Inactivation of Ascaris eggs in soil by microwave treatment compared to UV and ozone treatment

This study reports on the effect of microwave radiation for inactivation of Ascaris lumbricoides eggs in 25 g of soil compared to ultraviolet irradiation and ozone expose. Microwave radiation at 700 W with 14% water content (w/w) achieved approximately 2.5 log inactivation of eggs in soil within 60 s. On the other hand, UV irradiation at 3 mW cm⁻² with and without shaking soil for 3600 s achieved approximately 0.32 and 0.01 log inactivation of eggs, respectively. In ozone treatment, 0.13 log inactivation of eggs was achieved with 5.8 ± 0.7 mg L⁻¹ of dissolved ozone dose for 30 min in a continuous diffusion reactor. In addition, the inactivation of eggs by three disinfection techniques was conducted in water in order to compare the inactivation efficiency of eggs in soil. The inactivation efficiency of microwave radiation was found to be no significant difference between in soil and water. However, the inactivation efficiency of UV irradiation was significantly increased in water while in ozone expose there was no significant difference between in soil and water. Microwave treatment thus proved to be the most efficient method in controlling A. lumbricoides eggs in soil.     

Biodegradability of alkylates as a sole carbon source in the presence of ethanol or BTEX

The biodegradability of alkylate compounds in serum bottles was investigated in the presence and absence of ethanol or benzene, toluene, ethylbenzene, and p-xylene (BTEX). The biomass was acclimated to three different alkylates, 2,3-dimethylpentane, 2,4-dimethylpentane and 2,2,4-trimethylpentane in porous pot reactors. The alkylates were completely mineralized in all three sets of experiments. They degraded more slowly in the presence of BTEX than in their absence because BTEX inhibited the microbial utilization of alkylates. However, in the presence of ethanol, their slower biodegradation was not related to inhibition by the ethanol. Throughout the experiments alkylates, ethanol, and BTEX concentrations did not change in the sterile controls.     

Characterization of PM2.5 aerosols dominated by local pollution and Asian dust observed at an urban site in Korea during aerosol characterization experiments (ACE)--Asia Project

Daily fine particulate matter (PM2.5) samples were collected at Gwangju, Korea, during the Aerosol Characterization Experiments (ACE)-Asia Project to determine the chemical properties of PM2.5 originating from local pollution and Asian dust (AD) storms. During the study period, two significant events occurred on April 10-13 and 24-25, 2001, and a minor event occurred on April 19, 2001. Based on air mass transport pathways identified by back-trajectory calculation, the PM2.5 dataset was classified into three types of aerosol populations: local pollution and two AD aerosol types. The two AD types were transported along different pathways. One originated from Gobi desert area in Mongolia, passing through Hunshandake desert in Northern Inner Mongolia, urban and polluted regions of China (AD1), and the other originated in sandy deserts located in the Northeast Inner Mongolia Plateau and then flowed southward through the Korean peninsula (AD2). During the AD2 event, a smoke plume that originated in North Korea was transported to our study site. Mass balance closures show that crustal materials were the most significant species during both AD events, contributing -48% to the PM2.5 mass; sulfate aerosols (19.1%) and organic matter (OM; 24.6%) were the second greatest contributors during the AD1 and AD2 periods, respectively, indicating that aerosol properties were dependent on the transport pathway. The sulfate concentration constituted only 6.4% (4.5 microg/m3) of the AD2 PM2.5 mass. OM was the major chemical species in the local pollution-dominated PM2.5 aerosols, accounting for 28.7% of the measured PM2.5 mass, followed by sulfate (21.4%), nitrate (15%), ammonium (12.8%), elemental carbon (8.9%), and crustal material (6.5%). Together with substantial enhancement of the crustal elements (Mg, Al, K, Ca, Sc, Ti, Mn, Fe, Sr, Zr, Ba, and Ce), higher concentrations of pollution elements (S, V, Ni, Zn, As, Cd, and Pb) were observed during AD1 and AD2 than during the local pollution period, indicating that, in addition to crustal material, the AD dust storms also had a significant influence on anthropogenic elements.     

Oxidation of elemental mercury using atmospheric pressure non-thermal plasma

The oxidation of gas phase elemental mercury (Hg0) by atmospheric pressure non-thermal plasma has been investigated at room temperature, employing both dielectric barrier discharge (DBD) of the gas mixture of Hg0 and injection of ozone (O3) into the gas mixture of Hg0. Results have shown that the oxidative efficiencies of Hg0 by DBD and the injection of O3 are 59% and 93%, respectively, with energy consumption of 23.7 J L(-1). This combined approach has indicated that O3 plays a decisive role in the oxidation of gas phase Hg0. Also the oxidation of Hg0 by injecting O3 into the gas mixture of Hg0 proceeds with better efficiency than DBD of the gas mixture of Hg0. These results have been explained by the incorporation of the competitive reaction pathways between the formation of HgO by O3 and the decomposition of HgO back to Hg0 in the plasma environment.     

First-trimester screening for Down syndrome; the role of nasal bone assessment in the Korean population

Objectives The aim of this study was to evaluate the role of nasal bone assessment in first-trimester screening for Down syndrome (DS) in the Korean population. Methods From July 2004 to March 2006, we prospectively evaluated the fetal nasal bones at 11–14 weeks' gestation in the Korean population. Results A successful evaluation was possible in 6490 of 6787 fetuses (95.6%). Absent, hypoechoic, and short nasal bones were seen in 4 (26.7%), 4 (26.7%), and 1 (6.7%) of 15 fetuses with DS, respectively, whereas in 5 (0.1%), 11 (0.2%), and 246 (3.8%) of 6456 normal fetuses. The incidence of absent and hypoechoic nasal bone showed significant differences between normal fetuses and fetuses with DS (P < 0.0005, both). Screening for DS using an absent or hypoechoic nasal bone resulted in a sensitivity of 53.3%, a specificity of 99.8%, a positive likelihood ratio of 215.2, and a negative likelihood ratio of 0.5. Conclusion Our study showed that nasal bone abnormality at 11–14 weeks of gestation had a high association with DS in the Korean population. This suggests that nasal bone assessment can be used to supplement the current first-trimester screening for DS in the Korean population. Copyright © 2007 John Wiley & Sons, Ltd.     

Bactericidal effect of TiO2 photocatalyst on selected food-borne pathogenic bacteria

Titanium dioxide (TiO(2)) photocatalysts have attracted great attention as a material for photocatalytic sterilization in the food and environmental industry. This research aimed to design a new photobioreactor and its application to sterilize selected food borne pathogenic bacteria, Salmonella choleraesuis subsp., Vibrio parahaemolyticus, and Listeria monocytogenes. The photocatalytic reaction was carried out with various TiO(2) concentrations and Ultraviolet (UV) illumination time. A feasible synergistic effect was found that the bactericidal effect of TiO(2) on all bacterial suspension after UV light irradiation was much higher than that of without TiO(2). As the concentration of TiO(2) increased to 1.0 mg/ml, bactericidal effect increased. However, the bactericidal effect was rapidly abbreviated at TiO(2) concentration higher than 1.25 mg/ml to all selected bacteria. UV illumination time affected drastically the viability of all bacteria with different death rate. Similar trends were obtained from S. choleraesuis subsp. and V. parahaemolyticus that their complete killing was achieved after 3 h of illumination. However, L. monocytogenes was more resistant and its death ratio was about 87% at that time.     

Degradation characteristics of toluene,benzene, ethylbenzene,and xylene by Stenotrophomonas maltophilia T3-c

Stenotrophomonas maltophilia T3-c, isolated from a biofilter for the removal of benzene, toluene, ethylbenzene, and xylene (BTEX), could grow in a mineral salt medium containing toluene, benzene, or ethylbenzene as the sole source of carbon. The effect of environmental factors such as initial toluene mass, medium pH, and temperature on the degradation rate of toluene was investigated. The cosubstrate interactions in the BTEX mixture by the isolate were also studied. Within the range of initial toluene mass (from 23 to 70 pmol), an increased substrate concentration increased the specific degradation of toluene by S. maltophilia T3-c. The toluene degradation activity of S. maltophilia T3-c could be maintained at a broad pH range from 5 to 8. The rates at 20 and 40 degrees C were 43 and 83%, respectively, of the rate at 30 degrees C. The specific degradation rates of toluene, benzene, and ethylbenzene by strain T3-c were 2.38, 4.25, and 2.06 micromol/g-DCW/hr. While xylene could not be utilized as a growth substrate by S. maltophilia T3-c, the presence of toluene resulted in the cometabolic degradation of xylene. The specific degradation rate of toluene was increased by the presence of benzene, ethylbenzene, or xylene in binary mixtures. The presence of toluene or xylene in binary mixtures with benzene increased the specific degradation rate of benzene. The presence of ethylbenzene in binary mixtures with benzene inhibited benzene degradation. The presence of more than three kinds of substrates inhibited the specific degradation rate of benzene. All BTEX mixtures, except tri-mixtures of benzene, ethylbenzene, and xylene or mixtures of all four substrates, had little effect on the degradation of ethylbenzene by S. maltophilia T3-c. The utilization preference of the substrates by S. maltophilia T3-c was as follows: ethylbenzene was degraded fastest, followed by toluene and benzene. However, the specific degradation rates of substrates, in order, were benzene, toluene, and ethylbenzene.     

Mercury removal from incineration flue gas by organic and inorganic adsorbents

Experiments were performed to investigate various adsorbents for their mercury removal capabilities from incineration flue gases. Four different materials were tested; Zeolite, Bentonite, activated carbon (AC), and wood char. Real incineration off-gas and in-lab simulated combustion flue gases (N2 + Hg) were used. Three cylindrical-shaped sorbent columns with 5 cm in diameter and 20 cm in length were used. The gas flow rate was fixed at 660 l/h at all times. Concentrations of NO, CO, O2, CO2, SO2, H2O, HCl, and mercury were continuously monitored. Mercury removal efficiencies of natural Zeolite and Bentonite were found to be much lower than those of the referenced AC. Amount of Hg removed were 9.2 and 7.4 microg/g of Zeolite and Bentonite, respectively. Removal efficiencies of each layer consisted of inorganic adsorbents were no higher than 7%. No significant improvement was observed with sulfur impregnation onto the inorganic adsorbents. Organic adsorbents (wood char and AC) showed much higher mercury removal efficiencies than those of inorganic ones (Zeolite and Bentonite). Mercury removal efficiency of wood char reached over 95% in the first layer, showing almost same effectiveness as AC which currently may be the most effective adsorbents for mercury. Amount of mercury captured by wood char was approximately 0.6 mg/g of wood char, close to the amount captured by AC tested in this study. Hence, wood char, made from the waste woods through a gasification process, should be considered as a possible alternative to relatively expensive AC.