Treatment of 1,3-Butadiene in an Air Stream by a Biotrickling Filter and a Biofilter

ABSTRACT

This paper presents results obtained from a performance study on the biotreatment of 1,3-butadiene in an air stream using a reactor that consisted of a two-stage, in-series biotrickling filter connected with a three-stage, in-series biofilter. Slags and pig manure-based media were used as packing materials for the biotrickling filter and the biofilter, respectively. Experimental results indicated that, for the biotrickling filter portion, the butadiene elimination capacities were below 5 g/m³/hr for loadings of less than 25 g/m³/hr, and the butadiene removal efficiency was only around 17%. For the biofilter portion, the elimination capacities ranged from 10 to 107 g/m³/hr for loadings of less than 148 g/m³/hr. The average butadiene removal efficiency was 75–84% for superficial gas velocities of 53–142 m/hr and a loading range of 10–120 g/m³/hr. The elimination capacity approached a maximum of 108 g/m³/hr for a loading of 150 g/m³/hr. The elimination rates of butadiene in both the biotrickling filter and biofilter were mass-transfer controlled for influent butadiene concentrations below about 600 ppm for superficial gas velocities of 29–142 m/hr. The elimination capacity was significantly higher in the biofilter than in the biotrickling filter. This discrepancy may be attributed to the higher mass-transfer coefficient and gas-solid interfacial area offered for transferring the gaseous butadiene in the biofilter.     

Decomposition of Gas Phase 1,3-Butadiene by Ultraviolet/Ozone Process

Abstract

A pilot-scale plug-flow reactor was built to investigate its performance in treating airborne 1,3-butadiene (BD) via ozonation (O₃) and ultraviolet (UV)/O₃ technologies. Governing factors, such as the initial molar ratio of ozone to BD, UV volumetric electric input power, and moisture content in the influent airstream, were investigated. Experiments were conducted at an influent BD concentration of ～50 ppm, an ambient temperature of 26 °C, and a gas retention time of 85 sec. Results show that an initial molar ratio of ozone to BD of 3.5 and 2 sufficed to obtain BD decompositions of >90% for ozonation and UV/O₃, respectively. The UV irradiance did not directly promote the decomposition of BD, rather, it played a role in promoting the production of secondary oxidants, such as hydroxyl radicals. Kinetic analyses indicate that both types of BD decomposition are peudo–first-order with respect to BD concentrations. Moisture content (relative humidity = 40–99%) and UV volumetric electric input power (0.147 and 0.294 W/L) are both factors that weakly affect the rate of BD decomposition. Economic evaluation factors, including both energy of ozone production and UV electric input power, were also estimated.     

Effect of typhoon on atmospheric particulates in autumn in central Taiwan

Previous studies have suggested that the ongoing global climate change will likely increase the intensity and frequency of extreme weather, such as typhoons. Since the beginning of global warming, it has become necessary to understand the influence of typhoons on air quality. Rare data, especially particulate measurements data could be used to establish the relationship between the air pollution and typhoons. One of main limiting factors is that most of the previous chemical analyses of particulates used a relatively long sampling time, which could dilute the temporal impact of particulate characteristics and their sources. This work, depending more time-resolved measurements, focus on the characteristics and sources of high particulate matter levels and the influence of typhoons and the Pacific high system. Depending on the measurements, two pollutant groups were clearly identified in this work. The first pollutant group was the emissions from neighboring riverbeds under the strong circulation of the typhoon in the driest season and characterized as high coarse particle concentrations with high mass fraction of Ca²⁺. The second pollutant group was characterized as the formation and transport of secondary particles with prevalent ions of NH₄⁺, NO₃^?, and SO₄^2? and occurred in the sea-land breeze circulation under the influence the Pacific high system.     

Association between prenatal exposure to phthalates and the health of newborns

Phthalates are developmental and reproductive toxicants for the fetus in pregnant rodents, and the ability of phthalates to penetrate the placenta have been reported. The aims of this study were to evaluate the association between maternal urine excretion, the exposure of fetus to phthalates in amniotic fluid, and the health of newborns. Amniotic fluid and urine samples from pregnant women were collected to measure five phthalate monoesters using liquid chromatography/tandem mass spectrometry (LC/MS-MS) and the newborns' birth weight, gestational age, and anogenital distance (AGD) were collected. The median levels of three phthalate monoesters in urine and amniotic fluid were 78.4 and 85.2 ng/mL monobutyl phthalate (MBP); 24.9 and 22.8 ng/mL mono-(2-ethylhexyl) phthalate (MEHP); 19.8 and Not Detected monoethyl phthalate (MEP). We found a significant positive correlation only between creatinine adjusted urinary MBP and amniotic fluid MBP (R(2)=0.156, p<0.05) in all infants and, only in female infants, a significantly negative correlation between amniotic fluid MBP, AGD (R=-0.31, p<0.06), and the anogenital index adjusted by birth weight (AGI-W) (R=-0.32, p<0.05). Although the influence of prenatal di-n-butyl phthalate (DBP) exposure on the endocrinology and physiology of the fetus is still a puzzle, our data clearly show that in utero exposure to phthalates in general has anti-androgenic effects on the fetus.     

Vegetation recovery patterns assessment at landslides caused by catastrophic earthquake: A case study in central Taiwan

The catastrophic earthquake, 7.3 on the Richter scale, occurred on September 21, 1999 in Central Taiwan. Much of standing vegetation on slopes was eliminated and massive, scattered landslides were induced at the Jou-Jou Mountain area of the Wu-Chi basin in Nantou County. We evaluated three methods for assessing landslide hazard and vegetation recovery conditions. (1) Self-organizing map (SOM) neural network coupled with fuzzy technique was used to quickly extract the landslide. (2) The NDVI-based vegetation recovery index derived from multi-temporal SPOT satellite images was used to evaluate vegetation recovery rate in the denudation sites. (3) The spatial distribution index (SDI) based on land-cover topographic location was employed to analyze vegetation recovery patterns, including the invading, surviving and mixed patterns at the Jou-Jou Mountain area. On September 27, 1999, there were 849.20 ha of landslide area extracted using the self-organizing map and fuzzy technique combined model. After six years of natural vegetation succession, the landslide has gradually restored, and vegetation recovery rate reached up to 86%. On-site observation shows that many native pioneer plants have invaded onto the denudation sites even if disturbed by several typhoons. Two native surviving plants, Arundo formosana Hack and Pinus taiwanensis Hayata, play a vital role in natural vegetation succession in this area, especially for the sites on ridgeline and steep slopes.     

Tidal influences on the habitat use of Indo-Pacific humpback dolphins in an estuary

This paper offers the first study of diurnal variations in the use of an estuarine habitat by Indo-Pacific humpback dolphins. Passive acoustic data loggers were deployed in the Xin Huwei River Estuary, Western Taiwan, from July 2009 to December 2010, to collect biosonar clicks. Acoustic encounter rates of humpback dolphins on the riverside of the estuary changed significantly over the four tidal phases, instead of the two diurnal phases based on the recordings from 268 days. Among the tidal phases, the encounter rates were lowest during ebb tides. Additionally, circling movements associated with the hunt for epipelagic fish significantly changed in temporal and spatial presence over the four tidal phases, matching the overall pattern of encounter rate changes in the focal estuary. Our findings suggest that the occurrence pattern and habitat utilization of humpback dolphins are likely to be influenced by the tidal-driven activity of their epipelagic prey.