Environmental impact of pyrolysis of mixed WEEE plastics part 1: Experimental pyrolysis data

Growth in waste electrical and electronic equipment (WEEE) is posing increasing problems of waste management, partly resulting from its plastic content. WEEE plastics include a range of polymers, some of which can be sorted and extracted for recycling. However a nonrecyclable fraction remains containing a mixture of polymers contaminated with other materials, and pyrolysis is a potential means of recovering the energy content of this. In preparation for a life cycle assessment of this option, described in part 2 of this paper set, data were collected from trials using experimental pyrolysis equipment representative of a continuous commercial process operated at 800 °C. The feedstock contained acrylonitrile-butadiene-styrene and high impact polystyrene with high levels of additives, and dense polymers including polyvinylchloride, polycarbonate, polyphenylene oxide, and polymethyl methacrylate. On average 39% was converted to gases, 36% to oils, and 25% remained as residue. About 35% of the gas was methane and 42% carbon monoxide, plus other hydrocarbons, oxygen and carbon dioxide. The oils were almost all aromatic, forming a similar mixture to fuel oil. The residue was mainly carbon with inorganic compounds from the plastic additives and most of the chlorine from the feedstock. The results showed that the process produced around 70% of the original plastic weight as potential fuel.     

RECYCLING OF POLYMERIC MATERIALS USED FOR FOOD PACKAGING: CURRENT STATUS AND PERSPECTIVES

Packaging materials are currently considered an important source of environmental waste because of their great volume. Although for materials like glass, aluminum, and paperboard recycling has been rather extensively practiced, it proved to be a much more arduous task for polymeric materials because of their great variety and the coexistence/mixing of various polymers either as blends or as copolymers. Therefore, constructive approach to recycling would consist of reviewing its current status worldwide to make a comprehensive presentation of the current trends and the state of art techniques for plastic disposal, sorting, and recycling. Although mechanical, feedstock, and chemical recycling of polymers are thoroughly analyzed within the frame of this review, other alternatives such as landfill, incineration, pyrolysis, reuse and recovery, and composting are also presented and commented.     

焚烧厂垃圾渗滤液零排放设计

近年来,垃圾焚烧发电成为城市生活垃圾处置的主要方式之一.对于垃圾焚烧发电厂而言,如何处理垃圾渗滤液变得尤为重要.本文总结了生活垃圾渗滤液的危害、特点和目前流行的处理技术,分析了垃圾焚烧发电过程中产生的渗滤液回收再利用及实现零排放的可行性,找到其中存在的问题,以期为全国其他相关企业提供技术参考.     

Response to waste electrical and electronic equipments in China: legislation, recycling system, and advanced integrated process

Over the past 30 years, China has been suffering from negative environmental impacts from distempered waste electrical and electronic equipments (WEEE) recycling activities. For the purpose of environmental protection and resource reusing, China made a great effort to improve WEEE recycling. This article reviews progresses of three major fields in the development of China's WEEE recycling industry: legal system, formal recycling system, and advanced integrated process. Related laws concerning electronic waste (e-waste) management and renewable resource recycling are analyzed from aspects of improvements and loopholes. The outcomes and challenges for existing formal recycling systems are also discussed. The advantage and deficiency related to advanced integrated recycling processes for typical e-wastes are evaluated respectively. Finally, in order to achieve high disposal rates of WEEE, high-quantify separation of different materials in WEEE and high added value final products produced by separated materials from WEEE, an idea of integrated WEEE recycling system is proposed to point future development of WEEE recycling industry.     

废旧纺织品处理的探讨（一）

介绍了废旧纺织品现行的4种常规处理方法：回收利用、焚烧、土地填埋和堆肥、通过比较、分析各种方法的优缺点，得出以下结论：回收利用环保且节约自然资源，值得提倡和推广，但工艺复杂、成本较高；焚烧和土地填埋是现在最普遍的处理方式，但会带来环境污染；堆肥方法环保且能肥沃土壤，但只能处理具有生物降解性的纺织品。因此作为具有环境友好...     

RoHS regulated substances in mixed plastics from waste electrical and electronic equipment

The disposal and recovery of plastics from waste electrical and electronic equipment (WEEE) are of considerable importance, both from an environmental and an economic perspective. This paper presents the results of a study investigating current concentrations of hazardous substances in mixed plastics from WEEE and their implications for an environmentally sound recovery. The study included 53 sampling campaigns for mixed plastics from WEEE. The samples were analyzed with regard to heavy metals (cadmium, chromium, mercury, and lead) and flame retardants (PentaBDE, OctaBDE, DecaBDE, DecaBB) regulated in the RoHS Directive. Besides these substances, other brominated flame retardants known to occur in electronics (HBCD, TBBPA) as well as the total bromine and phosphorus contents were considered. Results show that no mixed plastics fraction from WEEE is completely free from substances regulated in the RoHS Directive. The lowest number and average concentrations were found in flat screen monitors. The highest concentrations were found in mixed plastics from CRT monitors and TVs. Mixed plastics fractions with high average concentrations of heavy metals originate from the treatment of small household appliances (cadmium), ICT equipment (lead), and consumer equipment (lead). Mixed plastics fractions with high average concentrations of brominated flame retardants mainly originate from the treatment of small household appliances for high temperature applications (DecaBDE), CRT monitors (OctaBDE and DecaBDE) and consumer equipment (DecaBDE), in particular CRT TVs (DecaBDE). To avoid a dissipation of hazardous substances into plastics and the environment, it is recommended that mixed plastics from WEEE are subject to a strict quality management.     

Comparison of the recyclability of flame-retarded plastics

Mechanical recycling of plastics from waste from electrical and electronical equipment (WEEE) is increasingly expected by regulators and demanded by original equipment manufacturers (CEMs); however, mechanical recycling is generally recognized to be the most economically costly and technically challenging method of recovering WEEE plastics. With 12% of WEEE plastics requiring the use of flame-retardants in order to ensure appropriate levels of consumer fire safety, there is a distinct need for data from comparative tests on recyclability of various flame-retarded plastics. Ten commercially available flame-retarded plastic grades commonly used in electronic equipment (eight "halogen-free" grades and two grades containing brominated flame-retardants (BFRs)) were subjected to two different recycling scenarios. A standard recycling scenario was carried out by repeatedly extruding the materials and an accelerated hydrolysis scenario was carried out to study the influence of humidity from air during use on the process. Both, virgin and recycled materials were tested for a potential formation of polybrominated dibenzodioxins/furans (PBDD/Fs), their mechanical properties were assessed and the fire safety rating was determined. Results indicate that none of the tested materials showed a potential to form the PBDD/Fs regulated by the German Chemicals Banning Ordinance. The halogen-free plastic grades showed a significant deterioration of mechanical properties after recycling, whereas those plastics containing BFRs were able to pass all test criteria, thus maintaining their original properties. With respect to the fire safety rating, none of the eight tested halogen-free plastic grades could maintain their fire safety rating after five recycling loops, whereas both BFR plastics continued to achieve their fire safety ratings. Therefore the tested BFR containing plastic materials showed superior recycling properties compared to the tested halogen-free plastic grades with respect to all investigated parameters.     

Use of pyrolysis GC/MS for predicting emission byproducts from the incineration of double-base propellant

Gas chromatography/mass spectrometry was used to analyze the pyrolytic byproducts from an Army-unique propellant compound (AA2) that is composed of predominantly nitrocellulose and nitroglycerin. Compounds produced by AA2 pyrolysis were compared to compounds detected in the gaseous effluent from AA2 incineration. The light permanent gases and most of the higher molecular weight byproducts produced by AA2 incineration are replicated by laboratory pyrolysis on AA2. The reverse case also holds whereby 18 out of 24 high molecular weight AA2 pyrolytic byproducts are found in the incinerator emissions. Poor matching, however, was obtained between the two processes for the volatile, water-soluble species. None of these low molecular weight compounds produced under pyrolytic conditions were detected in the AA2 incinerator samples, likely indicating inefficient capture of these compounds from the effluent stream. Separate pyrolytic degradation of the individual components of AA2 provides evidence that nearly all of the incomplete combustion products detected during incineration originate not from the prevalent energetic ingredients but rather from the minor and trace additives in AA2. In addition, pyrolysis successfully identified the AA2 components capable of surviving the incineration process intact. This work illustrates the potential of bench-scale pyrolysis for predicting incineration behavior.     

The carbon footprint and energy consumption of beverage packaging selection and disposal

Most market products are offered to consumers in a wide range of packaging alternatives and the proportion of municipal solid waste attributed to packaging increases year after year. This study assesses the environmental impact of the commonest packaging options on the Spanish market for juice, beer and water. The production of different packaging materials and sizes was evaluated along with their method of final disposal (landfilling, incineration and recycling). Recycling was found to be the most environmentally friendly disposal option for all the packaging alternatives compared, and either incineration or landfilling was considered the second best option depending on the packaging material. The packaging options with the lowest environmental impacts were aseptic carton and plastic packaging (for sizes greater than 1 l). The environmental profile of the whole beverage life cycle was evaluated. The results of the evaluation of the entire life cycle show that the impact of beer packaging is similar to the impact of beer production and these are the highest impact stages in the life cycle of beer. Packaging was found to have the highest environmental impact in the life cycles of water and juice.     

SUBJECT: SOME ENVIRONMENTAL ASPEGTS OF WON-RETURNABLE PACKAGING WITH PARTIGUUR REFERENCE TO PAGKAGIWB OF DAIRY PRODUCTS IN PLASTICS

The types of plastics used for packaging dairy products are reviewed briefly and their advantages for non-returnable containers discussed. Virtual complete resistance to biodegradation, an important asset in packaging food products, has lead to suggestion of disposal difficulties. Detailed studies have, however, established that plastics currently present no major problems in any of the waste disposal methods used by municipalities and may present some advantages. The litter problem is primarily a social and aesthetic one rather than an ecological one. Attempts are being made to develop plastics which degrade more readily in sunlight. Possibilities for recycling plastics are also being studied. The launch of any product in a non-returnable pack should be preceded by careful study of likely environmental impact.     

Municipal solid waste fueled power generation in China: a case study of waste-to-energy in Changchun City

With rapid economic growth and massive urbanization in China, many cities face the problem of municipal solid waste (MSW) disposal. With the lack of space for new landfills, waste-to-energy incineration is playing an increasingly important role in waste management. Incineration of MSW from Chinese cities presents some unique challenges because of its low calorific value (3000-6700 kJ/kg) and high water content (approximately 50%). This study reports a novel waste-to-energy incineration technology based on co-firing of MSW with coal in a grate-circulating fluidized bed (CFB) incinerator, which was implemented in the Changchun MSW power plant. In 2006, two 260 ton/day incinerators incinerated 137,325 tons, or approximately one/sixth of the MSW generated in Changchun, saving more than 0.2 million m3 landfill space. A total of 46.2 million kWh electricity was generated (38,473 tons lignite was also burned as supplementary fuel), with an overall fuel-to-electricity efficiency of 14.6%. Emission of air pollutants including particulate matters, acidic gases, heavy metals, and dioxins was low and met the emission standards for incinerators. As compared to imported incineration systems, this new technology has much lower capital and operating costs and is expected to play a role in meeting China's demands for MSW disposal and alternative energy.     

聚酯纤维回收再利用及环境影响评价进展综述

聚酯纤维回收再利用不仅能节约资源,而且可以减轻环境负荷。文章综述了聚酯纤维回收再利用及其环境影响评价研究,结果表明:对聚酯纤维进行回收再利用比直接填埋或直接焚烧更具环境效益;聚酯纤维回收再利用方法主要有物理回收法、能量回收法和化学回收法,其中以物理回收法和化学回收法为主;物理回收法经济成本低,温室气体减排方面的环境效益好,但再生产品的质量有待提升;能量回收法通过焚烧的方式进行能量转换,产生较多的温室气体排放,环境效益较差;化学回收法得到的最终产物可以达到与原生聚酯纤维几乎相同的品质,降低回收再利用过程中的温室气体排放可以进一步提升该方法的环境效益。     

Form1ation and destruction of chlorinated pollutants during sewage sludge incineration

The limitations facing land filling and recycling and the planned ban on sea disposal of sludge leads to the expectation that the role of sludge incineration will increase in the future. The expected increase in sludge incineration will also increase scrutiny of the main drawbackto sewage sludge incineration--the formation of hazardous air pollutants (HAPs). Despite the extensive body of knowledge available on sewage sludge combustion, very few studies have been conducted on the formation of HAPs during sludge combustion. In this work, the interactions between sewage sludge pyrolysis products and sludge ash were investigated using a dual chamber flow reactor system and a horizontal laboratory scale reactor. The results of this study shows that sludge ash can catalyze oxidation and chlorination of organics. In the absence of HCl in the gas stream, sludge ash acts as an oxidizing catalyst, but in the presence of HCl, sludge ash acts as a chlorination catalyst producing high yields of organochloride compounds.     

Brominated flame retardants in waste electrical and electronic equipment: substance flows in a recycling plant

Brominated flame retardants (BFRs) are synthetic additives mainly used in electrical and electronic appliances and in construction materials. The properties of some BFRs are typical for persistent organic pollutants, and certain BFRs, in particular some polybrominated diphenyl ether (PBDE) congeners and hexabromocyclododecane (HBCD), are suspected to cause adverse health effects. Global consumption of the most demanded BFRs, i.e., penta-, octa-, and decaBDE, tetrabromobisphenol A (TBBPA), and HBCD, has doubled in the 1990s. Only limited and rather uncertain data are available regarding the occurrence of BFRs in consumer goods and waste fractions as well as regarding emissions during use and disposal. The knowledge of anthropogenic substance flows and stocks is essential for early recognition of environmental impacts and effective chemicals management. In this paper, actual levels of penta-, octa-, and decaBDE, TBBPA, and HBCD in waste electrical and electronic equipment (WEEE) as a major carrier of BFRs are presented. These BFRs have been determined in products of a modern Swiss recycling plant applying gas chromatography/electron capture detection and gas chromatography/mass spectrometry analysis. A substance flow analysis (SFA) technique has been used to characterize the flows of target substances in the recycling process from the bulk WEEE input into the output products. Average concentrations in small size WEEE, representing the relevant electric and electronic appliances in WEEE, sampled in 2003 amounted to 34 mg/kg for pentaBDE, 530 mg/kg for octaBDE, 510 mg/kg for decaBDE, 1420 mg/kg for TBBPA (as an additive), 17 mg/kg for HBCD, 5500 mg/kg for bromine, and 1700 mg/kg for antimony. In comparison to data that have been calculated by SFA for Switzerland from literature for the 1990s, these measured concentrations in small size WEEE were 7 times higher for pentaBDE, unexpectedly about 50% lower for decaBDE, and agreed fairly well for TBBPA (as an additive) and octaBDE. Roughly 60% of the total bromine input determined by SFA based on X-ray fluorescence analysis of the output materials of the recycling plant cannot be assigned to the selected BFRs. This is an indication for the presence of other brominated substances as substitutes for PBDEs in electrical and electronic equipment. The presence of BFRs, in particular PBDEs in the low grams per kilogram concentration range, in the fine dust fraction recovered in the off-gas purification system of the recycling plant reveals a high potential for BFR emissions from WEEE management and point out the importance for environmentally sound recycling and disposal technologies for BFR-containing residues.     

Recycling of meat and bone meal animal feed by vacuum pyrolysis

Due to the recent bovine spongiform encephalopathy (BSE) crisis in the European beef industry, the use of animal-derived products to feed cattle is now severely restricted. Large quantities of waste animal meat and bone meal (MBM), also known as animal flour, have to be safely disposed of or transformed. One disposal option is pyrolysis. Vacuum pyrolysis of an animal flour sample has been performed in a laboratory reactor. The results obtained revealed that vacuum pyrolysis can be an attractive alternative to incineration and cement kilns. The process generated a combustible gas (15.1 wt %), a high calorific value oil (35.1 wt %), a solid residue rich in minerals (39.1 wt %), and an aqueous phase rich in organics (10.7 wt %). The gas and the aqueous phase can be used to provide heat to the vacuum pyrolysis reactor and the MBM drying unit. The oil can be used alone or mixed with petroleum products as a fuel in boilers or gas turbines. Conversion of animal waste by pyrolysis into fuels can contribute to the reduction of greenhouse gases. It is suggested to use the solid residue for agricultural soil enrichment in minerals and as a soil moisturizer.     

南安市餐厨垃圾资源化处理厂工程设计浅析

南安市餐厨垃圾资源化处理厂设计处理能力为200 t/d,采用"预处理+厌氧消化+沼气发电"的主流工艺路线,主要包括预处理系统、厌氧消化系统、沼气净化及发电系统、除臭系统、固液分离及气浮系统等.预处理产生的粗油脂对外销售,厌氧消化产生的沼气经过净化提纯后实现沼气发电上网,并配备预热锅炉为厌氧发酵提供热源,实现热电联产.项...     

Comparison of trace element emissions from thermal treatments of heavy metal hyperaccumulators

Phytoextraction has become one of the most promising remediation techniques for heavy metal (HM) contaminated soils. However, the technique invariably produces large amounts of HM-enriched hyperaccumulators, which need further safe disposal. In this study, two different thermal treatment methods are investigated as potential options for evaporative separation of HMs from the residues. A horizontal tube furnace and a vertical entrained flow tube furnace were used for testing the disposal of grounded hyperaccumulators. The release characteristics of HMs (Cd, Cu, Pb, and Zn) into flue gas and residues were investigated for thermal treatment of the Cd and Zn hyperaccumulators Sedum plumbizincicola and Sedum alfredii. In a horizontal tube furnace, incineration favors the volatilization of Cu and Cd in contrast to pyrolysis. The percentages of HMs in residues after incineration are lower than those after pyrolysis, especially for Cd, Pb, and Zn. However, in an entrained flow tube furnace, Zn content in flue gas increases with increasing temperature, but Cu and Cd contents are fluctuated. In addition, a higher incineration temperature enhances the Cu content in residues.     

Research Developments in Methods to Reduce the Carbon Footprint of the Food System: A Review

Global warming is a worldwide issue with its evident impact across a wide range of systems and sectors. It is caused by a number of greenhouse gases (GHGs) emissions, in which food system has made up of a large part. Recently, reduction of GHG emissions has become an urgent issue to be resolved in the food system. Many governments and organizations are making great endeavors to alleviate the adverse effect of this phenomenon. In this review, methods to reduce the carbon footprint within the life cycle of a food system are presented from the technical, consumption behavior and environmental policies perspectives. The whole food system including raw material acquisition, processing, packaging, preservation, transportation, consumption, and disposal are covered. Improving management techniques, and adopting advanced technology and equipment are critical for every stage of a food system. Rational site selection is important to alleviate the influence of land use change. In addition, environmental choices of packaging stage, reduction in refrigeration dependence, and correct waste treatment are essential to reduce the total carbon footprint of the production. However, only technical methods cannot radically reverse the trend of climate change, as consumption behaviors present a great deal of influence over climate change. Appropriate purchase patterns and substitution within food product categories by low carbon products can reduce GHG emissions. Development of methods to calculate the carbon footprint of every kind of food and its processing technology enable people to make environmental choice. Policy can shape and cultivate the new code of consumption and influence the direction of emerging technology and science. From political perspectives, government intervention and carbon offset are common tools, especially for carbon tax and a real or implicit price of carbon. Finally, by mitigating the methodologies described above, the rate and magnitude of climate changes can be also reduced to some extent.     

我国垃圾焚烧发电行业发展前景

现如今,社会经济日新月异,人们的生活质量持续提升,各行各业方兴未艾,对电能需求日渐增加,各种新的发电技术屡见不鲜。垃圾焚烧发电是社会发展的关键产物,利用垃圾焚烧发电,可以有效防止垃圾外溢,实现垃圾资源的循环利用和无害化利用。然而,垃圾焚烧发电在具体应用中还存在一些问题,所以,文章对我国垃圾焚烧发电行业的发展前景做了详细论述,旨在可以为相关业界人士提供有价值的借鉴与参考,进而为行业的健康可持续繁荣发展贡献力量。     

废弃聚苯硫醚纤维的回收再利用研究进展

为解决废弃聚苯硫醚(PPS)纤维和滤袋通过焚烧或填埋方式处理,造成资源浪费和二次污染等问题,促进废弃PPS纤维的高效高价值回收利用,对目前国内外废弃PPS纤维回收再利用的研究现状进行综述。阐述了废弃PPS纤维的回收再利用方法,主要包括化学溶解、化学分解、机械粉碎、纤维拆解、熔融加工和直接利用,并梳理分析了不同方法的优缺点及其回收制品的特点;然后分别从废弃滤袋清灰处理、滤袋纤维成分复杂和回收利用成本高3个方面分析影响废弃PPS纤维回收再利用的技术难点;最后提出建立PPS滤袋生产、使用和回收三方企业的联动机制,根据不同工况条件分层分类管理回收废弃PPS滤袋,以期为PPS纤维的高值回收利用提供参考。