Liquefaction process for a hydrothermally treated waste mixture containing plastics

Most landfilled plastic waste is a mixture or is in the form of composites with incombustible wastes such as glass, metals, and ceramics. After hydrothermal treatment, including a steam-explosion process, the separation of mixed waste (MW) into organic and inorganic substances becomes easy. However, the effect of hydrothermal pretreatment on the subsequent liquefaction of organic substances from MW is not obvious. In this study, the effects on the liquefaction of polystyrene and high-density polyethylene are discussed. Moreover, optimum conditions for the liquefaction of organic substances from hydrothermally treated MW are identified. By means of this hydrothermal pretreatment, including the steam-explosion process, polystyrene and high-density polyethylene can be significantly converted to oil by liquefaction at 300°–400°C. In comparison with liquefaction of hydrothermally pretreated mixed waste (HMW) at 300°–400°C with a batch type reactor, the yield of oil increases significantly on liquefaction using a semi-batch type reactor. It is considered that the radical chain and termination reactions among the radicals from HMW were inhibited in the semi-batch type reactor. On liquefaction of HMW in a semi-batch reactor, the conversion of HMW to oil was enhanced on increasing the liquefaction temperature to 350°C and the holding time to 60 min. Chemical Feedstock Recycling & Other Innovative Recycling Techniques 6     

SALINITY AND SEDIMENTATION STUDY–COOPER RIVER REDIVERSION,CHARLESTON, SOUTH CAROLINA1

The study was prepared in 1966 for the Bureau of Sport Fisheries and Wildlife, Department of the Interior, for presentation to the United States Army Corps of Engineers which had under study several routes for rediversion of the discharge from the Santee-Cooper Hydro Electric Plant, Steam Plant and Lock. Each rediversion was designed to by-pass the Charleston Harbor and this study and report was concerned with one of those routes–Rediversion Route “B.” The channel was to be designed for a maximum fresh-water flow of 27,500 cfs and a mean flow of 15,500 cfs. The objectives of the study and report were to make an estimate of: (1) the geographical extent of salt marsh waters of which the salinity will be measurably reduced, and (2) the probable accumulation of fresh-water borne sediments in those same waters. Special consultants were Dr. F. H. Kellogg, Memphis State University, and Mr. K. L. Drennan, Gulf Coast Research Laboratory, Mississippi.     

Examining Flood Frequency Distributions in the Midwest U.S.1

Villarini, Gabriele, James A. Smith, Mary Lynn Baeck, and Witold F. Krajewski, 2011. Examining Flood Frequency Distributions in the Midwest U.S. Journal of the American Water Resources Association (JAWRA) 47(3):447‐463. DOI: 10.1111/j.1752‐1688.2011.00540.x Abstract: Annual maximum peak discharge time series from 196 stream gage stations with a record of at least 75 years from the Midwest United States is examined to study flood peak distributions from a regional point of view. The focus of this study is to evaluate: (1) “mixtures” of flood peak distributions, (2) upper tail and scaling properties of the flood peak distributions, and (3) presence of temporal nonstationarities in the flood peak records. Warm season convective systems are responsible for some of the largest floods in the area, in particular in Nebraska, Kansas, and Iowa. Spring events associated with snowmelt and rain‐on‐snow are common in the northern part of the study domain. Nonparametric tests are used to investigate the presence of abrupt and slowly varying changes. Change‐points rather than monotonic trends are responsible for most violations of the stationarity assumption. The abrupt changes in flood peaks can be associated with anthropogenic changes, such as changes in land use/land cover, agricultural practice, and construction of dams. The trend analyses do not suggest an increase in the flood peak distribution due to anthropogenic climate change. Examination of the upper tail and scaling properties of the flood peak distributions are examined by means of the location, scale, and shape parameters of the Generalized Extreme Value distribution.     

火焰原子吸收法测定苹果中波尔多液的农药残留

通过原子吸收法测定苹果果皮、果肉上波尔多液的农药残留铜的含量,结果表明:喷洒了波尔多液的苹果果皮上铜含量明显大于果肉,在果皮上有一定的农药残留;而未喷洒波尔多液的苹果果皮和果肉中铜的含量的差异很小。     

混合气体直接吸附分离回收过程研究

以精密陶瓷制造过程中排放的甲苯和异丙醇混合气体为目标气体,采用4段活性炭吸附柱串联吸附实验方式研究了混合组分气体直接吸附分离回收的可行性.结果表明,异丙醇和甲苯这2种物性具有一定差异的物质在吸附床的长度方向存在明显的分层吸附现象.在表观气速0.42 m·s-1、异丙醇与甲苯入口浓度分别为477 mg·m-3和746 mg·m-3、吸附柱总长为26cm条件下,通气吸附798 min时,0～10 cm长度段炭层吸附甲苯量为184.5 mg·g-1,吸附异丙醇量为0 mg·g-1,而21～26 cm长度段炭层吸附甲苯量为0.92 mg·g-1,吸附异丙醇量为91.2 mg·g-1,通过分段再生回收分别得到了纯度99%以上的甲苯和异丙醇回收液.弱吸附质异丙醇在吸附过程中存在气相浓度增浓现象,该现象导致实验条件下部分活性炭层区域对异丙醇的吸附量提高了27%以上.通过多段串联吸附、分段再生回收的方式可以实现混合气体的直接吸附分离回收.     

波尔多液对土壤过氧化氢酶活性与构象的影响

为初步探讨波尔多液对土壤过氧化氢酶的作用机理及变化规律,采用人工模拟和荧光光谱法研究了波尔多液对土壤过氧化氢酶活性特征及构象的影响.结果表明:1)不同浓度波尔多液对土壤过氧化氢酶活性总体呈现低浓度激活、高浓度抑制作用.不同配制方式波尔多液对土壤过氧化氢酶活性抑制效应顺序为多倍量式>倍量式>半量式>等量式.浓度为200mg·kg-1左右的等量式波尔多液处理对土壤过氧化氢酶活性的影响最小.2)24h培养时间下,随波尔多液浓度的增加,酶促反应米氏常数Km和最大反应速率Vmax均呈先减小后增大趋势.统计分析表明,Km和Vmax均与波尔多液浓度呈显著正相关(p<0.01),土壤过氧化氢酶Km值可表征波尔多液对土壤过氧化氢酶活性的影响程度,其作用机理为反竞争性抑制类型.3)波尔多液对离体过氧化氢酶的内源荧光有较强的猝灭作用,Cu(Ⅱ)和离体过氧化氢酶的结合常数K及结合位点数n分别为69.1831mol·L-1和0.6878.     

太湖水体中5种有机磷农药混合物生态风险评价

有机磷农药是一类广泛分布于我国水环境中的污染物,即使在水体中的污染水平处于规定“安全标准”之下,其联合暴露产生的风险仍有可能威胁水生生态安全。采用基于浓度加和模型与生物敏感度分布曲线的混合物风险商法,评价了太湖水体中敌敌畏、对硫磷、甲基对硫磷、马拉硫磷和乐果5种有机磷农药混合物产生的生态风险。结果表明：2003～2004年期间3个不同时期太湖水体中5种有机磷农药的混合物生态风险商(RQ_m )均大于1,有机磷农药混合物在2003～2004年期间对太湖水生生物构成了一定威胁。