Systematic assessment of dredged sludge dewaterability improvement with different organic polymers based on analytic hierarchy process

Organic polymeric flocculants are commonly used in improving dredged sludge dewaterability, but less attention has been paid to residual water quality. In this paper, the effects of cationic etherified starch (CS) and poly-dimethyl diallyl ammonium chloride (PDDA) on dredged sludge dewatering efficiency and residual water quality of Baiyangdian lake were comprehensively investigated and evaluated by analytic hierarchy process (AHP). The results indicated that PDDA had stronger electrical effect and flocculation performance compared with CS, resulting in more efficient dewatering performance. PDDA can reduce the pollutants of discharged residual water, while CS significantly promoted the increase of NH₄⁺-N and NO₃^–-N in the residual water. The increase of NH₄⁺-N in the residual water of CS was due to the release of dredged sludge, while the increase of NO₃^–-N was introduced by CS leaching. AHP showed that PDDA performed better in flocculation treatment of dredged sludge than other organic polymers. This work provides a method for optimization of flocculation treatment for dredged sludge dewaterability.     

Coupling magnetic particles with flocculants to enhance demulsification and separation of waste cutting emulsion for engineering applications

Magnetic particles were coupled with a flocculant to enhance the demulsification and separation of waste cutting emulsions. The optimal magnetic particle size and critical magnetic field conditions were investigated to achieve large-scale engineering application of magnetic demulsification separation for waste cutting emulsion treatment. The micro-scale magnetic particles were found to show comparable effects to nano-scale magnetic particles on enhancing the demulsification and separation of cutting emulsions, which are beneficial for broadening the selectivity of low-cost magnetic particles. The critical magnetic separation region was determined to be an area 40 mm from the magnetic field source. Compared to the flocculant demulsification, the magnetic demulsification separation exhibited a significant advantage in accelerating flocs–water separation by decreasing the separation time of flocs from 180–240 min to less than 15 min, compressing the flocs by reducing the floc volume ratio from 60%–90% to lower than 20%, and showing excellent adaptability to the variable properties of waste cutting emulsions. Coupled with the design of the magnetic disk separator, continuous demulsification separation of the waste cutting emulsion was achieved at 1.0 t/hr for at least 10 hr to obtain clear effluent with 81% chemical oxygen demand removal and 89% turbidity reduction. This study demonstrates the feasibility of applying magnetic demulsification separation to large-scale continuous treatment of waste emulsion. Moreover, it addresses the flocs–water separation problems that occur in practical flocculant demulsification engineering applications.     

废旧轮胎在国内外道路工程中的应用现状

汽车工业的发展和汽车数量的增加,在给人民生活带来方便的同时,也产生了大量的废旧轮胎。废旧轮胎的堆积和不当处理,将对生态环境带来严重的污染,国内外学者对废旧轮胎的综合利用开展了大量的研究,将废旧轮胎经粉碎等处理制成橡胶沥青,应用于道路工程不仅提高了道路的耐热等性能,而且减少了生态环境污染,具有良好的社会效益、经济效益和环境效益。本文介绍了国内外对废旧轮胎在道路工程中的应用情况,通过与国外研究和工程实践的对比,指出了我国在此方面研究中存在的问题,为进一步废旧轮胎在道路工程中综合利用提供指导作用。     

废弃钻井泥浆无害化处理与评价方法的研究

本文简述了废弃钻井泥浆对环境的影响及无害化处理原则,分析了废弃钻井泥浆处理存在的问题,详细论述了废弃钻井泥浆无害化评价标准、浸出毒性评价方法以及分析结果的应用,为废弃钻井泥浆分类贮存、处置和土壤环境修复提供合理化建议。     

基于层次分析法的库岸高速滑坡危险度评价

高速滑坡的判定是滑坡治理工作中的一项重要内容,但由于目前尚没有统一规范的滑速计算方法,因而给高速滑坡的预测带来了一定的困难。层次分析法是一种定性与定量相结合的多目标决策分析方法,针对库岸高速滑坡发生的各影响因子,采用层次分析法对鹅公带古滑坡体的高速滑坡体危险度进行了分析评价,为库岸高速滑坡的预测提供了一条新思路。     

Waste-based composites—Poverty reducing solutions to environmental problems

This paper highlights an innovative model of waste management combined with poverty reduction, which has been developed by the organisation Waste for Life (wasteforlife.org) - a network of academics, students, practitioners and on the ground cooperative partners in low income communities. The Waste for Life teams work with local cooperatives to create waste-based composites, which may be sold in local markets, thereby creating an income stream. The application of this model to the context of cartoneros (waste picker) cooperatives in Buenos Aires, Argentina, reveals that viable products can be made from paper and plastic waste, with low-impact material preparation that circumvents the need for chemically intensive, polluting and mechanically degrading procedures, preserving recycled fibre integrity. Tests on material samples indicate mechanical properties comparable to products made with more complex processing. The production model is based on the philosophy that not only the waste materials, but also the production equipment should be locally sourced and manufactured and products created to suit local markets. A simple reproducible model has been developed for the local manufacture of composites from waste, which can provide an income source for waste pickers as well as providing an innovative waste management solution.     

城市埋地天然气管道系统脆弱性评估指标研究

脆弱性作为安全领域研究的新兴名词,用来表示系统承受外界扰动的敏感性和易损性以及面对灾害后果的承受力和应对能力,是联系灾害与风险研究的重要桥梁,是系统安全状况的重要综合指标。文章在引用以及重新界定＂脆弱性＂概念的基础上,将其引入城市天然气管道系统的安全研究,结合城市天然气管道系统的灾害事故特点,分析影响城市埋地天然气管道系统脆弱性的主要因素,根据因素间的相互关系,建立包括致灾因子、灾害后果和应对措施等3个方面2、2项指标的多因素多级评价指标体系。运用层次分析法（AHP）的原理和计算过程确定各评价指标的权重,根据指标权重的大小比较,分析各指标对城市天然气管道系统安全脆弱性的影响程度,从而确定安全治理的主要方向。     

Municipal solid waste generation in Kathmandu, Nepal

Waste stream characteristics must be understood to tackle waste management problems in Kathmandu Metropolitan City (KMC), Nepal. Three-stage stratified cluster sampling was used to evaluate solid waste data collected from 336 households in KMC. This information was combined with data collected regarding waste from restaurants, hotels, schools and streets. The study found that 497.3 g capita(-1) day(-1) of solid waste was generated from households and 48.5, 113.3 and 26.1 kg facility(-1) day(-1) of waste was generated from restaurants, hotels and schools, respectively. Street litter measured 69.3 metric tons day(-1). The average municipal solid waste generation rate was 523.8 metric tons day(-1) or 0.66 kg capita(-1) day(-1) as compared to the 320 metric tons day(-1) reported by the city. The coefficient of correlation between the number of people and the amount of waste produced was 0.94. Key household waste constituents included 71% organic wastes, 12% plastics, 7.5% paper and paper products, 5% dirt and construction debris and 1% hazardous wastes. Although the waste composition varied depending on the source, the composition analysis of waste from restaurants, hotels, schools and streets showed a high percentage of organic wastes. These numbers suggest a greater potential for recovery of organic wastes via composting and there is an opportunity for recycling. Because there is no previous inquiry of this scale in reporting comprehensive municipal solid waste generation in Nepal, this study can be treated as a baseline for other Nepalese municipalities.     

Fuzzy risk assessment of oil and gas offshore wells

Risk evaluation of offshore wells is a challenging task, given that much of the available data is highly uncertain and vague, and many of the mechanisms are complex and difficult to understand. Consequently, a systematic approach is required to handle both quantitative and qualitative data as well as means to update existing information when new knowledge and data become available. Each Basic Risk Item (BRI) in a hierarchical framework is expressed as a fuzzy number, which is a combination of the likelihood of a failure event and the associated failure consequence. Analytical Hierarchy Process (AHP) is used to estimate weights required for grouping non-commensurate risk sources. Evidential Reasoning (ER) is employed to incorporate new data for updating existing risk estimates. It is envisaged that the proposed approach could serve as a basis for benchmarking acceptable risks in offshore wells.     

基于区间数层次分析法的机场应急能力评价模型

为了发现机场应急管理中存在的问题,提高机场应急管理水平,对机场应急管理问题进行分析,建立机场应急能力评价幂指数模型。通过研究机场应急管理过程,对应急管理全周期进行任务分解,并运用人-机-环境系统理论,建立机场应急能力递阶结构模型。针对专家群给出的判断矩阵元素实际落在一个区间里,使用一种改进的区间数层次分析法对各个能力的权重进行计算。对南方某机场进行实例分析,结果表明:模型能够对机场应急救援能力作出综合评价,同时还可以找出机场应急管理中的薄弱环节。