In the UK, a landfilltax has been applied, which is currently set to escalateeach year until 2010 in order to increase the incentiveto pert wastes from landfill to recovery actions suchas recycling (DEFRA 2007).(b) Incineration and energy recoveryIncineration reduces the need for landfill of plasticswaste, however, there are concerns that hazardous sub-stances may be released into the atmosphere in theprocess. For example, PVC and halogenated additivesare typically present in mixed plastic waste leading to therisk of dioxins, other polychlorinated biphenyls andfurans being released into the environment (Gilpinet al. 2003). As a consequence primarily of thisperceived pollution risk, incineration of plastic is lessprevalent than landfill and mechanical recyclingas a waste-management strategy. Japan and someEuropean countries such as Denmark and Sweden arenotable exceptions, with extensive incineratorinfrastructure in place for dealing with MSW, includingplastics.Incineration can be used with recovery of some ofthe energy content in the plastic. The useful energyrecovered can vary considerably depending on whetherit is used for electricity generation, combined heat andpower, or as solid refuse fuel for co-fuelling of blastfurnaces or cement kilns. Liquefaction to diesel fuelor gasification through pyrolysis is also possible(Arvanitoyannis & Bosnea 2001) and interest in thisapproach to produce diesel fuel is increasing, presum-ably owing to rising oil prices. Energy-recoveryprocesses may be the most suitable way for dealingwith highly mixed plastic such as some electronicand electrical wastes and automotive shredder residue.(c) DowngaugingReducing the amount of packaging used per item willreduce waste volumes. Economics dictate that mostmanufacturers will already use close to the minimumrequired material necessary for a given application(but see Thompson et al. 2009b, Fig 1). This principleis, however, offset against aesthetics, convenience andmarketing benefits that can lead to over-use of packa-ging, as well as the effect of existing investment in tool-ing and production process, which can also result inexcessive packaging of some products.(d) Re-use of plastic packagingForty years ago, re-use of post-consumer packaging inthe form of glass bottles and jars was common.Limitations to the broader application of rigid containerre-use are at least partially logistical, where distribution and collection points are distant from centralizedproduct-filling factories and would result in considerableback-haul distances. In addition, the wide range ofcontainers and packs for branding and marketing pur-poses makes direct take-back and refilling less feasible.Take-back and refilling schemes do exist in severalEuropean countries (Institute for Local Self-Reliance2002), including PET bottles as well as glass, but theyare elsewhere generally considered a niche activity forlocal businesses rather than a realistic large-scale strategyto reduce packaging waste.There is considerable scope for re-use of plastics usedfor the transport of goods, and for potential re-use orre-manufacture from some plastic components in high-value consumer goods such as vehicles and electronicequipment. This is evident in an industrial scale withre-use of containers and pallets in haulage (seeThompson et al. 2009b). Some shift away from single-use plastic carrier bags to reusable bags has also beenobserved, both because of voluntary behaviour changeprogrammes, as in Australia (Department ofEnvironment and Heritage (Australia) 2008)andasaconsequence of legislation, such as the plastic bag levyin Ireland (Department of Environment Heritage andLocal Government (Ireland) 2007), or the recentbanning of lightweight carrier bags, for example inBangladesh and China.(e) Plastics recyclingTerminology for plastics recycling is complex andsometimes confusing because of the wide range of recy-cling and recovery activities (table 2). These includefour categories: primary (mechanical reprocessing intoa product with equivalent properties), secondary(mechanical reprocessing into products requiringlower properties), tertiary (recovery of chemicalconstituents) and quaternary (recovery of energy).Primary recycling is often referred to as closed-looprecycling, and secondary recycling as downgrading.Tertiary recycling is either described as chemical orfeedstock recycling and applies when the polymer isde-polymerized to its chemical constituents (Fisher2003). Quaternary recycling is energy recovery, energyfrom waste or valorization. Biodegradable plastics canalso be composted, and this is a further example oftertiary recycling, and is also described as organic orbiological recycling (see Song et al.2009).It is possible in theory to closed-loop recycle mostthermoplastics, however, plastic packaging frequentlyuses a wide variety of different polymers and othermaterials such as metals, paper, pigments, inks andadhesives that increases the difficulty. Closed-looprecycling is most practical when the polymer constitu-ent can be (i) effectively separated from sources ofcontamination and (ii) stabilized against degradationduring reprocessing and subsequent use. Ideally, theplastic waste stream for reprocessing would also con-sist of a narrow range of polymer grades to reducethe difficulty of replacing virgin resin directly. Forexample, all PET bottles are made from similargrades of PET suitable for both the bottle manufactur-ing process and reprocessing to polyester fibre, whileHDPE used for blow moulding bottles is less-suitedto injection moulding applications. As a result, theonly parts of the post-consumer plastic waste streamthat have routinely been recycled in a strictly closed-loop fashion are clear PET bottles and recently inthe UK, HDPE milk bottles. Pre-consumer plasticwaste such as industrial packaging is currently recycledto a greater extent than post-consumer packaging, as itis relatively pure and available from a smaller numberof sources of relatively higher volume. The volumes ofpost-consumer waste are, however, 塑料回收英文文献和中文翻译(3):http://www.youerw.com/fanyi/lunwen_31406.html