Economic and Environmental Benefits of Using Hardwood Sawmill Waste as a Raw Material for Particleboard Production

Annually, sawmills and other wood-processing factories generate a significant amount of scrap materials which are sent to landfills or incinerated. The amount of residue generated in Australia annually is estimated at 200,000 tonnes. A research project conducted at RMIT University explored utilizing these waste materials as particleboard furnish. The research team has now established a methodology for making particleboard in the laboratory using 100% hardwood sawmill residues, developing a particleboard product made in the laboratory which has acceptable mechanical properties and density profiles in accordance with the Australian Standards. However, this board product has some perceived issues which have been hindering ready commercial uptake. The current product requires a 10% higher resin load, has a 10% higher board density, and requires 10% longer pressing times compared to normal softwood particleboard. The paper presents an analysis of the current production process of particleboard to investigate the economic feasibility of particleboard production using hardwood sawmill residues. A major challenge in the analysis is converting the environmental benefit of utilizing large quantities of sawmill residue to a monetary term. Investigation of the global impact of particleboard by considering emission of carbon dioxide to the atmosphere is also included. A comparison is presented between different methods of disposing wood residues to understand the environmental benefit of using hardwood residue in particleboard.     

缺氧折流板反应器的流态及污泥颗粒运动分析

采用缺氧折流板反应器(ABR)处理印染废水,当HRT为8 h时,ABR内的下向导流室雷诺数(Re)为1.1,上向漉反应室Re为0.1,均为层流.污泥颗粒经绕流运动分析.下向导流室污泥颗粒受到的绕流阻力和重力均向下,只有浮力向上,由于污泥颗粒密度大于流体的密度,此时重力大于浮力,污泥颗粒不能在下向导流室内稳定停留,即没有污泥层,与观察到的试验现象一致.在上向流反应室的污泥颗粒受到的绕绕阻力向上,重力与绕漉阻力、浮力处于动态平衡时的污泥颗粒的临界粒径(dcr)为85 μm.     

生态保护是建设生态文明的重要基础

十七大提出建设生态文明的奋斗目标,具有极其重大的意义.生态保护在建设生态文明中具有保护生存条件、保障生态安全、保护自然资源及生产力、保障可持续发展、促进生态文明观念在全社会牢固树立等重要作用.因此,生态保护是建设生态文明的物质基础、实现生态现代化的前提、建设生态道德的重要载体.     

Residual levels of DDTs and PAHs in freshwater and marine fish from Hong Kong markets and their health risk assessment

Axial and ventral muscle from 10 each species of freshwater and marine fish purchased from markets in Hong Kong were analyzed for dichlorodiphenyltrichloroethane (total DDTs including DDE, DDD and DDT) and polycyclic aromatic hydrocarbons (PAHs). Among the 10 freshwater fish species, rice field eel (Monopterus albus) showed significantly higher levels of DDTs in both ventral (125 ng/g wet wt) and axial muscle (127 ng/g wet wt) than the other species. The highest concentration of PAHs was detected in catfish (Clarias fuscus), with 24.8 ng/g in ventral muscle and 9.1 ng/g in axial muscle. As to marine fish, snubnose pompano (Trachinotus blochii) showed significantly higher levels of DDT and its metabolites (1018 ng/g in ventral and 409 ng/g wet wt in axial tissues) than all other marine fish species. The overall concentrations of PAHs in marine fish species were 15.5-57.0 ng/g (axial muscle) and 18.1-118 ng/g wet wt (ventral muscle) where yellow seafin (Acanthopeyrus latus) and golden threadfin bream (Nemipterus virgatus) exhibited the highest concentrations of PAHs in the axial and ventral muscles, respectively. In general, results showed that levels of PAHs in Hong Kong market fish was low and do not expect to cause any concern for human consumption. However, the levels of DDTs in fish samples ranged from 1.10 to 1018 ng/g wet wt, and based on a fish consumption rate of 142.2g/day to calculate the screening value of 14.4 ng/g wet wt for human consumption (USEPA, 2000. Guidance for assessing chemical contaminant, data for use in fish advisories, vol. 1: fish sampling and analysis, third ed. EPA 823-R-95-007. Office of Water, Washington, DC), there were 9 out of 20 (45%) muscle samples of freshwater fish species and 14 out of 20 (70%) muscle samples of marine fish species had elevated levels of DDTs exceeded the screening value. It was also suggested to use ventral muscle for detecting concentrations of persistent organic pollutants in fish.     

崇明岛种子植物区系及植被资源

崇明岛共有区系植物55科157属198种，区系组成复杂，地理成分多样，涵盖全部15个分布区类型，具有明显的热带-温带过渡性质，落叶树种占木本植物种类的90．5％，属于北亚热带常绿落叶阔叶混交林地带。群落外貌及属的相似性系数分析表明，崇明岛植物区系更接近江苏宜兴，而与临近的大金山岛和佘山差别略大。此外，岛上还有栽培植物和外来植物共235种，其中蔷薇科、菊科、禾本科、豆科、木犀科等科的种类较丰富，以加拿大一枝黄花、臭荠、刺果毛莨、一年蓬、空心莲子草、大米草、互花米草等对当地植被资源和生态系统的影响最大。崇明岛植物群落结构单一，缺乏灌木层，草本层多为广布杂草，其植被资源可以根据功能划分为江防海防林、湿地植被、道路绿化带、庭院景观林、游憩林、大田作物及经济林、水源涵养林等7大类，其中江防海防林及湿地植被是崇明岛植被生态系统的关键成分。提供了崇明岛新纪录野生及外来种子植物名录。     

UASB处理离子交换树脂生产废水的试验研究

本研究主要介绍，尝试采用UASB（Upflow Anaerobic Sludge Bed）反应器厌氧工艺处理某离子交换树脂生产废水试验。研究表明，在中温（37℃±1）环境下，容积负荷在6．0-7．0kgCODcr·m^-3·d^-1时，CODcr去除率维持在80％左右，运行稳定。本试验取得的试验效果，为以后的利用厌氧技术处理离子交换树脂生产废水提供了重要依据。     

催化臭氧氧化法处理甲醛废水

用异丙醇钛盐表面改性法制备TiO2／SiO2催化剂，对甲醛废水进行催化臭氧氧化处理。通过比表面积的BET测定法、X射线衍射和拉曼光谱等分析方法对TiO2／SiO2催化剂进行了表征，考察了TiO2／SiO2催化剂加入量、臭氧流量及溶液pH等因素对甲醛催化臭氧氧化效果的影响。实验结果表明，在SiO2表面，TiO2微晶粒子以锐钛矿型高度分散；在甲醛质量浓度700mg／L、COD1000mg／L、TiO2／SiO2催化剂加入量2．0g、臭氧流量2．5mg／min、溶液pH8．5的条件下，催化臭氧氧化反应30min后，甲醛质量浓度由700mg／L降至39mg／L，COD去除率认到87．5％．     

深圳市新一代暴雨强度公式的研制

首先构造了深圳市新一代暴雨强度公式研制的路线图，重点是利用深圳市气象局1954-2003年50年间的暴雨记录，用指数分布和P-Ⅲ分布进行分布曲线拟合和选优，得到了理论上的雨强-历时-重现期三联表，在此基础上再分别采用最优法、二分搜索法和广义逆法等3种方法求解分公式和总公式参数，根据误差最小的原则确定最优方法。结果表明：由指数分布拟合分布曲线，经过上述步骤求解得到的公式参数，误差最小，符合相关国标要求。     

Effects of aluminum on physiological metabolism and antioxidant system of wheat (Triticum aestivum L.)

We have found that rice bran effectively adsorbed chloroform from tap water. The amount of chloroform adsorbed was plotted against the equilibrium concentration of chloroform in solution on a logarithmic scale. A linear relationship was obtained, indicating that the adsorption reaction was a Freundlich type. The removal of chloroform by rice bran was attributed to the uptake into intracellular particles called spherosomes.     

临界距离老空水下薄煤层联合开采安全性分析

以现场实测结果为基础 ,利用数值模拟与反演方法分析了薄煤层联合开采的顶、底板破坏范围。根据分析的结果评价了临界距离老空水下薄煤层联合开采的安全性。