典型废旧塑料再生基地周边农田土壤中PAHs污染特征及健康风险评价

为了解废旧塑料再生行业对周边农田土壤环境的影响,在莱州市废旧塑料再生基地内部及周边农田采集22个土壤样品,利用高效液相色谱法对样品中16种多环芳烃(PAHs)含量进行了检测,并对其污染特征及健康风险进行了分析.结果表明,基地周边农田土壤中16种PAHs总含量为60.50～303.48μg··kg^-1,除■(Chr)、二苯并(a,h)蒽(DahA)外,其余组分的检出率均为100%.萘(Nap)、苊烯(Acy)、苊(Ace)为主要组分,分别占总量的49.57%、21.32%、14.95%.参考Maliszewska-Kordybach的土壤PAHs污染程度划分方法,仅有22.73%样品达到轻微污染且集中于基地内部.在空间分布上,基地内部农田土壤中PAHs含量显著高于外部,总体表现为距基地越远,农田土壤中PAHs含量越低.基地内部各采样点PAHs的构成具有相似性,主要以低环芳烃为主,占PAHs总量的89.56%以上,表明基地内部农田土壤有相对固定的PAHs来源.主成分分析法共提取到3个主成分,表明基地周边农田土壤中的PAHs主要与燃煤、生物质燃烧以及废旧塑料焚烧有关.健...     

Field investigation of pavement rehabilitation utilizing cold in-place recycling

Despite the widespread field and laboratory research works there are still a lot of unknown aspects about the cold in-place recycling. This paper presents the outcomes of a five year evaluation of a major highway in Iran which had been rehabilitated by cold in-place recycling. Before starting the rehabilitation process, a comprehensive field survey was performed. During the pavement surveying, type, severity and reason of distresses were investigated and PCI parameter was calculated. Furthermore, both destructive and nondestructive tests were carried out to evaluate the pavement condition and estimate the remaining life. On the basis of these investigations studied highway was divided to six design sections. Based on technical analysis four sections were recycled whereas two other sections were rehabilitated with the conventional cold milling and overlay method. Afterwards, the pavement performance was monitored during the next 5 years. After about six months of monitoring, structural failures were detected in about 10% of recycled areas. Based on field surveying, low compaction and load bearing of subgrade materials and lack of high quality unbound pavement layers accompanied by some shortcomings in recycled layer resulted in undesirable results in these areas. Based on obtained results and performed analysis a practical flowchart was presented which could be used as a project selection guideline.     

A comparative study between two ignition sources: Electric igniter versus pyrotechnic igniter

The risk assessment of combustible explosive dust is based on the determination of the probability of dust dispersion, the identification of potential ignition sources and the evaluation of explosion severity. It is achieved in most of cases with the two main experimental normalized devices such as the Hartmann tube (spark ignition) and the 20 L spherical bomb (with two 5 kJ pyrotechnic ignitors).Ignition energy of the 5 kJ ignitor is well calibrated and generates a reproducible ignition. But, on the other hand, this ignition is not punctual and the over pressure produced is nearly 2 bar. Moreover, the pyrotechnic igniter accelerates the combustion with multi ignition points in a large volume and that disturbs the flame propagation. In this way, this ignition source does not allow to analyze the combustion products because the composition of the pyrotechnic igniter was found in the combustion products.This paper deals with the comparison of two ignition sources in the 20 L spherical bomb. Different explosive dusts of great industrial interest are studied with electrical and pyrotechnic ignitors, in order to understand, first, the influence of each type of igniter on the explosion behaviour and then to evaluate the possibility of establishing a correspondence between parameters obtained with these two ignition sources.Severity parameters of nicotinic acid, aluminium powder and titanium alloy were measured by using the two types of ignition system in our 20 L spherical bomb equipped with the Kühner dihedral injector. The explosion overpressure $\mathrm{P}$ and the rate of pressure rise $\left(\raisebox{1ex}{$dP$}\!\left/ \!\raisebox{-1ex}{$dt$}\right.\right)$ were measured in a large range of concentration allowing to propose correlations between electrical and pyrotechnic ignition for each parameter and each type of powder. These correlations aim to link the tests used with two different collections of experimental parameters for the same dust. The relevance of these correlations will be discussed.     

An examination of governance within extended producer responsibility policy regimes in North America

Extended producer responsibility seeks to integrate environmental impacts into the product lifecycle and achieve greater economic efficiencies in the management of products at end of life. For such integration to be actualized, however, producers may need to be accorded greater programmatic authority and flexibility than is often in some EPR policies that stipulate defined roles for other entities along the product chain. The proper allocation of responsibility among the parties and, in particular, the roles of the producers and local authorities remains a principal component of EPR policy construction. The analysis outlines four broad categories of financial and programmatic responsibility that currently reside within EPR programs in North America. The article concludes with recommendations for a research agenda to further define the governance characteristics that result in effective and efficient EPR programs.     

A comprehensive waste collection cost model applied to post-consumer plastic packaging waste

Post-consumer plastic packaging waste (PPW) can be collected for recycling via source separation or post-separation. In source separation, households separate plastics from other waste before collection, whereas in post-separation waste is separated at a treatment centre after collection. There are also two collection schemes, either curb side or via drop-off locations. These different schemes have impact on total costs of collection at the municipal level. It can also influence the facility choices and network design. Therefore, a method which can compare costs of various collection schemes is needed.A comprehensive cost model was developed to compare costs of municipal collection schemes of PPW. The ‘municipal waste collection cost model’ is based on variables including fixed and variable costs per vehicle, personnel cost, container or bag costs as well as on emission costs (using imaginary carbon taxes). The model can be used for decision support when strategic changes to the collection scheme of municipalities are considered. The model takes into account the characteristics of municipalities, including urbanization degree and taxation schemes for household waste management.The model was applied to the Dutch case of post-consumer plastic packaging waste. Results showed that that in general post-separation collection has the lowest costs and curb side collection in urban municipalities without residual waste collection taxing schemes the highest. These results were supported by the conducted sensitivity analysis, which showed that higher source separation responses are negatively related to curb side collection costs. Greenhouse gas emission costs are a significant part of the total costs when collecting post-consumer plastic packaging waste due to the low density to weight ratio of the materials collect. These costs can amount to 15% of the total collection costs.     

Recycling for small island tourism developments: Food waste composting at Sandals Emerald Bay,Exuma, Bahamas

The ability for small islands to meet sustainability goals is exacerbated by the costs of transporting goods on, and then, wastes off the islands. At small scales, recycling can be prohibitive and complicated by labor costs; the need to profitably recycle and manage solid waste output from tourism is complicated by scale and available technologies. A multi-year study documents the amount of solid waste generated on Great Exuma (Exuma), The Commonwealth of The Bahamas since 2010 with one year of benchmarking, then limited recycling of food waste generation by an all-inclusive resort, Sandals Emerald Bay (SEB). For the island of Exuma, the rapid increase in the rate of accumulation of solid waste associated with a large destination resort has led to an increase in pests such as rats and flies, along with an increased occurrence of fires associated with unburied solid waste. Solid waste has accumulated faster than the island solid waste management can absorb. SEB kitchen and hotel operations contributes an estimated 36% of all solid waste generated on the island, about 1752 t¹ out of a total of 4841 t generated on the island in 2013 (exclusive of vegetation waste). Based on 4 weeks of benchmarking, 48.5% of all the waste coming out of the SEB resort is compostable, organic waste, but waste composition varies widely over time. Exuma Waste Management (EWM) and Recycle Exuma (RE), both privately-held Bahamian businesses, worked for one year (2012–2013) with SEB resort to implement a benchmarking and pilot recycling project to meet Earth Check green resort certification requirements. This paper outlines the costs and resources required for food waste recycling and some barriers to implementing more effective solid waste management for the tourism industry on small islands.     

Socially optimal and fund-balanced advanced recycling fees and subsidies in a competitive forward and reverse supply chain

Advanced recycling fees (ARFs) and government subsidy fees are important for curtailing the consumption of new products and encouraging recycling and disposal of end-of-life (EOL) products. We introduce a model consisting of a leader (the Environmental Protection Agency, EPA) and two groups of followers (MIS firms and recyclers) consisting of manufacturers, importers and sellers, and recyclers which compete in both consuming and recycling markets. The EPA determines the ARFs paid by the MIS firms and the fees subsidizing recyclers to maximize the social welfare in closed-loop supply chains where the MIS firms and recyclers attempt to maximize their respective profit functions. To compare with current practice, we describe a conceptual fund balance model to determine the ARF and subsidy fee on the basis of the balance between total collected ARFs and expenditure of subsidies. Using numerical examples for the laptop computer market in Taiwan, we demonstrate that our results outperform the current practice.     

碳中和视域下的垃圾精细化治理：日本吸收性卫生用品回收体系的构建经验及启示

通过循环利用，减少吸收性卫生用品产量和废弃量的陡增所带来的碳排放量，将加速碳中和进程。日本提供了吸收性卫生用品回收体系构建的先行经验，即以“政府引导—企业运作—社会团体协作”为顶层架构，明确制度、完备设施、完善渠道、宣传到户等。建议我国取长补短，在夯实法律法规和优化主体协同机制的基础上，重点着眼于突破技术壁垒、推动智慧化监管、深化绿色理念，以点带面推进吸收性卫生用品的回收循环试点，进一步推动垃圾分类精细化治理的进程。     

建筑垃圾资源化利用项目中特许经营模式的适用和争议——基于江苏省的实践启示

特许经营模式能够较好地发挥市场化、效率化、竞争化导向作用,充分发挥市场机制在资源配置中的决定性作用,在建筑垃圾资源化利用项目中得到了一定的应用。本文在分析江苏省建筑垃圾资源化利用项目中特许经营模式的实践经验和面临问题的基础上,总结了特许经营模式典型的交易结构,从物品属性、市场逻辑、风险分担和垄断之争四个方面对存在的争议问题和观点进行辨析,提出了国家层面制定规则、科学选择运作方式、确保采购充分竞争、合理确定项目补贴、加强政府规制作用和持续优化营商环境等政策建议,以期为未来建筑垃圾资源利用推广采用特许经营模式提供参考和启示。