below heptabromodiphenyl ethers (H7BDEs), detected in the leachate of the actual landfill, while significant amounts of nonabromodiphenyl ethers (N9BDEs) and decabromodiphenyl ether (D10BDE) were detected in the leachate of the leaching test.