国外电子废弃物资源化概述

随着信息工业的飞速发展,以及人们对电子废弃物认识的深入和环保意识的加强,电子废弃物的回收利用已逐渐成为一项新兴产业。通过分析国外发达国家对电子废弃物的环境管理、工艺技术以及回收体系状况,总结了发达国家的成功经验,对我国建立和完善电子废弃物管理体系,发展研究电子废弃物资源化技术提出对策和建议。     

我国电子废弃物回收处理体系比较与建议

根据目前我国电子废弃物回收处理体系的现实情况,从回收网络、处理情况和优缺点等方面,分析比较了我国五种电子废弃物回收处理体系：个体户回收处理体系、民间回收处理体系、供销社回收处理体系、生产商回收处理体系和电子废弃物专业拆解公司回收处理体系,并提出建立“个体户＋公司＋拆解基地”合作关系电子废弃物回收处理体系的建议。     

我国电子废弃物环境资源成本及回收责任分担研究

目前,我国电子废弃物回收体系仍存在回收无序、回收利用行业发展困难等问题,而其症结在于电子废弃物回收体系责任分配的不合理。在定义电子废弃物环境资源成本的基础上,对比国内外电子废弃物环境资源成本分担的现状,分析了我国电子废弃物回收过程责任分担存在的问题。最后通过确定责任分担原则,提出了我国电子废弃物回收体系各相关主体的责任分担对策。     

我国电子废弃物回收体系建设的思路与保障措施

随着电子信息产业的高速发展和人民生活水平的不断提高,电子废弃物的数量也不断增长,成为21世纪增长最快的固体废弃物。从我国电子废弃物的回收利用现状入手进行分析,提出建设一套专业回收利用体系,形成以城市社区回收点为基础,中转交投中心为纽带,资源循环利用为目的,点面结合、三位一体的电子废弃物回收利用体系,逐步提高回收、集散、循环利用能力,促进行业健康、有序发展。     

电子废弃物回收利用体系建设初探

电子废弃物是目前世界上增长最快的固体废弃物之一,其不合理处置会造成人体健康危害和环境污染,作为一种潜在可回收利用的二次资源,正日益引起人们的高度关注。概述了当前世界上一些发达国家电子废弃物回收利用体系现状,分析了我国目前的相关情况,提出了建设电子废弃物综合回收利用体系对于构建循环经济和和谐社会的必要性与重要性。     

“双碳”背景下电子废弃物全生命周期评价与管理对策

日益增长的电子废弃物具有高污染性和高附加值的双重属性,在“双碳”背景下高效回收利用电子废弃物成为我国必须面临的环境管理问题。从电子废弃物的基本特征分析入手,对回收、运输、储存和再生利用环节当前面临的现状与困境进行了剖析。并围绕“碳中和、碳达峰”的目标,提出通过发展基于大数据的全生命周期管理体系强化监督,加强回收体系建设构筑社会化回收网络,发展绿色低碳技术提高资源化综合利用率,通过技术的有效融合,推进电子废弃物资源循环产业化,建立健全绿色低碳循环发展经济体系。     

试论电信企业在ICT电子废弃物循环利用中的作用

电子废弃物回收再利用是发展循环经济的重要抓手。针对ICT(Information and CommunicationTechnology,信息和通信技术)行业发展带来日益严峻的电子废弃物问题,剖析了现有电子废弃物的回收再利用体系存在的弊端,在解读现有法律法规政策的基础上,提出优化原有体系的设想,即充分认识电信企业"管家式"运营特点有利于低成本高效率地实现电子废弃物回收再利用,电信企业介入的回收再利用模式是政府、企业与社会多赢的模式,在当前可通过签订环境合同,实现政府与电信企业的合作。     

电子废弃物的再循环利用:企业、政府与公众的角色和责任

电子废弃物不仅种类繁多,而且成分复杂,含有多种有毒、有害物质,已成为固体废物中最大的重金属污染源.长期以来,由于对电子废弃物问题缺乏足够认识和有效管理,电子废弃物对人体健康及生活环境可能构成的危害常常被忽视.实现电子废弃物的再循环利用,关键是明确企业、政府和公众在电子产品设计、生产、消费、回收、处置和再利用整个过程中的相关责任.因此,解决电子废弃物的问题,首先要对相关行为主体的角色进行准确定位.     

电子废弃物回收处置及再循环利用——基于在校大学生的问卷调查

随着现代科技的迅猛发展和人们消费水平的日益提高,越来越多的电子产品被时尚性淘汰,其次最功能性淘汰,而由于耐久性淘汰的电子废弃物所占比例越来越低.问卷调查结果表明,体验消费,追求时常和更多功能是在校大学生消费电子产品的主要特征;大多数被调查者不满意目前的电子废弃物回收途径,期待能有所改善;接近三成的在校大学生不知道如何合理处置电子废弃物;消费者、生产者和废品回收者的环保意识水平较低,市场不规范和政府在法律法规及监管上的疏漏,是造成目前电子废弃物回收市场秩序混乱的主要原因.     

积极扩大家电以旧换新试点 认真抓好回收体系建设

电子废弃物是再生资源的一个极其重要的组成部分,开展电子废弃物的回收利用是再生资源产业由传统型向科技型转变的重要途径,既能取得较好的经济效益,又能为建设资源节约型和环境友好型社会作出积极的贡献。现刊发2010年7月28日中再生协会第五届三次理事会扩大会暨电子废弃物回收处理分会成立会上的领导讲话,供读者参考。     

Distribution of Cd,Ck, Pb and Zn in Soil and Vegetation Compartments in Stands of Five Boreal Tree Species in N.E. Sweden

Concentrations and total quantity of cadmium (Cd), cupper (Cu),lead (Pb) and zink (Zn) were determined in biomass and soil compartments in a replicated tree species experiment with 27-yr-old stands growing on former farmland in N.E. Sweden. Sequentialextractions of soil samples were performed in order to estimate the exchangeable and an organically bound fraction of each element. The tree species included were Picea abies (L.)H. Karst., Pinus sylvestris L., Pinus contorta Dougl., Larix sibirica Ledeb., and Betula pendula Roth.Tree species influenced the rate of removal of Cu, Pb and Zn incase of stemwood harvesting, and of Cd, Cu and Zn in the case ofwhole-tree harvesting. B. pendula and P. abies had higher quantities and average concentrations of Zn in the biomass. For all species, >50% of the Zn in the stems was found in the bark. P. abies and L. sibirica had higher quantities of Cu in the biomass than the other species.P. abies and P. contorta had high quantities of Cd inthe biomass in relation to the other species. Branches and stembark contained high concentrations of Cd and Pb in relation to foliage and stemwood. Dead branches had especially high concentrations of Pb. The high accumulation rate of Zn in thebiomass of B. pendula was related to a low exchangeable amount of Zn in the A horizon. In the superficial centimeters ofthe A horizon, a depletion similar to that found for Zn was detected for Cu, whereas for Cd and Pb, no correlations were found between quantities of elements in the trees and element pools in the soil.     

Starch-plastic materials—Preparation,physical properties,and biodegradability (a review of recent USDA research)

Recent starch-plastic research at the National Center for Agricultural Utilization Research is reviewed and related worldwide efforts are noted. Properties of starch that influence its formulation and performance in plastics are discussed. Methods are given for preparation of starch-poly(methyl acrylate) graft copolymer, starch-poly(ethylene-co-acrylic acid), and starch-poly(ethylene-co-acrylic acid)-polyethylene plastics. Their physical properties are discussed, as is degradability by enzymes or amylolytic organisms from soil, ponds, and streams.The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Application of Cellulose Microfibrils in Polymer Nanocomposites

Cellulose microfibrils obtained by the acid hydrolysis of cellulose fibers were added at low concentrations (2–10% w/w) to polymer gels and films as reinforcing agents. Significant changes in mechanical properties, especially maximum load and tensile strength, were obtained for fibrils derived from several cellulosic sources, including cotton, softwood, and bacterial cellulose. For extruded starch plastics, the addition of cotton-derived microfibrils at 10.3% (w/w) concentration increased Young’s modulus by 5-fold relative to a control sample with no cellulose reinforcement. Preliminary data suggests that shear alignment significantly improves tensile strength. Addition of microfibrils does not always change mechanical properties in a predictable direction. Whereas tensile strength and modulus were shown to increase during addition of microfibrils to an extruded starch thermoplastic and a cast latex film, these parameters decreased when microfibrils were added to a starch–pectin blend, implying that complex interactions are involved in the application of these reinforcing agents.     

四氮唑废水处理工艺设计

高浓度、高盐分的四氮唑生产废水通过三效蒸发浓缩,馏出液经铁炭氧微电解和混凝预处理,再采用水解酸化一接触氧化一反应二沉主体组合工艺进行处理。研究了该工艺所需构筑物和设备的设计与选型。该工艺在正常运行条件下,处理后出水pH6～9,COD 302mg／L,BOD5 108mg／L,SS30mg／L,色度36倍,水质达到GB8978--1996（污水综合排放标准》三级标准。     

Bioassessment of silvicultural impacts in streams and wetlands of the Eastern United States

Bioassessment is a useful tool to determine the impact of logging practices on the biological integrity of streams and wetlands. Measuring biota directly has an intuitive appeal for impact assessment, and biota can be superior indicators to physical or chemical characteristics because they can reflect cumulative impacts over time. Logging can affect stream and wetland biota by increasing sedimentation rates, altering hydrologic, thermal, and chemical regimes, and changing the base of food webs. Biotic impacts of logging on streams compared to wetlands probably differ, and in this paper we review some of those differences. In streams, invertebrates, fishes, amphibians, algae, and macrophytes have been used as indicators of logging impacts. In wetlands, bioassessment is just beginning to be used, and plants and birds are the most promising indicator taxa. Various best management practices (BMPs) have been developed to reduce the impacts of logging on stream and wetland biota, and we review quantitative studies that have evaluated the efficacy of some of these techniques in streams and wetlands in the eastern United States. Remarkably few studies that address the overall efficacy of BMPs in limiting biotic changes in streams and wetlands after BMP implementation have been published in scientific journals, although some work exists in reports or is unpublished. We review these works, and compile conclusions about BMP efficacy for biota from this body of research.     

Characterization of air emissions and residual ash from open burning of electronic wastes during simulated rudimentary recycling operations

Air emissions and residual ash samples were collected and analyzed during experiments of open, uncontrolled combustion of electronic waste (e-waste), simulating practices associated with rudimentary e-waste recycling operations. Circuit boards and insulated wires were handled separately to simulate processes associated with metal recovery. The average emissions of polychlorinated dibenzodioxins and dibenzofurans (PCDD/PCDFs) were 92 ng toxic equivalency (TEQ)/kg [n = 2, relative standard deviation (RSD) = 98%] and 11 900 ng TEQ/kg (n = 3, RSD = 50%) of the initial mass of the circuit boards and insulated wire, respectively. The value for the insulated wire is about 100 times higher than that for backyard barrel burning of domestic waste. The emission concentrations of polybrominated dibenzodioxins and dibenzofurans (PBDD/PBDFs) from the combustion of circuit boards were 100 times higher than for their polychlorinated counterparts. Particulate matter (PM) sampling of the fly ash emissions indicated PM emission factors of approximately 15 and 17 g/kg of the initial mass for the circuit boards and insulated wire, respectively. Fly ash samples from both types of e-waste contained considerable amounts of several metallic elements and halogens; lead concentrations were more than 200 times the United States regulatory limits for municipal waste combustors and 20 times those for secondary lead smelters. Leaching tests of the residual bottom ash showed that lead concentrations exceeded U.S. Environmental Protection Agency landfill limits, designating this ash as a hazardous waste.     

Does Soil Acidification Affect Spruce Needle Chemical Composition and Tree Growth?

In 1994, a large survey of soil chemistry was undertaken in thecounty of Värmland in central Sweden (Lundström et al., 1998).The southern part of the county was affected by soilacidification whereas there were no such indications in thenorthern part. To investigate the influence of soil chemistryon the trees at the specific sites, the survey was continued byan analysis of needle chemistry (Norway spruce) which wasundertaken at 150 of the 180 sites, and of tree growth at 65 ofthe 180 sites. Growth was expressed as a ratio between expectedgrowth, estimated with a national, empirical growth model, andthe growth observed in the field. In statistical analyses,using rank correlation, PCA and PLS, there were only weakindications of an influence of soil chemistry on needlechemistry and on tree growth. A moderate correlation betweennitrogen and sulphur in needles was found, which wasinterpreted as an effect of deposition and of processes in thetree canopy. No obvious regional pattern of the growth ratiowas found, in contrast to the clear pattern of soilacidification. The statistical analysis could not with anycertainty point out any of the soil chemistry variables asespecially important for the tree growth ratio.     

Solubility and Potential Mobility of Heavy Metals in Two Contaminated Urban Soils from Stockholm,Sweden

The solubility and potential mobility of heavy metals (Cd, Cu,Hg, Pb and Zn) in two urban soils were studied by sequential andleaching extractions (rainwater). Compared to rural (arable) soils on similar parent material, the urban soils were highlycontaminated with Hg and Pb and to a lesser extent also with Cd,Cu and Zn. Metal concentrations in rainwater leachates were related to sequential extractions and metal levels reported fromStockholm groundwater. Cadmium and Zn in the soils were mainly recovered in easily extractable fractions, whereas Cu and Pb were complex bound. Concentrations of Pb in the residual fractionwere between two- and eightfold those in arable soils, indicatingthat the sequential extraction scheme did not reflect the solidphases affected by anthropogenic inputs. Cadmium and Zn conc. inthe rainwater leachates were within the range detected in Stockholm groundwater, while Cu and Pb conc. were higher, whichsuggests that Cu and Pb released from the surface soil were immobilised in deeper soil layers. In a soil highly contaminatedwith Hg, the Hg conc. in the leachate was above the median concentration, but still 50 times lower than the max concentration found in groundwater, indicating the possibilityof other sources. In conclusion, it proved difficult to quantitatively predict the mobility of metals in soils by sequential extractions.     

High Immobilization of NH4+ in Danish Heath Soil Related to Succession,Soil and Nutrients: Implications for Critical Loads of N

During recent decades heathlands havechanged into grasslands in regions with high atmosphericnitrogen deposition. In regions with intermediatedeposition level (e.g., Denmark) changes have been lesspronounced which may be due to delay or decrease inresponse of the ecosystem. The mor layer (O horizon) mayplay an important role for this delay due to high sinkstrength for N. In this study, the capacity for netNH₄ ⁺ immobilization and mineralization wasstudied during short- and long-term incubations (2–36 days)of mor samples from Danish dry inland heaths. High short-term capacity for net NH₄ ⁺ immobilization wasfound to be a general characteristic of Danish heath morlayers both under heather (Calluna vulgaris) andcrowberry (Empetrum nigrum ssp nigrum), the latterdominating late stages in heathland succession. The netNH₄ ⁺ immobilization was higher under youngcompared to old or dead vegetation, and higher on lessnutrient poor soils than on extremely nutrient poor soils.The addition of N, P and C stimulated CO₂ productionand net NH₄ ⁺ immobilization, but not net Nmineralization. The immobilization of ¹⁵NH₄ ⁺caused release of dissolved organic N, increased N anddecreased C/N ratio in the microbial biomass, and indicatedgrowth of microorganisms with other metabolic abilitiesthan the indigenous population. No evidence was obtained ofstabilization of immobilized ¹⁵NH₄ ⁺ intosoil organic matter during the experiment. On background ofthe results and current knowledge it was concluded that therecognition of the high capacity for net NH₄ ⁺immobilization in mor layers does not allow for a raiseof critical loads for N for northern dry inland heaths.     

Biodegradation of Injection Molded Starch-Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) Blends in a Natural Compost Environment

Injection molded specimens were prepared by blending poly (hydroxybutyrate-co-valerate) (PHBV) with cornstarch. Blended formulations incorporated 30% or 50% starch in the presence or absence of poly-(ethylene oxide) (PEO), which enhances the adherence of starch granules to PHBV. These formulations were evaluated for their biodegradability in natural compost by measuring changes in physical and chemical properties over a period of 125 days. The degradation of plastic material, as evidenced by weight loss and deterioration in tensile properties, correlated with the amount of starch present in the blends (neat PHBV < 30% starch < 50% starch). Incorporation of PEO into starch-PHBV blends had little or no effect on the rate of weight loss. Starch in blends degraded faster than PHBV and it accelerated PHBV degradation. Also, PHBV did not retard starch degradation. After 125 days of exposure to compost, neat PHBV lost 7% of its weight (0.056% weight loss/day), while the PHBV component of a 50% starch blend lost 41% of its weight (0.328% weight loss/day). PHB and PHV moieties within the copolymer degraded at similar rates, regardless of the presence of starch, as determined by ¹H-NMR spectroscopy. GPC analyses revealed that, while the number average molecular weight (Mn) of PHBV in all exposed samples decreased, there was no significant difference in this decrease between neat PHBV as opposed to PHBV blended with starch. SEM showed homogeneously distributed starch granules embedded in a PHBV matrix, typical of a filler material. Starch granules were rapidly depleted during exposure to compost, increasing the surface area of the PHBV matrix.