Experimental and life cycle assessment analysis of gas emission from mechanically–biologically pretreated waste in a landfill with energy recovery

The global gaseous emissions produced by landfilling the Mechanically Sorted Organic Fraction (MSOF) with different weeks of Mechanical Biological Treatment (MBT) was evaluated for an existing waste management system. One MBT facility and a landfill with internal combustion engines fuelled by the landfill gas for electrical energy production operate in the waste management system considered. An experimental apparatus was used to simulate 0, 4, 8 and 16 weeks of aerobic stabilization and the consequent biogas potential (Nl/kg) of a large sample of MSOF withdrawn from the full-scale MBT. Stabilization achieved by the waste was evaluated by dynamic oxygen uptake and fermentation tests. Good correlation coefficients (R²), ranging from 0.7668 to 0.9772, were found between oxygen uptake, fermentation and anaerobic test values. On the basis of the results of several anaerobic tests, the methane production rate k (year^?1) was evaluated. k ranged from 0.436 to 0.308 year^?1 and the bio-methane potential from 37 to 12 N m³/tonne, respectively, for the MSOF with 0 and 16 weeks of treatment. Energy recovery from landfill gas ranged from about 11 to 90 kW h per tonne of disposed MSOF depending on the different scenario investigated. Life cycle analysis showed that the scenario with 0 weeks of pre-treatment has the highest weighted global impact even if opposite results were obtained with respect to the single impact criteria. MSOF pre-treatment periods longer than 4 weeks showed rather negligible variation in the global impact of system emissions.     

SBR工艺处理皂素废水的实验研究及对策分析

废水处理是皂素产业可持续发展的关键,为解决这一问题,我们综合考虑了皂紊废水处理的技术、经济和运行管理等方面,预选了SBR工艺,并以反应时间为中心,试验分析了基质浓度、污泥浓度、温度和曝气强度对反应时间的影响。试验结果表明,氧的传质是SBR工艺处理皂素废水的核心问题,并据此分析了提高经济性和运行管理可操作性的对策。     

测定废水BOD5时水样稀释倍数的确定

根据测定BOD5所须具备条件,经过理论推导,得出水样稀释倍数的大致范围,对多种工业废水测试证,表明方法简便易行。     

Pt颗粒尺寸对Pt/CeO2催化氧化甲苯性能影响

使用乙二醇还原法制备了一系列不同尺寸的Pt-x纳米颗粒(x=1.41、1.57、1.79、1.95、2.12、2.32 nm),将其负载于棒状(rod)CeO_2载体上.考察了不同尺寸的Pt颗粒催化剂Pt-x/CeO_2-rod在甲苯催化氧化反应中的催化性能.结果显示,随着Pt颗粒尺寸的增加,催化剂活性先升高后降低.其中,Pt颗粒尺寸为1.79 nm时催化剂催化活性最好,T90=133℃.一般认为,Pt颗粒尺寸增加其分散度减小,导致催化活性降低.然而本实验结果表明,随Pt尺寸增加催化活性先升高后降低,并且基于催化剂表面Pt原子计算的TOFs(turnover frequencies)随Pt尺寸增加逐渐变大.紫外拉曼光谱(UV Raman)、XRD、XPS显示,随着Pt颗粒尺寸增加,催化剂Pt-x/Ce-rod表面氧空位的浓度逐渐增加.氧空位有效提高了催化剂晶格氧的流动,促进了氧气的吸附活化及传递过程.Pt/Ce催化剂催化氧化甲苯反应活性是Pt分散度以及CeO_2表面氧空位浓度双重作用的结果.     

Model parameterization for aerobic decomposition of plant resources drowned during man-made lakes formation

The formation of man-made reservoirs generates several impacts on water quality. In order to minimize some of these impacts mathematical models are currently used. This paper aims to discuss the issue associated with the degradation of plant resources (leaves, branches, barks and litter) that remain within the watershed of the new man-made lakes and parameterize a kinetic model related to decay of plant detritus. In these environments, the short-term variation of limnological parameters is mainly connected with biomass decay drowned during the filling operation. The kinetics of the degradation processes in reservoirs are discussed on the basis of information with related to detritus sources and the chemical properties of different types of compounds (i.e. labile and refractory fractions). Overall, the parameterization of the (first order) kinetic model showed that refractory fractions (ca. 86%) are predominant and the mineralization is a slow process, constituting the main route for decomposition and being affected by changes of environmental variables. The mineralization of labile and hydrosoluble compounds (ca. 14%) is responsible for the short-term water quality variation owing to decomposition; basically, the intensities of these changes depend on the labile/soluble compounds content of detritus and its chemical composition.     

Anthraquinone acted as a catalyst for the removal of triphenylmethane dye containing tertiary amino group: Characteristics and mechanism

Herein, we found that anthraquinone (AQ) acted as a catalyst for the rapid and effective removal of triphenylmethane dye containing tertiary amino group (TDAG). Results showed that AQ had an enhanced catalytic reactivity towards the removal of TDAG compared to hydro-quinone, which was further proved and explained using density functional theory (DFT) calculations. AQs could achieve a TDAG removal efficiency and rate of approximately 100% and 0.3583 min⁻¹, respectively, within 20 min. Quenching experiments and electron paramagnetic resonance (EPR) tests indicated that the superoxide radical (O₂^•−) generated through the catalytic reduction of an oxygen molecule (O₂) by AQ contributed to the effective removal of the TDAG. In addition, it was found that the electrophilic attack of the O₂^•− radical on the TDAG was the driving force for the dye degradation process. Decreasing the pH led to protonation of the substituted group of AG, which resulted in formation of an electron deficient center in the TDAG molecule (TDAG-EDC⁺) through delocalization of the π electron. Therefore, the possibility of the electrophilic attack for the dye by the negative O₂^•- radical was significantly enhanced. This study revealed that the H⁺ and the O₂^•− generated by the catalytic reduction of O₂ have synergistic effects that led to a significant increase in the dye removal rate and efficiency, which were higher than those obtained through persulfate oxidation.     

Organic matter composition in sediments of the Oman Margin

The quantity and biochemical composition of organic matter (OM) in the sediments underlying and below oxygen minimum zone (OMZ) in the Arabian Sea were studied to provide information on the diagenetic processes of organic carbon under different environmental conditions. Concentrations of total organic carbon (TOC), total nitrogen (TN) and total hydrolysable amino acids (THAA) were significantly higher in sediments within rather than below OMZ, while those of total carbohydrates (TCHO) were slightly lower in the latter, suggesting the presence of a larger supply of labile compounds into the sea bottom at the shallower site (i.e. within OMZ). Hydrolysable amino acid and carbohydrate contribution to TOC were even lower (about 10% in surficial sediments) than the values obtained from the abyssal oligotrophic North Pacific, suggesting that OM food availability in the Oman Margin sediments within OMZ was lower than that observed at abyssal depths. The presence of the highest THAA and TCHO concentrations in the top 40?mm of the sediment core at both sites reflected the presence of bioturbation processes. In contrast with the general view of the deep sea as a stable and constant system, below OMZ in the Arabian Sea sediments, some differences were observed in the two investigated cores indicating the presence of a certain spatial variability in OM content and diagenesis.     

PM-support interfacial effect and oxygen mobility in Pt,Pd or Rh-loaded (Ce,Zr,La)O2 catalysts

• Pt/CZL exhibits the optimum catalytic performance for HC and NO_x elimination. • The strong PM-Ce interaction favors the oxygen mobility and DOSC. • Pd/CZL shows higher catalytic activity for CO conversion due to more O_latt species. • Great oxygen mobility at high temperature broadens the dynamic operation window. • The relationship between DOSC and catalytic performance is revealed. The physicochemical properties of Pt-, Pd- and Rh- loaded (Ce,Zr,La)O₂ (shorted for CZL) catalysts before/after aging treatment were systematically characterized by various techniques to illustrate the relationship of the dynamic oxygen storage/release capacity and redox ability with their catalytic performances for HC, NO_x and CO conversions. Pt/CZL catalyst exhibits the optimum catalytic performance for HC and NO_x elimination, which mainly contribute to its excellent redox ability and dynamic oxygen storage/release capacity (DOSC) at lower temperature due to the stronger PM (precious metals)-support interaction. However, the worse stability of Pt-O-Ce species and volatile Pt oxides easily result in the dramatical decline in catalytic activity after aging. Pd/CZL shows higher catalytic activity for CO conversion by reason of more O_latt species as the active oxygen for CO oxidation reaction. Rh/CZL catalyst displays the widest dynamic operation window for NO_x elimination as a result of greater oxygen mobility at high temperature, and the ability to retain more Rh-O-Ce species after calcined at 1100°C effectively restrains sintering of active RhO_x species, improving the thermal stability of Rh/CZL catalyst.     

上海市南汇大治河水质CODcr的监测评价

南汇大治河化学需氧量(CODcr)含量的调查结果表明,大治河的CODcr含量逐年上升,水质从Ⅲ级水体下降到Ⅳ级水体,个别断面有恶化到Ⅴ级水源的趋势,通过分析认为CODcr含量的上升与工业废水大量不达标排放以及生活污水的乱排放有关。     

座舱减压时间对应急供氧参数的影响

通过实验和理论计算的方法对座舱爆炸减压过程中压力变化进行了研究 ,推导了座舱减压时间的计算公式 ;并就座舱减压时间的变化对应急供氧参数进行了分析。结果表明 :减压时间与座舱的容积成正比 ,与爆炸孔的有效面积成反比 ;减压时间的不同 ,对爆炸减压峰值有影响 ,而对剩余压力、稳定值影响不大。研究结果为今后进行供氧系统的爆炸减压实验提供了依据