Waste Management 30 (2010) 921–933

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Waste Management

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A comparison of municipal solid waste management in Berlin and Singapore

Dongqing Zhang a,*, Tan Soon Keat b, Richard M. Gersberg c

a DHI-NTU Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singaporeb Maritime Research Centre, School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singaporec Graduate School of Public Health, San Diego State University, Hardy Tower 119, 5500 Campanile, San Diego CA 92182-4162, USA

a r t i c l e i n f o

Article history:Accepted 21 November 2009

0956-053X/$ - see front matter � 2009 Elsevier Ltd. Adoi:10.1016/j.wasman.2009.11.017

* Corresponding author. Tel.: +65 8165 6212; fax: +E-mail address: dqzhang@ntu.edu.sg (D. Zhang).

a b s t r a c t

A comparative analysis of municipal solid waste management (MSWM) in Singapore and Berlin was car-ried out in order to identify its current status, and highlight the prevailing conditions of MSWM. An over-view of the various aspects of MSWM in these two cities is provided, with emphasis on comparing thelegal, technical, and managerial aspects of MSW. Collection systems and recycling practiced with respectto the involvement of the government and the private sector, are also presented.

Over last two decades, the city of Berlin has made impressive progress with respect to its waste man-agement. The amounts of waste have declined significantly, and at the same time the proportion thatcould be recovered and recycled has increased. In contrast, although Singapore’s recycling rate has beenincreasing over the past few years, rapid economic and population growth as well as change in consump-tion patterns in this city-state has caused waste generation to continue to increase. Landfilling of MSWplays minor role in both cities, one due to geography (Singapore) and the other due to legislative prohi-bition (Berlin). Consequently, both in Singapore and Berlin, waste is increasingly being used as a valuableresource and great efforts have been made for the development of incineration technology and energyrecovery, as well as climate protection.

� 2009 Elsevier Ltd. All rights reserved.

1. Introduction

Municipal solid waste management (MSWM) is an integral partof urban environmental planning. The characteristics and quantityof MSW arising from domestic, commercial and industrial activi-ties in a region is not only the result of growing population, risingstandards of living and technology development, but also due tothe abundance and type of the region’s natural resources. The col-lection, transport, treatment and disposal of solid wastes, particu-larly wastes generated in medium and large urban centres, havebecome a relatively difficult problem to solve (UNEP, 2005). Topromote sustainable development, waste management hasevolved into material flow management in many developed coun-tries, and includes careful handling of raw materials and reductionof emissions as well as climate/environment protection.

This study compares MSWM in two cities – Singapore and Ber-lin, Germany with regard to MSW – generation and composition,the methods of collection, disposal and recycling. The two citieswere chosen for this comparative study due to their similar so-cial-economic condition (e.g., population size and density, totalgeographic area and economic performance (Gross Domestic Prod-uct). The objective of this paper is to show, with respect to MSWM,

ll rights reserved.

65 6790 6620.

how the rather different geography (land availability), structure ofurban housing, recent rates of population growth, and regulatoryregimes, between the two cities might allow a better appreciationand understanding how MSWM is shaped by these external forces.

2. Demography of Singapore and Berlin, Germany

Table 1 shows the demographic characteristics of Berlin, Ger-many and Singapore. Berlin is Germany’s largest city in terms ofland area and the second most populous city in Germany. It coversa land area of 892 km2 with a population of 3.4 million within itscity limits. Singapore is a small but highly urbanized and industri-alized city-state with strong focus on the manufacturing and ser-vice sectors in Southeast Asia, located about 137 km north of theEquator, and has a total population of 4.84 million people (2008).Singapore has a land area of 682.7 km2 and faces severe land scar-city problem (Yearbook of Statistics Singapore, 2008).

Since 1960, the Housing and Development Board (HDB) in Sin-gapore has been responsible for planning and developing qualitypublic housing and related facilities. With a very high populationdensity of 7088 person/km2 and a land area of 682.7 km2 (seeTable 1), Singapore can be considered a land-scarce country, andalmost 83% of the residents live in multi-story high-rise publichousing buildings (Kalaiarasan et al., 2009). In contrast, the typicalGerman family often lives in a condominium, row house and/or a

Table 1Geographical and social-economical data of Berlin and Singapore.

Berlin (2005) Singapore (2008)

Inhabitants 3395,189a 4839,400b

Area (km2) 892a 682.7b

Density (PE/km2) 3806c 7088c

Gross Domestic Product (GDP) (PPP) 39,004a 53,110b

a Thürmer (2007).b Yearbook of Statistics Singapore (2008).c Population density = inhabitants/area.

922 D. Zhang et al. / Waste Management 30 (2010) 921–933

detached single-family home. The most common type of housingin Berlin is the 19th century block apartment with a primary andsecondary courtyard.

3. Legislation on waste management

3.1. Germany

Waste management in Germany has evolved substantially sincethe early 1970s. The first independent Waste Disposal Act wasadopted in Germany in 1972 and its primary aim was to shut downuncontrolled refuse dumps and replace them with central, regu-lated and supervised landfill sites. The latter falls under the respon-sibility of the regional and local governments (Schnurer, 2002).Instead of creating new landfill sites and incineration plants, thenew Waste Avoidance and Management Act of 1986 was intro-duced, and stipulated by the principle that the avoidance and recy-cling of waste were to be given precedence over waste disposal.

Thereafter, according to BMU (2009), a series of legislation,ordinances, administrative provisions and voluntary commitmentsof waste management has been put in place. In particular, these in-clude the following:

� German Packaging Ordinance (1991).� Technical Instructions on the Storage, Chemical, Physical and

Biological Treatment, Incineration and Storage of Waste Requir-ing Particular Supervision (1991).

� Technical Instructions on Waste from Human Settlement (1993).� Act for Promoting Closed Substance Cycle Waste Management

and Ensuring Environmentally Compatible Waste Disposal(KrW-/AbfG) (1994).

� Closed Substance Cycle and Waste Management Act (1996).� Waste Storage Ordinance (2001).

These ordinances and acts have been discussed by variousauthors such as Vehlow (1996), Schnurer (2002), Schulze (2009),Giegrich and Vogt (2005), and Municipal Solid Waste ManagementReport (2006), etc. In addition, European Union (EU) waste lawforms the legally binding basis for waste legislation of the EUMember States and Germany is required to translate all EU Regula-tions and EU Directives, into national legislation within a statedperiod, e.g., European Landfill Directive (1999), European WasteIncineration Directive (2000), and European Directive on Packagingand Packaging Waste (1994).

In Berlin, the Act for Promoting Closed Substance Cycle andWaste Management and Ensuring Environmentally CompatibleWaste Disposal in Berlin came into force in 1999 (Schulze, 2009).Land Berlin is responsible for the disposal of the waste generatedwithin the city. The duties relating to the collection and disposalof waste from private households and of disposable waste fromother sources are entrusted to the Berliner Stadtreinigungsbetriebe(BSR). Construction waste is disposed of by the Berlin Departmentfor Health, the Environment and Consumer Protection. At present,there is no specific legislative instrument that prevents Berlin fromdisposing of its waste outside its area.

3.2. Singapore

In Singapore, the goal of waste management is to establish asound material recycling society through the ‘‘3Rs” (reduce, reuse,and recycle). The legislation dealing with solid waste managementis the Environmental Pollution Control Act (EPCA). It came intoforce on the first of May, 1999 and is a consolidation of existinglegislations on the control of air, water and waste, including theEnvironmental Public Health Act (HPHA) and the regulationspassed under EPHA (APCEL Report, 2006; Bai and Sutanto, 2002;Foo, 1997):

� Environmental Public Health (Public Cleansing) Regulations(1970).

� Environmental Public Health (Toxic Industrial Waste) Regula-tions (1988).

� Environmental Public Health (General Waste Collection)Regulations.

� Environmental Public Health (Corrective Work Order)Regulations.

Solid waste management in Singapore is traditionally under-taken by the Ministry of Environment. Under the Public Cleansingand General Waste Collection Regulations, all generated solidwaste has to be collected in Singapore.

4. Waste generation and composition

4.1. Berlin

Different types of municipal solid waste in Berlin can be catego-rized in terms of their origins, as follows:

� Domestic refuse waste: comes mainly from private households.The local authority takes solely the responsibility of the house-hold waste management service. Some 70% of municipal wastein Berlin is domestic waste, and the rest 30% is trade or indus-trial waste.

� Trade waste: produced by enterprises and comes mostly fromservice providers, retailers and small business.

� Commercial waste: produced by small business, retail shops,service companies, public institutions or industrial firms.

� Bulky waste: mainly comes from private household. This kind ofsolid waste is too bulky to fit into the normal bins or containers,which is therefore collected separately from the other domesticwaste.

� Road sweepings: can include vehicle tyre particles and wornroad surface, dead leaves, and grit spread in the winter.

Fig. 1 illustrates the development of MSW generation over theperiod 1996–2005 in Berlin. In 1996, the overall quantity ofMSW produced in Berlin, which includes both disposed and recy-cled waste, totaled 2.12 million tonnes. By 2005, this had been re-duced to 1.68 million tonnes, a reduction of 20.75%.

Since early 1990s, there has been a remarkable decline in theamount of disposed waste by incineration and landfill. In 1992,there was 2.32 million tonnes of waste for disposal, and this hadfallen by 2007 to only 0.97 million tonnes, which represents areduction in the municipal waste disposed by incineration andlandfill in Berlin of approximately 60% (Schulze, 2009). In addition,as recyclable waste (e.g., organic waste, paper, light-packagingwaste) accounts for approximately 80% of the total amount of com-mercial waste (Schwilling et al., 2004), great efforts have beenmade on separation and recycling of recyclable waste and there-fore, commercial waste has reduced to 10-fold over the period1992–2007.

445,000 504,000 574,000 636,000 623,000 642,000 629,000 593,000 546,000 615,000

139,000 74,000 17,000 2,000 2,000 1,000 1,000 1,000 29,00048,000

400,000 356,000 270,000 256,000 215,000 144,000 113,000 87,000 68,000113,000

97,00057,000

54,000 39,0007,000

2,000 2,000 1,000 1,0001,000

1,041,0001,013,000

979,000 973,000975,000

956,000929,000

891,000 905,000906,000

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Recycled waste Disposed road sweeping Disposed commercial wasteDisposed bulky waste Disposed household waste

Tonnes/year

2,004,0001,894,00 1,906,000

1,822,000 1,745,001,674,00

1,683,000

1,549,000

1,573,00

2,122,000

Fig. 1. Development of municipal solid waste generation 1996–2005 in Berlin. (Data source: Wowereit and Lopmscher, 2007.)

1,310,000 1,440,000 1,410,000 1,410,000 1,460,000 1,500,000 1,480,000

1,530,000 1,070,000 1,070,000 1,130,000 1,100,000 1,070,000 1,140,000

1,860,000 2,220,000 2,310,000 2,470,000 2,660,000 3,030,0003,340,000

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

1998 2003 2004 2005 2006 2007 2008

Disposed domestic waste Disposed non-domestic waste Recycled waste

4,700,000 4,730,000 4,790,0005,010,000 5,220,000

5,600,0005,970,000Tonnes/year

Fig. 2. Development of municipal solid waste generation 1998–2008 in Singapore. (Data source: Yearbook of Statistic Singapore, 2009.)

D. Zhang et al. / Waste Management 30 (2010) 921–933 923

4.2. Singapore

Solid waste in Singapore can be broadly classified into threemain categories:

� Domestic refuse (solid waste generated by households, markets,food centers and commercial premises such as hotels, restau-rants, shops, etc.).

� Industrial refuse (not including toxic and hazardous waste thatrequires special handling, treatment and disposal).

� Institutional refuse (solid waste from various Government andStatutory Board installations, hospitals, schools, recreationalfacilities and public development project).

Fig. 2 shows data for municipal solid waste generation from1998 to 2008 in Singapore. The total annual generation ofMSW has increased steadily from 4.70 million tonnes in 1996

to 5.97 million tons in 2008. Similarly, the generation of domes-tic waste also shows increasing tendency – from 1.31 milliontonnes in 1998 to 1.48 million tonnes in 2008. According toNEA and MEWR (2006), the daily output of solid waste in Singa-pore has escalated from an average refuse output of 1260 ton-nes/day in 1970 to 7700 tonnes/day in 2001 and to 7000tonnes/day in 2005.

With the rapid economic and population growth, higher stan-dard of living and changing lifestyles, the refuse output in Singa-pore has been increasing steadily. Statistics on demographicsshow that the Singapore population has increased from 3.17 mil-lion people in 1998 to 4.84 million people in 2008 (34.5% increase),including 1.2 million of non-resident population and 0.48 millionof Permanent Residents. In addition, Singapore’s GDP has increasedfrom $160 billion in 2000 to $257 billion in 2008 (61% increase)(Yearbook of Statistics Singapore, 1998; Yearbook of Statistics Sin-gapore, 2008).

Food waste, 9.51%

Paper/cardboard, 21.15%

Plastic, 11.46%

Constructed debrits, 15.44%

Wood/timber, 4.52%

Horticaltural waste, 3.84%

Metals, 14.56%

Used slag, 9.48%

Sludge, 1.92%Glass, 0.96%

Textile/leather, 1.56%

Scrap tyres, 0.42% Others, 5.16%

Fig. 3. Composition of municipal solid waste in Singapore in 2008. (Data source: NEA – National Environment Agency, 2008.)

924 D. Zhang et al. / Waste Management 30 (2010) 921–933

However, according to the National Environment Agency Singa-pore (NEA, 2008), the waste disposal rate in 2006, 2007 and 2008 is0.89, 0.88, and 0.84 kg/day/capita, respectively. By comparison, thedomestic waste rate showed a similar value for Berlin �0.88 kg/day/capita in 2007 (Schulze, 2009), pointing to the fact that popu-lation growth alone is most probably the major cause of the rapidgrowth of MSW in Singapore.

Fig. 3 illustrates the typical municipal solid waste composition(excluding hazardous waste) in 2008 in Singapore. The highestproportion is made up of paper (21.15%), followed by constructiondebris (15.44%) and ferrous metals (13.14%). A significant differ-ence can be observed then this composition is compared to thatof in 2000 (Bai and Sutanto, 2002). The latter indicated that theconcentration of the kitchen waste in urban solid waste makesup the highest proportion (38.83%), and followed by paper(20.6%) and wood (8.91%). In Singapore, plastics make up only

Paper/carton, 20%

Metal, 2%

Wood, 13%

Textile, 1%

Mineral material , 2%

Other trade waste, 11%

Compound,

Fig. 4. Composition of municipal solid waste in Berlin in 2003 (p

11.46% of the total MSW (see Fig. 3). By comparison, the highestproportion of municipal solid waste in Berlin is plastics (23%), fol-lowed by paper (20%) and food waste (15%) (see Fig. 4).

4.3. Common features in Berlin and Singapore

In both Berlin and Singapore, paper/cartons are the major frac-tion of the MSW. The higher percentage of plastics in Berlin showsincreasing avoidance of using glass for beverage container whichhas been substituted by returnable plastic bottles. In contrast,there was no information to indicate that Singapore has any sys-tem of a bottle bill/deposit. If residents were required to paydeposits on glass and metal container, then the capture rates forthese recyclable materials would increase. Alternatively, plasticrefillable bottles could be encouraged as this would minimize theneed for glass production.

Organic waste, 15%

Plastic, 23%

Glass, 7%

7%

ercentage in weight). (Data source: Schwilling et al., 2004.)

D. Zhang et al. / Waste Management 30 (2010) 921–933 925

5. Waste collection

5.1. Berlin

In general, waste generated in Berlin is collected in the follow-ing ways:

� Domestic refuse is regularly collected by public waste utilities instandard containers, and transported away for further treat-ment. All households are obliged to take part in this systemand to pay the waste collection fees charged by the local publiccollection service supervised by the local or municipal authority.In Berlin, this is BSR.

� Trade waste is collected together with household waste. In thetypical residential buildings in Berlin’s inner-city, the smallbusinesses frequently share the waste containers with the apart-ment dwellers in the same building.

� Commercial waste is produced either by small business, servicecompanies, public institutions or industrial firms, or is con-tracted by a specialist company for collection. It is mostly col-lected in large or small containers and taken by the produceror the contracted collection company to the waste disposalplant, where it is treated together with the household waste.

� Bulky waste can be collected by BSR and taken for recycling ordisposal. Usually there is a charge for this service.

� Road sweepings are collected by the BSR road sweeping vehiclesand disposed of.

In order to reduce the quantities of household waste requiringtreatment, in Germany many municipal authorities have adoptedor are considering more far-reaching measures to separate/sortand recycle bulky waste, organic waste and other types of packag-ing waste (see Section 8).

5.2. Singapore

Two collection methods have been adopted in Singapore (Foo,1997; Bai and Sutanto, 2002):

� Direct collection: waste is directly collected from individualhouseholds, especially from private residential estates and shophouses. This method is time consuming and labor intensive.

� Indirect collection: which includes two types: (i) as used in oldhigh-rise apartment blocks where waste is stored in substantialamounts in bulk containers at the foot of the block; (ii) central-ized refuse-chute (CRC) system that has been implemented innewer flats since 1989. Refuse is discharged directly throughcommon hoppers located in individual flats to the central refusecontainer. Thereafter, waste is transferred from a central refuse-chute of each apartment block to the waste collection truckmechanically. The introduction of CRC system has greatlyimproved the efficiency of domestic waste collection andincreased the control of smell and leakage during collectionand transportation.

Prior to 1996, waste collection came under the responsibility ofthe Environmental Health Department (EHD) of ENV and the pri-vate waste collectors. EHD provided daily collection services todomestic households, trade and institutional premises, while theprivate waste collectors served mainly industrial premises, com-mercial buildings, shopping centers, construction sites, etc. (Baiand Sutanto, 2002; NEA and MEWR, 2006). To introduce competi-tion, improve collection efficiency and service quality, ENV startedto liberalize the collection services in 1998 (Bai and Sutanto, 2002;NEA and MEWR, 2006).

For solid waste from institutional and commercial premises, SE-MAC Pte Ltd. remains to be the main collector, while industrial so-lid waste is still collected by the licensed private wastecontributors (Bai and Sutanto, 2002; NEA and MEWR, 2006).According to Foo (1997), the overall system of daily solid wastemanagement begins with a network of collection vehicles, oper-ated by both public and private sectors, to mechanical compactors,transfer stations and container trucks before reaching incinerationplants or sanitary landfills.

6. Sanitary landfill

6.1. Berlin

The Municipal Solid Waste Management Report in Germany(2006) indicated that methane emissions from landfills have inthe past account for about 25% of the total methane emissions inGermany. Therefore, landfilling of untreated waste with high or-ganic content or leakage of contaminants has been prohibited sinceJune 2001 by the waste disposal act which specifically refers todomestic waste in Germany (BMU, 2005; Hempen, 2005; Berghoffand Kim, 2006; Wagner and Bilitewski, 2009).

In recent years, the need for landfills has been reduced signif-icantly in Germany. Major reasons are the increasing amount ofwaste which has been channeled for recycling and recovery.The remaining solid waste goes to waste incineration, for co-incineration in coal-fired power-stations, cement kilns and formechanical and biological treatment. After the above-mentioneddeadline in 2005, only the low calorific fraction from mechanicalbiological treatment facilities, slag/ashes from waste incinerationand construction/demolition waste are allowed in landfills. Thisdevelopment has led to a situation that no new landfills are nec-essary in Germany and several hundred old landfills need to beclosed down. For example, in the 1970s, Germany had around50,000 landfills, while in 2000 the number of landfills had re-duced dramatically to 333 (Schnurer, 2002; Hempen, 2005). Atpresent, there are only about 160 landfill sites still in operationnationwide and in Berlin, there are currently three landfill sites(Schulze, 2009). At the same time, there has been a significant in-crease in the number of waste incineration plants (from sevenincinerators with capacity of 718,000 tonnes/year in 1965 to 72incinerators with capacity of 17,800,000 tonnes/year in 2007)(BMU, 2005), and also mechanical–biological plants for municipalwaste disposal.

6.2. Singapore

In Singapore all three landfills in Singapore are outside the citylimits. In addition, over the past 35 years, there has been a 2.09million tonnes increase in the amount of solid waste generated(NEA, 2008). This growth in solid waste generation has imposedconsiderable demand on waste management and disposal facili-ties. Therefore, landfilling is the last option in the MSW manage-ment decision in Singapore, although it still plays significantroles in other countries. Because of limited land space, landfillcapacity in Singapore is principally reserved for the waste that can-not be treated or disposed of in any other way. About 91% of wastecollected is incinerated, and the remaining 9%, along with the ashgenerated from incineration are disposed of at Semakau landfill(NEA and MEWR, 2006).

On the mainland, Singapore once had two landfill sites. The LimChu Kang dumping ground in the north-western part of Singaporewas filled in 1992, and the Lorong Halus dumping ground in thenorth-eastern part of Singapore reached its capacity in 1999 (Baiand Sutanto, 2002).

7,000 tonnes, 1%

340,000 tonnes, 36%

74,000 tonnes, 8%

505,400 tonnes, 54%

8,000 tonnes, 1%

MA MPS MBT Incineration Landfill & others

Fig. 5. Waste disposal in 2008 in Berlin. (Data source: BSR, 2008) (MA: Mechanical treatment; MPS: Mechanical–physical stabilization; MBT: Mechanical–biologicaltreatment.)

926 D. Zhang et al. / Waste Management 30 (2010) 921–933

Presently, Semakau Landfill, an offshore landfill that is createdto meet waste disposal needs, is Singapore’s only landfill for wastedisposal. The facility covers a total area of 350 ha and has a landfillcapacity of 63 million m3. Semakau landfill is situated 25 km southof mainland Singapore (Khoo, 2009; Bai and Sutanto, 2002).According to the Ministry of Environment (1998), it is predictedthat phase 1 will be filled by 2019, phase 2 by 2027 and phase 3by 2045. However, the lifespan of the Semakau facility will largelydepend on future solid waste generation and the disposal option.Only inorganic waste and ash are allowed at Semakau landfill.

7. Incineration and other methods for solid waste disposal

7.1. Berlin

Over the last years the need for landfills has been reduced sig-nificantly in Germany and the major reasons are the increasingamount of waste that has been recycled and recovered (e.g., paper,light-packaging, construction waste, bio-waste, etc.). Much of theremaining solid waste not recycled, is incinerated, for co-incinera-tion, mechanical–physical stabilization (MPS) and for mechanicaland biological treatment (MBT).

Mechanical–physical stabilization and mechanical–biologicaltreatment are innovative methods for solid waste treatment inan environmentally ‘‘friendly” manner. Both methods rely on sort-ing and separating the waste into either combustible fraction (thatmay be used for waste-to-energy recovery), or in the case of MBT,into a biodegradable fraction that is subjected to biological treat-ment and then composted under aerobic conditions. In Berlin,two MPS plants are in operation in Pankow (with a capacity of160,000 tonnes/year) and Reinickendorf (with a capacity of180,000 tonnes/year) with total capacities of 340,000 tonnes/year(approximately 36% of total amount of waste disposal in 2008).In addition, there is currently one MBT plant located on the out-skirts of Berlin (Schöneiche Plant with a capacity of 74,000 ton-

Table 2Incineration plants in Singapore (NEA Singapore, 2008; Khoo, 2009; NEA and MEWR, 200

Location of incineration plant Year built Construction co

Ulu Pandan 1979 130Tuas 1986 200Senoko 1992 560Tuas South 2000 900

nes/year) (approximately 8% of total amount of waste disposal in2008).

Fig. 5 illustrates the waste disposal in 2008 in Berlin. The totalamount of disposed waste is 934,400 tonnes, in which 505,400 ton-nes went for incineration and accounted for 54% of the total amountof disposed waste in 2008. Currently, there is one incineration plant(The Ruhleben Incineration Plant) with a total annual capacity of upto 520,000 tonnes/year, and forms the center piece of Berlin’s wastedisposal plan (Thürmer, 2007). In terms of by-products, metals areseparated out for recycling, the slag can be reused after reprocessing,and the energy output can be used as heat and electric power. Onlysmall quantities of scrubber residue are left over to be disposed of aswaste. The remaining scrap metal is removed from the slag. This pro-cedure contributes approximately 13,000 tonnes of ferrous scrapannually (Schulze, 2009). Most of the slag and ash are recoveredfor use in civil engineering projects (e.g., road construction).

7.2. Singapore

At present, Singapore has four incinerators: Tuas (2000 tonnes/day), Ulu Padan (1700 tonnes/day), Senoko (2400 tonnes/day), andTuas’ South Incinerator (3000 tonnes/day) (see Table 2). The totalcapacity of 8200 tonnes/day was sufficient for incineration of allthe solid waste in Singapore until 2007. With the anticipatedaverage annual increase of 5% in waste generation, additionalincineration capacity is necessary. A fifth incineration plant (thewaste-to-energy plant), located at Tuas South and run by KeppelSeghers Engineering Singapore Pte Ltd. and built under thePublic–Private Partnership (PPP), has been in operation since early2009 and is able to treat 800 tonnes/day of solid waste and gener-ate more than 20 MW of green energy (Ministry of Environmentand Water Resources (MEWR), 2008). In addition, one of the strat-egies to decrease the amount of waste to be disposed in landfill isto recycle incineration bottom ash and non-combustible waste dis-posed of at the landfill (Lang, 2007).

6).

st (million) Boiler/incinerator Capacity (tonnes/day)

4 units 11005 units 17006 units 24006 units 3000

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

1992 1994 1996 1998 2000 2001 2002 2003 2004 2005 2006 2007

Recycled waste

Disposed waste

Tonnes/year

Fig. 6. The development of recycled and disposed waste from 1992–2007 in Berlin. (Data source: Schulze, 2009.)

D. Zhang et al. / Waste Management 30 (2010) 921–933 927

8. Waste recycling

8.1. Berlin

Germany’s high material, energy and labor and waste disposalcosts favour the economics of recovering, reuse and recycling asmuch waste as possible. The waste management in Berlin has beendeveloped towards resource management. Two main biodegrad-able municipal waste fractions are paper waste and bio-waste fromhouseholds and municipal services. The strategies for waste recy-cling are: (1) to separate bio-waste collection and treatment to re-duce biodegradable waste going to landfills; (2) to increasematerial recycling of paper, glass, plastic and metal; (3) to intensifythe activities of waste-to-energy and climate protection.

Fig. 6 illustrates the development of recycled and disposedwaste from 1992–2007 in Berlin. While the amount of disposedwaste has been declining, the amount of recycled waste has stea-

Table 3The composition of Berlin’s disposed and recycled municipal waste in 2007 (Datasource: Schulze, 2009).

Type of waste Amount in2007 (tonnes)

Percentage byweight (%)

Amount per capita(kg/capita�year)

Domestic waste 1089,000 67.3 319.5For disposal 710,000 43.9 (65%) 208.3For recycling 379,000 23.4 (35%) 111.2Trade waste 177,00 10.9 51.9For disposal 177,00 10.9 51.9For recycling 0 0 0Waste recycled by

‘‘Green dot”192,000 5.7 27.0

Domestic bulkywaste

118,000 7.3 34.6

For disposal 0 0 0For recycling 118,000 7.3 34.6Commercial

waste80,000 4.9 23.5

For disposal 80,000 4.9 23.5For recycling 0 0 0Road sweeping 62,000 3.8 18.2For disposal 1000 >0.1 0.3For recycling 61,000 3.8 17.9Total 1618,000 100,0 474.8Of which disposed 968,000 59.8 284.1Of which recycled 650,000 40.2 190.7

dily increased. Whereas only 269,000 tonnes was recovered in1992, the amount of recycled waste has increased to 650,000 ton-nes in 2007. The proportion being recycled rose from about 10% in1992 to more than 40% in 2007 (Schulze, 2009). High recoveryrates were achieved through separate collection of glass, paper,cardboard, light weight packaging and organic wastes.

Table 3 presents the composition of Berlin’s disposed and recy-cled municipal solid waste in 2007. The total generation of muni-cipal solid waste was 1618,000 tonnes in 2007, in which thetotal disposed of and recycled wastes were 968,000 tonnes and650,000 tonnes, respectively, which accounted for 59.8% and40.2% of the total generated waste respectively. In terms of domes-tic waste, the disposal and recycling percentage was 65% and 35%,respectively. Domestic bulky waste and road sweepings were com-pletely recycled, while trade and commercial waste were com-pletely disposed of by treatment by incineration plant, or MBT,or MPS.

8.1.1. Bio-waste recycling from domestic wasteIn Berlin’s inner-city area, organic waste is collected in separate

‘‘brown bins” by the BSR and taken to one of the composting sitesor a fermentation plant. Krogmann (1992) indicated that in resi-dential areas with gardens, considerable fluctuations in bio-wastequantity can be detected, dependent on public relations work,available container volume, etc. Despite separate collection, theremaining MSW still contains considerable portions of bio-waste.On average, each individual using an organic waste bin disposesof about 15 kg of bio-waste annually, and a total of 53,000 tonnesof bio-waste is collected every year in Berlin (Schulze, 2009). Bergs(2005) also reported that the separated collected bio-waste has in-creased from 1 million tonnes in 1990 to 8 million tonnes in 2002nationwide. In addition, Vogt (2009) reported that bio- and green-waste are mainly composted in Germany and only bio-waste (frombio-waste bin) is anaerobically digested. Table 4 shows the bio-waste generation and disposal in Berlin in 2007.

8.1.2. Packaging waste recycling from domestic wasteIn order to promote the collection, separation and recycling of

packaging from both households and small business, the (Dual Sys-tem Germany) Duales System Deutschland (DSD) was established.By participating in the DSD system program, manufacturers mayattach the ‘‘Green Dot” label to their products. A ‘‘Green Dot” indi-

Table 4The amount of bio-waste generation and the disposal methods in 2007 (Data source: Thürmer, 2008).

Types of bio-waste Generation amount in 2007 (Mg) Percentage in 2007 (%) Disposal methods

Bio-waste from household 52,800 44 Composting and anaerobic digestionLeaves collected in bag 31,000 26 CompostingLoose leaves in street 32,300 27 CompostingShrubs and bushes 1500 1 Bulky material for composting and thermal utilizationChristmas tree 3000–400,000 trees 2 Balky material for compostingTotal 120,600 100 –

928 D. Zhang et al. / Waste Management 30 (2010) 921–933

cates to the consumer that the manufacturer of the product is aparticipant in the program, and that instead of returning the pack-aging to the manufacturer or distributor the packaging should becollected, sorted, and recycled through the DSD system.

Fig. 7 shows the development of separated collected and recy-cled packaging waste from households and small enterprises inBerlin 1997–2003. The total amount of separately collected pack-aging waste showed a declining trend, and has decreased byaround 80,000 tonnes from 1997 to 2003 (20% reduction). Besides

134,000 123,000 119,000

205,000 215,000 214,000

99,000 99,000 99,000

0

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

450,000

500,000

1997 1998 1999

Tonn

es

Glass Papar

Fig. 7. Development of the recycled glass, paper and light-packaging w

2.3 3.1 3.7 3.75.7

13.5

4.14.5 3.4 3.4

1.5

1.1

0

2

4

6

8

10

12

14

16

1992 1993 1994 1995 1996 1997

Recycled waste

Milliontonnes/year

Fig. 8. Development of non-domestic waste in Berlin 1

changing packaging material, one of the main reasons for this is theabove-mentioned ‘‘one-way drink packaging”, which resulted inthe diversion of recycling flow of light-packaging and glass (recy-cled by the supermarket, shops, etc.).

8.1.3. Non-domestic waste recyclingMaterials resulting directly from demolition and construction

site waste are both of higher value and more difficult to recoverand process for reuse. Fig. 8 illustrates the development of non-

108,000 92,000 85,000 74,000

210,000 215,000 212,000 204,000

90,000 89,000 88,00080,000

2000 2001 2002 2003

/carton Light-packaging

aste in Berlin 1997–2003. (Data source: Schwilling et al., 2004.)

8.45.8 5.9 4.9 4.6 4.5

0.5

0.2 0.10.1 0.1 0.1

1998 1999 2000 2001 2002 2003

Disposed waste

992–2003. (Data source: Schwilling et al., 2004.)

D. Zhang et al. / Waste Management 30 (2010) 921–933 929

domestic waste, namely construction and demolition (C&D) overthe period 1992–2003 in Berlin. The total amount of C&D genera-tion showed a declining tendency (with one exception in 1997,when many new residential buildings were constructed under aspecial building strategy). In 1992, the total amount of recycledC&D was 2.3 million tonnes and accounted for 35.9% of total C&Dgeneration (6.4 million tonnes), while in 2003 recycled C&D wasteincreased to 4.6 million tonnes and accounted for 98% of total C&Dgeneration. The percentage of recycling was 86.2% in 2003 inGermany.

8.1.4. Waste-to-energy and climate protectionAccording to Thürmer (2008), the amount of CO2 emission

attributable to solid waste in Berlin in 1999 was approximately605,000 tons, while the amount of CO2 emissions in 2007 had de-creased to 150,000 tons. This achievement was attributed to:

� The utilization of heat for the generation of combined heatingand power (CHP) in the Ruhleben incineration plant.

� Generation of combustible material or fuel from householdwaste for the replacement of non-renewable energy, e.g., coal,natural gas etc.

� The capture and utilization of methane from landfill.� Energy efficiency for construction management.� Application of natural gas for transportation.

Table 5 illustrates the data on energy recovery through inciner-ation and landfilling in 2008 in Berlin. The electricity generatedfrom incineration and landfill gas were 235 million kWh (Thürmer,2008). In comparison, according to Gamperl (2005), the total en-ergy recovery from steam and landfill gas is 307 million kWh in2005 and the main reason for the reduction of energy recovery isthat the amount of waste disposed by incineration and landfillhas been decreasing in Berlin. And the ash from incinerator usedfor road construction is 137,000 tonnes and scrap for steel produc-tion sum up to 10,000 tonnes in 2005.

8.2. Singapore

8.2.1. Domestic and non-domestic waste recyclingAlthough Singapore’s NEA adopted the strategy focusing on vol-

ume reduction by incineration that relieved pressure for more landto be used for landfilling, it is not suitable to rely completely onincineration and landfilling to solve the solid waste problem dueto rising costs and environmental concerns. Therefore, NEAadopted a multi-pronged approach focusing on recycling as it savesenergy and conserves resources. The approach includes:

� Minimization of waste generated at source.� Waste recycling to reduce the amount of waste that needs to be

disposed of.

Table 5Waste-to-Energy in Berlin in 2008 (Data source: Thürmer, 2008).

Waste disposal plants in Berlin

Category Capacity (tonnes/year)

Incineration plant (1): Ruhleben 520,000Landfill plants (3): Shwanebeck, Werndorf, Schöneicher –Mechanical–physical stabilization (2)

Pankow 160,000Reinickendorf 180,000Mechanical treatment plant: (1) Köpenick 100,000

� Volume reduction of combustible waste through waste-to-energy incineration.

� Reduction of waste to landfilling in order to extend the life of theSemakau Landfill.

To overcome the problem of increasing solid waste, the NationalRecycling Progromme (NRP) was launched by the National Envi-ronment Agency (NEA) in April 2001 (Claudio, 2004). Under theNRP, recycling bins have been placed at public areas, such as thepedestrian walkways of busy street, petrol service stations, com-mercial areas and some of residential areas. According to Claudio(2004), since August 2001, 4100 sets of centralized recyclingdepositories have also been placed in public areas. The HousingDevelopment Board (HDB) which provides public housing toapproximately 85% of the population and provides similar recy-cling depository services to complement the door-to-door collec-tions of recyclables.

In addition, as Singapore has a highly industrialized economywith strong focus on the manufacturing, its approach to the green-ing industry is a two-spronged strategy: first resource conservationthrough a more intensive and coordinated effort at developing therecycling industry; and second, waste reduction and elimination atsource through product and process innovations as well as devel-oping green technologies for industry through private–public col-laborations (Lang, 2007). Two approaches are particularlysignificant in accelerating the development of a viable recyclingindustry in Singapore: (i) the establishment of two recycling parks:first, the Sarimbum Recycling Park was created to attract the set-ting up of recycling facilities with low cost rental. Twenty recyclingplants are found on site currently and focus on the recovery ofhigher value-added secondary construction material. The second– Ecopark is situated beside the Tuas incinerator sorting recyclablehousehold refuse such plastics, glass and metals, (ii) the NEA is ac-tively promoting recycling among small and medium-sized facto-ries by collaborating with the Jurong Town Council which iscritical as it is Singapore’s leading developer and manager of indus-trial facilities and business park.

Construction and demolition (C&D) waste is one of the majorwaste streams to be disposed of at the landfill in Singapore. In2008, the total amount of generated constructed debris was920,000 tonnes, in which 99% were recycled (Ministry of the Envi-ronment and Water Resource, 2008). To support recycling of C&Dwaste, the NEA set up several recycling facilities converting C&Dwaste into (the low value-added) secondary aggregates for furtherprocessing into non-structural concrete products for use in newbuildings or as materials for temporary road access in constructionsites. Hence, NEA also encouraged collaborations among recyclingand construction companies and research institutions to explorethe innovative use of recycled materials as substitutes for conven-tional construction material, and to examine the performance ofthese recycled building materials and products. In addition, used

Waste generation

Electricity generation: 190 million GWh/year, Heat: 450 million GWh/year,Landfill gas (CH4 + CO2) generation: 45 million m3/year,Combustible material and fuel generation: 160,000 Mg/year, which isequivalent 635 million GWh

Combustible material and fuel generation: 50,000 Mg/year, which isequivalent 115 million GWh

Table 6Current status of municipal solid waste landfilled and incinerated in Singapore (MEWR – Ministry of the Environment and Water Resource, 2008).

Solid waste treatment Unit 2006 2007 2008

Total waste generated Million tonnes/year 5.22 5.60 5.97Total waste recycled Million tonnes/year 2.66

(51%)3.03(54%)

3.34(56%)

Total waste landfilled Million tonnes/year (%) 0.23(4%)

0.19(3%)

0.18(3%)

Total waste incinerated Million tonnes/year (%) 2.33(45%)

2.38(43%)

2.45(41%)

Total Energy produced from incineration MWh 954,237 974,945 1048,072Lifespan of landfill Years 35–40 35–40 35–40

930 D. Zhang et al. / Waste Management 30 (2010) 921–933

copper slag from the marine industry is also recycled to producenew slag, concrete paving blocks and ready mix concrete. Steel slagfrom the electric arc furnace of scrap iron mills, is also being recy-cled to produce road-building material. This strategy if it be suc-cessful, will enable Singapore to move towards zero landfilling.

Through these strategies, a significant improvement in solidwaste management has been achieved. According to NEA (2008),Singapore’s recycling rate has increased from 40% in 2000 to 54%in 2007. The results of great efforts in waste minimization andrecycling have helped tremendously to divert waste from endingup in the landfill. This has contributed directly to increasing thelifespan of the Semakau Landfill from 20–30 years to 35–40 years,while the need for additional incineration plants has been reducedfrom one in every 5–7 years to one in every 7–10 years. Further-more, the Singapore Green Plan 2012 proposed to increase therecycling rate to 60% by 2012 and strive towards zero-landfill.

Table 6 shows the composition of solid waste, actual amount ofwaste disposal, total waste recycled and total waste output in Sin-gapore in 2008. Some 5.97 million tonnes of municipal waste weregenerated in 2008 in Singapore, 56% of which was recycled, 41%incinerated and 3% landfilled. According to NEA and MEWR(2006), currently around 22,800 tonnes/year of scrap are recovered(by magnetic separation from incinerated ash) and 980 millionKWh of electricity are generated per year, which could cover 2–3% of the electricity demand for Singapore. In contrast, approxi-mately 23,000 tonnes of scrap metal were recovered and onlysome 391 million KWh of electricity were generated in 1992(Leong and Quah, 1995).

Table 7 presents the waste generation and recycling rate for2008 in Singapore. The total waste generation was 5.97 million

Table 7The waste generation and recycling rate for 2008 in Singapore (Ministry of theEnvironment and Water Resource, 2008).

Waste stream Amount of wastegenerated (tonnes/year)

Amount of wasterecycled (milliontonnes/year)

Recyclingrate (%)

Used slag 570,000 560,000 99Construction

debris920,000 900,000 98

Ferrous metals 780,000 740,000 94Scrap tyres 30,000 20,000 88Non-ferrous

metals90,000 70,000 85

Wood/timber 270,000 190,000 71Paper/cardboard 1260,000 610,000 48Horticultural

waste230,000 100,000 42

Glass 60,000 10,000 18Food 570,000 70,000 12Textile/leather 90,000 10,000 12Plastics 680,000 60,000 8Others (e.g., e-

waste)310,000 10,000 3

Sludge 110,000 0.00 0Total 5970,000 3340,000 56

tonnes and 3.34 million tonnes of total generated waste were recy-cled. The recycling rate of total municipal solid waste was 56%. Inparticular, used slag reached the highest recycling rate (99%), fol-lowed by construction debris (98%) and ferrous metals (94%). Therecycling rate of paper was 48%, and the recycling rate for glasswas relatively low (12%).

8.2.2. Impediment and challenge in waste recyclingWaste recycling was started in early 1990s and currently most

of the recycling practice is confined mainly in the industrial andcommercial sectors (Foo, 1997; Claudio, 2004; Bai and Sutanto,2002). There is certainly much space for the household and com-mercial sector to participate actively in recycling. Although a Na-tional Recycling Program for Households was launched in 2001,collection of recyclable waste and refuse had been promoted to85% of the population and ‘‘Green Bags” have been distributed toresidential households for door-to-door collection of the separatedmaterials (Claudio, 2004), what to do with the separated materialsis another challenge in Singapore. To sustain the waste separationand recycling programs, Singapore might need to set up its ownwaste recycling industry.

According to Bai and Sutanto (2002), Singapore has only onerecycling plant that produces compost and soil fertilizer. Mean-while, according to NEA and MEWR (2006), the recycling rate forfood waste is only 8% (while it is 90% in inner-city city area of Ber-lin and 47% nationwide in Germany).

In terms of packaging waste recycling, Fig. 9 presents the devel-opment of recycled plastic, paper and glass in 1999, 2007 and 2008in Singapore. Both Fig. 9 and Table 7, showed that in comparisonwith industrial solid waste (e.g., used slag, constructed debris, met-als), solid waste such as paper, glass and plastics (which are widelyused in our daily activities) showed the tendency of low recyclingrate and had not been recycled to a satisfactory level in Singapore.According to the Ministry of the Environment and Water Resource,in 1999, 2007 and 2008, the recycling rate for paper was 40.3%, 51%

Table 8Charging fees of municipal solid waste from household and small trade in Berlin2009–2010 (BSR, 2009).

Volume of waste bin (litre) Price (Euro/quarter year)

Regular collection For additional containers

60 63.5 20.2120 75.3 21.1240 98.6 22.9660 220.8 32.21100 303.8 38.660 (bio-waste) 30.5 17.6120 (bio-waste) 31.4 17.7240 (bio-waste) 35.4 18.0660 (bio-waste) 77.9 21.31100 (bio-waste) 93.4 22.5Slag 94.7 22.6

D. Zhang et al. / Waste Management 30 (2010) 921–933 931

and 48%; 10%, 9% and 18% for glass; and for plastic it was 15.6%,11%, and 8%, respectively.

In the recycling project and survey of Tanjong Pagar, Foo (1997)concluded that paper was the type of material most frequentlyrecycled, followed by drink cans, then plastic and other materials.The main reason was that the recycling bins located at the lift lob-bies were mostly for the collection of paper and recycling of drinkcans and plastics have to be rinsed and cleaned first before beingdeposited into the various bins. He also indicated that all the recy-cling bins in Singapore should be conveniently located and prefer-ably at the individual floors of residents’ blocks. It was suggestedthat door-to-door recycling could be implemented on a trial basis.Simple and convenient methods of separating and storing recycla-ble waste, and proper labeling of bins need to be further promoted.

Ho (2002) reported that Singaporeans seems to think they haveno time for recycling, and this suggests that either Singaporeansfind recycling to be a time-consuming activity or that Singaporeanslead a hectic life that leaves very little time for other activities. It isno doubt that Singaporeans works in a fast-paced environment andthis is unavoidable for a country with no natural resources andonly human resources to depend on. It is not possible to changea whole society’s attitude towards work and time so that moretime can be allocated for recycling. Both Foo (1997) and Ho(2002) suggested increasing accessibility of recycling facilities asan important factor to increase Singaporeans’ recycling behavior.

Research has shown that knowledge about the specifics of recy-cling is more closely related to recycling behavior than generalenvironmental knowledge. Most importantly, recycling programs

Table 9Solid waste collection fee charged per month in Singapore (Bai and Sutanto, 2002).

Type Pasir Ris-TampinesAltvater JakobPte Ltd. ($)

Bedok sector(Colexholding Ltd.)($)

Rest ofSingapore(SEMAC PteLtd.) ($)

ResidentialFlats 8.63 6.23 8.7Landed residential 23.93 22.95 23.45

Non-residential<170 litre/day 42.66 40.23 41.06170–<350 litre/day 108.68 101.53 104.17350–<700 litre/day 277.6 253.6 258.57700–<1000 litre/day 426.34 370.62 379.1>1000 litre/day 447.35 378.14 388.01

3400 5800

388800

619000

29900

75000

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

1999 2007

Tonnes/year

Fig. 9. Development of recycled plastic, paper and glass in 1999, 2007 and 2008 in Sing2008.)

in Singapore are reporting problem due to Singaporeans’ ignoranceof what can or cannot be recycled. And a high percentage of Sin-gaporeans believed recycling is an activity that is the responsibilityof waste collection companies or other relevant authorities but notthemselves. Therefore, Singapore needs to pay attention to howenvironmental education is being carried out in schools or con-veyed to the public when promoting recycling behavior. Singaporemay need to devote more efforts towards educating Singaporeansabout proper household waste recycling etiquette in order to seeprogress in the recycling rate.

While these are important strategies for Singapore to reduce theamount of waste that goes into landfills or incinerators, it does nothelp decrease the amount of waste generated. Singapore needs toconsider introducing extended producer responsibility to get tothe root of the waste management problem. Regarding the typeof recycling program survey participants would like Singapore toadopt, Ho (2002) reported that an incentive program like the de-posit refund with the return of drink cans and bottles (which iscurrently being used in Berlin) was frequently cited as a programparticipants say they would like to see Singapore adopt in future.In addition, extended producer responsibility can help. The realsolution is found at the beginning of the life cycle stage, and truewaste minimization happens when production decreases. To de-crease production, consumption needs to decrease.

9. Charging fee system

9.1. Berlin

The waste charging system in Berlin is a two-tier pricing systembased on the PAYT system. Table 8 shows charge fees for municipalsolid waste from households and small trades in Berlin. This is avolume-based fee system. The resident only pays for the serviceused and a resident can directly influence the ensuing cost. In addi-tion, in order to avoid waste generation and promote waste recy-cling, there are 15 recycling centres for drop-off waste within thecity operated by BSR. Residents and small business enterprisescan bring their recycles to the responding recycling centres neartheir resident location free of charge.

9.2. Singapore

In Singapore, the system for waste collection and disposal is flatrate system. The fee has to be paid regardless how much of the ser-

10000

610000

61200

2008

Plastic

Paper/carton

Glass

apore. (Data source: Ministry of the Environment and Water Resource, 1999, 2007,

932 D. Zhang et al. / Waste Management 30 (2010) 921–933

vice is used by the generator. According to Foo (1997), domestic pre-mises are charged a monthly flat rate of either S$20 (for house-to-house service) or S$8 per dwelling (central bin collection). In addi-tion, the Ministry of Environment (MOE) also operates a special re-moval service for the disposal of bulky household wastes such asold furniture and electrical goods. The fee is charged S$ 50 per vehi-cle trip. Furthermore, in order to encourage waste recovery and recy-cling, waste disposal fees (mainly incineration) have been raisedfrom S$ 67 in 2002 to S$ 87 in 2007 to reduce the need to subsidize.

Table 9 shows the waste collection fees currently charged inSingapore (Ministry of Environment, 1999). For residential solidwaste, the collection fee is charge per household, and for non-res-idential solid waste, the collection fee is charge on the basis ofwaste volume.

10. Conclusion

Both Germany and Singapore are industrialized nations withwell-developed economies and with GDP per capita among thehighest in the world. Both have the common will to conducthigh-level research and development for environmentally-soundsolutions to their waste problem. With this as this background,the policies, regulations and legislation in both countries are aimedat closed cycles of materials and at the establishment of environ-mentally compatible methods for the disposal of wastes. Neverthe-less, the rapid economic and population growth, and the increasingstandard of living and changing lifestyles in Singapore makeMSWM a more critical concern than that in Germany.

Important conclusions from this comparative study can bedrawn and include the followings:

1. Total annual generation of MSW in Singapore has increasedsteadily from 4.70 million tonnes in 1996 to 5.97 million tonnesin 2008, while Berlin’s MSW generation showed steadilydecreasing tendency over the same period (from 2.12 milliontonnes in 1996 to 1.68 million tonnes in 2005). The latter wasachieved mostly because waste prevention measures haveproved very effective, and because of the increasing amountof MSW that has been channeled for recycling and reuse, so thatless and less waste needs to be disposed of. In addition to rapideconomic and population growth in Singapore, change in con-sumption patterns also has increased waste generation thatmay outstrip the gains made with strategies on waste recyclingand minimization. And the recent increase in solid waste gener-ation has imposed a considerable burden on waste manage-ment and disposal facilities. Daily per capita MSW generationin Singapore (0.88 kg/capita/day) was similar to that of Berlin.

2. On the legislative front, Germany has promulgated a series oflaws which addressed more extensive, detailed and specificissues relating to waste management. For instance, the provi-sions of The German Closed Substance Cycle and Waste Man-agement Act (1996) is a milestone introducing the ‘‘polluterpays” principle to its logical conclusion by reducing the onuson public authorities and making private sector generators ofwaste, not just municipalities, responsible for dealing withwaste. The Waste Storage Ordinance (2001) mandated thatany exemptions permitting untreated waste to be landfilledcannot be granted. The German Packaging Ordinance (1991)addressed the fact that packaging materials have to be pro-duced from environmentally compatible material, have to bereduced as far as possible and recovered before all other dis-posal options. In addition, Germany is required to keep confor-mity of laws with all EU legislations.

3. The Berlin strategy of MSW management comprises the sepa-rate collection and recycling of secondary raw materials, further

development of sorting technology for mixed domestic waste,pre-treatment of mixed household waste in mechanical–biolog-ical treatment plants, recovering waste incineration residues,and energy recovery from incineration. Waste which can berecycled, in particular paper, glass, light-packaging and biode-gradable waste, is separated in Berlin by private householdsand businesses. Approximately 50% of the households currentlyparticipate in separate bio-waste collection systems nationwidein Germany. On average, each individual using an organic wastebin collects about 15 kg of bio-waste annually, and a total of53,000 tonnes of bio-waste is collected every year in Berlin. Incontrast, the high-rise apartments in Singapore limited wasteseparation by private household.

4. Landfilling is the last option in the MSW management decisionin both cities: one due to geography (Singapore) and the otherone due to legislative prohibition (Berlin). In Singapore, approx-imately 90% of the non-recyclable waste is incinerated and theremaining non-incinerable waste is landfilled despite theextreme scarcity of land. In contrast, other than incinerationand landfilling, mechanical–physical stabilization (MPS) andmechanical biological treatment (MBT) play a very importantrole and are practiced in Berlin. Approximately 54% of MSWgoes for incineration while the remaining wastes are treatedby MPS (36%), MBT (8%), and landfilling & others (2%)respectively.

5. The key policies for waste management have given top priorityto the recycling, recovery and reuse of waste materials in bothcities. The total MSW recycling rate in Berlin in 2007 was 40.2%,while it was approximately 56% in 2008 for Singapore. How-ever, the plethora of high-rise public apartments in Singaporeand its consumer society have made waste recycling muchmore cumbersome and solid waste from each household is dis-charged directly through a common discharge chute. Therefore,waste recycling mainly takes place in the industry sector in Sin-gapore. While industry – associated material such as used slag(99%), constructed debris (98%) and metals (94%) show highrecycling rates, those material widely used in our daily activi-ties such as paper (48%) and plastic (8%) present low recyclingrates. While those strategies for Singapore to reduce theamount of waste that goes into landfills or incinerators areimportant, they do not help decrease the amount of waste gen-erated. Singapore needs to pay attention to how environmentaleducation is being carried out in schools or conveyed to thepublic when promoting recycling behavior and to considerintroducing extended producer responsibility to get to the rootof the waste management problem. Increasing accessibility ofrecycling facilities is important factor to increase recycling. Inaddition, the real solution is found at the beginning of the lifecycle production and true waste minimization happens whenproduction decreases. To decrease production, consumptionneeds to decrease.

6. The two cities have adopted different charging fee systems: res-idential solid waste is currently charged at a fixed rate of fee perhousehold in Singapore, while solid waste is charged on thebasis of volume (i.e., Pay-As-You-Throw (PAYT)) in Berlin. Fur-thermore, even if such a PAYT waste charging system is adoptedin Singapore, the scheme can be difficult to implement in den-sely populated high-rise buildings.

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