Abstract Industrialization and urbanization result in sig-nifi cant changes in lifestyle. These lifestyle changes seem to lead to unsustainable consumption patterns and increase the generation of various kinds of environmental loads, especially the amount of municipal solid waste (MSW). Taiwan is a small island with scarce natural resources. The economic development in Taiwan has resulted in the gen-eration of large amounts of MSW. As a result, the Taiwan Environmental Pollution Administration (TEPA) has pro-duced regulations for waste minimization and has imposed several important policy measures that have successfully reduced the MSW discard rate in recent years and have established a public recycling network as a part of the MSW collection. Nowadays, the objective of the MSW policies in Taiwan is to develop a “zero-waste society.” This article aims to review the MSW management progress in Taiwan and to project future MSW discards up to 2011 based on the national plan and assumed scenarios for socioeconomic variables. According to the analysis results, a more sustain-able consumption pattern can be proposed and the corre-sponding MSW management system can be planned so as to develop a low-waste-discard society.

Key words Municipal solid waste management · Develop-ing country · Changes in lifestyle · Consumer behavior · Econometric modeling

Introduction

Taiwan is a small island with limited natural resources, but has one of the highest population densities in the world (634 people/km2).1 Taiwan has achieved signifi cant eco-

nomic growth in the past few decades by shifting the eco-nomic structure from the agriculture sector to the industrial and service sectors. Additionally, there was liberalization in the social and political environment after the abrogation of martial law in 1987. Industrialization and urbanization dif-fused rapidly throughout Taiwan, causing dramatic changes in lifestyle and consumer behavior.

Some socioeconomic indices in terms of lifestyle changes are examined. The offi cial database1 was used for analysis of the period from 1984 to 2005, and the indices analyzed in this study are described in Table 1. Figure 1 demonstrates the normalized trends of these indices, and the high correla-tion coeffi cients (see Table 2) among the indices confi rm their intrinsic interaction, which may result from the simi-larities in overall lifestyle. Such evolution may be regarded as a characteristic of a developing country. Figure 2 shows the time series data of per capita consumption expenditure by category from 1984 to 2005; all the consumption expen-ditures changed signifi cantly with changes in lifestyle.

However, as recent studies have indicated, this rapidly increasing production and consumption may not be hap-pening in a sustainable way and is likely to lead to global environmental problems.2–5 The consumer behavior origi-nating from the contemporary lifestyle has a great potential for increasing environmental loads, particularly municipal solid waste (MSW) generation and discard.6–9 In this study, MSW discards is defi ned as the amount of MSW generation that will be regularly collected and treated by the local municipalities.

The situation of MSW discards and treatment in Taiwan

As the socioeconomic environment changes, the MSW gen-eration rate also changes to a great extent. In this study, MSW is classifi ed into eight categories by physical property for treatment and fi nal disposal planning. Since the MSW composition analysis was conducted on a dry basis before 2004, the moisture of waste is separated and taken as a single category (however, the analysis changed to a wet

J Mater Cycles Waste Manag (2009) 11:110–122 © Springer 2009DOI 10.1007/s10163-008-0233-1

Yu-Chi Weng · Takeshi Fujiwara · Yuzuru Matsuoka

Municipal solid waste management and short-term projection of the waste discard levels in Taiwan

Y.-C. Weng (*) · Y. MatsuokaDepartment of Urban and Environmental Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8540, JapanTel. and Fax: +81-86-251-8994e-mail: yev73001@cc.okayama-u.ac.jp

T. FujiwaraGraduate School of Environmental Science, Okayama University, Okayama, Japan

Received: May 12, 2008 / Accepted: November 23, 2008

SPECIAL FEATURE: ORIGINAL ARTICLESolid Waste Management in Asia and Pacifi c Islands 1

111

Table 1. Description of the representative indices related to changes in lifestyle in Taiwan

Index Description Unit

Poput The total population in year t CapitaHhldt The number of households in year t HouseholdHlbrrt The proportion of employees among household members in year t %Hpopt The household size in year t CapitaAveaget The average age of the population in year t YearsHun15rt The proportion of younger people (under 15 years) in the overall population in year t %Hov65rt The proportion of the older people (above 65 years) in the overall population in year t %SFt The ratio of families in which the number of persons per household is less than fi ve in year t %WKt The percentage of women in the labor force in year t %Ginit The Gini coeffi cient (an indicator for the income lag between the poor and the rich) in year t %Engelt The Engel ratio in year t %Unempt The ratio of the unempolyment in the labor force in year t %Savingt The saving rate of disposable expenditure in year t %

Table 2. Correlation matrix of the representative indices related to changes in lifestyle

Hhldt Hpopt Hlbrrt Aveaget Hun15rt Hov65rt SFt WKt Ginit Engelt Unempt Savingt

Hhldt 1.000* 0.995* −0.995* 0.975* 0.993 −0.998* 0.997* 0.985* 0.943* 0.955* −0.962* 0.664*Hpopt 0.995* 1.000* −0.994* 0.971* 0.997 −0.998* 0.996* 0.974* 0.962* 0.959* −0.942* 0.722*Hlbrrt −0.995* −0.994* 1.000* −0.980* −0.988 0.994* −0.997* −0.988* −0.938* −0.957* 0.967* −0.661*Aveaget 0.975* 0.971* −0.980* 1.000* 0.971 −0.977* 0.979* 0.979* 0.944* 0.931* −0.951* 0.616*Hun15rt 0.993* 0.997* −0.988* 0.971* 1.000 −0.996* 0.994* 0.971* 0.967* 0.958* −0.934* 0.723*Hov65rt −0.998* −0.998* 0.994* −0.977* −0.996 1.000* −0.998 −0.978* −0.955* −0.949* 0.953* −0.692*SFt 0.997* 0.996* −0.997* 0.979* 0.994 −0.998* 1.000* 0.980* 0.946* 0.953* −0.964* 0.681*WKt 0.985* 0.974* −0.988* 0.979* 0.971 −0.978* 0.980* 1.000* 0.909* 0.940* −0.969* 0.567*Ginit 0.943* 0.962* −0.938* 0.944* 0.967 −0.955* 0.946* 0.909* 1.000* 0.931* −0.839* 0.813*Engelt 0.955* 0.959* −0.957* 0.931* 0.958 −0.949* 0.953* 0.940* 0.931* 1.000* −0.907* 0.736*Unempt −0.962* −0.942* 0.967* −0.951* −0.934 0.953* −0.964* −0.969* −0.839* −0.907* 1.000* −0.498Savingt 0.664* 0.722* −0.661* 0.616* 0.723* −0.692* 0.681* 0.567* 0.813* 0.736* −0.498 1.000

* Correlation is signifi cant at the 1% level (two-tailed)

-3

-2

-1

0

1

2

3

1984 1987 1990 1993 1996 1999 2002 2005

Poput

Aveaget

Hhldt

Hlbrrt

Hpopt

Hun15rt

Hov65rt

SFt

WKt

Ginit

Engelt

Unempt

Savingt

Fig. 1. Normalized time series data of the variables associated with the changes in lifestyle from 1984 to 2005 (see Table 1 or the defi nitions of the variables).Note: calculation of normalization for a seriex Xi:

ZX X

Sii

x

= −

where Zi is the normalized value; Xi is the original series; X is the mean of the series Xi; Sx is the standard deriation of the series Xi

basis in 2005). Based on such classifi cation, essential infor-mation can be obtained for designing recycling, treatment, and disposal plans.

Figure 3 illustrates the offi cial records of the composition of discarded MSW in Taiwan. The dataset covers the period 1992–2004, whereas per capita overall MSW discard levels, which denote the overall amount of discard for all the waste

fractions, are available from 1988 to 2006.10 In Fig. 3, a declin-ing trend can be observed in overall per capita MSW discard levels in recent years due to MSW policy interventions.

Considering the changing lifestyle in Taiwan, the Taiwan Environmental Protection Administration (TEPA) and its previous administrations have executed several counter-measures to control the rapidly growing solid waste discard

112

from both households and industries since 1974.11 In 1987 TEPA was promoted as an independent administrative department in charge of environmental affairs, and more specifi c waste regulations were set up afterward. At the beginning, TEPA cooperated with the municipalities to establish the MSW collection, treatment, and disposal system. Subsequently, the MSW collection rate, represent-ing the proportion of the MSW collected by the local munic-ipalities, has been boosted to more than 95% since 1990. Meanwhile, the MSW disposal rate, representing the pro-portion of MSW undergoing recycling, treatment, and dis-posal by the municipalities, improved notably from 2.55% (1984) to 90.17% (2000), and to more than 95% since 2002.10 To date, landfi lling and incineration have been the main options for intermediate treatment technologies in Taiwan: 163 landfi ll sites and 22 incinerators are in operation12,13 (basic information is shown in Table 3).

In the past, the people of Taiwan were not aware of waste problems. Almost all waste was dumped directly into landfi ll sites without proper separation. By the 1980s, some landfi ll sites were completely fi lled, and some cities did not even have a place to temporarily dump MSW. At that time, TEPA adopted incineration as the treatment approach instead of landfi lling due to the limited land resources in

Taiwan. The fi rst incinerator was operated in 1992, and most incinerators planned by TEPA were in operation during the period from 1998 to 2001, following which, they handled more than 45% of MSW. Figure 4 depicts the share of MSW undergoing intermediate treatment and disposal (at landfi lls, incinerators, dumping, and other disposal sites). Furthermore, the national environmental plan aimed at treating 80% of MSW by incineration in 2006.14 In fact the fraction of MSW treated by incineration exceeded the target value (82.79%) of the plan. In 2007, a new regulation ordered that combustible waste not be dumped in landfi lls until it is incinerated so as to improve recycling activities and to reduce MSW volume.11

However, another potential risk arose since some incin-erators are operated with insuffi cient feed because the

0

50,000

100,000

150,000

200,000

250,000

1984 1987 1990 1993 1996 1999 2002 2005

Miscellaneous

Amusement andeducation

Transportation andcommunication

Medicines andmedical care

Householdappliances

Housing

Clothing

FoodAnn

ual p

er c

apit

a co

nsum

ptio

n ex

pend

itur

e (T

aiw

an d

olla

r at

200

1 pr

ices

)

Fig. 2. Annual per capita consumption expenditure in Taiwan: 1984–2005

Ann

ual p

er c

apit

a ov

eral

l MS

W d

isca

rd (

kg)

0

100

200

300

400

500

1992 1994 1996 1998 2000 2002 2004

Miscellaneous-incombustibleMiscellaneous-combustibleMoisture

Food

Glass

Metal

Plastics

Paper

Fig. 3. Trends in per capita municipal solid waste (MSW) discards in Taiwan (on a dry basis): 1992–2004

Table 3. Basic information of the major municipal solid waste (MSW) intermediate treatment and fi nal disposal facilities in Taiwan

Type Number Design capacity (tonnes/year)

Throughput in 2006 (tonnes/year)

Landfi ll site 163 – 864 354Incinerator 22 7 672 500a 4 163 968a The operation period was assumed to be 330 days per year

113

incinerators are distributed inadequately. The actual MSW throughput of the incinerators is still less than the design capacity (see Table 3). Thus, a regional MSW transporta-tion and treatment network will have to be built soon.

Review of MSW management policies in Taiwan

According to the supportive regulations, several adminis-trative projects using economic instruments have played important roles in controlling MSW generation.15–17 The MSW policy measures based on the “polluter pays princi-ple” can be categorized into three types: the command and control type, the economic instrument type (e.g., subsidies, taxes, charges, and deposits), and the mixed type. Primarily, the MSW management system in Taiwan is designed based on the “3R” principle (reduce, reuse, and recycle). Mean-while, since land resources are limited, it was inevitable that incineration would be adopted as the main intermediate treatment technology. Meanwhile, the “not in my back-yard” phenomenon has occurred. Many protests against the construction of landfi lls and incinerators were held due to concerns about the potential health risks from the MSW intermediate treatment and fi nal disposal facilities, espe-cially those relating to incinerators. In order to prevent dioxin emissions from the incinerators, TEPA imparted extensive social education to the citizens regarding the importance of reducing the moisture content of wastes and of conducting MSW separation. MSW policy measures in Taiwan can be classifi ed into those at the national level and those at the city level.

City-level policy measures

The fi rst important MSW elimination project, Keep Trash off the Ground, was implemented in Taipei city in 1995, and this project nowadays has been extended to the majority of urban areas in Taiwan. This policy stipulates that citizens cannot directly dump their waste at collection sites; instead, the residents have to hand their waste to workers using col-

lection trucks. This measure successfully eliminated the leachate draining away from MSW during the collection process. In addition, if citizens mishandle the waste for the collection cargos, they have to keep the waste in their house. To a certain extent, households have to reduce the amount of waste discarded. However, this project requires an enor-mous administrative budget to sustain its performance; therefore, it is implemented only within the major urban areas.

Local municipalities also started to decrease the MSW collection frequency and to impose MSW treatment charges in different ways in different cities. For example, Taipei city started to charge a MSW treatment fee for standardized collection bags from 2000, whereas some local municipali-ties charge a MSW treatment fee based on the fee for household water usage. Fourteen counties even started to recycle used plastic bags within the MSW collection system from 2006. In addition, nongovernmental groups play an important role in local recycling programs.

National-level policy measures

The Resource Recycling Four-in-One Project was launched in 1998. This fi rst national-level project not only improved waste recycling networks but also aroused public concern over issues related to MSW. In order to control the poten-tial dioxin emission from incinerators, in 2002, TEPA started limiting the use of plastic bags and some plastic products (the Restrictions on the Use of Plastics Bags project).

In 2004, the Review and Prospect of Solid Waste Treat-ment project set the ultimate goal of the MSW management system as promoting a “zero-waste society,” highlighting the importance of waste reduction. Hence, the municipali-ties have to promote environmental education to facilitate the current consumption pattern and to encourage reuse along with the other recycling activities, i.e., to change peo-ple’s lifestyle. Also, in 2004 TEPA imposed stricter classifi -cation standards (the Mandatory Recycling of MSW project) for MSW collection in Taipei city and extended this regula-

0%

20%

40%

60%

80%

100%

1990 1992 1994 1996 1998 2000 2002 2004 2006

Others

Dumping

General landfilling

Sanitarylandfilling

Incineration

The

sha

re o

f th

e M

SW

trea

ted

by

inte

rmed

iate

trea

tmen

t and

fin

al d

ispo

sal

faci

liti

es (

%)

Fig. 4. The share of discarded MSW handled by intermediate treatment and fi nal disposal facilities: 1990–2006

114

tion to major metropolitan areas in 2005; food waste and potential resources in MSW had to be collected separately from the MSW discards. Moreover, waste food oil was des-ignated a recyclable material from the end of 2007.

Tables 4 and 5 summarize the important regulations and administrative projects pertaining to MSW management in Taiwan. Moreover, frontier regulations and projects are being launched. Mainly, MSW policy measures are designed to improve 3R activities, especially recycling, by designating several kinds of mandatory recyclable materials. The municipalities are responsible for the recycling activities.

Such efforts can be revealed through the increasing trend of the recycling rate, which denotes the proportion of overall recycled MSW within the total MSW generated (see Fig. 5). The command and control type of policy measures seem to work well, and the annual per capita MSW genera-tion has continued to fall (see Fig. 3).

The national environmental plan14 has set up several target values for MSW management (see Table 6). In order to achieve the ultimate goal of developing a “zero-waste society,” promoting the recycling rate of potential resources and reducing excess utilization of plastics are the short-term

Table 4. Major regulations relating to MSW management in Taiwan11,17

Law Supplemental regulation Effective date Brief description

Waste Clean-up Act

26/07/1974 The fi rst law for solid waste management in Taiwan.Gives a fundamental defi nition of solid waste and its categories.Clarifi es the obligations and responsibilities of waste management

affairsCharge of clean-up and

treatment charge for MSW31/07/1991 Orders the charge for MSW treatment to citizens on the basis of

the polluter pays principleRecycle, clean-up, and

treatment of MSW23/04/1997 Orders the classifi cation, collection, treatment technology, and

treatment facilities for waste recycling issuesRecycling general waste

items by implementation agency

17/04/2006 Designates potential resource items that should be collected by the local government

Management criteria for public landfi ll facilities

01/01/2007 Orders combustible MSW not be dumped in landfi ll sites until it has been incinerated

Environmental Fundamental Law

11/12/2002 Provides a fundamental law for sustainable development.Promotes green consumption, recycling, reuse, life-cycle analysis

of products, and clean production in waste management systemsResource Reuse

and Recycling Act

03/07/2002 Provides the defi nitions of recycling items and fundamental principles.

Clarifi es the obligation and responsibilities of the recycling of goods

Restrictions of product overpackaging

01/07/2006 Restricts the size and weight of specifi c commodities including: cookies, cosmetics, wine, drinks, refi ned foods, packaged goods, and present boxes among others

Table 5. Major administrative measures relating to MSW management in Taiwan11,17

Project Duration Brief description

Keeping trash off the ground

1995 to date (fi rst offi cially adopted by local municipalities)

Stops the use of cargo for fi xed point waste collection; instead, the households have to directly dump their waste in the collection truck.

Bans temporary dumping at the collection sitesResource recycling

four-in-one project01/1997 to date Builds an integrated recycling network among citizens (community), private

recycle companies (the recycling industry), local government, and the recycling foundation.

Improves the business value of reuse, recycling, and treatmentRestrictions on the use

of plastics bags01/07/2002 to date Imposes restrictions on the utilization of packaging and tableware that are

composed of Styrofoam and plasticsReview and prospect

of solid waste treatment

12/2004 to date Examines the previous solid waste generation trends and treatment capacity.Proposes the “zero-disposal society” as the fi nal goal of the solid waste

policyMandatory recycling

of MSW01/2005 to date Orders that households have to make a strict classifi cation of waste before

collection by the local government.Categorizes items that can be sorted, including the following:

(a) Combustible general waste(b) Food waste(c) Waste of potential resources(d) Furniture and waste of large size

Recycling of general plastic bags

05/2006 to date Recycles plastic bags with the MSW collection system in 14 major counties

Recycling of waste food oil

09/2007 to date Includes “waste food oil” as one item on the mandatory recycle substance list for specifi c food and service companies.

Encourages households to collect waste oil that is used in making food and uses it as a raw material in the biofuel production industry

115

objective, as shown in Tables 4–6. In the following section, a short-term projection of MSW discard levels will be con-ducted to assess the evolution of future changes on the basis of the targets of the national environmental plan.

Short-term projection of MSW discard levels and policy implication

MSW discard estimation model system

In order to estimate MSW discard levels on a national scale by waste fraction, the authors have proposed the MSW discard estimation model system (called the estimation model system) in previous works.18,19 In this study, for the purpose of projecting future MSW discard levels, the con-sumption forecasting model composed of a macroecono-metric model is newly established in support of the

estimation model system, and the short-term projection of the annual per capita MSW discards for Taiwan is con-ducted based on three future scenarios.

The projection model system is made up of the consumer behavior model (layers 2 and 3), the MSW discard model (layer 4), and the newly established consumption forecast-ing model (layer 1) (see Fig. 6). In this section, the con-sumption forecasting model and short-term future scenarios are described after the explanation of the consumer behav-ior model and MSW discard model in the estimation model system.

The consumer behavior model

The estimation model system is constructed by assuming that MSW discard levels are primarily infl uenced by the individual’s consumption as well as governmental policy measures.19 Hence, the estimation model system simulates MSW discard by waste fraction based on the consumption expenditure and MSW policy interventions.

The estimation model system is constructed by using econometric modeling approaches,20–22 including the linear expenditure system (LES) model in layer 2, the multinomial logit (MNL) model in layer 3, and the multiequation regres-sion model in layer 4 [the simultaneous equation system (SES) model).

First, per capita consumption expenditure is used as the input of the consumer behavior model and is hierarchically analyzed by the LES model and the MNL model with regard to the categories and subcategories of the consumption expenditure. The LES model is used in the development of the fi rst layer of the consumer behavior model to analyze the consumer’s preference among the categories of consump-tion expenditure. In the LES model, each equation is devel-oped to present the behavior of the distribution of the consumption expenditure for one category. The equations make up an equation system and are solved simultaneously. The overall per capita consumption expenditure and the socioeconomic indices refl ecting changes in lifestyle play the role of the exogenous variables. Here, the exogenous vari-ables are those determined outside the equation system in the econometric modeling. On the other hand, the consump-tion expenditures for the categories are determined within the equation system and are called endogenous variables.

0

10

20

30

40

50

60

1990 1992 1994 1996 1998 2000 2002 2004 2006

Rec

ycli

ng r

ate

(%)

National target value in 2006

National target value in 2001

National target value in 1996

National target value in 2011

Fig. 5. Historical trend of the recycling rate in Taiwan: 1990–2006

Table 6. The short-term policy targets for MSW management14

Index Target year

1996 2001 2006 2011

MSW Recycling rate (%) 7 25 45 50MSW disposal rate (%) 80 85 90a 90Incineration rate (%) 19.52 70 80a 80a Denotes that the target value was achieved in the scheduled year

Layer 2

Layer 3

Layer 4

...

Food waste

Paper waste

Plasticwaste

Metal waste

…

Consumer’s behavior model II (Multinomial logit model)

ExpenditureCategories

ExpenditureSubcategories

Consumer’s behavior model I (Linear expenditure system)

MSW discard model (Simultaneous equation system)

Consumption forecasting model (Single-equation regression)

Macro-economic indicators

Individual’s consumption expenditure

Layer 1

Socioeconomic indicators

MSW policy variables

HousingClothingFood

Fig. 6. Flow diagram of the model estimation system of MSW discards

116

In the LES model, an individual spends to maximize his/her utility with his/her budget constraint. In addition, the LES model assumes that a consumer’s demand is divided into the subsistence level and the nonsubsistence level (requirement exceeding basic needs), which implies that the consumers will choose what they desire to have after deduct-ing the minimum subsistence value from their consumption expenditure. Thus the consumer’s behavior is depicted in detail. Furthermore, this study assumes that the minimum subsistence level under each category is infl uenced by socio-economic variables in terms of changes in lifestyle. In this study, the LES model can be formulated as:

c c PCons ci t i t i t j tj

, , ,= ′ + − ′⎛⎝⎜

⎞⎠⎟∑α (1)

and

c b b vi t i ik k tk

, ,′ = + ∑ (2)

where ci,t is the amount of annual per capita consumption expenditure for the ith category in year t, including food, clothing, housing, household appliance, medicines and medical care, transportation and communication, amuse-ment and education, and miscellaneous items; ci,t′ or cj,t′ is the subsistence (or minimum required) amount of con-sumption of the ith or jth category in year t; αi is interpreted as the marginal budget share of each expenditure category with the constraint αi

i

=∑ 1; PConst is the amount of overall

annual per capita consumption expenditure in year t; vk,t denotes the socioeconomic variable related to the changes in lifestyle in year t; and bi and bik are parameters.

The ratio of older people in the population (Hov65rt) and the saving rate (Savingt) are used as the explanatory variables in the case study for Taiwan in the LES model. The parameters were estimated during the period from 1984 to 2003, and the LES model was validated for the period from 2004 to 2005.

The values of marginal budget share of the consumption expenditure categories depict a detailed structure of con-sumer preferences that result from the contemporary life-style. The categories of housing, medical and health services, and amusement and education have large values of mar-ginal budget share, implying that the categories make up the higher priorities in the distribution of the nonsubsis-tence level for the individual’s consumption expenditure during the period.

Subsequently, the outcomes of the LES model are used as the input of the next model. At this stage, a general type of discrete choice–experiment model, the MNL model, is applied to simulate the distribution of an individual’s expen-diture under one category into its subcategories, and is for-mulated as follows:

probc

cij tij t

ij tj

tT

ij

tT

ijj

ψ ,,

,

exp

exp( ) = = ( )

( )∑ ∑v

vb

b (3)

where prob(yij,t) denotes the probability for spending con-sumption expenditure on the jth subcategory in the ith cat-egory in year t; j is the label of subcategories of consumption

expenditure; vt denotes the column vectors of the explana-tory variables that refl ect the socioeconomic situation, e.g., the household attributes and the socioeconomic indices; and bij is the column vector of the parameters.

Hov65rt and Savingt are used as the explanatory variables in the case study for Taiwan in the MNL model. The para-meters were estimated for the period from 1984 to 2003, and the models were validated for the period from 2004 to 2005. Therefore, consumer behavior for the subcategories of the consumption expenditure could be obtained.

The MSW discard model

Previous modules have established the quantitative rela-tionship between the consumption expenditure and socio-economic variables hierarchically. Thus, the estimated consumption items serve as the input of the MSW discard model.18 The MSW discard model is constructed by using the SES model approach. Per capita MSW discard by waste fraction is assumed to be a linear function of the consump-tion variables and MSW policy variables. The equations for MSW fractions are formulated as follows:

WE s zm t m l tT

l k tT

k, , ,= + +a d z (4)

where WEm,t is the set of the levels of MSW discards for fraction m in year t; sl,t is the column vector for consumption variables composed of an individual’s consumption expen-diture by category and subcategory in year t; zk,t is the column vector of policy variables, including dummy or con-tinuous variables; and am, dl, and zk are the column vectors of the parameters.

The parameters were estimated for the period from 1992 to 2004, and the model was validated for the period from 2005 to 2006. Table 7 provides a description of the variables in the MSW discard model. The model fi tting results and the model validation are evaluated by the overall per capita MSW discard for all waste fractions. The results indicate that the MSW discard model quantitatively defi nes the relation-ship among MSW discards by waste fraction, consumption variables, and the relevant MSW policy variables. The MSW discard model also estimates the impacts of these factors on the respective MSW discard level. Detailed descriptions regarding the fi tting process of the consumer behavior model as well as the MSW discard model in the Taiwanese case study are given in earlier published studies.18,19

The consumption forecasting model

In order to estimate future MSW discard levels, the con-sumption forecasting model is introduced to the projection system in this study and serves as the fi rst-layer model for the estimation model system (see Fig. 6). Considering econometric modeling approaches, the forecasting model is composed of a single-equation regression model. Initially, annual per capita consumption expenditure is estimated by using macroeconomic variables and the variables related to the changes in lifestyle within the consumption forecasting

117

model. Per capita consumption expenditure is assumed to be a function of the macroeconomic and socioeconomic indices:

PCons x v PCons,t t t tf= ( )−, 1 (5)

where PConst is the vector of annual per capita consump-tion expenditure in year t, in 104 Taiwan dollar (NT$) at 2001 prices; PConst−1 is the one-year lag term of PConst; f (·) is the consumption function; and xt and vt denote the vectors of macroeconomic variables and socioeconomic variables in year t, respectively.

This study assumes a linear relationship between per capita consumption expenditure and the explanatory vari-ables. The parameters were estimated for the period from 1984 to 2003 and the model was validated for the period from 2004 to 2005. Equation 6 presents the model fi tting results using the ordinary least-squares method (the value in the parenthesis denotes the t statistics):

PCons PGDP PConst t t= × + ×

−−

0 209 0 550

0 1874 57 4 74

1

2 35

. .

.( . ) ( . )

-

( . )××

= = =−

−

Unempt

R21984 2003

2004 2005

0 996 1 42 1 56. , . , . %,DW MAPE

MAPE == 2 09. %

(6)

where Unempt is the unemployed rate (%) and PGDPt is the per capita gross domestic product (104 NT$ at 2001 prices); DW is the Durbin-Watson statistic; MAPE is the mean absolute percent error.

The results of the consumption forecast model indicate that the current consumption is infl uenced by the current income level, the past consumption level (representing the individual’s consumption habit), and the current socioeco-nomic situation. The implication is that consumer behavior

in Taiwan is consistent with the “permanent income hypoth-esis” proposed by Friedman.23,24

Consequently, by coupling the four models, the inte-grated model system can serve as a forecasting tool. Since the consumption variables can be estimated within the esti-mation model system, for the overall estimation model system, the socioeconomic indices and the MSW policy measures serve as the exogenous variables, i.e., they are wholly determined by outside systems.

Thus a projection of MSW discard levels can be achieved with projections of the exogenous variables. Even, the pro-jections of the exogenous variables can be estimated by other models, or assumed by the policy target values. Table 8 describes the exogenous variables used in the estimated model system for Taiwan.

Scenario analysis

For the future projection of MSW discard levels by waste fraction, three scenarios are assumed for the period from 2006 to 2011, which coincides with the 100th year of the Republic Era. The scenario analysis aims to evaluate the effectiveness of the current national environment plan, which is scheduled up to 2011.

The fraction of older people in the population is forecast by a domestic report showing an increasing trend.25 The setting of the MSW policy variables will follow the target values of the national environmental plan as presented in Table 9. Other parameters are assumed as described below.

In scenario A, the business as usual scenario, per capita GDP is assumed to increase by 5% annually; the saving rate is kept at the same level as that for 2005, 21.63%; the unem-

Table 7. Descriptions of variables used in the development of the MSW discard model

Variable Description Unit

WEi,t

WEm,t

Annual per capita MSW discards by eight categories in year t.m = paper, plastics, food, moisture, miscellaneous combustible items

(abbreviated as “mis-c”), metal, glass, and miscellaneous incombustible items (abbreviated as “mis-inc”)

kg

PConst Annual per capita consumption expenditure in year t Taiwan dollars (NT$) at 2001 pricesFdt, AEt Annual per capita consumption expenditure on food and amusement and

education, respectively, in year tNT$ at 2001 prices

FAEt The summation of Fdt (food) and AEt (amusement and education) in year t NT$ at 2001 pricesFdj,t Annual per capita consumption expenditure on subcategory j, food, in year t NT$ at 2001 pricesHAj,t Annual per capita consumption expenditure on subcategory j, household

appliances, in year tNT$ at 2001 prices

MISt The summation of Fd4,t (miscellaneous food commodities), Fd6,t (beverages), HA1,t (furniture), and HA3,t (household durable equipment) in year t

NT$ at 2001 prices

Dum1 Dummy variable for the Resource Recycling Four-in-One Project: before 1997, the value is zero, and is 1 otherwise

none

Dum2 Dummy variable for the Restrictions on the Use of Plastics Bags: before 2001, the value is zero, and is 1 otherwise

none

Dum3 Dummy variable for the Mandatory Household Classifi cation and Food Waste Recycling imposed in Taipei city: before 2003, the value is zero, and is 1 otherwise

none

Incit The fraction of MSW discards treated by incinerators in year t, a continuous variable

%

Recyt The recycled fraction of MSW generation in year t, a continuous variable %

Considering that policy measures are often launched 1 year earlier for some example areas, the setting of validating dummy variables are 1 year before the formal year of introduction

118

ployed rate is assumed to be at a moderate level of 4%; the fraction of older people in the population is set based on a national report;25 the MSW policy variables are set accord-ing to the national environmental plan, except that the incineration rate is kept at the same level as that for 2006, 82.76%.14

In scenario B, the low consumption scenario, per capita GDP is assumed to increase by 3% annually (based on the lower level of historical trends); the saving rate is assumed to be at a higher level than that of 2005 at 24%; the unem-ployed rate is assumed at a higher level of 5% (compared with the historical trend); the fraction of older people in the population is set based on the national report;25 and the MSW policy variables are set according to the national environmental plan, except that the incineration rate is kept at the same level as that for 2006, 82.76%.14

In scenario C, the high consumption scenario, per capita GDP is assumed to increase by 7% annually (based on a higher level than the historical trend); the saving rate is assumed to be at a lower level than that of 2005 at 21%; the unemployed rate is assumed at a low level of 2.5% (com-pared with the historical record); the fraction of older people in the population is set based on the national report;25 and the MSW policy variables are set according to the national environmental plan, except that the incineration rate is kept at the same level as that for 2006, 82.76%.14

Based on the assumed scenarios, the estimation model system yields sequential outputs: (1) per capita consump-tion expenditure; (2) the distribution of per capita con-

Table 8. Descriptions of the exogenous variables for the estimation model system of MSW discards in the Taiwanese case study

Indices Description Unit

Socioeconomic variables PGDPt Per capita gross domestic product NT$ at 2001 prices Unempt The unemployment rate in the labor force in year t % Hov65rt The proportion of older people (over 65 years) in the overall population % Savingt The saving rate with regard to disposable expenditure in year t %MSW policy variables Dum1 Dummy variable for the Resource Recycling Four-in-One Project: before 1997, the value

is zero, and is 1 otherwisenone

Dum2 Dummy variable for the Restrictions on the Use of Plastics Bags: before 2001, the value is zero, and is 1 otherwise

none

Dum3 Dummy variable for the Mandatory Household Classifi cation and Food Waste Recycling imposed in Taipei city: before 2003, the value is zero, and is 1 otherwise

none

Incit The fraction of MSW discard treated by incinerators in year t, a continuous variable % Recyt The recycled fraction of MSW generation in year t, a continuous variable %

0

10

20

30

40

1984 1987 1990 1993 1996 1999 2002 2005 2008 2011

Scenario A

Scenario B

Scenario C

True value

Model fitting

Ann

ual p

er c

apit

a co

nsum

ptio

n ex

pend

itur

e (1

04 NT

$ at

200

1 pr

ices

)

Fig. 7. Projection of annual per capita consumption expenditure. Sce-nario A, business as usual; scenario B, low consumption; scenario C, high consumption

Table 9. Conditions in the future scenarios

Exogenous variable Scenario

A B C

Consumption level BAU low highGrowth rate of per capita GDP (%/year) 4 2 5Saving, rate, Savingt (%) 21.63 25 20Unempolyed rate, Unempt (%) 4 5 2Elder population rate, Hov65rt (%) The values are 9.95, 10.15, 10.35, 10.53, 10.60, 10.72 for the period from

2006 to 2011, respectivelyRecycled portion, Recyt (%) At a constant increasing rate from 34.97 (actual value) in 2006 to 50

(target value) in 2011Incineration rate, Incit (%) 82.76Dum1, Dum2, and Dum3 The policy measures are activated in the three scenarios.

sumption expenditure among the categories and the subcategories; and (3) per capita MSW discard by waste fraction. The forecasting was performed with the statistical software TSP 5.0.

Figure 7 shows the projection of per capita consumption expenditure under the three scenarios by the consumption forecasting model. The distribution of per capita consump-tion expenditure for the detailed categories and subcatego-ries are forecast by the consumer behavior model based on the assumptions of the scenarios. As examples, Figs. 8 and 9 demonstrate the projections of per capita consumption

119

0

2

4

6

8

10

1984 1987 1990 1993 1996 1999 2002 2005 2008 2011

Scenario A

Scenario B

Scenario C

True value

Model fitting

Ann

ual p

er c

apit

a fo

od e

xpen

ditu

re

(104

NT

$ at

200

1 pr

ices

)

Fig. 8. Projection of annual per capita food expenditure

0

0.5

1

1.5

2

2.5

1984 1987 1990 1993 1996 1999 2002 2005

Cereals & meat -S

Cereals & meat

Milk-S

Milk

Vegetables-S

Vegetables

Miscellaneous food commodity -S

Miscellaneous food commodity

Food out from home-S

Food out from home

Beverages-S

Beverages

Tobacco and betel nut-S

Tobacco and betel nut

0

0.5

1

1.5

2

2.5

3

3.5

4

2006 2007 2008 2009 2010 2011

Cereals & Meat Scenario ACereals & Meat Scenario BCereals & Meat Scenario CMilk Scenario AMilk Scenario BMilk Scenario CVegetables Scenario AVegetables Scenario BVegetables Scenario CMiscellaneous food commodity Scenario AMiscellaneous food commodity Scenario BMiscellaneous food commodity Scenario CFood out from home Scenario AFood out from home Scenario BFood out from home Scenario CBeverages Scenario ABeverages Scenario BBeverages Scenario CTobacco and betel nut Scenario ATobacco and betel nut Scenario BTobacco and betel nut Scenario C

Ann

ual p

er c

apit

a fo

od e

xpen

ditu

re b

y su

bcat

egor

y (1

04N

T$

at 2

001

pric

es)

(a) Model fitting

(b) Future projection

ili

Fig. 9. Projections of annual per capita food expenditure by subcategory: a model fi tting (the subcategory’s name with appended S denotes the model fi tting value) and b future projection

expenditure on food and its subcategories. Next, the projec-tions of MSW discard levels for MSW fractions are esti-mated under the three scenarios (see Fig. 10) and depict the possible evolution of MSW discard levels infl uenced by the effects of the consumption factors and those of MSW policy measures. In addition, the projection of annual per capita MSW discard levels can be obtained by adding the projec-tions of discard levels of the respective MSW fractions (see Fig. 11).

Discussion and policy implication

From Fig. 7 to Fig. 11, the model fi tting results for the period 1984 (or 1985 in Fig. 7) to 2005 (or 2004 in Figs. 10 and 11) are good approximations, implying that the estima-tion model system has been successfully. The sequential projections show that the different increasing or decreasing trends of MSW fractions are caused by changes in the eco-nomic and social conditions. In Fig. 7, all the projections of per capita consumption expenditure for the three scenarios are increasing since the economy continues improving at different speeds in the assumed scenarios. In Figs. 8 and. 9, different socioeconomic variables in the assumed scenarios, refl ecting the infl uences of lifestyle changes on consumer behavior, lead to different distributions of consumer expen-

diture among the categories and subcategories. The differ-ent levels of consumption give rise to the corresponding projections in the MSW discard level by waste fraction, given the assumed MSW policy variables.

The evolution in terms of MSW discards by waste frac-tion is caused by a trade-off between the effects of the consumption factors and those of the MSW policy mea-sures. Therefore the discard levels of MSW fractions are all the highest in the high consumption scenario (Scenario C), intermediate in the business as usual scenario (Scenario A),

120

0

20

40

60

80

100

1992 1995 1998 2001 2004 2007 2010

0

20

40

60

80

100

1992 1995 1998 2001 2004 2007 2010

0

20

40

60

80

100

1992 1995 1998 2001 2004 2007 2010

0

50

100

150

200

250

300

350

1992 1995 1998 2001 2004 2007 2010

0

5

10

15

20

25

1992 1995 1998 2001 2004 2007 2010

0

5

10

15

20

25

1992 1995 1998 2001 2004 2007 2010

0

10

20

30

40

50

1992 1995 1998 2001 2004 2007 2010

0

2

4

6

8

10

12

1992 1995 1998 2001 2004 2007 2010

etsaw scitsalP )b( etsaw repaP )a(

(c) Food waste (d) Moisture of waste

(e) Metal waste

(h) Miscellaneous incombustibles (g) Miscellaneous combustibles

(f) Glass waste

Fig. 10. Projections of annual per capita MSW discards by waste fraction. Except for part d, the y-axis denotes annual per capita MSW discards (dry-based kg/capita/year). For part d, the y-axis indicates the water contained in MSW discards (kg/capita/year)

121

0

100

200

300

400

500

600

700

1992 1995 1998 2001 2004 2007 2010

Scenario A

Scenario B

Scenario C

True value

Model fitting

Ann

ual p

er c

apit

a M

SW

em

issi

on (

kg)

Fig. 11. Projections of annual per capita MSW discard

and the lowest in the low consumption scenario (Scenario B), since the effects of MSW policy measures are assumed to be the same for each scenario.

In Fig. 10, the future trends of the MSW discard levels can be classifi ed into four types. Based on the assumed socioeconomic changes and the policy variables in the scenarios, plastic waste, metal waste, and glass waste are seen to increase monotonously to a certain extent (see Fig. 10 b,e,f), implying that the effects of consumption factors prevail over those of the policy measures during 2006–2011. Therefore, more enhanced policy measures should be taken for these three waste fractions. In particular, these three fractions have decreasing trends during 2001 to 2004, in which the effects of policy triumph over the consumption factors. As for plastic waste, the Restriction on the Use of Plastic Bags measure (Dum2) has a signifi cant impact on reducing the amount discarded, but since 2004, the effects of consumption factors appear to triumph over that of Dum2. Hence, strict regulations in terms of reducing the discard of plastic waste, e.g., a ban on using plastic packag-ing, should be carried out (actually, it was implemented in July 2006; however, more updated quantitative data is required to identify its effectiveness), or, alternatively, some green consumption activities on reducing the excess con-sumption in terms of plastic waste can be advocated and promoted. The projections of the discard levels of metal waste and glass waste will rise as well in the near future due to the prevailing effects of the consumption factors. Current recycling policy measures for these two materials should be enhanced so as to improve the policy effectiveness on reducing the two waste fractions.

The discards of food waste and the moisture content of waste appears to undergo slight increases during 2006–2011 (see Fig. 10c,d). For food waste, the effect of the Mandatory Household Classifi cation and Food Waste Recycling (Dum3) may be anticipated; however, the increasing projections of the discard levels of food waste suggest that additional policy measures are still needed. It should be noted that the ratio of expenditure on “food out from house,” i.e., eating out, to the total food expenditure will rise signifi cantly due to lifestyle changes. Since the food waste in Fig. 10c includes the waste from the commercial food sector, e.g., restau-

rants, the signifi cantly increasing consumption from those eating out makes restaurants a potentially large source of discarded food waste. Some countermeasures can be pro-posed on the commercial food sector. As for the moisture content of waste, its future trend appears to continue down-ward because of the signifi cantly prevailing MSW policy effect. In addition, new strict regulations implemented after 2006, such as the revised Management Criteria for Public Landfi ll Facilities and Recycling of Waste Food Oil (as shown in Tables 4 and 5), may reduce the discards of food waste and the moisture content to a higher extent. Thus, the projections of the discard levels of these two fractions may be overestimated; nevertheless, the effectiveness of the new regulations cannot be identifi ed until the latest information has been provided.

Owing to the rapidly increasing recycling rate expected in the scenarios, the discard level of paper waste is set to diminished signifi cantly (see Fig. 10a). It can be expected that a large amount of paper waste is to be recycled for further reuse.

The last type is the behavior of the miscellaneous items of combustibles and incombustibles. In Fig. 10g,h, the pro-jections of the two fractions show that the discard levels are expected to stay roughly the same, implying that the infl u-ences of the consumption factors and the MSW policy mea-sures appear to be balanced during the period.

Up to the present time, TEPA has made much effort to establish a public recycling system. However, the next national MSW plan should focus on promoting new policy measures associated with the reduce and reuse aspects of the 3R principle, if consumption continues to increase. Pos-sibilities include improving the citizens’ environmental con-sciousness by means of comprehensive social education activities, proposing policy measures with economic incen-tives for “green buy” activities, or imposing environmental taxes on the commodities that may result in high environ-mental loads. Since the majority of developing countries prioritize economic development, resulting in increased consumption, a more sustainable consumption pattern with a smaller environmental load is crucial for the process of economic development.

On the other hand, the effectiveness of the current MSW policy measures should be continually improved by raising the administrative budget of MSW policy measures; increas-ing the manpower of the civil servants who are in charge of MSW affairs; or promoting regional cooperation for the MSW collection, treatment, and recycling system. Mean-while, more standard landfi ll sites for the fl y ash and bottom ash from the incinerators should be established, since incin-eration remains the main intermediate process technology. Besides, from Fig. 10d, the heat value of the MSW is expected to increase since the moisture content of waste is set to be at a lower level before 2011. Hence, two ways of resource recovery should be considered and enhanced for incineration in the near future: reprocessing the MSW into refuse-derived fuel (RDF) and recovering energy from the incineration process.

In addition, since higher recycling rates are expected in the future, more recyclable waste will be collected. Thus an

122

economically effi cient market for the recycled materials and a cost-effi cient reproduction industry, which uses the recy-cled resources as the raw materials in the production process, are required. The economic instrument type of policy measure, such as subsidy and tax exemption, would be effi cient in developing the recycling market and repro-duction industry.

Conclusion

Focusing on the recycling of waste, this article presents a history of MSW discard levels and MSW management in Taiwan. Moreover, a methodology was established to project MSW discard levels by waste fraction through an estimation model system based on consumption expendi-ture and MSW policy measures. Under three possible future scenarios, the amount of MSW discarded until 2011 was forecasted and discussed. It has been acknowledged that consumer behavior, infl uenced by changes in lifestyle, is an important driving factor of environmental loads, particu-larly for MSW discard levels. After a period of rapid eco-nomic development, Taiwan has successfully reduced MSW discard levels by imposing policy measures. Such progress can be viewed as a typical process in the development of a civilization. The experiences gained in promoting MSW management in Taiwan may provide helpful information to current developing countries. However, in order to achieve the ultimate goal of promoting a “zero-waste society,” a more sustainable consumption pattern and more effective MSW policy measures should be addressed.

To help achieve this goal, the authors developed a con-sumption forecasting model in support of a previously established estimation model system so as to analyze and simulate consumer behavior in a detailed way. Thus, the extended estimation model system can provide reliable sequential projections for per capita consumption expendi-ture, the distribution of per capita consumption expenditure among the categories and the subcategories, and MSW discard levels for different waste fractions through scenario analysis. Hence, the effects of current MSW policy mea-sures on MSW discard levels can be examined, and concrete modifi cations are proposed to facilitate current policy mea-sures and account for the possible changes in lifestyle and consumption factors.

To conclude, the authors hope that the review of the development of MSW management in Taiwan and the out-comes from the presented methodology will contribute to policy design and help us move forward to a low-waste-discard society.

Acknowledgment This research was supported by the Global Envi-ronment Research Fund of the Ministry of Environment, Japan (BC-088).

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