Waste Management 33 (2013) 2372–2380

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Waste Management

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WEEE and portable batteries in residual household waste: Quantificationand characterisation of misplaced waste

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⇑ Corresponding author. Tel.: +45 45 25 16 07.E-mail addresses: mkkb@env.dtu.dk (M. Bigum), claus_petersen@econet.dk (C.

Petersen), thho@env.dtu.dk (T.H. Christensen), chas@env.dtu.dk (C. Scheutz).

Marianne Bigum a, Claus Petersen b, Thomas H. Christensen a, Charlotte Scheutz a,⇑a Technical University of Denmark, Department of Environmental Engineering, Miljøvej 113, 2500 Kgs. Lyngby, Denmarkb Econet A/S, Strandboulevarden 122, 5, 2100 København Ø, Denmark

a r t i c l e i n f o a b s t r a c t

Article history:Received 7 February 2013Accepted 22 May 2013Available online 26 July 2013

Keywords:Residual wasteWaste electrical and electronic equipmentWEEEPortable batteriesTonersCables

A total of 26.1 Mg of residual waste from 3129 households in 12 Danish municipalities was analysed andrevealed that 89.6 kg of Waste Electrical and Electronic Equipment (WEEE), 11 kg of batteries, 2.2 kg oftoners and 16 kg of cables had been wrongfully discarded. This corresponds to a Danish household dis-carding 29 g of WEEE (7 items per year), 4 g of batteries (9 batteries per year), 1 g of toners and 7 g ofunidentifiable cables on average per week, constituting 0.34% (w/w), 0.04% (w/w), 0.01% (w/w) and0.09% (w/w), respectively, of residual waste. The study also found that misplaced WEEE and batteriesin the residual waste constituted 16% and 39%, respectively, of what is being collected properly throughthe dedicated special waste collection schemes. This shows that a large amount of batteries are being dis-carded with the residual waste, whereas WEEE seems to be collected relatively successfully through thededicated special waste collection schemes. Characterisation of the misplaced batteries showed that 20%(w/w) of the discarded batteries were discarded as part of WEEE (built-in). Primarily alkaline batteries,carbon zinc batteries and alkaline button cell batteries were found to be discarded with the residualhousehold waste. Characterisation of WEEE showed that primarily small WEEE (WEEE directive catego-ries 2, 5a, 6, 7 and 9) and light sources (WEEE directive category 5b) were misplaced. Electric toothbrushes, watches, clocks, headphones, flashlights, bicycle lights, and cables were items most frequentlyfound. It is recommended that these findings are taken into account when designing new or improvingexisting special waste collection schemes. Improving the collection of WEEE is also recommended asone way to also improve the collection of batteries due to the large fraction of batteries found as built-in. The findings in this study were comparable to other western European studies, suggesting that therecommendations made in this study could apply to other western European countries as well.

� 2013 Elsevier Ltd. All rights reserved.

1. Introduction

Waste Electrical and Electronic Equipment (WEEE) has beenstated as one of the fastest growing waste streams (Crowe et al.,2003; Morf et al., 2007; Widmer et al., 2005) and both WEEE andbatteries are known to contain hazardous substances as well asrecyclable materials.

The United Nations Environment Programme has identified‘‘Resource Efficiency’’ as a priority; thus, setting a worldwide focuson supporting and facilitating resource efficiency in a more envi-ronmentally sustainable way (UNEP, 2010). The European Union(EU) initiated its EU Raw Materials Initiative, which focuses onthe growing demand for raw materials and identified 14 raw mate-rials that have a high supply risk (the majority of these being met-als) (ECEI, 2010). The high rate at which Electrical and Electronic

Equipment (EEE) is being used, combined with the stockpiling ofWEEE and limited material recovery efforts, are considered to leadto resource depletion (Ongondo et al., 2011). The importance ofWEEE and batteries as a source of both hazardous compoundsand valuable raw materials was recognised when the EU imple-mented the European WEEE directive (CEC, 2003; revised in2012) as well as the European Battery directive (CEC, 2006). It istherefore crucial that these wastes are efficiently collected andrecycled.

Hazardous and toxic substances in WEEE and batteries arenumerous (AEA Technology, 2004; Gross et al., 2008; Onwugharaet al., 2010; Robinson, 2009). Commonly, the hazardous substancesfound in WEEE are: lead (Pb), barium (Ba), cadmium (Cd), mercury(Hg), brominated flame retardants (BFRs) and polyvinyl chloride(PVC). In batteries, the primary hazardous compounds are Cd, Pband Hg, and in toners Cd is of concern (Tsydenova and Bengtsson,2011). Safe treatment and recycling of WEEE and batteries is nec-essary to avoid hazardous compounds ending up in the environ-ment. Also, there are significant environmental benefits to be

M. Bigum et al. / Waste Management 33 (2013) 2372–2380 2373

obtained when recycling in terms of avoided emissions and savedresources (Bigum et al., 2012; Hischier et al., 2005; Wäger et al.,2011). Especially the recovery of precious and rare earth metals in-stead of virgin mining is considered to have significant environ-mental benefits (Bigum et al., 2012; ECEI, 2010; Schüler et al.,2011), and Dodson et al. (2012) even considers municipal solidwaste as being one of the largest potential resources for the recov-ery and recycling of scarce elements. WEEE and batteries, whichare not sorted out for recycling and recovery, do not only imply aloss of materials and metals but could also lead to pollution ofother waste streams.

Only a few residual waste composition studies have includedWEEE and batteries. Riber et al. (2009) performed a study of20 Mg of residential waste from 2210 single and multi-familyhouseholds from several cities and towns in Denmark. The studyincluded the amount of discarded batteries per household butnot characterisation of the batteries, and did not consider WEEEas a separate waste type. Bernstad et al. (2011) did a study on a res-idential area in Sweden (Augustenborg, Malmö) and performedfour waste composition analyses; one before and three after theintroduction of property-close source separation, sorting 6.5–8.5 Mg of residential waste. Bernstad et al. (2011) distinguishedbetween WEEE and batteries and divided WEEE into sub-fractionsthat did not correspond to the 10 WEEE directive categories (seeCEC (2012) for definitions). A Dutch technical report provided anestimation of the flows of WEEE in the Netherlands and from anumber of different surveys, estimated the amount of WEEE inresidual waste, including what type of equipment was typicallydiscarded (Huisman et al., 2012). Lack of detail in the reportingof this study however makes it difficult to compare with. Dimit-rakakis et al. (2009) conducted a study of three areas in Dresden,Germany, and sorted approximately 15 Mg of residual waste. Dim-itrakakis et al. (2009) sorted WEEE into sub-fractions representingthe 10 WEEE directive categories, as well as aggregating detachedcomponents and unclassifiable items, such as cables and othersinto an additional ‘‘category 11’’. Following this, a material andcomposition analysis of the WEEE was performed. The amount ofsingle portable batteries discarded with the residual waste wasalso determined. Previous studies differed in their approach anddefinitions and general conclusions can be hard to derive. Fewstudies on the amount of special waste in residual householdswaste have been made, and fewer contained detailed analysis ofthis type of waste that could be used to improve the collection rate.None of the studies related the amounts of misplaced special wasteto the amounts collected through the dedicated collection schemesmeaning that an assessment as to whether or not the misplace-ment is actually significant and to which degree improvement oncollection could be made, remains unanswered. Generally thereis a need for better data on the amounts of special waste being dis-carded with the residual waste, and on how the collection of thesewastes can be improved. This study aims at filling some of theseidentified knowledge gaps.

Table 1Examples of dedicated collection schemes for WEEE and portable batteries in Denmark.

Full service system� Bag/box system; Single-family households may place sWEEE, light sources and/or p

waste bin. It is then collected with the residual waste. Being introduced in an incr� Joint full service; Multi-family households may place WEEE or portable batteries in

waste. Common in DenmarkPublic collection point system� Boxes or similar devices placed near glass and paper containers. Fairly common for� Boxes places in libraries, supermarkets, businesses and institutions, etc. Very commCurbside collection system� Waste is scheduled for collection at the curbs at announced dates (typically 4–8 tim

The primary objective of this study was to quantify the amountof WEEE and portable batteries discarded with residual householdwaste. The discarded amounts was compared to the amount ofspecials wastes collected through the dedicated special waste col-lection schemes. WEEE was sorted according to the 10 WEEE direc-tive categories thus allowing for data comparison betweenmember states of the European Union. This is of high importancewhen considering European collection and recycling targets ofWEEE.

Denmark has a population of around 5.5 million and consists of98 municipalities. The municipalities have the responsibility forwaste collection and management and to ensure that nationalguidelines, as well as EU directives, are followed. The collectionof WEEE and batteries is however paid by the producers due tothe imposed producer responsibility.

This study wished to support municipalities in improving thecollection of WEEE and batteries. The secondary objective of thispaper was therefore to identify and characterise the types of WEEEand batteries being discarded with the residual household waste,which would be valuable information when planning and design-ing information campaigns.

2. Methodology

2.1. Waste sampling

The sampling presented in this paper were conducted in collab-oration with six other studies contracted by the municipalities andthe Danish Environmental Protection Agency (EPA). The selectionof the households included in the sampling was conducted bythe municipalities, and depended on their objectives. Some studiesonly included single households, others a mix of both single- andmultifamily households. In one study consent from the householdsto participate in the study was obtained. However in all cases theactual sampling of the waste was done without the householdshad been given prior notice.

Table 4 provides an overview of the waste sampling, includingthe number of households and the studied municipalities. In total,3129 households (2272 single and 857 multi-family households) in12 municipalities in Denmark were included. The number ofhouseholds investigated in each municipality varied betweenapproximately 200 and 370. The total amount of waste sampledfrom each municipality varied between 730 and 5930 kg. Oneweek of residual waste was collected from each household (onaverage approximately 8.3 kg of waste per household) and manu-ally sorted. In total, 26.1 Mg of residual waste was sampled andsorted during 2011.

As a consequence of some municipalities only including single-family households, the share of these was higher (72%) in compar-ison to the overall Danish society (60%). The sampling was con-ducted by the municipalities, who were asked to ensure thatissues such as income, socioeconomic background and citizens’age profile were representative of each of the municipalities.

ortable batteries in a small plastic bag/box and place it on top of the householdeasing number of municipalities in Denmarkseparate containers in the courtyard. The waste is then collected with the bulky

batteries in Denmarkon for batteries in Denmark

es per year). Common in Denmark

2374 M. Bigum et al. / Waste Management 33 (2013) 2372–2380

One of the primary deciding factors for the amounts of mis-placed WEEE and batteries was by the authors considered to be re-lated to the available collection schemes. The municipalitiesincluded in this study have different schemes and in order to jus-tify using the 12 municipalities as one representative sample formisplaced special waste in Denmark, this hypothesis needed tobe tested.

In Denmark, all households have access to recycling centreswhere they can dispose of their waste without charge. The differ-ent municipalities can choose to offer additional dedicated collec-tion schemes for special wastes, such as WEEE and batteries. Thededicated collection schemes were grouped into three systems fullservice, public collection points and curbside collection (seeTable 1).

A ‘‘full service’’ system is a system where the waste is collecteddirectly at the home of the citizen and is considered to be the mostefficient system because it is the most convenient for the citizens.Single-family households have individual waste bins and it istherefore possible to introduce a bag/box system for special wasteto be collected simultaneously with the residual waste, typically ona weekly basis. Multi-family households do not have individualwaste bins and the best option for a full service system for mul-ti-family households is a ‘‘joint full service’’, where separate con-tainers for WEEE and batteries are placed in the courtyard.

‘‘Public collection points’’ are boxes or containers placed in pub-lic areas that people regularly pass by, e.g., near supermarkets, li-braries, etc. The use of ‘‘public collection points’’ is considered tobe effective as it is convenient for the citizen to dispose of theirWEEE and batteries during errands and typically, the system ischeaper than a ‘‘full service’’ system. A ‘‘curbside collection sys-tem’’ refers to a system where a municipality collects certain wastetypes, including special waste such as WEEE, at scheduled dates.The citizen would have to leave the waste by the curb and in mostcases alert the municipality in advance that there is waste to becollected. However, the system is less convenient than the ‘‘fullservice’’ and ‘‘public collection points’’ systems, because it doesnot address the need of the citizen at the exact moment it arisesand the citizen would have to store the waste for a period of time

Table 2Municipalities arranged according to their choice of collection scheme for WEEE andportable batteries. All citizens in the municipalities have relatively easy access torecycling centres.

System Municipality Provided collection scheme

Full service Brøndby Bag system (sWEEE and batteries), joint fullservice, scheduled curbside collection

Kolding Box system (sWEEE and batteries), joint fullservice

Helsingør Bag system (sWEEE and batteries), joint fullservice

Holstebro Bag system (batteries and light sources),joint full service

Lemvig Bag system (batteries and light sources),joint full service

Struer Bag system (batteries and light sources),joint full service

Frederiksberg Bag system (batteries), joint full service,public collection points (batteries),scheduled curbside collection

Viborg Bag system (batteries), joint full service

Publiccollectionpoints

Frederikssund Public collection points (batteries), joint fullservice, scheduled curbside collection

Gladsaxe Public collection points (batteries), joint fullservice, scheduled curbside collection

Gribskov Public collection points (batteries)

Curbsidecollection

Hvidovre Scheduled curbside collection

in the household which could be inconvenient. This increases therisk of people disposing of their waste incorrectly e.g. bymisplacement.

Table 2 shows the types of dedicated waste collection schemesfor WEEE and batteries available in the municipalities included inthis study. The experimental setup of this study was not designedto evaluate the efficiency of the three different systems. Such astudy would have to include issues such as the citizens’ awarenessof the collection schemes, general environmental awareness andhabits. It would also require a setup where the sorting analyseswere conducted prior and after the introduction of a collectionscheme similar to Bernstad et al. (2011), or that the sorting analy-ses were conducted on municipalities with comparable societycompositions but different dedicated collection schemes. In thisstudy the included municipalities contributed differently with re-spect to number and type of households and the amount of sortedresidual waste, and such a comparison was therefore not possible.

The influence of the special waste collection scheme on theanalysis was tested using a two-sided unequal variance t-test onthe ‘‘full service’’ and ‘‘public collection points’’ systems for WEEEand batteries with t (9), in order to justify the sample as being rep-resentative of average Danish conditions. The effect of ‘‘curbsidecollection’’ could not be tested, as this comprised of just one sam-ple (Hvidovre).

2.2. Waste sorting

The waste sorting was done following a two-step procedure.Initially the residual waste collected from each municipality wasmanually sorted according to waste type and the amount perhousehold was recorded. Following this, the electronic waste frac-tion and battery fraction from the individual households wereaggregated into a separate bag per municipality for the purposeof further detailed sorting. The initial data recorded, showed thenumber of individual households for each municipality and thetype of household (multi- or single family). The electronic wasteand batteries were aggregated into one sample for each municipal-ity prior to the detailed sorting analysis.

Secondly, each battery was weighed and categorised accordingto type: primary batteries (alkaline, zinc carbon and button cells(including type of button cell)) and secondary (rechargeable) bat-teries (including type of secondary battery), and whether it wasdiscarded as part of WEEE (built-in). Each WEEE item was likewiseweighed and categorised according to item type, WEEE directivecategory and treatment category.

WEEE is commonly considered to be treated in six differentways (Huisman et al., 2007), and treatment categories are hence

Table 3The defined treatment categories and their associated WEEE directive categorynumbers along with examples of item types belonging to the treatment category.

Treatmentcategories

Categoriesof WEEE

Example of item types

Heating whitegoods

1, 10 Washing machines and stoves

Cooling whitegoods

1, 10 Equipment containing cooling liquid, e.g.,refrigerators

Small WEEE:Low-gradefraction

2, 5a, 6, 7,8, 9

WEEE with low concentrations of preciousmetals, e.g., vacuum cleaners, toasters,appliances for body care, lamps, toys

Small WEEE:High-gradefraction

3, 4 WEEE with high concentrations of preciousmetals, e.g., computers, mobile phones,radios and video recorders

TV and monitors 4 Cathode ray tubes and flat screensLightsources (5b) 5 Straight fluorescent lamps and other light

sources containing mercury or rare earthmetals

M. Bigum et al. / Waste Management 33 (2013) 2372–2380 2375

the fractions that WEEE would be sorted into when collected andsubsequently treated and recycled. The treatment categories areshown in Table 3 with the associated WEEE directive categories.WEEE directive category 5 is in the treatment categories subdi-vided into luminaries (5a) and lamps (5b). The treatment category‘‘small WEEE’’ would typically be collected as one category andcould then be further separated into a low-grade and a high-gradefraction. Sorting WEEE according to the treatment categories is anecessary step when wanting to assess the environmental aspectsof separate collection of WEEE and batteries as it would enable theassessment of burdens related to the waste not being recycled.

Unidentifiable cables were in our study not considered as WEEEbut chargers and cables for electronic products were, considered asWEEE when the product for which it belonged to could be identi-fied. The amount of unidentifiable cables and chargers found in theresidual waste was included as a separate fraction ‘‘cables’’. Tonersare not defined as WEEE in the WEEE directive, but were in thisstudy considered as a special waste type in relation to WEEE andwere therefore included.

2.3. Data on the amount of WEEE and batteries collected by the specialwaste collection schemes

Data on the amount of WEEE and batteries collected from the12 municipalities were available from the annual reports producedby the Danish Producer Association (DPA) (DPA-system, 2011). Theannual reports include the amount of collected WEEE and batteriesand WEEE is registered according to the WEEE directive categories.Of the 12 municipalities included in this study, data from Frederi-ksberg does not appear in the DPA statistics because its collectionpoints are located in the neighbouring municipality of Copenha-gen. The amount of collected WEEE and batteries was thereforeestimated as the national average reported for 2010.

3. Results and discussion

3.1. Special waste discarded with residual waste

In total, 26.1 Mg of residual waste was sorted and 89.6 kg ofWEEE (414 items), 11.0 kg of batteries (586 items), 2.2 kg of toners

Table 4Amounts of special waste discarded with residual waste in 12 Danish municipalities (g sperelative to the special waste collected by dedicated special waste collection schemes – ca

Dedicated special wastecollection scheme

Municipality (number ofhouseholds/waste sample (kg))

Special waste in re

(g household�1 we

WEEE(na)

Batterie(na)

Full service Brøndby (199/1912) 20 (7) 6 (14)Kolding (200/1796) 22 (3) 2 (6)Helsingør (202/1796) 9 (3) 3 (6)Holstebro (354/2588) 64 (7) 4 (10)Lemvig (228/1254) 14 (8) 2 (7)Struer (369/2856) 9 (5) 2 (6)Frederiksberg (656/5930) 51 (10) 5 (10)Viborg (198/1697) 11 (8) 4 (9)

Public collection points Frederikssund (207/1941) 11 (4) 3 (10)Gladsaxe (216/1932) 11 (5) 2 (6)Gribskov (100/731) 59 (18) 6 (14)

Curbside collection Hvidovre (200/1660) 22 (5) 3 (7)Average 29 (7) 4 (9)Standard deviation (±) 20 (4) 2Standard deviation (%) 72 43

a Observations for 1 week scaled to 1 year in order to provide a reasonable number ob Only the WEEE directive categories 2–7 and 9 are included, as the categories 1, 8 an

and 16.0 kg of cables were found. Table 4 provides an overview ofthe results of the sorting analysis of the residual waste, showingthe amount of misplaced special waste (WEEE, batteries, tonersand cables) discarded per household per week. On average, ahousehold discarded 29 g of WEEE, 4 g of batteries, 1 g of tonersand 7 g of cables per week, constituting 0.34% (w/w), 0.04% (w/w), 0.01% (w/w) and 0.09% (w/w), respectively, of the residualwaste. The 29 g of WEEE corresponds to a yearly average ofapproximately 7 items per household and the 4 g of batteries cor-responds to a yearly average of 9 batteries per household (Table 4).

The amount of special waste discarded varied significantly be-tween the different municipalities (standard deviation > ±43%),and as an example, the amount of misplaced WEEE variedbetween 9 and 64 g per household per week. The samples fromHolstebro, Frederiksberg and Gribskov were significantly aboveaverage (64 g household�1 week�1, 51 g household�1 week�1 and59 g household�1 week�1, respectively) and Frederiksberg andGribskov were above average with respect to the number of dis-carded items (10 and 18, respectively). This is also reflected in therelative waste composition, for which the three municipalitieswere also above average (0.88% (w/w), 0.56% (w/w) and 0.81%(w/w), respectively).

With respect to batteries, three municipalities: Brøndby, Fred-eriksberg and Gribskov, were discarding more than average; how-ever, there are large variations between all the municipalities. Theamount of discarded toners showed significant variation betweenmunicipalities, but the amounts in the residual waste were quitesmall (in the order of 0–2 g household�1 week�1 or 0–0.02% ofthe waste composition) and were easily influenced by small varia-tions. With regard to cables, the standard deviation was also signif-icant and samples from five of the municipalities were aboveaverage.

The influence of the dedicated collection schemes on the resultswas tested by a t-test comparing the two collection systems ‘‘fullservice’’ and ‘‘public collection points’’. The t-test showed a p-valuegreater than 0.05 and despite large variations in the results a dif-ference between the two collection schemes could therefore notbe proven. This justifies considering the results as one samplebeing representative for the amount of special waste discardedwith the residual waste in Denmark.

cial waste household�1 week�1, fraction of the residual waste (% w/w), and expressedlled ‘‘misplaced’’ (% w/w).

sidual waste Misplaced

ek�1) (% w/w of residual waste) (% w/w)

s Toners Cables WEEE Batteries Toners Cables WEEEb Batteries

1 9 0.21 0.06 0.01 0.09 9 780 3 0.25 0.02 0 0.03 15 191 1 0.1 0.03 0.01 0.01 4 360 12 0.88 0.06 0 0.16 31 371 0 0.25 0.04 0.02 0 7 210 4 0.11 0.03 0 0.05 5 291 6 0.56 0.06 0.01 0.07 32 732 2 0.13 0.04 0.03 0.03 6 26

0 3 0.12 0.03 0 0.04 5 252 1 0.12 0.02 0.02 0.01 7 201 12 0.81 0.08 0.01 0.17 33 47

1 7 0.26 0.04 0.01 0.09 18 731 5 0.34 0.04 0.01 0.06 16 391 4 0.28 0.02 0.01 0.06 11 22

87 81 80 44 90 90 71 57

f discarded items per household per year (n household�1 year�1).d 10 were not found in the residual waste.

Table 5WEEE found in the residual waste according to the WEEE directive category number, the average disposed amount of WEEE per household per week and the relative distributionof each fraction both in terms of weight (w/w) and number of items (n/n).

WEEE directive categories WEEE in the residual waste

Amount (g household�1 week�1) Number of items (n) Distribution (%, w/w) Distribution (%, n/n)

1. Large household appliances 0 0 0 02. Small household appliances 10 98 36 243. IT and telecommunication equipment 5 82 18 204. Consumer equipment and photovoltaic panels 8 100 29 245. Lighting equipment 1 47 3 116. Electrical and electronic tools 0.3 3 1 17. Toys, leisure and sports equipment 3 75 11 188. Medical devices 0 0 0 09. Monitoring and control instruments 0.3 9 1 210. Automatic dispensers 0 0 0 0Total 29 414 100 100

2376 M. Bigum et al. / Waste Management 33 (2013) 2372–2380

3.2. WEEE and battery waste characterisation

3.2.1. WEEETable 5 shows the amount of WEEE discarded in the residual

waste per household per week, according to the WEEE directivecategories, and the total number of items. Table 5 also shows thepercentage distribution of the items found, both with respect toweight (w/w) and the number of items (n/n). If considering onlythe weight, which for practical reasons is the way that WEEE istypically recorded, it can be seen that the type of WEEE most likelyto be found in the residual waste is category 2 (36%), followed by:category 4 (29%), 3 (18%), 7 (11%). Category 5 (3%), 6 (1%) and 9(1%) were discarded in smaller amounts and no category 1, 8 or10 were found. That larger items such as categories 1 and 10 werenot found makes sense since the residual household waste bins aregenerally smaller than these particular items, also statistics on themarketed amounts show that category 10 is not marketed tohouseholds. In the case of medical devices only small amountsare marketed to households which might explain the absence ofthese items in the residual waste as well.

Considering the actual number of discarded items (n) mightprovide a better characterise of the type of WEEE being discardedby the citizens as it disregards the weight of the items and is purelyrelated to the misplacement frequency. Considering the number ofitems (n/n), the most typical WEEE to be discarded with the resid-ual waste are category 2 and category 4 (both 24%), followed bycategory 7 (18%) and category 5 (11%). Using this approach showsthat WEEE categories 7 and 5 are actually being discarded morefrequently than it would have appeared if only having assessed thison a weight basis. Especially the misplacement of category 5 isseen to be significant.

Table 6 shows the amount of WEEE (g household�1 week�1)found in the residual waste according to treatment categories, totalnumber of items observed for 1 week (n) and the relative distribu-

Table 6WEEE found in the residual waste according to the treatment categories numbers, the averain the study and the relative distribution of each fraction, both in terms of weight (w/w)

Treatment categories(corresponding WEEE directive categories)

WEEE in the residual waste

Amount (g household�1 week-1

1. Large equipment (1, 10) 02. Cooling white goods (1, 10) 03a. sWEEE: low-grade fraction (2, 5a, 6, 7, 8, 9) 103b. sWEEE: high-grade fraction (3, 4) 144. TV and monitors (3, 4) 45. Light sources (5b) 1

Total 29

tion of the these categories calculated based on weight (w/w) andon number of items (n/n). Table 6 shows that WEEE discarded withthe residual waste can be categorised as ‘‘small WEEE: low-gradefraction’’ (36% w/w and 45% n/n), ‘‘small WEEE: high-grade fraction(49% w/w and 44% n/n), TV and monitors (12% w/w and 0.2% n/n)and ‘‘light sources’’ (3% w/w and 11% n/n). The misplacement of‘‘lighting equipment’’ (Table 5) and ‘‘light sources’’ (Table 6) isthe same because no luminaries were found in this study.

A single item belonging to the treatment category ‘‘TV and mon-itors’’ was found. This one item constituted 12% (w/w) of the over-all amount of WEEE, which results in the treatment category ‘‘TVand monitors’’ seeming relative significant. The example with thecathode ray tube (CRT) monitor is a good example of the issues re-lated to using the w/w or the n/n approach. Using the w/w ap-proach the misplacement of CRT monitors seems to be asignificant issue, however using the n/n approach the presence ofthis treatment category is actually insignificant (0.2%). It can there-fore be concluded that CRT monitors misplaced with residualwaste are relatively rare.

Fig. 1 shows the weight of the individual WEEE items – found inthe residual waste, as a function of the WEEE directive categorynumber. In general, the average weight of each item varied be-tween 0.1 and 0.3 kg. The figure shows four outliers (one CRT,one speaker set, one radio and one printer) which were signifi-cantly larger than the majority of the items. The largest outlierwas the CRT weighing 11 kg. The average weight of the items with-in each WEEE directive category appears along with the standarddeviations in the figure. The standard deviations are significantand in most cases exceed the average. This supports the statementthat WEEE is a heterogeneous waste type and that determining anaverage weight of WEEE items discarded with the residual wastewould not be representative of much. This heterogeneity and theexample with the CRT monitor shows that using only a weight-based approach to characterise WEEE in residual waste might not

ge disposed amount of WEEE per household per week, the total number of items foundand number of items (n/n).

) Number of Items (n) Distribution (%, w/w) Distribution (%, n/n)

0 0 00 0 0

185 36 45181 49 44

1 12 0.247 3 11

414 100 100

5

4

3

2

1

01 2 63 7 954 8 10

]gk[metifothgie

W

WEEE directive category

CRT

RadioSpeakerset

Printer

0.3±0.5

0.3±0.40.1±0.2

0.2±0.50.3±1.2

0.1±0.0 0.1±0.0

11

Fig. 1. The weight of the individual WEEE items found in the residual waste as afunction of the WEEE directive category number. Each point in the figurecorresponds to one single item. The figure also shows the average weight andstandard deviation of the items in each WEEE directive category.

M. Bigum et al. / Waste Management 33 (2013) 2372–2380 2377

provide accurate information about the WEEE found in the residualwaste.

Within the WEEE directive categories, some items were dis-carded more frequently than others. In category 2, electric toothbrushes (9% n/n), wrist watches and clocks (10% n/n) often seemto occur; otherwise, this fraction appeared very mixed. When con-sidering category 3, the cable fraction was the most dominant (32%n/n) and for category 4 headphones (46% n/n) and cables (25% n/n)dominated the fraction and only a single photovoltaic panel wasfound. Within category 7 toys (45% n/n), flashlights and bicyclelights (25% n/n) were commonly found to be misplaced.

Overall, it can be concluded that some products occur in theresidual waste more frequently than others and that cables consti-tute a rather large portion of the misplaced WEEE items. In addi-tion to this, unidentifiable cables were included in Table 4 as aseparate fraction, meaning that the misplacement of cables is evenmore significant. This could imply that people are not consideringcables to be WEEE, or are simply not aware that this waste typeshould be disposed of as special waste with the purpose of recy-cling. It could also mean that people are actually able to recognisemany of the individual products as WEEE and are therefore dispos-ing of these through the dedicated collection schemes, leaving only

]g[yrettabfothgie

W

22.2±15.3

20.3±13.4

0.5±0.5

1.3±2.43.2±

145

135

125

Primary batteries

Alkaline Zinccarbon

Silveroxide

Zinkair

Alkaline Mercuryoxide

Lithi

Button cells

70

60

50

40

30

20

10

0

Fig. 2. The weight of the individual batteries found in the residual waste as a function of tthe average weight and standard deviation of the individual batteries within each batte

cables to be discarded. In the case of category 2, the waste fractionappeared to be quite mixed, which could likewise imply that peo-ple have difficulties recognising category 2 items as WEEE.

Knowledge about which WEEE is most frequently discardedwith the residual household waste should be used when designinginformation campaigns or sorting instructions with the purpose ofimproving the collection rate and reducing WEEE in the residualwaste. Focusing on WEEE directive category 2, 5b and 7 as wellas cables as being a waste type to be disposed of through the ded-icated systems with examples of the individual type of items couldstrengthen the information material distributed by the municipal-ities to the citizens.

3.2.2. BatteriesThe sorting analysis showed that 80% (w/w) and 79% (n/n) of

the batteries in the residual waste were found as portable singlebatteries and the remaining 20% (w/w) and 21% (n/n) as built-inwith WEEE (Fig. 3 shows examples of WEEE items with built-inbatteries). This is quite a high share of built-in batteries and reduc-ing the amount of WEEE being misplaced could be one way ofincreasing the collection of batteries.

Fig. 2 shows the weight of the individual batteries – as a func-tion of the battery type. The average weights of the batteries with-in each battery type appear together with the standard deviations.In general, the average weight of batteries discarded with theresidual waste varied between 0.5 and 38.5 g. The standard devia-tion of the average weight of the different battery types was smal-ler than in the case of WEEE and showed that the battery typesdiscarded with the residual waste seem to be a relatively homoge-neous in weight. It can also be seen that most of the alkaline bat-teries were within the range of 10–12 g and 22–24 g, whichcorresponds to AAA batteries and AA batteries, respectively. Simi-larly, for zinc carbon batteries, the ranges were 6–8 g and 16–18 g(Fig. 2). The weight of the lithium button cells and the alkaline but-ton cells were found primarily to be in the order of 0.5–2 g and0.3–2 g, respectively.

Table 7 shows the types of batteries found in the residual waste.The batteries were categorised according to the following type andonly a few batteries were unidentifiable (unknown). The sortinganalysis showed that on a weight basis, it is primarily alkaline bat-teries (82%, w/w) followed by zinc carbon batteries (12%, w/w) thatwere misplaced with the residual waste. Considering the number(the n/n approach) of discarded batteries alkaline batteries is still

38.5 17.8±7.7

16.3±1.5

22.8±7.5

4.1

0.8

Secondary batteries

um Unknown

Unknown

NiCd NiMH Li-ion Lead

ype. Each point in the figure corresponds to one single battery. The figure also showsry type.

Fig. 3. Examples of batteries found as a part of WEEE in residual waste (built-in).

Table 7Batteries found in the residual waste according to the battery type, the average disposed amounts per household per week, the total number of batteries found in the study andthe relative distribution of each battery type, both in terms of weight (w/w) and number of batteries (n/n).

Battery type Amount (g household�1 week�1) Number of batteries (n) Distribution (%, w/w) Distribution (%, n/n)

Primary batteries Alkaline 2.9 404 82 69Zinc carbon 0.4 64 12 11Button cellsAlkaline 3 � 10�2 71 1 12Lithium 1 � 10�2 12 0.3 2Mercury oxide 0 0 0 0Silver oxide 3 � 10�4 2 8 � 10�3 0.3Zink air 0 0 0 0Unknown 2 � 10�4 1 7 � 10�3 0.2

Secondary batteries NiCd 1 � 10�2 1 0.3 0.2NiMH 0.1 25 4 4Li-ion 2 � 10�2 3 0.4 1Lead acid 0 0 0 0

Unknown 2 � 10�2 3 0.6 1Total 4 586 100 100

2378 M. Bigum et al. / Waste Management 33 (2013) 2372–2380

the predominantly misplaced battery type (69%, n/n), but the sec-ond most misplaced battery type is now the alkaline button cell(12%, n/n) closely followed by the zinc carbon battery (11%, n/n).This means that button cell batteries are also a battery type beingrelatively frequently misplaced even if the total amount of the bat-teries is small. The sorting analysis showed that silver oxide buttoncells, nickel cadmium (NiCd) and lithium ion (Li-ion) secondarybatteries were rarely discarded with the residual waste and thatno zinc air button cell batteries, mercury oxide button cell batteriesand no lead acid batteries were discarded with the residual house-hold waste. This could be due to these battery types being lesscommonly purchased than alkaline and zinc carbon batteries, how-ever statistical data on the marketed amount of portable batteries,does not report the different types of batteries, and it is thereforenot possible to determine if this is the case.

3.3. Improvement potential for special waste collection in Denmark

The amounts of misplaced WEEE and batteries were comparedto the collected amounts in order to determine if the amounts are

actually significant and to what extent the collection of thesewastes can be improved. The result of this assessment is presentedin Table 4. The assessment of the special waste collection in Den-mark was determined by comparing the observed amounts ofWEEE and batteries discarded with the residual waste, to theamounts of the same wastes collected through the dedicated spe-cial waste collection schemes. This assessment included only theWEEE directive categories 2–7 and 9, as categories 1, 8 and 10 werenot found in the residual waste. An assessment of misplaced tonersand cables was not included due to lack of data on the collectedamounts of these via the dedicated special waste collectionschemes.

On a national average WEEE and batteries discarded with theresidual waste constituted 16% and 39% of what is collectedthrough the dedicated special waste collection schemes. Thisshows that WEEE seems to be collected relatively successfullythrough the existing special waste collection schemes and thatthe amount of misplaced batteries is fairly significant. Howeverfor both waste types the assessment shows that there is animprovement potential with regard to increasing the collectionrate.

A recent survey was conducted by the Danish EPA among 1126citizens in four municipalities on their behaviour when it comes todiscarding of WEEE and batteries. One of the questions was regard-ing what it would take for the citizen to use the dedicated collec-tions schemes for their electronic waste, light sources andbatteries. To this question, 78% answered that they were alreadyusing the dedicated special waste collection schemes for all of theirelectronic waste, 63% stated the same for their light sources and90% claimed the same for their batteries (Petersen et al., 2012).The survey corresponds fairly well with our study with respect toelectronic waste and light sources, even though the two cannotbe directly compared because our measurements are weight-based(the w/w approach) and the survey addressed people’s attitudesand thus relate more to frequency (the n/n approach), which thisstudy has shown can give differing results. Also the notion of whatpeople actually perceive as being WEEE is important to consider.Our study showed that certain items are more frequently mis-placed than others perhaps due to people unknowingly discardingWEEE with their residual waste. In the case of batteries, there is anobvious discrepancy between the two studies and it is striking that90% of those interviewed stated that they always use the dedicatedspecial waste collection schemes for their batteries, when ourstudy shows that misplaced batteries constitute 39% (w/w) of thebatteries collected via the dedicated collection schemes. Some ofthis discrepancy might be explained by the 20% (w/w) found as

M. Bigum et al. / Waste Management 33 (2013) 2372–2380 2379

built-in WEEE, however still with taken this into account it is un-likely that the remaining 10% of the responders are solely respon-sible for the high misplacements of batteries. The survey indicatesthat the vast majority are aware of the dedicated collectionschemes for batteries, meaning that the information level is gener-ally quite high. It is therefore doubtful that the collection of batter-ies could be increased solely with better information campaigns.Seeking to improve collection of batteries could possibly be donesimultaneously with improving collection of WEEE. Alternativemeans could be by supplementing with regulatory or legal instru-ments such as a fee or a deposit return system.

3.4. Generalising on a western European level

The identified studies on special waste in residual householdwaste differed in approach, scope and definitions, but the findingscan nonetheless be compared in some aspects, and thus provideinformation about the conditions for special waste discarded withthe residual waste on an overall western European level.

Dimitrakakis et al. (2009) found that in Germany, the averageshare of WEEE constituted 1.27% (w/w) of the residual waste. Huis-man et al. (2012) found the composition of WEEE in Dutch residualwaste to be 0.44–0.88% (w/w), and we found it to be 0.34% (w/w).The amount of WEEE in Germany is relatively larger than the Dutchand Danish findings but Dimitrakakis et al. (2009) also included a‘‘category 11’’ that constituted almost half of the WEEE, includingfractions not considered to be WEEE according to the WEEE direc-tive, which the Dutch and Danish study did not.

Prior to the introduction of the source segregation the Swedishstudy (Bernstad et al., 2011) showed an average of 35–48 g ofWEEE being discarded per household per week and 18.4–23.3 gafter, dependent on whether cables and filament bulbs were in-cluded in the accounting. The Swedish results are comparable withthe Danish findings of 29 g of WEEE per household per week(Table 4).

The characterisation of the types of WEEE found in the Germanstudy showed that WEEE directive categories 2 and 4 were mostlikely to be discarded with residual waste, which is similar to theDanish study. Interestingly, the German study found only smallamounts of WEEE directive category 3 and category 7, where thesewere significantly being misplaced in the Danish residual waste.On the other hand, the German study found smaller amounts ofmisplaced WEEE directive categories 1, 8 and 10, where the Danishstudy found none of these.

The Dutch study categorised misplaced WEEE as being predom-inantly ‘‘small household appliances’’ and ‘‘IT and telecommunica-tions’’ and that the three most important appliance types discardedwere: household luminaries (9.1% w/w), loudspeakers (5.7% w/w)and adapters (5.0% w/w). The significant presence of householdluminaries in the Dutch residual waste is interesting as none werefound in the Danish residual waste. One explanation could be thatwhat the Dutch study refer to as luminaries is what the Danishhave defined as light sources. However, it has not been possibleto confirm this. The German study showed that 35.7% (w/w) ofthe WEEE consisted of cables and that 6.54% (w/w) of their ‘‘cate-gory 11’’ was also cables, and the significant representation ofcables is similar to the Danish findings.

The German study determined the amount of batteries to be0.04% of the residual waste, which was also what the Danish studyfound. This corresponded to an amount of misplaced batteries of4 g per household per week, which is what the Swedish studyfound after introduction of property-close separation, whereasprior to this 7 g of batteries per household per week was being dis-carded. The German study found that built-in batteries constituted5.7% (w/w) of the misplaced WEEE compared with 2.4% (w/w) in

our study. This could suggest that built-in batteries being dis-carded with WEEE are also significant in Germany.

The Danish study found that on average, a household discarded5 g of cables per week in addition to the identifiable cables andchargers that were considered to be WEEE. The Swedish studyfound that on average 6 g of cables per household per week beforeand 1.8 g per household per week after the introduction of prop-erty-close separation was discarded with the residual waste. Theexperiences from the Swedish study show that it should be possi-ble to reduce the misplaced amounts of cables in the residualwaste.

There seems to be relatively good agreement between the stud-ies on the amount of WEEE, batteries and cables discarded withresidual waste. This suggests that the findings and recommenda-tions in this study could be used for other western Europeancountries.

4. Conclusion and perspectives

In conclusion, a total of 89.6 kg of WEEE, 11 kg of batteries,2.2 kg of toners and 16 kg of cables were found in household resid-ual waste sorting analyses, corresponding to 29 g (7 items peryear), 4 g (9 batteries per year), 1 g and 5 g, respectively, per house-hold per week and a waste composition of 0.34% (w/w), 0.04% (w/w,) 0.01% (w/w) and 0.06% (w/w), respectively. WEEE and batteriesdiscarded with the residual household waste corresponded to 16%and 39%, respectively, of what was collected through the specialwaste collection schemes. In conclusion, WEEE seems to be col-lected relatively successfully through the existing special wastecollection schemes, whereas a large amount of batteries are stillbeing discarded with the residual household waste. However, thereis still considered to be an improvement potential for the collectionof both WEEE and batteries.

Characterisation of WEEE showed that primarily WEEE direc-tive category 2, 5b and 7 as well as cables were discarded withthe Danish residual waste. Based on the characterisation it is rec-ommended that information material focuses more on these WEEEdirective categories as a means to improve collection of WEEE. Cer-tain specific items were also found to be misplaced more fre-quently with the residual waste. Information material couldtherefore also be improved by specifically addressing items suchas electric tooth brushes, watches, clocks, headphones, flashlightsand bicycle lights.

Characterisation of the batteries showed that 20% of the dis-carded batteries were discarded as built-in WEEE. Primarily alka-line batteries, carbon zinc batteries and alkaline button cellbatteries were found to be discarded with residual householdwaste. The information level among the citizens on the need to dis-card of batteries properly was considered to already be quite highsuggesting that further improvement in this regard would proba-bly not be sufficient to improve collection. However as a largeamount of batteries was found as built-in, one of the ways to im-prove the collection could be by improving the collection of WEEE.Alternative means to improve the collection rate could be by a feeor a deposit return system on batteries.

The findings in this study were comparable to other westernEuropean studies, suggesting that the recommendations made inthis study could apply to other western European countries as well.

For further research, it is recommended that the efficiency ofdifferent special waste collection schemes for WEEE and batteriesis evaluated, in order to determine which provides the most effi-cient collection of special wastes in Denmark and abroad. Thisstudy was not able to statistically show a difference between col-lection schemes due to the experimental setup. However, this can-

2380 M. Bigum et al. / Waste Management 33 (2013) 2372–2380

not be used to conclude that the choice of collection schemes hasno effect.

It is also recommended that further research is done on quanti-fying the environmental burdens of these wastes ending up in theresidual waste resulting in the release of hazardous compounds tothe environment and depletion of resources thus highlighting theenvironmental benefits and importance of improving collectionof these wastes.

Acknowledgements

We would like to thank all the employees of Econet A/S for par-ticipating in this study and assisting with facilities, data and guid-ance. We would also like to thank the municipalities for providinginformation and data about the amounts of WEEE and batteriescollected separately in the municipalities. Finally, we would liketo thank employees of DPA system for giving guidance on the col-lection, reporting and processing of data on marketed and collectedWEEE and batteries in Denmark.

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