Decomposing detonation and deflagration properties of ozone/oxygen mixtures

In this study, the decomposing detonation and deflagration properties of ozone/oxygen mixtures of up to 20 vol.% of ozone in oxygen under high pressure of up to 1.0 MPa in a tube were experimentally investigated. The mixtures were ignited by an electric spark at the end of the tube. Flame propagation properties such as flame velocity and pressure were measured with thermocouples and piezo electric transducers mounted along the tube. Slow and constant flame propagation profiles were obtained. We also investigated the quenching ability of a wire gauze as well as the concentration limit for flame propagation. However, in spite of slow flame propagation velocity and easy flame quenching properties under these experimental conditions, direct initiation of detonation by the driver detonation of the stoichiometric oxy-hydrogen mixture was easily achieved at much lower concentrations than the limit of deflagration. The observed detonation properties, such as wave velocity and pressure, agreed fairly well with C–J calculated values. The detonation velocity (900–1200 m/s) and the pressure ratio to initial pressures (5–9.5) were not affected by the initial pressure of the mixtures. Near the detonation limit, typical spinning detonations with oscillatory pressure waves were observed.     

Arsenic and Mn levels in Isaza (Gymnogobius isaza) during the mass mortality event in Lake Biwa, Japan

The present study measured the concentrations of 25 elements (Li, Mg, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, Hg, Tl, Pb and Bi) in the whole body of Isaza which is an endemic fish species to Lake Biwa, Japan, and compared the values in the specimens from the mass mortality Isaza (MMI) and normal fresh Isaza (NFI). The mean levels of Mn and total As (T-As) were relatively higher in MMI than in NFI. In the T-As, highly toxic inorganic As was detected in MMI. Moreover we found Mn and As concentrations in surface sediment were extremely high and temporally increased. From all these results, we could infer that the dissolution of Mn and As from surface sediment of Lake Biwa might have been one of the cause for the mass mortality of Isaza.     

Soil contamination by halogenated polycyclic aromatic hydrocarbons from open burning of e-waste in Agbogbloshie (Accra,Ghana)

Detailed composition of chlorinated and brominated polycyclic aromatic hydrocarbons (Cl-PAHs and Br-PAHs) generated during informal recycling of e-waste and their toxic relevance are still poorly understood. This study investigated the occurrence of Cl-PAHs and Br-PAHs in surface soil samples from the Agbogbloshie e-waste recycling site (Accra, Ghana) using quantitative gas chromatography–mass spectrometry (GC–MS) and comprehensive two-dimensional GC–time-of-flight mass spectrometry (GC × GC–ToFMS) profiling. The results of GC–MS analysis showed elevated concentrations in open e-waste burning areas (160–220 and 19–46 ng/g dry weight for Cl- and Br-PAHs, respectively) with substantial contribution from unidentified compounds (respectively, more than 36 and 70%, based on the total areas of potential peaks). Cl- and Br-PAHs from e-waste burning had a distinctive composition dominated by ring–ring compounds. Several homologue groups not monitored with GC–MS were found using GC × GC–ToFMS: PAHs with up to 5Cl or 3Br, mixed halogenated PAHs and chlorinated methylPAHs. The dioxin-like toxic equivalents of the identified Cl-/Br-PAHs in soils, estimated from their in vitro AhR agonist potencies relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin, were much lower than the range reported for chlorinated and brominated dioxins. However, the toxicity of the unidentified halogenated PAHs remained unclear.     

Preparation of zeolitic material with simultaneous removal of NH4 + and PO4 3− from paper sludge ash via acid leaching

This study investigates the preparation of zeolitic material with removal of both NH₄ ⁺ and PO₄ ^3? from paper sludge ash (PSA) via acid leaching. PSA typically has a low Si and high Ca content, owing to the presence of calcite fillers. Acid leaching with 3 M HCl was used firstly to reduce the Ca content of the PSA, whereafter a zeolite-P (Na-P) product with high cation exchange capacity (CEC) was synthesized through reaction with 2.5 M NaOH solution at 80 °C. Ca-P zeolitic products were prepared by Ca-treatment with the leachant that had been in contact with the PSA. The product with high CEC capacity including Na-P could be synthesized from the acid-leached ash, and the high Ca content in the ash could be reduced by extraction of the Ca into the leachant via the acid leaching. The Ca-P zeolitic product could be prepared by Ca-treatment with the solution obtained from neutralization of the leachant with NaOH. This product was capable of removing NH₄ ⁺ and PO₄ ^3? from aqueous solution, simultaneously.     

Exposure assessment of lead to workers and children in the battery recycling craft village,Dong Mai,Vietnam

Human exposure to lead (Pb) due to uncontrolled Pb-acid battery recycling has been an environmental health issue in newly developed industrial regions. We conducted a human monitoring survey in Dong Mai, a battery recycling village in Vietnam, to assess exposure status to Pb. Lead level was measured in hair, blood and urine samples of residents in Dong Mai and two reference sites during 4 years spanning 2007–2011. In Dong Mai, Pb levels in three matrixes were significantly higher than those in reference sites. Blood Pb levels of all adults and children exceeded 10 μg/dL, the Centers for Disease Control and Prevention definition of an elevated blood Pb level. Clear increase of urinary δ-aminolevulinic acid (ALA) level with increasing blood Pb level indicated disruption of heme synthesis. One adult exceeded 100 μg/dL of blood Pb, where encephalopathy is of concern. The blood Pb levels achieved various toxic effect threshold values, and elevated blood Pb was not limited to recycling workers, but was also in children and women of reproductive age. Serious pollution status of Dong Mai village suggests an importance of further monitoring surveys in various developing Asian countries.     

Ammonia removal from pretreated methane fermentation effluent through a soil trench system: a column experiment

In order to find the optimal running conditions and mechanisms of ammonia removal through a soil trench system that is designed for treating pretreated methane fermentation effluent, a soil column whose structure was similar to the soil trench system was prepared, and irrigated with wastewater below 30 °C. At the beginning, ammonia was mainly adsorbed by the soils, and the ammonia adsorption capacity of soils gradually saturated. After the 12th day, nitrification began in the soil column; the ammonia in the soil column decreased sharply, and the nitrite and nitrate peak appeared sequentially as the wastewater application rate decreased from 0.74 to 0.37 l h⁻¹. When the nitrification in the soil column reached a steady-state, 98% of all the ammonia in the influent was transformed into nitrate.

By changing the running conditions such as temperature, aeration, and wastewater application rate, it was found that the ammonia removal efficiency can be improved by aeration and impeded by low temperature. In these three variables, wastewater application rate has much greater affect on the ammonia removal efficiency; a lower wastewater application rate can increase the ammonia removal efficiency substantially because of the longer travel time.     

Waste generation in traditional organized bazaars: a case study of organic waste sources in Da Nang City,Viet Nam

Journal of Material Cycles and Waste Management - Traditional organized bazaars are important retail venues in Viet Nam, but there are concerns about their waste management programs. This study...     

Female sex pheromone and male behavioral responses of the bombycid moth <Emphasis Type="Italic">Trilocha varians</Emphasis>: comparison with those of the domesticated silkmoth <Emphasis Type="Italic">Bombyx mori</Emphasis>

Analysis of female sex pheromone components and subsequent field trap experiments demonstrated that the bombycid moth Trilocha varians uses a mixture of (E,Z)-10,12-hexadecadienal (bombykal) and (E,Z)-10,12-hexadecadienyl acetate (bombykyl acetate) as a sex pheromone. Both of these components are derivatives of (E,Z)-10,12-hexadecadienol (bombykol), the sex pheromone of the domesticated silkmoth Bombyx mori. This finding prompted us to compare the antennal and behavioral responses of T. varians and B. mori to bombykol, bombykal, and bombykyl acetate in detail. The antennae of T. varians males responded to bombykal and bombykyl acetate but not to bombykol, and males were attracted only when lures contained both bombykal and bombykyl acetate. In contrast, the antennae of B. mori males responded to all the three components. Behavioral analysis showed that B. mori males responded to neither bombykal nor bombykyl acetate. Meanwhile, the wing fluttering response of B. mori males to bombykol was strongly inhibited by bombykal and bombykyl acetate, thereby indicating that bombykal and bombykyl acetate act as behavioral antagonists for B. mori males. T. varians would serve as a reference species for B. mori in future investigations into the molecular mechanisms underlying the evolution of sex pheromone communication systems in bombycid moths.     

Hazard evaluation of hydrogen–air deflagration with flame propagation velocity measurement by image velocimetry using brightness subtraction

Deflagration phenomena in hydrogen–air mixtures initially filled in 1.4 m³ spherical latex balloons were measured using a high-speed digital video camera and pressure transducers. The image velocimetry using brightness subtraction was introduced to eliminate the background effects for obtaining accurate time evolution records of flame propagation velocity. The maximum flame propagation velocity of about 100 m/s was observed with maximum overpressure 15 kPa at 1 m from ignition point. According to the detailed flame propagation velocity records, there were long deceleration durations. The observed maximum overpressure was smaller than the overpressure estimated by the basis of the observed maximum flame propagation velocity and the pressure wave theories of spherical flames. A new blast curve plot of scaled overpressure vs. distance was tentatively proposed.