Quantifying construction and demolition waste: An analytical review

Quantifying construction and demolition (C&D) waste generation is regarded as a prerequisite for the implementation of successful waste management. In literature, various methods have been employed to quantify the C&D waste generation at both regional and project levels. However, an integrated review that systemically describes and analyses all the existing methods has yet to be conducted. To bridge this research gap, an analytical review is conducted. Fifty-seven papers are retrieved based on a set of rigorous procedures. The characteristics of the selected papers are classified according to the following criteria - waste generation activity, estimation level and quantification methodology. Six categories of existing C&D waste quantification methodologies are identified, including site visit method, waste generation rate method, lifetime analysis method, classification system accumulation method, variables modelling method and other particular methods. A critical comparison of the identified methods is given according to their characteristics and implementation constraints. Moreover, a decision tree is proposed for aiding the selection of the most appropriate quantification method in different scenarios. Based on the analytical review, limitations of previous studies and recommendations of potential future research directions are further suggested.     

Anaerobic co-digestion of kitchen waste and fruit/vegetable waste: Lab-scale and pilot-scale studies

The anaerobic digestion performances of kitchen waste (KW) and fruit/vegetable waste (FVW) were investigated for establishing engineering digestion system. The study was conducted from lab-scale to pilot-scale, including batch, single-phase and two-phase experiments. The lab-scale experimental results showed that the ratio of FVW to KW at 5:8 presented higher methane productivity (0.725 L CH₄/g VS), and thereby was recommended. Two-phase digestion appeared to have higher treatment capacity and better buffer ability for high organic loading rate (OLR) (up to 5.0 g (VS) L^?1 d^?1), compared with the low OLR of 3.5 g (VS) L^?1 d^?1 for single-phase system. For two-phase digestion, the pilot-scale system showed similar performances to those of lab-scale one, except slightly lower maximum OLR of 4.5 g (VS) L^?1 d^?1 was allowed. The pilot-scale system proved to be profitable with a net profit of 10.173 $/ton as higher OLR (?3.0 g (VS) L^?1 d^?1) was used.     

A novel auditory working-memory vigilance task for mental fatigue assessment

An auditory working-memory vigilance task (AWVT), which involves higher mental abilities of a person, like working-memory and decision-making, in addition to vigilance, is presented for measuring human mental fatigue in this paper. A 25-h sleep deprivation study, with hourly testing by AWVT (3 min), PalmPVT (5 min) and self-report of sleepiness, is conducted on eight healthy subjects. The trend of mental fatigue level as measured by a specially proposed score, AWVT Fatigue Index (AFI), during the 25-h study shows very similar pattern to those of PalmPVT lapses and self-report sleepiness. AFI even shows closer correspondence to self-report sleepiness than PalmPVT lapses. This suggests that AWVT is able to measure performance decrement due to sleep deprivation, and it can even provide better measurement of mental fatigue than PalmPVT. AWVT shows a learning curve of less than 3 trials indicating that no skill is required in performing AWVT. Furthermore, repeat studies are done on five of the eight subjects. Pearson’s correlation analysis and other statistical exhibits suggest that AWVT has good test–retest reliability and within subject consistency, which are even better than those of PalmPVT. These results suggest that the AWVT can be used as a reliable objective measure of mental fatigue, and it can even track mental fatigue more accurately than PalmPVT in the real world where most tasks require not just a reaction time type response, but also higher mental abilities.     

Evaluating growth of larval walleye pollock, Theragra chalcogramma, using cell cycle analysis

Cell cycle analysis of muscle cell division rates offers a new and efficient technique to analyze growth of larval fish. Using this approach, growth of larval walleye pollock was estimated by determining cell proliferation rates, reasoning that growth during early life stages is probably attributed to increases in cell number rather than to increases in cell size. Characteristic patterns of brain and muscle cell division rates were produced in larval walleye pollock by manipulating their diet in the laboratory. The fraction of dividing muscle cells and, to a lesser extent, the fraction of dividing brain cells were direct indicators of fast and slow growth. A model was produced to estimate average growth rate from the fraction of dividing muscle cells. We developed a simple method for preparing and storing the muscle tissue that ensures nucleic acid stability for subsequent analyses and permits sampling in the field. We envision that the cell cycle methodology will have on-site applications, presenting an opportunity to attain real-time estimates of larval fish growth at sea. Determining the proportion of first-feeding larvae with a high fraction of dividing muscle cells may yield a means for predicting the proportion of fast-growing fish, i.e., the potential survivors.     

胶东半岛三生空间的时空演变与冲突测度研究

优化国土空间开发格局是推进生态文明建设的重要举措,在对胶东半岛的三生空间时空演变规律分析的基础上,构建基于“风险源—风险受体—风险效应”三生空间冲突测度模型,识别三生空间冲突的区域和强度。结果表明：2000—2015年胶东半岛三生空间的面积变化具有“一降一升一稳定”的特点,其生产空间占比最高,其次是生活空间,二者占比之和约为85%。胶东半岛三生空间平均冲突指数呈不断增加的趋势,稳定可控区域主要分布在生态空间内部的自然保护区,严重失控级别主要分布在生态空间与生产空间、生态空间与生活空间之间的交错地带。不同空间类型的空间冲突程度为生产空间>生活空间>生态空间,三生空间冲突水平在空间类型和县域也存在较大差异,并随着时间发生变化。

     

焙烧镁铝水滑石的制备及其对水中Cl-和SO42-的吸附特性

采用共沉淀法制备了n(Mg):n(Al)=3:1的镁铝水滑石(LDH),进一步通过焙烧得到改性产物LDO,用XRD与FT-IR对LDO进行了表征,系统研究了其对水中Cl-和SO42-的吸附特性。结果表明:焙烧温度为400℃时,LDO对Cl-和SO42-的吸附量较焙烧前分别提高了75.00%和78.20%;pH值在4~10之间,LDO对Cl-和SO42-的吸附量基本无变化;LDO对Cl-和SO42-的吸附分别符合准一级、准二级动力学模型,吸附等温线均可以用Langmuir方程来描述,最大吸附量分别为61.88和227.79 mg/g。LDO对不同浓度的盐渍土洗盐废水的吸附研究结果表明,LDO对洗盐废水中Cl-和SO42-的去除具有较好的效果。LDO投加量相同情况下,Cl-和SO42-浓度分别为60.71和50.03 mg/L时,LDO对Cl-和SO42-的吸附量分别为16.97和22.85 mg/g;当废水中Cl-和SO42-浓度分别为585.75和513.08 mg/L时,LDO对Cl-和SO42-的吸附量分别为0.89和112.47 mg/g。以上研究结果表明,利用LDO处理轻度的氯化物(氯化物硫酸盐)型盐渍土洗盐废水和中度硫酸盐(硫酸盐氯化物)型盐渍土洗盐废水时,吸附效果较好。     

SPE-HPLC法检测环境水样中的痕量三氯卡班

建立了环境水样中三氯卡班(TCC)的预处理和测定方法。考察了3种固相萃取(SPE)小柱、5种洗脱液对TCC回收率的影响。结果表明,采用ENVI-18 SPE小柱、以乙酸乙酯/乙腈(1:1)为洗脱液、高效液相色谱仪-紫外检测器(HPLC-UV)检测,以蒸馏水为背景溶液TCC的加标回收率高达95%,仪器检出限与定量限分别为2.37与7.89μg/L。该方法用于实际环境水样,TCC加标浓度1~10μg/L,污水厂进水、出水与地表水中TCC的加标回收率分别在89.38%~96.90%、87.74%~94.34%与83.64%~94.61%之间,表明所建立的SPE-HPLC法适合城市生活污水和地表水中痕量TCC的检测。运用该方法测定实际环境水样中的TCC含量,集美污水处理厂进水与出水中TCC浓度分别为1.35与0.22μg/L;华大污水厂进水与出水中TCC浓度分别为1.05与0.53μg/L;白鹭湖水样中的TCC浓度为1.11μg/L。     

综合利用镁合金废料制氢及氢氧化镁

AZ31B镁合金废片-盐水体系能同时产生氢气和Mg(OH)2,研究了催化剂,Cl-浓度和反应温度对该体系产氢速率的影响,并分析了产物Mg(OH)2的化学成分和形态结构。实验结果表明,与CuCl2相比,铜线作为催化剂不仅产氢的速率高,且不会污染形成的Mg(OH)2。Cl-浓度和反应温度影响对体系产氢速率有较大影响,当温度为60℃,盐水浓度为4 mol/L时产氢速率达到最大值为62 mL/(min·g)。采用扫描电镜、X射线能谱仪表征分析中间产物,探讨Cl-点蚀反应的机理,对产物氢氧化镁粉末进行表征和物相分析的结果表明,产物为高纯度Mg(OH)2纳米材料,其晶体结构和分散性随温度的增加变好,80℃下获得规整的六方晶体。     

复合多管除尘器在湿法水泥回转窑除尘中的应用

把具有惯性沉降除尘、旋风子除尘两级一体功能的复合多管除尘器用于带湿式蒸发器的湿法水泥回转窑尾气除尘，替换原“旋风除尘器＋电除尘器”除尘系统中的多筒旋风器。运行测试表明，它的除尘效率达到９４６％，确保了窑尾排放烟尘浓度达到国家标准。