The Optimization of Methods for the Collection of Aerosolized Murine Norovirus

Globally, norovirus is the most common gastroenteritis causing pathogen. Annually, norovirus causes 685 million cases of acute gastroenteritis and 200,000     

Effects of Asian dust events on atmospheric bacterial communities at different distances downwind of the source region

Aeolian dust particles arising from arid and semiarid zones are known to carry microbes by air currents. The effect of wind-borne bacteria on atmospheric bacterial population at various downwind distances from the dust source regions must be clarified, but has not yet been reported. This study monitored the bacterial abundance and community composition in outdoor aerosol samples in Beijing, China, which is close to the Asian dust source regions, and compared them with the results obtained in a distant region(Osaka, Japan).The Asian dust collected in Beijing contained(4 ± 3) × 10~4 bacterial cells/m~3, approximately~4 times higher than in Osaka. On 15 April 2015, Beijing experienced severe Asian dust events with a 1000-fold increase in bacterial abundance, relative to non-Asian dust days. Dominant bacterial phyla and classes in Asian dust collected in Beijing were Actinobacteria, Bacilli and Acidobacteria, and the bacterial community composition varied more widely than in Osaka.The bacterial community compositions differed between the Beijing and Osaka dusts, even for the same Asian dust events. These results indicated that aerosol bacterial communities nearer the dust source are more affected by eolian dust than their distant counterparts.     

A nanofilter composed of carbon nanotube-silver composites for virus removal and antibacterial activity improvement

We have developed a new nanofilter using a carbon nanotube-silver composite material that is capable of efficiently removing waterborne viruses and bacteria.The nanofilter was subjected to plasma surface treatment to enhance its flow rate,which was improved by approximately 62%.Nanoscale pores were obtained by fabricating a carbon nanotube network and using nanoparticle fixation technology for the removal of viruses.The pore size of the nanofilter was approximately 38 nm and the measured flow rate ranged from 21.0 to 97.2 L/(min·m~2)under a pressure of 1–6 kgf/cm~2 when the amount of loaded carbon nanotube-silver composite was 1.0 mg/cm~2.The nanofilter was tested against Polio-,Noro-,and Coxsackie viruses using a sensitive real-time polymerase chain reaction assay to detect the presence of viral particles within the outflow.No trace of viruses was found to flow through the nanofilter with carbon nanotube-silver composite loaded above 0.8 mg/cm~2.Moreover,the surface of the filter has antibacterial properties to prevent bacterial clogging due to the presence of 20-nm silver nanoparticles,which were synthesized on the carbon nanotube surface.     

Design and modeling of optimal distillation sequence for recovery of valuable components from a waste photoresist stripper

Currently, waste photoresist stripper from the semiconductor industries is generally incinerated at high temperatures or processed as a high-calorie fuel, which can have adverse effects on the environment and economy. Recovery of valuable solvents from waste photoresist strippers is, therefore, very important for thin flat transistor-liquid crystal display (TFT-LCD) manufactures to reduce the production costs and protect the environment against industrial waste. In the present work, systematic laboratory-scale distillation experiments were carried out to regenerate the organic solvents from the waste photoresist stripper and determine if they are feasible to recycle for commercial TFT-LCD grade chemicals: in particular, 1-hydroxyethylpiperazine and methyl diglycol were mainly tried to retrieve. Based on the experiment results, possible alternative distillation sequences were examined through intensive techno-economic analysis using a rigorous process simulator. As a result, an optimal distillation sequence and condition were drawn to separate valuable organic solvents from waste photoresist stripper for a commercial purpose recovery process.     

Methane production from food waste leachate in laboratory-scale simulated landfill

Due to the prohibition of food waste landfilling in Korea from 2005 and the subsequent ban on the marine disposal of organic sludge, including leachate generated from food waste recycling facilities from 2012, it is urgent to develop an innovative and sustainable disposal strategy that is eco-friendly, yet economically beneficial. In this study, methane production from food waste leachate (FWL) in landfill sites with landfill gas recovery facilities was evaluated in simulated landfill reactors (lysimeters) for a period of 90 d with four different inoculum–substrate ratios (ISRs) on volatile solid (VS) basis. Simultaneous biochemical methane potential batch experiments were also conducted at the same ISRs for 30 d to compare CH₄ yield obtained from lysimeter studies. Under the experimental conditions, a maximum CH₄ yield of 0.272 and 0.294 L/g VS was obtained in the batch and lysimeter studies, respectively, at ISR of 1:1. The biodegradability of FWL in batch and lysimeter experiments at ISR of 1:1 was 64% and 69%, respectively. The calculated data using the modified Gompertz equation for the cumulative CH₄ production showed good agreement with the experimental result obtained from lysimeter study. Based on the results obtained from this study, field-scale pilot test is required to re-evaluate the existing sanitary landfills with efficient leachate collection and gas recovery facilities as engineered bioreactors to treat non-hazardous liquid organic wastes for energy recovery with optimum utilization of facilities.     

Possible particulate nitrite formation and its atmospheric implications inferred from the observations in Seoul,Korea

Simultaneous measurements of gaseous species and fine-mode, particulate inorganic components were performed at the University of Seoul, Seoul in Korea. In the simultaneous measurements, a certain level of nitrous acid (HONO) was observed in the gas-phase, indicating possible heterogeneous HONO production on the surface of the ambient aerosols. On the other hand, high particulate nitrite (NO^2?) concentrations of 1.41(±2.26) μg/m³ were also measured, which sometimes reached 18.54 μg/m³. In contrast, low HONO-to-NO₂ ratios of 0.007(±0.006) were observed in Seoul. This indicates that a significant fraction of HONO is dissolved in atmospheric aerosols. Around the Seoul site, sufficient alkalinity may have been provided to the atmospheric aerosols from the excessive presence of NH₃ in the gas-phase. Due to the alkaline particulate conditions (defined in this study as a particle pH >～3.29), the HONO molecules produced at the surface of the atmospheric aerosols appeared to have been converted into particulate nitrite, thereby preventing their further participation in the atmospheric O₃/NO_y/HO_x photochemical cycles. It was estimated that a minimum average of 65% of HONO was captured by alkaline, anthropogenic, urban particles in the Seoul measurements.     

Hydrogen-rich fuel gas production from refuse plastic fuel pyrolysis and steam gasification

In this study, experimental conditions were optimized to maximize the production of hydrogen gas from refuse plastic fuel (RPF) by pyrolysis and steam gasification processes conducted in a laboratory-scale reactor. We carried out gasification using 10-g RPF samples at different temperatures (700°-1000°C) with and without steam. The effect of the amount of steam (0–0.25 g/min) for RPF steam gasification was also studied. The effect of K₂CO₃ as a catalyst on these processes was also investigated. Experimental results showed that the hydrogen gas yield increased with temperature; with respect to the gas composition, the hydrogen content increased mainly at the expense of other gaseous compounds, which highlights the major extension of secondary cracking reactions in the gaseous fraction at higher temperatures.