Papers by Keyword: Working Surface

Abstract: The estimation of odorous compounds production from landfill sites is a very complicated task because of the various chemical and biological species that exist in landfill gas. In this study, the correlative concentration between ethanol and other odorous compounds emitted from the working surface at a landfill in Beijing was analyzed. Gas sampling was conducted at the landfill on several selected days from March 2012 to March 2014, representing the different periods throughout the two years. A total of 41, 59, 66, 54, 63, 54, 41, 42 species of trace compounds were identified and quantified during eight sampling activities, respectively, and a total of 86 species of trace compounds were identified and quantified all together. The measured trace compounds were classified into six different categories (Oxygenated compounds, Halogenated compounds, Terpenes, Sulfur compounds, Aromatics and Hydrocarbons). The total average concentrations of the oxygenated compounds, sulfur compounds, aromatics, halogenated compounds, hydrocarbons and terpenes were 2.450 mg/m³, 0.246 mg/m³, 0.203 mg/m³, 0.319 mg/m³, 0.530 mg/m³, 0.217 mg/m³, respectively. The correlative concentrations of the odorous compounds with respect to the concentration of ethyl alcohol (ethyl alcohol taken 1000 ppm total) were determinate, which could make great significance to the estimation of odorous compounds emitted from the landfill sites.

Abstract: With the rapid urbanization and economic growth in China especially near 2 decades, the vast amount of municipal solid waste (MSW) were produced annually. Landfills are the predominant disposal sites for MSW in China, receiving more than 75% of the collected MSW every year. While the volume concentration is usually less than 1%, NMOCs are generally considered as the main source of the odorous problem at MSW landfills, because they include many compounds with very low odor thresholds. What’s more, aromatics is vital part of NMOCs for its toxic effect, which contains Benzene. The main objective of this study was to understand the comprehensive behavior of aromatics of landfill gas. In this work we present an integrated evaluation of working surface concentration distribution and emission rate of a municipal solid waste landfill. And in order to understand the transportation of aromatic, a new parameter was introduced to analyze this process. Thus, result shows, the fugitive emission of aromatics in the operating surface may need pay more attention. The highest average concentration for aromatics was found in autumn. Aromatic’s emission rate in winter was larger than autumn, the highest emission rate of aromatics toluene, 0.011g/m²/h. The B:T ratio in winter was significant higher that of other seasons.

Abstract: When there are storey-to-storey relationships or construction storey by storey, to discuss the flow construction cycle time with technology intermission or organizing intermission time. When the category of the construction sections can meet the requirements of formula, i.e. , has included middle storey intermission in construction period calculation formula, there is not single item; When the category of the construction sections can not meet the requirements of formula, i.e. or , there should make single item in middle storey intermission in construction period calculation, at that time, the working team can not be continuous and the working surface can make maximum connection.

Abstract: The grinding should be improved to be the skill-free process executed based on the quantified criteria. In this study, the evaluation methods are applied to evaluate the dressing process to clarify how the dressing changes the cutting-edge distribution. From the results, the following facts have been clarified: There is the critical value of the depth of cut for suppressing the release of grain. The spark-out in dressing releases grains damaged by collision with dresser, and then, it also increases the cutting-edge density.