Open burning of household waste: Effect of experimental condition on combustion quality and emission of PCDD, PCDF and PCB

Open burning for waste disposal is, in many countries, the dominant source of polychlorinated dibenzodioxins, dibenzofurans and biphenyls (PCDD/PCDF/PCB) release to the environment. To generate emission factors for open burning, experimental pile burns of about 100 kg of household waste were conducted with emissions sampling. From these experiments and others conducted by the same authors it is found that less compaction of waste or active mixing during the fire - “stirring” - promotes better combustion (as evidenced by lower CO/CO₂ ratio) and reduces emissions of PCDD/PCDF/PCB; an intuitive but previously undemonstrated result. These experiments also support previous results suggesting PCDD/PCDF/PCB generation in open burning - while still highly variable - tends to be greater in the later (smoldering) phases of burning when the CO/CO₂ ratio increases.     

Agricultural waste as household fuel: Techno-economic assessment of a new rice-husk cookstove for developing countries

In many rural contexts of the developing world, agricultural residues and the organic fraction of waste are often burned in open-air to clear the lands or just to dispose them. This is a common practice which generates uncontrolled emissions, while wasting a potential energy resource. This is the case of rice husk in the Logone Valley (Chad/Cameroon). In such a context household energy supply is a further critical issue. Modern liquid fuel use is limited and traditional solid fuels (mainly wood) are used for daily cooking in rudimentary devices like 3-stone fires, resulting in low efficiency fuel use, huge health impacts, increasing exploitation stress for the local natural resources. Rice husk may be an alternative fuel to wood for household energy supply. In order to recover such a biomass, the authors are testing a proper stove with an original design. Its lay-out (featuring a metal-net basket to contain the fuel and a chimney to force a natural air draft) allows a mix of combustion/gasification of the biomass occurring in a completely burning fire, appropriate for cooking tasks. According to results obtained with rigorous test protocols (Water Boiling Test), different lay-outs have been designed to improve the performance of the stove. Technical and economic issues have been addressed in the development of such a model; building materials have been chosen in order to guarantee a cost as low as possible, using locally available items. The feasibility of the introduction of the stove in the studied context was assessed through an economic model that keeps into account not only the technology and fuel costs, but also the energy performance. According to the model, the threshold for the trade-off of the stove is the use of rice husk to cover 10–15% of the household energy needs both with traditional fireplaces or with improved efficiency cookstoves. The use of the technology proposed in combination with improved woodstove would provide householders with an appropriate and convenient cooking technology portfolio, increasing the opportunities of choice of the preferred energy system for the user and allowing significant savings for the family budget (up to 50% of the total annual cooking energy expenditure). The proposed model may be used also as a tool for the evaluation of the affordability or for the comparison of different cooking technologies also in other similar contexts, given their specific techno-economic parameter values.     

化工园区安全准入理论框架探讨

目前化工行业及化学工业园区的安全准入主要依据是现行的法律、规范和标准,而化学工业及化工园区的飞速发展使得现有的规范、标准等存在严重地滞后性,远远不能满足化工园区区域安全准入及风险承载核算的要求。论文针对化工园区目前建设及发展状况,主要分析化工园区安全准入的内涵、现存状况及存在的局限性,构建化学工业园区规划及企业安全准入的基本理论框架,研究思路从化学工业园区的定性、定量风险着手,阐述准入的具体步骤、关键把握的重点以及风险承载状况,并针对国外的风险容许标准,确定适合我国化工园区的风险准入准则,最后提出下一步的研究重点,对指导我国目前化工园区安全准入具有一定的理论和现实意义。     

荧光废水中COD_(Cr)闭管与开管消解测定方法研究

通过考察6个实验室中,标准溶液和标准样品的试验分析数据,得出闭管法较开管法具有更优的准确度、精密度和氧化能力,其闭管法的最佳氧化浓度(并非检测限)在150～850mg/L;结合水样的监测数据,研究了两种快速测定方法的优缺点和适用性,得出两种方法均普遍适合工业废水监测,其中闭管法在测定中、高浓度荧光废水时,结果更准确、更环保,而开管法适用于相对低浓度的废水测定;总结归纳了CODCr监测分析过程中影响准确性的因素及需要注意的问题。     

国家重点生态功能区产业准入负面清单制度的现状、问题与优化建议

国家重点生态功能区对维护国家和区域生态安全至关重要,产业准入负面清单制度是促进区域国土空间布局优化、引导产业绿色发展的重要举措。本文分别选取了水源涵养、水土保持、防风固沙、生物多样性维护不同类型国家重点生态功能区的案例区,深入开展产业准入负面清单制定的现状分析与问题识别。结果表明：现有产业准入负面清单以限制类为主且多为现有发展产业,禁止类产业较少且多为规划发展产业,在实施过程中仍存在与主体功能定位不符、区域协调性不足、实施困难大、缺乏动态跟踪管理等四方面问题。在此基础上,结合国家有关政策要求和不同区域主导功能定位,提出水源涵养、水土保持、防风固沙、生物多样性维护四类重点生态功能区的通用性和差异性产业准入负面清单优化政策建议,为国家重点生态功能区保护与管理提供决策参考。     

面向信息安全的具有时间特性RBAC授权策略

授权管理是访问控制中一个非常重要的部分。以往对于RBAC访问控制模型的约束的讨论多是基于非时间特性的。具有时间特性的RBAC授权策略的研究对传统的RBAC模型进行了透彻的分析,引入时态条件约束。从访问控制策略的数学建模出发,提出了对用户、资源、策略等的数学定义,设计出了基于时态角色的跨域授权策略规则,并用形式化的数学定义来描述。     

开放型公共场所应急疏散标识优化设计方法研究

为优化设计开放型公共场所的应急疏散标识,根据最短疏散时间、出口匹配原则建立两步优化模型,利用计算机仿真技术及数学优化模型,对开放型公共场所的疏散方案进行优化,合理分配各出口的疏散人数,对区域进行划分并设置相应的疏散标识。以某广场为例,运用上述方法进行疏散标识的优化设计,验证了该方法的可行性和适用性。优化结果表明,各出口的疏散人数分别调整至为282、143、152和424人后,疏散时间较初始状态降低了45.3%。该优化设计方法不仅可为开放型公共场所应急疏散标识的设置提供支持,还可为其他场所制定疏散方案、设置疏散指引标识提供参考。     

Emissions of unintentional persistent organic pollutants from open burning of municipal solid waste from developing countries

Open burning of waste is the most significant source of polychlorinated dibenzo-para-dioxins and dibenzofurans (PCDD/PCDF) in many national inventories prepared pursuant to the Stockholm Convention on Persistent Organic Pollutants. This is particularly true for developing countries. Emission factors for POPs such as PCDD/PCDF, dioxin-like polychlorinated biphenyls (dl-PCB) and penta- and hexachlorobenzenes (PeCBz/HCB) from open burning of municipal solid waste in China and Mexico are reported herein. Six different waste sources were studied varying from urban-industrial to semi-urban to rural. For PCDD/PCDF, the emission factors to air ranged from 3.0 to 650 ng TEQ kg⁻¹ waste and for dl-PCB from 0.092 to 54 ng TEQ kg⁻¹ waste. Emission factors for PeCBz (17-1200 ng kg⁻¹ waste) and HCB (24-1300 ng kg⁻¹ waste) spanned a wide but similar range. Within the datasets there is no indication of significant waste composition effect on emission factor with the exception of significantly higher Mexico rural samples.     

Consolidation in an Individual Transferable Quota Regime: Lessons from New Zealand, 1986–1999

Market-based approaches to environmental regulation (such as tradable permits or transferable quotas) are frequently offered as innovative solutions to many environmental problems. Globally, one of the most well-established forms of this approach is individual transferable quotas (or ITQs) in fisheries management. Within the natural resource management community, there is considerable debate over the effects ITQs have on the fishing industry and fisher behavior although this approach is not well-established in the United States. The previously imposed moratorium on ITQs in the United States has expired and the 2006 reauthorization of the Magnuson-Stevens Act explicitly provides for limited access privileges (LAPs). A variety of fishers, regulators, and conservation organizations are enthusiastically seeking to introduce ITQ management. With debate over whether and how ITQs should be used in American fisheries reinvigorated, it is timely to examine the evidence on the social and economic effects of ITQs in other nations’ fisheries. After briefly summarizing the debate on ITQs, we examine the case of New Zealand, one of the earliest and longest-lived ITQ-based fisheries regimes. We use multiple data sources and methods to analyze the extent to which industry consolidation and aggregation has occurred, including surveys of industry participants, expert interviews, reviews of academic reports and analyses, analysis of trade publications, and direct analysis of quota ownership patterns. This analysis shows a more complex outcome than recent debates in the ITQ literature would predict. These findings suggest that policy makers considering ITQs can learn from the experiences of other countries related to key issues such as quota allocation, aggregation limits, transferability, cost recovery, and resource sustainability when designing ITQ and other LAP systems. It is also important to explicitly identify economic and social objectives and then carefully design ITQ regimes to meet these objectives.     

基于P3-T3方法的飞机LTO阶段氮氧化物排放量计算与分析

飞机起飞着陆循环(LTO)阶段包含高推力的起飞和爬升阶段,具有排放强度高、排放特性不稳定的特点.同时,该阶段飞行高度低,尾气排放会直接影响机场周边人群.因此,本文依据机载快速存取记录器(QAR)数据中的低压转子转速等特征参数,对LTO进行精确的阶段划分.同时,建立发动机排放特性参数与推力关系模型,并使用P_3-T_3方法对国际民航组织公布的发动机各阶段排放指数进行修正,最终计算GE90-115B发动机某次LTO阶段的实际氮氧化物排放量.结果表明,该方法与国际民航组织推荐的标准LTO估算方法相比,总量相差约40%,与原有的BM2方法相比也存在一定差异.分析认为,这种依据QAR实际飞行数据并结合发动机排放特性参数的发动机排放量计算方法,可以更加真实地反映发动机性能对排放特性的影响,可很好地适用于具体航班氮氧化物排放量的精确估算,为近地面飞机排放评估乃至机场排放清单的编制提供更加准确的依据.