Analyses of the recycling potential of medical plastic wastes

This study analyzed the recycling potential of plastic wastes generated by health care facilities. For this study, we obtained waste streams and recycling data from five typical city hospitals and medical centers and three animal hospitals in Massachusetts. We analyzed the sources, disposal costs and plastic content of medical wastes, and also determined the components, sources, types and amounts of medical plastic wastes. We then evaluated the recycling potential of plastic wastes produced by general city hospital departments, such as cafeterias, operating rooms, laboratories, emergency rooms, ambulance service and facilities, and animal hospitals. Facilities, laboratories, operating rooms, and cafeterias were identified as major sources of plastic wastes generated by hospitals. It was determined that the recycling potential of plastics generated in hospital cafeterias was much greater than that in other departments. This was mainly due to a very slight chance of contamination or infection and simplification of purchasing plastic components. Finally, we discuss methods to increase the recycling of medical plastic wastes. This study suggests that a classification at waste generating sources, depending upon infection chance and/or plastic component, could be a method for the improved recycling of plastic wastes in hospitals.     

废聚苯乙烯的化学回收方法

废聚乙烯（ＰＳ）转化为燃料油和化学品的化学回收方法,分为废ＰＳ单独裂解及废ＰＳ与其它废塑料混合裂解两种方式,分别阐述了两种回收方式的研究成果和工艺现状,并就存在的问题进行了讨论。     

Effects of plastics in anaerobic digestion of urban solid wastes

Anaerobic digestion is a possible method for treating urban solid wastes. This pilot plant study was undertaken to ascertain the effect of plastic refuse on the anaerobic digestion process of municipal solid wastes. The air-blown polyethylene film present in the air classified light fraction of solid waste from Pompono Beach, Florida, U.S.A. was removed by visual separation. Control digesters operating on this substrate, produced more gas than test digesters to which the plastic scraps had been returned.     

Solid industrial wastes and their management in Asegra (Granada, Spain)

ASEGRA is an industrial area in Granada (Spain) with important waste management problems. In order to properly manage and control waste production in industry, one must know the quantity, type, and composition of industrial wastes, as well as the management practices of the companies involved. In our study, questionnaires were used to collect data regarding methods of waste management used in 170 of the 230 businesses in the area of study. The majority of these companies in ASEGRA are small or medium-size, and belong to the service sector, transport, and distribution. This was naturally a conditioning factor in both the type and management of the wastes generated. It was observed that paper and cardboard, plastic, wood, and metals were the most common types of waste, mainly generated from packaging (49% of the total volume), as well as material used in containers and for wrapping products. Serious problems were observed in the management of these wastes. In most cases they were disposed of by dumping, and very rarely did businesses resort to reuse, recycling or valorization. Smaller companies encountered greater difficulties when it came to effective waste management. The most frequent solution for the disposal of wastes in the area was dumping.     

Use of recycled plastic in concrete: a review

Numerous waste materials are generated from manufacturing processes, service industries and municipal solid wastes. The increasing awareness about the environment has tremendously contributed to the concerns related with disposal of the generated wastes. Solid waste management is one of the major environmental concerns in the world. With the scarcity of space for landfilling and due to its ever increasing cost, waste utilization has become an attractive alternative to disposal. Research is being carried out on the utilization of waste products in concrete. Such waste products include discarded tires, plastic, glass, steel, burnt foundry sand, and coal combustion by-products (CCBs). Each of these waste products has provided a specific effect on the properties of fresh and hardened concrete. The use of waste products in concrete not only makes it economical, but also helps in reducing disposal problems. Reuse of bulky wastes is considered the best environmental alternative for solving the problem of disposal. One such waste is plastic, which could be used in various applications. However, efforts have also been made to explore its use in concrete/asphalt concrete. The development of new construction materials using recycled plastics is important to both the construction and the plastic recycling industries. This paper presents a detailed review about waste and recycled plastics, waste management options, and research published on the effect of recycled plastic on the fresh and hardened properties of concrete. The effect of recycled and waste plastic on bulk density, air content, workability, compressive strength, splitting tensile strength, modulus of elasticity, impact resistance, permeability, and abrasion resistance is discussed in this paper.     

Recycling of plastic packaging waste in Bandung City,Indonesia

Economic growth, changing consumption and production patterns are resulting in rapid increase in the generation of plastic wastes, including plastic packaging waste (PPW). A variety of PPW is identified in the municipal solid waste (MSW) stream. In this paper, quantity and composition of PPW at generators (residential and nonresidential sectors) and at the informal sector of waste recycling were measured, and accordingly the flow of PPW within Bandung City, Indonesia was analyzed. Though the generation rate per capita is not so high (25.1 g per day), total PPW generated by 2.3 million inhabitants in Bandung becomes 58.4 tonnes per day (3.76 % of total MSW generated). Due to lack of integrated MSW management, most of PPW is neither collected properly nor disposed of in appropriate manner by the municipality. Collection of valuable wastes including PPW is done predominantly by the informal sector without regard to health and safety. It is predicted that total PPW recycled by various informal waste recycling players like scavengers, junkmen, intermediates, and dealers is 27.5 tonnes per day (64.6 % of total PPW generated). Interviews regarding the existing handling methods and incentives preferred by generators to increase the recycling rate are also presented.     

Electrostatic separators of particles: Application to plastic/metal, metal/metal and plastic/plastic mixtures

Electrostatic separation is a generic term given to a significant class of technologies of industrial waste processing, widely used for the sorting of granular mixtures due to electric forces acting on particles whose average size is approximately 5mm. The focus of this paper is on three electrostatic processes of separation used for processing of different types of mixtures: (i) role-type electrostatic separator, used to sort mixtures containing metal/plastic particles (copper/PVC for example); (ii) plate-type electrostatic separator, used to sort mixtures containing metal/metal particles (copper/lead for example) and (iii) free-fall electrostatic separator, used to sort mixtures of plastic/plastic particles (PVC/PE for example). Experiments carried out on industrial samples using laboratory electrostatic separators confirm the efficiency of these processes and show that the processes can improve the recovery and purity of products resulting from industrial wastes.     

上海市一次性塑料饭盒的管理现状分析及建议

梳理了上海市在一次性塑料饭盒管理工作中回收处置系统难以正常运转的主要问题，提出了建立全国一盘棋的格局，将其他塑料废弃物纳入回收处置的管理范畴，并建立对废塑料回收处置的奖励或补贴政策，从而继续控制视觉污染，促进生活垃圾减量化和资源化。     

Rapid discrimination of plastic packaging materials using MIR spectroscopy coupled with independent components analysis (ICA)

Plastic packaging wastes increased considerably in recent decades, raising a major and serious public concern on political, economical and environmental levels. Dealing with this kind of problems is generally done by landfilling and energy recovery. However, these two methods are becoming more and more expensive, hazardous to the public health and the environment. Therefore, recycling is gaining worldwide consideration as a solution to decrease the growing volume of plastic packaging wastes and simultaneously reduce the consumption of oil required to produce virgin resin. Nevertheless, a major shortage is encountered in recycling which is related to the sorting of plastic wastes. In this paper, a feasibility study was performed in order to test the potential of an innovative approach combining mid infrared (MIR) spectroscopy with independent components analysis (ICA), as a simple and fast approach which could achieve high separation rates. This approach (MIR-ICA) gave 100% discrimination rates in the separation of all studied plastics: polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS) and polylactide (PLA). In addition, some more specific discriminations were obtained separating plastic materials belonging to the same polymer family e.g. high density polyethylene (HDPE) from low density polyethylene (LDPE). High discrimination rates were obtained despite the heterogeneity among samples especially differences in colors, thicknesses and surface textures. The reproducibility of the proposed approach was also tested using two spectrometers with considerable differences in their sensitivities. Discrimination rates were not affected proving that the developed approach could be extrapolated to different spectrometers. MIR combined with ICA is a promising tool for plastic waste separation that can help improve performance in this field; however further technological improvements and developments are required before it can be applied at an industrial level given that all tests presented here were performed under laboratory conditions.     

Facile characterization of polymer fractions from waste electrical and electronic equipment (WEEE) for mechanical recycling

In view of the environmental problem involved in the management of WEEE, and then in the recycling of post-consumer plastic of WEEE there is a pressing need for rapid measurement technologies for simple identification of the various commercial plastic materials and of the several contaminants, to improve the recycling of such wastes.This research is focused on the characterization and recycling of two types of plastics, namely plastic from personal computer (grey plastic) and plastic from television (black plastic). Various analytical techniques were used to monitor the compositions of WEEE. Initially, the chemical structure of each plastic material was identified by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). Polymeric contaminants of these plastics, in particular brominated flame retardants (BFRs) were detected in grey plastics only using different techniques. These techniques are useful for a rapid, correct and economics identification of a large volumes of WEEE plastics.     

Advances in the recycling of plastic wastes for metallurgical coke production

This paper aims to provide useful knowledge on the use of plastic wastes as additives to coking blends for the production of metallurgical coke. It focuses on the influence that the composition of plastic wastes has upon the development of coal fluidity, the generation of pressure during the coking process and the quality of the cokes produced in a semipilot oven. Several plastic mixtures of two types of thermoplastics, polyolefins (HDPE, LDPE and PP) and aromatic polymers such as PET, were used. The overall addition rate of plastics to a medium-fluid coal blend was 2 wt%. It is shown that polyolefins, weaker modifiers of coal fluidity, may be employed to maintain coke quality but that they have a negative effect on the generation of coking pressure, while plastics of the aromatic type such as PET, a strong modifier of coal fluidity, can be used to counteract the generation of coking pressure. From the results, it is deduced that the protocol developed is useful for determining the optimum amount of each type of polymer (polyolefins and aromatic polymers) that is needed in order to counteract the generation of pressure during the coking process and to maintain the quality of the cokes.     

A mathematical model to predict the composition and generation of hospital wastes in Iran

The aim of this study is to investigate the quality and quantity of hospital wastes in Iran. The generated hospital wastes have been estimated by the number of hospitals and the number of active beds in each province of Iran in 2001. All data and information have been gathered from: (i) Iran Statistics Center, (ii) literature review, and (iii) hospital waste investigations for an average hospital. Physical analyses have been conducted in terms of various materials (plastic, textile, paper, metal, and others) and components (biological, infectious, medical, and regular wastes). Based on the above-mentioned investigation and information, a mathematical model has been developed to calculate the generation of (infectious) hospital wastes for any desired year. Utilizing the model, generated infectious hospital wastes has been estimated as 698,937 tones for 2008 (short-term) and 3,494,387 tones for 2028 (long-term period). If the real infectious wastes are collected separately, then the generated infectious wastes will be reduced by 15.1% of the above-mentioned amount (139,787 tones for 2008, and 698,877 tones for 2028). Results of physical analysis show the components of the hospital waste as: (a) infectious, 67.3%; (b) medical, 8.8%; (c) biological, 1.8%; and (d) common municipal wastes, 22.1%. An appropriate collection method requires training the staff at hospitals along with preparation of the required facilities. Of course, both of these requirements are cost intensive.     

Design and first experimental results of a bubbling fluidized bed for air gasification of plastic waste

Plastic wastes have an especially high potential for use as alternative fuels, considering their high heating value and their large and stable availability. They could be used in electricity production based on gasification technologies, wherein electricity is produced in engines by means of the conversion of plastic wastes into a valuable gas. However, there are still some technical barriers to overcome before this technology can access the commercial stage, and further scientific research is needed to gain deeper understanding of the process and to be able to control and optimize it. This research presents the design and first experimental results of a bubbling fluidized bed gasifier conceived for the gasification of actual plastic residues. The experimental tests revealed that the selection and design of the reactor were adequate and proved some of the advantages of using plastic as a fuel, related in part to the absence of ashes and char. A valuable syngas over 5 MJ/m³ was generated, which contained a considerable fraction of methane as well as hydrogen and carbon monoxide as main combustible gases. The highest efficiency was achieved when the equivalence ratio was increased to 0.35, reaching 61 % in terms of cold gas efficiency and 66 % carbon conversion.     

Minimizing waste polymers in space

Waste polymers, essentially plastic packages, make up a significant fraction of solid wastes in a crewed space habitat. While logistic limitations preclude consideration of recovery/recycling technologies that have proven viable on Earth, the challenge in space is to provide materials and processes that minimize the volume of stored waste plastics and which allow recovery at the completion of a mission.     

Gasification and smelting system using oxygen blowing for plastic waste including polyvinyl chloride

A new type of waste gasification and smelting system using oxygen blowing based on high-temperature metallurgy, was developed by Sumitomo Metals, Japan. This system can steadily gasify and melt not only municipal waste, but also plastic waste and polyvinyl chloride (PVC) waste by using a top-blow oxygen lance together with sideways-blow oxygen lances. As a result of gasification in the high-temperature reducing atmosphere and rapid gas cooling, dioxin-free, high-calorie purified gas was produced. Ash components in the wastes were smelted in a high-temperature reducing atmosphere, and high-quality slag free of heavy metals was produced. Most of the chlorine in the wastes was converted into hydrogen chloride in the off gas. The hydrogen chloride can be recovered as hydrochloric acid or chlorine, which are recyclable to PVC manufacturing.     

Pyrolysis of virgin and waste polypropylene and its mixtures with waste polyethylene and polystyrene

A comparison of waste and virgin polypropylene (PP) plastics under slow pyrolysis conditions is presented. Moreover, mixtures of waste PP with wastes of polyethylene (PE) and polystyrene (PS) were pyrolyzed under the same operating conditions. Not only the impact of waste on degradation products but also impacts of the variations in the mixing ratio were investigated. The thermogravimetric weight loss curves and their derivatives of virgin and waste PP showed differences due to the impurities which are dirt and food residues. The liquid yield distribution concerning the aliphatic, mono-aromatic and poly-aromatic compounds varies as the ratio of PP waste increases in the waste plastic mixtures. In addition to this, the alkene/alkane ratio of gas products shows variations depending on the mixing ratio of wastes.     

Field-scale rotary kiln incineration: Oxygen responses at the kiln,afterburner, and stack

There currently exists a need for better characterization and simulation of the processes that occur during the incineration of hazardous wastes in the environment of a rotary kiln. Addressing this need, a comprehensive research program was formed with the goal of developing a rudimentary predictive capability for rotary kiln incineration of hazardous wastes. This comprehensive program is headed by Louisiana State University and includes interaction with the University of Utah and also various industrial participants. Such cooperation allows use of laboratory, pilot, and field scale equipment. While laboratory scale experiments provide the necessary decoupling of complex phenomena and a high degree of experimental control, and pilot scale studies provide more realism at the expense of experimental control, the problems of scale-up make generalization of results to field scale units very tenuous. The unique aspect of the LSU program is the coupling of the laboratory and pilot scale units with afield scale unit in order to overcome these generalizations. In this study, plastic packs containing a mixture of toluene and sorbent were fed to a field-scale rotary kiln incinerator at a rate of one pack every 10 minutes. Selected continuous gas samples and temperatures were obtained from the exit of the rotary kiln, from the afterburner, and from the stack. These measurements were obtained during various operating conditions. These data provide, for the first time, an ability to compare conditions in the kiln to simultaneous conditions in the afterburner and stack. This paper outlines several new experimental features of our field-scale tests conducted in October 1990. Oxygen responses from the kiln, the afterburner, and the stack are compared during various operating conditions.     

Fluidized bed gasification of waste-derived fuels

Five alternative waste-derived fuels obtained from municipal solid waste and different post-consumer packaging were fed in a pilot-scale bubbling fluidized bed gasifier, having a maximum feeding capacity of 100 kg/h. The experimental runs utilized beds of natural olivine, quartz sand or dolomite, fluidized by air, and were carried out under various values of equivalence ratio. The process resulted technically feasible with all the materials tested. The olivine, a neo-silicate of Fe and Mg with an olive-green colour, has proven to be a good candidate to act as a bed catalyst for tar removal during gasification of polyolefin plastic wastes. Thanks to its catalytic activity it is possible to obtain very high fractions of hydrogen in the syngas (between 20% and 30%), even using air as the gasifying agent, i.e. in the most favourable economical conditions and with the simplest plant and reactor configuration. The catalytic activity of olivine was instead reduced or completely inhibited when waste-derived fuels from municipal solid wastes and aggregates of different post-consumer plastic packagings were fed. Anyhow, these materials have given acceptable performance, yielding a syngas of sufficient quality for energy applications after an adequate downstream cleaning.     

Solid waste recycling in Rajshahi city of Bangladesh

Efficient recycling of solid wastes is now a global concern for a sustainable and environmentally sound management. In this study, traditional recycling pattern of solid waste was investigated in Rajshahi municipality which is the fourth largest city of Bangladesh. A questionnaire survey had been carried out in various recycle shops during April 2010 to January 2011. There were 140 recycle shops and most of them were located in the vicinity of Stadium market in Rajshahi. About 1906 people were found to be involved in recycling activities of the city. The major fraction of recycled wastes were sent to capital city Dhaka for further manufacture of different new products. Only a small amount of wastes, specially plastics, were processed in local recycle factories to produce small washing pots and bottle caps. Everyday, an estimated 28.13 tons of recycled solid wastes were handled in Rajshahi city area. This recycled portion accounted for 8.25% of the daily total generated wastes (341 ton d^?1), 54.6% of total recyclable wastes (51.49 ton d^?1) and 68.29% of readily recyclable wastes (41.19 ton d^?1). Major recycled materials were found to be iron, glass, plastic, and papers. Only five factories were involved in preliminary processing of recyclable wastes. Collecting and processing secondary materials, manufacturing recycled-content products, and then buying recycled products created a circle or loop that ensured the overall success of recycling and generated a host of financial, environmental, and social returns.     

Thermal valorization of post-consumer film waste in a bubbling bed gasifier

The use of plastic bags and film packaging is very frequent in manifold sectors and film waste is usually present in different sources of municipal and industrial wastes. A significant part of it is not suitable for mechanical recycling but could be safely transformed into a valuable gas by means of thermal valorization. In this research, the gasification of film wastes has been experimentally investigated through experiments in a fluidized bed reactor of two reference polymers, polyethylene and polypropylene, and actual post-consumer film waste. After a complete experimental characterization of the three materials, several gasification experiments have been performed to analyze the influence of the fuel and of equivalence ratio on gas production and composition, on tar generation and on efficiency. The experiments prove that film waste and analogue polymer derived wastes can be successfully gasified in a fluidized bed reactor, yielding a gas with a higher heating value in a range from 3.6 to 5.6 MJ/m³ and cold gas efficiencies up to 60%.