Biodegradable plastics: a solution or a challenge?

Journal of Cleaner Production 11 (2003) 27–40www.cleanerproduction.net

Biodegradable plastics: a solution or a challenge?

X. RenInternational Center for Science and High Technology (ICS-UNIDO) Building L2, AREA Science Park, Padriciano 99, 34012 Trieste, Italy

Received 29 August 2001; accepted 28 January 2002

Abstract

Though developed as a solution for the waste problem, biodegradable plastics create new challenges on waste management withrespect to policies and laws, waste management technologies and application of market-based instruments. A holistic view andintegrated approach are necessary to address the implication of each component of this picture on others and on the whole. In aneffort to tackle the challenges, the paper makes an in-depth analysis of the waste management system with biodegradable plasticsas an element, emphasizing on regulatory and economic aspects. 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Biodegradable plastics; Waste management; Environmental management and policies

1. Introduction

The annual world production of polymer materialswas around 150 million tones in 1996, with the averageper capita consumption of plastics in developed coun-tries ranging from 80–100 kg per year [1]. Though theper capita consumption of plastics in developing coun-tries is still lower by order of magnitude, the total pro-duction and consumption is substantial. The plastic con-sumption in China was estimated to be 16 million tonsin 2000, the fifth in the world after USA, Japan, Ger-many and South Korea. Local production accounts forabout 40% with more than 50% imported. Nearly onefifth (about 3.5–4 million tons) of the total plastic con-sumption is used as packaging, of which half is foamedplastics (dominated by expanded polystyrene (EPS)).Each year about half a million tons of mulching films isused by agriculture in China. The annual generation ofplastic wastes in China amounts to 4 million tons withonly 10% recovered and recycled (dropped from about20% in 1980), 20–30% incinerated or landfilled and 60–70% dumped, littered and washed away [2]. The rapidincrease in production and consumption of plastics hasled to the serious plastic waste problems, so called‘White Pollution’, and landfill depletion, due to theirhigh volume to weight ratio and resistance to degra-

E-mail address: [email protected] (X. Ren).

0959-6526/02/$ - see front matter 2002 Elsevier Science Ltd. All rights reserved.PII: S0959-6526 (02)00020-3

dation. Accumulated plastic film residues in soil havecaused significant decrease in yield. Plastic wastes float-ing on rivers and lakes are increasingly threatening fish-ery, navigation, operation of hydropower plants, irri-gation and other public works. Moreover, as over 99%of plastics are of fossil fuel origin, their rapid increasewill put further pressure on the already limited non-renewable resources on earth.

Biodegradable plastics may serve as a promising sol-ution to the over-loaded landfills by diverting part ofbulky volume plastics to other means of waste manage-ment, and to littering of disposable plastic productswhich are otherwise difficult to recycle. Biodegradableplastics of renewable resources origin also help to pre-serve the non-renewable resources and contribute to sus-tainable development. The development in law and pol-icy, advance in technology and in waste management,adoption of economic and market-based instrumentsgenerate many new challenges in the decision makingprocess with regard to waste management. All theserequire a comprehensive understanding of implicationsand an insight into the potential problems.

2. Environmental problems expected to bealleviated

Problems that are expected to be alleviated or solvedby biodegradable plastics mainly include:

28 X. Ren / Journal of Cleaner Production 11 (2003) 27–40

(a) Increasing pressure on landfills; it is hoped thatbiodegradable plastics would divert part of bulky plas-tic wastes from landfilling. It will also facilitate organicwaste management by eliminating the cost involved inremoving the collection bags before entering compostfacilities.(b) Littering of difficult-to-recycle products, forinstance foodservice disposables, has led to enormousenvironmental and visual pollution, which is of alarm-ing concern particularly in some emerging economies,such as China. Recycling of plastics is not always econ-omically favorable due to the high cost in hauling thelightweight and high volume plastic waste to the recy-clers. Cost and environmental impacts of cleaning thehighly contaminated foodservice products are also sig-nificant.(c) Biodegradable plastics of renewable sources willcontribute to a more sustainable society by conservingthe non-renewable resources, the fossil fuel.

Can biodegradable plastics really meet these expec-tations, thus contributing to environmentally soundwaste management and sustainability? If yes, under whatconditions? First, what is environmentally sound wastemanagement?

As defined by the United Nations Environmental Pro-gram (UNEP), it means taking all practical steps toensure that wastes are managed in a manner which willprotect human health and the environment against theadverse effects. The major principles to be consideredin such waste management are recognized by the inter-national community as follows [3]:

(1) The source reduction principle—means to minimizethe generation of waste in quantity and its potential tocause pollution by appropriate plant and processdesigns and cleaner production.(2) The integrated life-cycle principle—by which sub-stances and products should be designed and managedsuch that minimum environmental impact is causedduring their whole life cycle.(3) The integrated pollution control principle—requiresthat the waste management should be based on a strat-egy which takes into account the potential for crossmedia and multi-media synergistic effects.(4) The polluter pays principle—by which the potentialpolluter must act to prevent pollution and those whocause pollution pay for remedying the consequences ofthat pollution.(5) The standardization principle—which requires theprovision of standards for the environmentally soundmanagement of wastes at all stages of their processing,treatment, disposal and recovery.(6) The principle of public participation—waste man-agement options are considered in consultation with the

public, and that the public has access to informationconcerning the management of hazardous wastes.

Derived from these principles, a sound waste manage-ment should follow the hierarchy of Four-R, namelyReduce, Reuse, Recycle (or recovery of materials) andRecovery of the energy content if not recyclable beforefinal disposal. A number of legal, institutional and tech-nical conditions need to be met:

� A regulatory and enforcement infrastructure (seeFig. 1).

� Authorized facilities have adequate technology andmeans of pollution control and effective monitoring.

� More sophisticated yet efficient measures based onmarket mechanism.

� Public participation and information schemes (e.g.Eco-label), awareness raising campaign.

3. New challenges on waste management

In order to answer question (a), how biodegradableplastics can really reduce the pressure on landfills andfacilitate organic recycling, first of all we need to scrut-inize the possible impacts of biodegradable plastics onprevailing waste management technologies and practice.

3.1. Challenges on waste management technologies

The pros and cons of major waste treatment means,i.e. recycling, composting, incineration and landfilling,are listed in the Table 1. The discussion shows thatacquisition of the benefits and overcoming of potentialproblems of these waste treatment technologies relymore on management than on investment. The new tech-nical challenges possibly imposed by biodegradableplastics are envisaged to be the following.

Introduction of biodegradable plastics is mainlydriven by the situation under which plastic products aredifficult or non-recyclable in an economically viableway. Inherently, biodegradable plastics are not createdfor material recycling. In general, thermal plastics can berecycled more readily than thermal-set. A typical plasticrecycling process involves re-heating, during whichbiodegradable plastics will usually decompose and makefurther processing impossible. Mixing of biodegradableplastics in the feedstock of recycling will thus damagethe process and the quality of recycled products. For thissake, products made of biodegradable plastics should belabeled as such, so that they can be sorted out from recy-clables. It is evident that clear labeling and identificationof materials, necessary for an effective sorting, willbecome more important after biodegradable plastics arewidely adopted. It would be necessary for policy makers

29X. Ren / Journal of Cleaner Production 11 (2003) 27–40

Fig. 1. Diagram of the infrastructure for a municipal waste management.

Table 1Pros and cons of major waste treatment technologies

Technology Pros Cons

Recycling

� �Reduce amount of wastes for disposal Not everything economically recyclable� �Save resources and energy in virgin Recycling consume energy, emit pollutants

production � Recycled product inferior in quality, thus� only lower grade application, limitedExtend product’s lifetime, conserve

resources market

Composting � �Reduce load of landfill by digesting Economics still unfavorableorganics � Risk of odor and pest problem

� �End product useful for soil amendment No reliable market for end product� (compost)Need less energy than recycling,

incineration

Incineration � �Reduce waste substantially by High capital and operational costsvolume/weight � Emission of hazardous substances (Dioxin,

� etc.)Generate energy� �Need small space, reduce burden of landfill More stringent in operation and control

Landfilling

� �Final and indispensable disposal of wastes, Suitable sites become scarce worldwideresidues from recycling, incineration etc. � Cost is increasing significantly due to

� higher environmental and sanitaryRelatively easy to build and operaterequirement

� Leachate and gas emission problems


as well as industry itself to prepare for the change inadvance.

Composting is the most relevant waste treatment tech-nology for biodegradable plastics. Internationallyaccepted definitions and standards for biodegradableplastics are all based on their compostability so far. Thesuccess of biodegradable plastics will be decided by theavailability of composting/digestion facilities. Experi-ence worldwide reveals the economic viability of com-posting depending on the following factors [3]:

� Mixed wastes composting has a large negative effecton the quality and marketability of the compost.Enhancement of separate collection of organic wastesand recovery of non-compostables are necessary inmany developing countries, and manual picking canhelp.

� There must be a market or use for the compost. Thismarket does not have to produce net income, but ithas to be factored into the cost of composting. Thecloser the market, the more likely that compostingis sustainable.

In contrast to composting as an aerobic treatment processof organic wastes, gasification, an anaerobic processusing existing sewage treatment facility or controlledlandfill, has gained attention recently in some Europeancountries. Europe is one of the few regions that attachessuch importance to composting that EU is preparing anew Directive dedicated to composting.

With regard to photochemically degradable plasticswhich found their application mainly in agriculture, thepolymer chains are attacked at the existing functionalgroups or with the help of sensitizing additives(aromatic/ heavy metal compounds) under the influenceof sunlight (UV radiation). There is still dispute aboutwhether biological degradation follows, in addition tothe concern about heavy metal contaminants. Thereforethey are not suitable for recovery by composting.

Incineration is not the desired destination of biodeg-radable plastics, though as polymers containing mainlycarbon and hydrogen, biodegradable plastics producesignificant amounts of heat thus acceptable in inciner-ators. Consideration of heavy metals and persistentorganic pollutants generated from incineration is alsoapplicable to biodegradable plastics. The heat value ofplastic wastes are gathered in Table 2.

Accidental entry of biodegradable plastics, except forits volume, should not cause any problem in a standardlandfill which is designed to be inert with wastes insidedegrading very little. However, as substandard landfillis common in many less developed countries, entry ofbiodegradable plastics will increase the biodegradationalready existing by generating more leachate and gasesand thus worsen the contamination of ground and surfacewater, and ambient environment. This again shows the

Table 2Energy values of plastic wastes compared with fuels, source: [11][12]

Waste KJ/kg Fuels KJ/kg

Polyethylene 41,000 Gasoline 46,000Polypropylene 40,000 Diesel oil 44,400Polystyrene 37,000 Kerosene (no.1 42,600

fuel oil)Mixed plastics 30,000–40,000 Coal 27,000–30,000

Wood 14,000Rubber 22,000Newspapers 16,000Corrugated boxes 15,000Textile 14,500Municipal solid ~10,000wastes

importance of clear labeling and segregation of biodeg-radables (not only plastics) from other waste streams. Itcan be said that biodegradable plastics are not made forbeing landfilled.

Many industrial composting facilities tend to oralready decline plastic bags as organic waste bags dueto the high capital and operation cost involved in de-bagging. Many debaggers lack a good separation per-centage, often leaving about 10–25% [4] of the plasticin the compost. Compost with plastic contaminants isobviously of lower quality and not accepted well inthe market.

Compared with conventional plastic bags, paper bagsare not waterproof, while most organic wastes containhigh moisture. In addition, they are not transparent.While with transparent bags, mixing of trashes otherthan organic wastes decreases since the bag cannot hidethe content easily. The use of biodegradable plastic bagscan offer composting operators saving of de-bag cost,increased quality and quantity of compost products.First, a better quality can command a higher price forfinished compost than product contaminated with poly-ethylene. Second, processing costs is reduced by avoid-ing debagging and separation of plastic and compost atthe time of screening. Third, operators actually willrecover more material to sell and less go to landfill ascontaminated. Normally there are 10–20% [4] sellablecompost lost at commercial compost facilities. Whenclean, the residues (or so called overs) are re-introducedand eventually end up as sellable compost. When con-taminated, overs normally have to be disposed of bylandfill.

Lower cost of composting could lead to a lowercharge at the community, which in turn provides anincentive to encourage the use of generally more expens-ive biodegradable bags for organic wastes.


3.2. Source separation and life cycle approach

The last section analyses the possible challenges thatmight be brought about by commercialization of biodeg-radable plastics on commonly practiced waste manage-ment technologies. It highlights the importance of inte-grated waste management with focus on sourceseparation and sound operation. Take the example ofcomposting as it is the most relevant to biodegradables.It has been identified that the reduction of contaminantlevel is crucial for the success of composting, which inreturn provides guarantee for the acceptance of biodeg-radable materials. There are various options to get cle-aner compost:

1. Reduce or eliminate contaminants in product designso as to facilitate the after-use disposal and improvethe quality of recycled products, such as compost. Itcalls for life cycle consideration beyond waste man-agement system to design, production and consump-tion.

2. Source separation of waste by households and com-mercial consumers into recyclables, compostables(organic wastes and non-recyclable papers etc.) andwastes for final disposal.

3. Sorting at a centralized facility after collection andprior to composting, is included in most of the mod-ern municipal waste composting facilities.

4. To separate contaminants after composting, tra-ditional practice of municipal waste composting.

Evidence from the experimental trials and operatingfacilities show that options at the top of the above listhave higher potential to reduce contaminant level thanthose lower down thus should be prioritized and encour-aged (see Fig. 2a and b). It is very expensive to removecontaminants from mixed waste compost in order tomeet the increasingly stringent requirements set by manycountries on quality of compost. This is actually themajor reason why industrial scale composting did notsucceed in the past. Centralized sorting before com-posting becomes increasingly difficult and less effectivetoo with the increase in separation cost. Moreover, someliquid contaminants, fine dust or paint chips containingheavy metals and/or toxic chemicals can attach to theotherwise clean organic wastes during collection andstorage.

Source separation, on the other hand, provides higherquality of compost with significant lower contaminantlevels than centralized sorting and after-compostingscreening, as revealed by research in some Europeancountries and a study in USA (see Fig. 2a and b). Sourceseparation of organic wastes can achieve a high level ofdiversion potential of wastes from landfill, estimated inthe range of 25–50% [5], which is comparable to thatof centralized sorting. Effective source separation needs

cooperation of a well-motivated public by educationalprograms, environmental awareness raising campaignsand mass media. More important is the integration inpolicies, regulations, economic instruments so as to cre-ate a concerted pressure as well as economic incentiveto promote source reduction and separation.

Introducing life cycle consideration into the design ofnovel polymers and polymeric products is a new chal-lenge facing polymer scientists and producers. One ofthe main ideas of the so-called design-for-the-environ-ment (DfE) or Eco-design is to go beyond the traditionallogic and procedure of product design to take the after-use stage of the product into account. A truly environ-mentally benign product should have minimum adverseimpacts on human health and the environment, not onlyduring its production and use phases, but also in finaldisposal after being discarded. As discussed previously,Eco-design of biodegradable plastics might includedecreasing the use of toxic chemicals and heavy metalsin plastic additives, unwanted by all disposal methodsand organic recycling in particular. This should be bornein mind while developing biodegradable plastics andplanning for new applications.

In short, biodegradable plastics can benefit wastemanagement only if collected and treated separately. Inaddition, it is vital to make sure that there is no mixturewith conventional plastic waste destined for recycling.Even the smallest amount of degradable plastics canendanger the re-usability of recycled plastic and thus thesuccess achieved in plastic recycling. To fulfill theserequirements, it is essential that biodegradable materialsare labeled and identified in a sensible and easily reco-gnizable way. The technical challenges brought by biod-egradable plastics pose a higher requirement on inte-gration and life-cycle approach in waste management,which calls for integration in policies, regulation andstandards.

4. Implications on legal means

4.1. Integrated waste management

To achieve the benefit of biodegradable plastics, it isnecessary to adopt them to a scale enough for thechange. Obstacles imposed by improper or fragmentedpolicies and regulations should first be identified, modi-fied or removed.

A comparison study on policies and regulatory issueswas made in order to gain insight and inspiration. Europeand East Asia are selected due to the fact that the policiesand regulations in the two regions are good represen-tations of those in developed and in less developed coun-tries respectively. Availability of information also countsin selecting countries and regions for this comparison.


Fig. 2. (a) Lead (Pb) levels in municipal waste composts from experimental studies comparing several separation approaches. Standards fromseveral US states, Canadian provinces, and European countries are listed on the right axis. (b) Average mercury (Hg) and cadmium (Cd) levels inmunicipal waste composts from centralized separation versus source separation of organic compostables in North America and Europe. USEPA(NOAEL (No Observed Adverse Effect Level)/APL (Alternate Pollutant Limit) for sewage sludge, not for compost yet) standards and that fromthe Netherlands are included. Source of (a) and (b): Municipal Solid Waste Composting: Strategies for Separating Contaminants, last updated inMay 1998 [5].

4.1.1. EuropeIn Europe as well as worldwide, legal actions support-

ive to strategy and hierarchy described in Section 2 aregenerally underdeveloped than those targeting specificwaste problems, and less enforceable due to their generalcharacter. However, new efforts are underway, support-ing the strategy in more concrete terms.

European Parliament and Council Directive 94/62/ECof 20 December 1994 on packaging and packagingwaste, the so-called Packaging Directive proved to bethe decisive law. It states clearly that the prevention ofwaste should be ‘a first priority’ , while reuse, recyclingand other forms of recovering are ‘additional fundamen-tal principles’ for the ‘ reduction of the final disposal ofsuch waste’ . Particularly, the Article 6, Recovery andrecycling, is proved to be the most influential provisionfor it sets quantitative targets and timetable for memberstates to fulfill, as exhibited in Table 3.

Notably, the Packaging Directive specifies the require-ment on marking and identification of packaging. Wehave discussed its pertinence to plastics, especially biod-egradable plastics, since the identification of differentplastic material is difficult and time consuming even fora professional. It has been proved to be a big obstaclefor an economically viable sorting and thus recycling(including composting). The Directive also highlightsthe key role played by public participation for the suc-cess of waste management. It emphasizes that it isimportant to let them know what they are expected todo, why and how to do. As a comprehensive regulation,it also promotes the use of economic instruments.

European Parliament and Council Directive1999/31/EC of 26 April 1999 on the landfill of waste,is proved to be yet another regulatory driving force forbiodegradables including plastics in Europe. The core ofthis so called ‘Landfill Directive’ lies in Article 5, Waste


Table 3Key requirements of the EU landfill directive and packaging directive

Key requirements set by the EU Landfill Directive

Timetable Reduction of biodegradables inlandfill (of total weight ofbiodegradable wastes produced in1995)

By 2004 Reduced to 75%By 2007 Reduced to 50%By 2014 Reduced to 35%

Key requirements set by the EU Packaging Directive

Timetable Recovery and recycling (byweight) for packaging wastes

By 2001 Recovery rate: 50%-65% should berecoveredRecycling rate: 25–45%; Min. 15%for each material

By 2006 Recovery and recycling rate:determined by the Council

and treatment not acceptable in landfills, in which mem-ber states are required to take measures to reduce biodeg-radable wastes going to landfills. It too sets up quantitat-ive targets and timetable (also see Table 3).

It is clear that the current recovery and recycling prac-tices in Europe are not able to reach the targets set byboth directives unless composting as a way of organicrecycling would be performed at a commercial scale.The Landfill Directive imposes direct pressure on divert-ing organic wastes from landfill by ‘organic recycling’approaches, aerobic (composting) and anaerobic (biogasproduction) methods. By doing so, it strengthens thehigher tier of the 4-R hierarchy, namely recyclingorganics. Both directives require, and generate thedemand for, the development and large scale applicationof degradable materials of which biodegradable plasticscan find its niche. A new EU legislation underway thatcan have an influence on biodegradable plastics is theDirective on composting. As a step further from Packag-ing and Landfill Directives, it focuses more on sourcereduction of wastes by encouraging home composting.The first draft was finished in November 2000 and theDirective is expected to be effective in one to two years.

4.1.2. AsiaIn Asia, notably East Asia, different countries and

regions took similar actions in the last decade dealingwith waste and plastic waste management. In China, theLaw of Solid Waste Pollution Prevention and Controlcame into force from April 1st, 1996. It defines theresponsibility of producers, sellers and users in recoveryand recycling of the recyclable packaging in a fashion

conforming to relevant regulations. Producers and usersshould choose easily recyclable, disposable and environ-mentally assimilatable materials as packaging or as pro-ducts. Similar laws on wastes management came intoeffect in 1991 in South Korea. It goes further as to spec-ify the adoption of economic instrument, such as deposit.Further in 1993 came the regulation on packagingmethod and criteria for packaging material, aiming atreducing packaging waste. It required producers toreduce the plastic packaging for electronic appliance by30% by weight of the amount used in 1992. Taiwan alsoset up quantitative objectives for waste management. Forexample, in its regulation on PET bottles effective from1989, a recovery rate of 50% was prescribed and it wasraised to 60% in 1992. The General Methods for Recyc-ling and Cleaning of Containers were issued in 1994which specified the recycling targets for various packag-ing materials. For instance, the target for EPS was setas 50%. While the real recycling rate achieved in 1995was 56.1%, indicating an effective implementation. Thisled to the cancellation of the ban on EPS as disposablefood containers.

The major differences between developed and lessdeveloped countries in regulatory systems and theirimplication on waste management and biodegradableplastics application lie in that:

� Laws and regulations in developed countries are ingeneral more comprehensive, e.g. EU PackagingDirective not only specified command and controlmeans, but also encouraged the use of economicinstruments and provided guidelines on public partici-pation.

� Developed countries usually set up more concrete,even quantitative objectives with a timetable. Whilstin developing countries, such as China, regulationsdefine principles and responsibilities, but often fail toclearly designate operational means for enforcementand subsequent instruments for supervision or penaltyfor non-compliance.

� As a result, implementation and enforcement in manydeveloping countries are generally rather poor sincethere is usually neither criteria nor timetable againstwhich the compliance can be checked. Nor is thecapacity and arrangement for implementation inplace.

Application of environmentally benign technologysuch as biodegradable plastics in many developing coun-tries are mostly driven by the government’s command,in the form of either a ban or a semi-compulsory rec-ommendation of certain technology. Very often theseregulatory means target specific environmental problemsat the end-of-pipe, rather than promote the higher tiersof waste management hierarchy, such as reduction andrecycling. Solutions at the source, as demonstrated by


EU directives and their enforcement, would be moreefficient and cost effective, though probably more soph-isticated. In the developed countries, instead of simplybanning or promoting certain technologies or products,regulatory and economic instruments tend to be com-bined and structured in an integrated manner to create aconcerted driving force. This is lacking in manydeveloping countries due to the amount of skills andcapacity it entails.

4.2. Standards and guidelines

Experience of the last decade, both success and fail-ure, shows that standardization of biodegradability andcompostability of biodegradable plastics will pave theway for their large-scale application.

Guidelines and standards dealing with waste manage-ment facilities (such as incineration, composting), asso-ciated requirements on source separation and the qualityof compost are equally important. But in many countries,particularly developing countries, they lag far behind,hindering the proper operation of the facilities and theireconomic viability. Take the example of composting,Europe and North America are the only areas of theworld with clear compost quality standards. Theiremphasis on compost marketability has led its develop-ment from mixed waste composting to composting ofsource-separated bio-waste, which greatly improved thecompost quality. Though a few other countries, such asChina, have developed standards and criteria for biodeg-radable plastics, lack of standards on composting andcompost leads to lack of environmentally sound meansto recycling and market to absorb the after use biodeg-radable plastic, thus affecting its wide acceptance.

In China, two standards regarding biodegradablepackaging have been effective since January 1st, 2000.They are: General specification for single use anddegradable lunch container and drinking set (GB18006.1-1999) and Test method for determining thedegradability of single use and degradable lunch con-tainer and drinking set (GB/T 18006.2-1999). The speci-fications set up the criteria for degradable containers,including basic technical, functional, hygiene and safetyrequirements in addition to degradability. The standardscover two kinds of degradability, photo-biodegradabilityand biodegradability. Disintegration, decrease of weight-average molecular weight of polymers (%), percentageof the small molecules (molecular weight �10,000), car-bonyl index and the generation of CO2 are adopted asmajor indicators for photo-biodegradability of non-foamed plastics. Whilst the compostability is applied asa major criterion for biodegradable materials made ofpaper, plant fiber and starch or starch blend, but not yetfor any other biodegradable plastics. At least, it is notexplicitly stated whether compostability criteria is com-pulsory. Though paper, plant fiber and starch are of natu-

ral origin and not chemically modified materials, theyare not taken for granted as biodegradable in China asthey are in Europe.

The test methods are modeled after ISO 846:1997(Plastics—Evaluation of the action of microorganisms),ASTM D5272-92, ASTM 5247-92 and ASTM 5338-92.As a result, the definition, measuring methods of degrad-ability and compostability are similar to the prevailinginternational practice. However, again composting iscompulsory as a major mean to measure degradabilityof containers made of paper, plant fiber and starch/starchblend, but not yet for other biodegradable plastics inChina. Consequently, there is no such requirements thatare comparable to those listed in Table 4 as pass level,maximum duration, compost quality, etc. for biodegrad-able plastics.

The Chinese standards require proper labeling, trans-portation and storage of biodegradable containers, they,however, do not include requirements on identificationof materials, such as what kind of polymer they are madefrom, nor labels like ‘biodegradable’ . It is not surprising,for the standards are developed jointly by ministries foreconomy, science and public health without involvementof environmental authority. They failed to take environ-mental dimension, i.e. waste management, into consider-ation while developing such standards that are meant forimproving the environment. This itself is a goodexample to show how policy effort is fragmented, eventhe most crucial stakeholder is not included in thedecision making process.

The ‘Comite Europeen de Normalisation’ (CEN) isthe standardization organization of the European Union.The CEN compostability standards (EN 13432) havefour categories of major requirements: (1) materialcharacteristics; (2) complete biodegradation; (3) disinte-gration; and (4) compost quality. The material character-istics include a minimum content of organic matterdetermined as volatile solids (minimum 50%) and amaximum level of heavy metals. CEN standards havestrict requirements on the heavy metals. A comparisonof the CEN and Chinese compostability standards ispresented in Table 4.

One of the future challenges facing CEN is how toregulate home composting, a more varied compostingmethod than industrial composting. Since home com-posting is regarded as a way of waste reduction, it isbeing encouraged and the need for standardization willincrease. Furthermore, eco-toxicity tests have been sug-gested but are for the moment not required because ofinsufficient experience and know-how regarding the testprocedure and the acceptance criteria. Another challengeis to develop standards and guidelines for anaerobicorganic recycling process, bio-gasification.

The unsuccessful industrial scale composting in Eur-ope in the past is mainly due to the mixed wastes,resulting actually in an upgrade of wastes rather than


Table 4Comparing compostability standards of CEN and China

CEN (EN13432:2000) China

1. Material characteristics

� �Organic matter (VS) �50% No requirement� �Heavy metals �50% of compost norm No compost norm yet

2. Biodegradation � �Natural unmodified materials exempted Not exempted� �Necessary for all relevant organic No requirement

components (�1%) � Paper: �30%, Plant fiber: �60%,� Starch/starch blends: �60%, biodegradablePass level: 90% mineralization for blends

and co-polymers, 60% for homo-polymers plastics: No requirement� �Maximum duration: 6 months Duration: 2 months

3. Disintegration � �12 week pilot- or full-scale composting test Require to check whether disintegrated to� fractions �2cm×2cmPass level: �10% of input dry weight in

�2 cm compost fraction � No pass level(e.g. percentage) is stipulated

4. Compost quality

� �Physico-chemical requirements No norm for compost� Plant germination and growth tests

compost. This illustrates the key role played by sourceseparation. If the standards and guidelines forcomposting/gasification were not in place by which thediscarded can be properly disposed off, the environmen-tal benefits of biodegradables cannot be obtained. With-out standards to guarantee the quality of compost, a suf-ficient market pull for composting and subsequentlybiodegradables is difficult to find. In other words, frag-mented policies, regulations and standards with no con-sideration and coordination of each other will, as provedin many cases, more likely generate confusions andobstacles than facilitate. A holistic view, an integratedapproach with comprehensive consideration of all keystakeholders over each stage of product life cycle shouldbe taken.

5. Can biodegradable plastics solve the litteringproblem?

In many parts of the world, such as some Asian coun-tries, the plastic waste problem first and more pressinglyemerged as the sanitary and environmental problemcaused by littering rather than the concern over landfills.Biodegradale plastics, therefore, are more in urgent needas disposable packaging, such as food service containers(e.g. the so-called lunch boxes) and mulching films inagriculture. Their market niche in these countries nowis created mainly by the ban or regulation of the govern-ments, such as China and South Korea. However, canthe use of biodegradable plastics alone solve the lit-tering problem?

It is conceivable that without much change inbehavior, people will keep on throwing away the dispos-able lunch boxes made of biodegradable plastics any-where they want with perhaps even less care than before,since they are told that the boxes will degrade in duetime and be assimilated by the environment. To meetthis perception of consumers and regulators as well,biodegradable plastics need to possess balanced shelf lifewith rapid degradability after use. The question is: is itreally possible and feasible?

Without certain prerequisites, it is infeasible in reality.Because it is impossible to ensure or even predict howlong a certain biodegradable plastics product may remainon shelf and then in use so as to develop the productaccordingly. Perhaps the only exception is biodegradablemulching films used in agriculture. In contrast to mostconsumer goods, the use and discard of mulching filmis more or less predictable within certain regions as thecrops are sawed and harvested in more or less fixed time.The huge amount of film consumed each year alsodeserves a specially designed biodegradable plasticwhich possesses the timed biodegradability. It is hopedthat there would be no need to collect and dispose ofthe waste film after harvest. Instead, the biodegradablefilms usually just need to be ploughed under the soil,which is apparently not the same as littered in open air,to allow decomposition. BASF in Germany has recentlydeveloped such film trademarked Ecoflex [6]. It claimsthat this product can be broken down by a multitudeof common microorganisms in soil and in composting.Ecofelx will decompose after only three months in nor-mal composting facility. How is the Ecoflex degradation


in soil, which is more important for its destined appli-cation in agriculture, was, however, not reported.

For most other applications, in view of the ever chang-ing real circumstances, it is generally impractical, ifpossible, to develop such biodegradable plastics. Fur-thermore, the biodegradation under uncontrolled con-ditions, such as littered, can never be guaranteed. It canbe foreseen that even before disintegrating, these biodeg-radable litters might be collected with other debris andended up in landfills, which is undesired. We alreadyargued in Section 3 that they will worsen the situationin substandard landfill than conventional plastics whilecompleting their biodegradation. With standard landfill,they will make no difference from those plastics theyhave replaced.

Therefore it is undesirable for biodegradable plasticsto degrade under ambient conditions except perhaps foragricultural application. Quick degradation after discardought to be triggered and accelerated only by extra con-dition. This extra condition could be found in the humanbody, as in the case of medial application, or in a con-trolled composting or gasification facility. It also justifiesthat biodegradable plastics alone cannot solve either theproblem of littering or that of landfills.

To close the loop, there should be a mechanism tocollect and sort out the biodegradables after use, facili-ties to recycle organics (controlled biodegradation bycomposting or gasification) and market to absorb therecycled product (compost or gases). Thus, it is morepractical and enforceable to develop standards andmethods regarding biodegradables that use com-postability or bio-degradability under prescribed con-ditions than to search for a plastic product with balancedshelf life and quick degradation after use. Biodegradablepackaging cannot stand alone as a solution to littering.It is more pertinent to affect people’s behavior, i.e.reducing and returning the used packaging instead of lit-tering, in the meantime, to provide tools and facilities forthese desired behaviors, such as labeling the products,providing separate collecting bins in the vicinity. Experi-ence shows that, in addition to education and awarenessraising, the economic and market-based instruments aremore effective in changing the behavior and generatingdemand for recycled products.

6. Economic and market-oriented instruments

The economic instruments play an increasinglyimportant role in today’s environment and waste man-agement all over the world. If carefully designed, theywould be more efficient than direct command and con-trol. More important, they will promote a continualsearch for ‘cleaner’ alternatives since in many cases theynarrow down the price difference between conventionalproducts and the more environmentally friendly substi-

tutes. Environmental charges and taxes, extended pro-ducer responsibility (EPR) and Eco-label are among themost relevant and frequently used economic and market-based instruments in waste management. Table 5 lists,not exhausts, the major characteristics and limits of thethree kinds of instruments. As a demand pull forenvironmentally friendly products, public procurement isgaining more attention too.

To alleviate the pressure on landfills, the wastes goingto landfill should be either reduced or diverted. Regard-ing plastics, this involves re-design (to prolong servicetime and facilitate recycling), material recovery andrecycling and change of people’s behavior. Informationdissemination and awareness campaigns are necessary toeducate people about the environmental impacts of theirbehavior and of what they should do to help reduce theimpacts. It is particularly indispensable when introduc-ing any economic mechanism is difficult, for examplesource separation of wastes by consumers, which provedto be crucial for organic waste management. Neverthe-less, the schemes based on economic incentive wouldbetter sustain the desired change in behavior. In this sec-tion, we will examine the role of each major instrument,their applicability, limitation and potential problemswhen adopted in the management of biodegradable plas-tics.

6.1. Environmental charges and taxes

Environmental charges and taxes adopted in wastemanagement usually aim at partial recovery of financialburden and waste reduction. Ideally the amount chargedshould include economic, environmental and socialcosts, while the way of collecting should incur leastadministrative cost. In reality, waste managementcharges are usually only able to recover part of the econ-omic cost of waste management system and based eitheron volume (‘pay per bag’ ) or on weight. A very highfee would lead to increased illegal dumping or burningof waste; when it is not noticeable, the expectedreduction in consumption and subsequent waste gener-ation may not be observed. In most countries, instead of‘pay per bag’ by consumers’ purchasing and using thespecial trash bag, municipalities are still more likely tolevy a flat fee included in an utility bill, or to simplypay for services out of taxes, though both have hardlyany steering effect on people’s behavior.

Biodegradable plastics have been introduced as trashbags for separate collection of organic wastes. It is morefor the quality and convenience of the composting oper-ation since separating plastic bags, as in the case of con-ventional plastic bags, can be avoided. Biodegradableplastic bags might have to be offered for free to demon-strate and encourage its use for organic wastes since anyextra fee may lead to the unwanted use of cheaper con-ventional plastic shopping bags. As commonly per-


Table 5Advantages and drawbacks of major economic instruments relevant to SWM

Instruments Advantages Drawbacks

Environmental taxes/fees (Compared withdirect control)

� �More cost-effective and efficient Difficult to decide a proper tax rate (info.� unavailable on cost/damage)Provide continuous incentive for reduction� �Reflect polluters pay principle(PPP) Political resistance for competitive� advantages or when the national /localRelative lower administrative cost� economy is badFund raining for environment investment

� Unsuitable for total mass control

EPR � �Producers take both economic and Implementation requires mature legal andphysical/tech. responsibilities of wastes market system

� �More efficient since producers are the most Free-rider problems, inclusion of importedcompetent in handling their products as goods, trade disputeswell as wastes after discarding � Design of EPR is challenging

� Better collection and source separation

Eco-label

� �Provide reliable and comparable Not legal binding, a voluntaryinformation for consumer in choosing environmental schemegreener products � Extensive inspection required to ensure the

� reliability of Eco-labelIncentive for continuous improvement forproducers in environmental performance � Mutual recognition of eco-labels from

� different countriesStimulate market demand by giving clearsignal for consumers and public purchaser

ceived, a free trash bag provides no incentive for wastereduction. But, how big is the potential to reduce theorganic wastes from a household?

‘Pay per bag’ might have noticeable motivating effectin organic waste reduction in countries or regions wherethe population density is not very high so that the house-holds can live in houses with courtyards or enough spaceto maintain home composting. The successful appli-cation of home composting, or so called methane gasproducing facilities as in rural areas of a number ofdeveloping countries (e.g. China), is often quoted as agood example. The rural areas of the great majority ofdeveloping countries are not served by waste collectionand management systems. Home composting is encour-aged as a way of energy saving, conserving forest andproper disposal of wastes to a lesser extent, rather thanwaste reduction. For densely populated urban areas,home composting at each household becomes difficult,if not impossible. Under such conditions, it is doubtfulwhether organic wastes which, unlike other materials,cannot be reused or recovered by means other than com-posting or digestion could be reduced.

If the potential in waste reduction is not big enough,the steering effect on behavior can hardly be the majorconcern in selecting a policy. What concerns us morewould be: which is more beneficial environmentally andeconomically for overall waste management and society,

to recover the extra cost that the municipality paid forusing biodegradable trash bags or to ensure proper com-posting and thus diversion from over-loaded landfills?Based on the US experience, Tyler [4] gave a good cal-culation showing that it would be economically ben-eficial to offer biodegradable plastic bags to residentssince the cost saving exceeds the additional cost of usingthese bags.

Charges or taxes based on the recycled content ordegradability of plastic products are another methodoften recommended. They are expected to have directeffects on consumption patterns, i.e. to reduce the con-sumption of plastic packaging and encourage the use ofrecycled and biodegradable products. However, whenthe relevant standards are neither in place nor clearlydefined, or compliance is not effectively supervised, pro-ducers are inclined to seek higher recycled content anddegradability at the expense of other less strictly regu-lated properties, for example durability. It is more likelythat they may simply declare so in order to getcharge/tax exemption and keep on selling at a low price.Minimizing such a free-rider problem needs significantsurveillance, testing and institutional capacity, which islacking in many less developed countries. Nevertheless,clear and easy-to-access standards and product labelingwill reduce such problems, in the meantime, help con-sumers in choosing products and sorting them out when


discarding, re-gain trust in such products and facilitatethe administrative process.

As a summary, the success of an economic or market-oriented instrument depends on:

� The design, particularly what, how and how much tocharge with minimum administrative effort.

� Clear and easily accessible standards.� Adequate regulatory infrastructure, such as regu-

lations and institutional capacity for enforcement.

6.2. Eco-labeling

Eco-labeling programs are driven by the demand ofconsumers for intelligible and reliable information aboutthe environmental performance of a product, particularlywhen it is claimed as environmental-friendly. The pri-mary function of Eco-label is to stimulate industry toreplace conventional products with more environmen-tally friendly ones, and give the guarantee to the publicthat the products’ compliance with established ecologicalcriteria has been certified by independent third parties.Eco-label granted to biodegradable products will gener-ally facilitate its wide acceptance.

When developing Eco-label for biodegradable pro-ducts, the environmental impacts over the whole lifecycle should be taken into account. In comparison withconventional plastics made from petrochemicals, theconclusion of some life cycle investigations are not fav-orable to biodegradables on the basis of energy intensity[7]. From the perspective of these authors, the thirdexpected benefit of biodegradables of renewable origin(see Section 2), conserving the earth’s non-renewableresources, seems questionable. While many other LCAstudies are in favor of biodegradables if taking intoaccount emissions such as green house gases [8]. Furthercomprehensive studies are needed in this field.

6.3. Extended producer responsibility

EPR is an environmental strategy which implies thatthe responsibility for a product over its life cycle lieswith the producer. Before production is commenced, theproducer should know how the waste, as a result of pro-duction, should be treated and how the product should betaken care of when discarded. Based on such rationale,producers, including manufactures and retailers, are heldresponsible for take-back, recycling and disposal of theproduct. Producers’ responsibility mainly includes econ-omic responsibility, which reflects the polluter-pay prin-ciple, physical and legal responsibilities. EPR principleshave achieved remarkable success in recovery of pack-aging and reduction of the waste in several Europeancountries. EPR implemented with deposit-refund is parti-cularly effective in encouraging customers to return thepackage back even in the richest countries like Sweden.

This suggests the potential of introducing EPR in thecountries where biodegradable plastics are mainlyexpected as a solution to littering.

The littering problem is due both to the improper habitand the lack of suitable and convenient alternatives fordiscarding the wastes. The government, mass media andvarious educating programs can influence the public sig-nificantly. But, as proved in many countries, it is theeconomic instruments that sustain the desirable changein people’s behavior in a more efficient way. In addition,the revenue raised by such instruments can provide fin-ancial support for proper handling of those otherwise lit-tered wastes.

In China, a study on recycling of EPS disposable foodservice containers shows that there are limited producersin contrast to the huge number in distributors [9]. It canbe predicted that this pattern will remain much the samefor biodegradable plastic containers considering theirhigher technical complexity in manufacture. This offersa good soil for cultivating an EPR scheme. A deposit onbiodegradable food service containers, instead of cur-rently free EPS containers, will be able to give incentivesfor consumers to return them back after use and forretailers to collect them for recycling (composting). Forthose that littered anyway, scavengers who play animportant role in waste collection in most developingcountries will be more motivated to collect the littersdue to the higher value attached to them. Proper designof the EPR scheme in order to minimize free riders andthe black market will be a challenge for its success, parti-cularly in many developing countries. A very highdeposit may lead to returning non-degradable productsmixed together with biodegradable ones which will dam-age the composting process and products. A very lowdeposit cannot ensure the desired degree of take-back.

Repetitive use of EPS disposable containers and pack-aging in food service, which is sanitarily unacceptable,is not rare among the poor in developing countries. Withthe use of biodegradable ones, which is currently three–eight times more expensive, though anticipated to beable to drop to the level of around one time of that ofconventional plastics (whose price is currently 1–2USD/kg for commodity products [1]), this problemmight emerge more significantly.

Unlike other material recycling for which the pro-ducers hold the best knowledge and facilities, organicrecycling is highly specialized technology for which theproducers, e.g. plastic producers and processors, havelittle knowledge. In most cases, it is the municipality andits contracted waste treatment companies that can pro-vide an environmentally sound organic recycling. Conse-quently, an EPR scheme involving biodegradable pack-aging cannot be run almost entirely by producers as itis for conventional packaging. Government might needto play a more active role in technical assistance andsupervision to ensure a sound organic recycling.


6.4. Public procurement

Governments are the largest consumers in many coun-tries. Their purchasing activities could generate signifi-cant market demand. Governments’ commitment for sus-tainable development could make public procurement,traditionally following the economic principle, ‘greener’ ,and influence positively the organization and corporatepurchasing. Environmental preference in public procure-ment should take into account the impacts over the sup-ply chain to achieve optimization as a whole. This is theso-called environmental supply chain dynamics (ESCD)where environmental concerns and innovations diffusefrom customer firms or public purchasers to supplierfirms. A recent investigation in UK and Japan on thephenomenon reveals that ESCD emerges when a cus-tomer possesses technical understanding of their sup-pliers’ capabilities and has sufficient influence on the lat-ter [10].

Reliable, comparable and easy-to-access informationabout environmentally sounder products are importantin facilitating such understanding and establishing trustamong public procurers toward these products. Eco-labelschemes are good channels to convey such informationabout products and facilitate individual consumers aswell as public purchasers in selecting products with lessenvironmental impacts. The success of Eco-label wouldalso offer a considerable market incentive for manufac-turers to switch to cleaner technology and to research inthat direction. Clear and enforceable quality standardsfor the recycled and ‘greener’ products, such as biodeg-radable plastic products and compost from wastes, areessential to stimulate and sustain such green purchasing.

6.5. Conclusion

Wide acceptance of biodegradable plastics will bringabout new challenges and higher requirements on inte-grated waste management, ranging from clear labeling,source separation to sound operation of composting andapplication of compost. With fragmented regulations andstandards at work, biodegradable plastics can hardly ach-ieve the objective of reducing pressure on landfill.Unlike what was expected, biodegradable plastics cannotsolve the littering problem either, if not worsen them.Therefore, it is more pertinent and practical to influencepeople’s behavior through education andeconomic/market-based instruments, to complete andimprove the waste management system. Technologyadvancement in the field will make the biodegradableplastics of renewable origin more comparable with con-ventional plastics in energy consumption, performanceand cost, though the last also depends on the scale ofproduction, thus successful commercialization of biode-gradable plastics.

A holistic and life-cycle approach is needed for the

commercial scale application of biodegradable plastics,and in a broader sense all biodegradable substitutes.With regard to waste management, such an integratedframework should include:

1. Promoting source separation of waste through com-pulsory labeling and identification of all major com-modity plastics and biodegradable products by manu-facturers, providing separate collection bins or bagswith sufficient instruction for organic wastes.

2. Biodegradability standards and test methods for biod-egradable plastics under various controlled con-ditions, and at a later stage, under ambient conditions.This is also crucial for the successful implementationand supervision of economic and market-based instru-ments.

3. Guidelines, standards and technical assistance for theoperation and emission control of organic recycling,namely composting, biogasification and home com-posting.

4. Quality standards for the recycled products (the com-post etc.) and guideline on its application.

5. Tax reduction applicable to other material recyclingand recovery should be extended to biodegradableswhich can be organically recycled, and to compostingand gasification which are also kinds of recycling pro-cesses. Support the price of recyclables and biodegra-dables or remove /modify the subsidies for the con-ventional products.

6. Use biodegradable products or their recycled productsin public sector and public projects; or specify thegovernment contractors to use them as much as poss-ible in government-funded projects.

Acknowledgements

The author would like to thank Prof Stanislav Miertus,ICS-UNIDO, and Prof Emo Chiellini, Pisa University,Italy, for their kind support in the research.

References

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