Upload
vo-dang-tinh
View
224
Download
3
Embed Size (px)
Citation preview
A REVERSE LOGISTICS COST MINIMIZATION MODEL FOR THE TREATMENT OF WEEEDoan Thi Truc Linh 1, Nguyen Thi Le Thuy2, Tran Thi My Dung3
Department of Industrial Management, Can Tho University, Viet Nam
ABSTRACT: Attention with Waste Electrical and Electronic Equipment (WEEE) has become increased during last
decade since accelerating technological changes and market expansion of EEE products. In order to prevent
negative effects of WEEE on the environment, humans, and the valuable materials that can be reused in them, the
WEEE need to be handled, disposed, reused, recycled, remanufactured or treated properly. Based on the analysis of
the WEEE reverse logistic network and the characteristics of its planning, this paper presents a recycling network
which has a cost minimization model for multi-products reverse logistic system. The factors considered in the
proposed model include the cost of collection, treatment, sales income as well as transportation cost with different
fractions of returned products. Especially, the proposed model is solved by an algebraic modeling package AMPL
(A Mathematical Programming Language). The proposed optimization model can help determine the optimal
facilities and the material flows in the network. In addition, Radio Frequency Identification (RFID) technology is
suggested to manage the information of returned products at collection points that can help managers increase
efficiency of logistic operations in collection facilities
Keywords: Recycling, Reverse Logistics, WEEE, RFID.
1. Introduction
According to Environmental Protection Agency
(EPA), there are 20 to 50 million metric tons of
WEEE generating worldwide every year, comprising
more than 5% of all municipal solid waste.
Developing countries are estimated to triple their
output of WEEE by 2010. In the US alone, some 14
to 20 million PCs are thrown out every year. In
Western Europe, 6 million tons of WEEE (waste of
electrical and electronic equipment) were generated
in 1998 and the amount of WEEE is expected to
increase by at least 3-5% per annum. By 2010, the
European Union will be producing around 12 million
tons of electrical and electronic waste annually. It
was estimated that about 1.6 million obsolete EEE
were generated in 2003 in China with TV accounting
for nearly half of the total [Liu et al. (2006)].
WEEE is a non-homogeneous and complex in terms
of materials and components. Many of the materials
are highly toxic (Dimitrakakis et al., 2009; Hicks et
al, 2005), as well as WEEE has high residual value.
In view of the negative effects of WEEE on the
environment, humans, and the valuable materials that
can be reused in them, legislations in many countries
have focused their attention on the management of
WEEE, and new techniques have been developed for
the recovery of WEEE. In particular, the European
Union (EU) adopted the 2002/96/EC and 2002/95/EC
(Restriction of Hazardous Substances- RoHS
directive), which causes essential changes in the field
of electronic scrap recycling. Producers are requested
to finance the collection, treatment, recovery, and
environmentally sound disposal of WEEE. The
directive imposes a high recycling rate for all targeted
products. The directive imposes a high recycling rate
of all targeted WEEE products. Reuse, recycling and
recovery rates ranging from 50% to 80% according to
the category of equipment considered, must be
achieved by producers of EEE [He et al, 2006].
The recycling of WEEE is an important step of the
end-of-life strategies for WEEE treatment. Although
there is an increasing amount of research on material
recycling models and specific products (Krikke,
1998; Barros and Scholten, 1998; Ammons and
Realff, 1999; Newton, 2000; Nunes et al., 2009;
Reynaldo, 2009), as well as reverse logistics
networks (Mutha, 2009; Reynaldo, 2009; Kannan,
2010), studies specifically addressing WEEE
problems (Assavapokee, 2004; Deepali, 2005;
Rahimifard, 2009; Grunow, 2009; Geraldo, 2010;
Achillas, 2010; Jang and Kim, 2010; Silveria and
Chang, 2010) are rare and still limited to some
specific areas of WEEE reverse logistics.In view of
lack of in-depth with respect to WEEE reverse
logistics operations in the literatures, this paper
presents a recycling network for multi-products
reverse logistic system as well as to analyze the
material and component flows of returned products at
treatment and final stage particularly so that the cost
of the recycling can be achieved effectively. The
factors considered in the proposed model include the
cost of collection, treatment, sales income as well as
transportation cost with different fractions of returned
products. Specially, the proposed model is solved by
an algebraic modeling package AMPL. In addition,
RFID technology is suggested to manage the
information of returned products at collection points
that can help managers increase efficiency of logistic
operations in collection
2. Recycling sequence
Figure1.Flow of returned products in recycling model
Figure 1 shows Flow of returned products in
recycling model. There are four layers of recycling
model from left to right. Each layer has its own
function which can be described as follows:
First Layer (Collection Site): Returned products are
received from collection points such as retailers,
permanent drop-off sites by classified groups. They
are then transported to disassembly site
- Second Layer (Disassembly Site):
This site receives the collected wastes from collection
sites. It has two main functions; the first one is to
separate the recycled product into fractions (different
components and parts). Second, determine whether a
component (or part) is in fact re-usable and in which
way through the inspection activity. The re-usable
component (or part) will be transported to a
secondary market; the rest of the parts will be
transported to an extraction facility for further
treatment. Also, through the separation processing,
some fractions that belong to the same type of
materials could be compressed leading to a smaller
transportation volume. In other words, it can reduce
the recycled product volume which means the
truckload utility increases. The disassembly site can
also collect large quantities of components (parts), to
ensure that transportation vehicles are fully loaded.
-Third Layer (Extraction Facility): An extraction
facility receives the disassembled fractions which
need further treatment from disassembly sites. The
following typical fractions can be extracted and can
be reused or disposed in different ways: ferrous metal
tractions are used in iron smelters; most non-ferrous
metals go to copper smelters, aluminum smelters, and
lead smelters; plastics can become regenerated
material; hazardous materials would be disposed of in
special landfills properly.
- Fourth Layer (Termination Site-reuse/resell or
disposal):
This layer is for the reuse or resell of the
regenerated material and components (parts). For
non-recyclable material and hazardous materials,
they will be disposed of properly.
We summarize the sequences as follows: an
end-of-life product will be sent to an initial collection
site which is the closest point to the customer. After a
period of time, all products from the collection site
will be transported to a disassembly site for
separation. Next, the re-usable components (parts)
would be transported to a secondary market directly,
and the fractions which needed further treatment
would be sent to an extraction site to be processed.
The regenerated materials and hazardous materials
will be extracted from those fractions. Finally, the
regenerated raw materials will be sold to
manufacturers or material suppliers for reuse or
reselling. The non-recyclable wastes and hazardous
materials will be properly disposed of.
It has to be mentioned that the product’s total
transportation cost changes alone with the recycling
process. When a product is sent to disassembly site
and to be disassembled into many different parts, the
total volume of sending those parts to a disposal site
and termination site may change. There are three
kinds of situation and what would happen depends on
the different product types. The first case is the
product volume remains the same, like recycling
books. The second case is the volume decreases, for
example some plastic part could be compressed into a
smaller volume. The third case, when a product is
disassembled the total volume increase due to the
separated parts needing more space to be delivered.
For a Less Than Truckload (LTL) carrier, the
transportation cost that will be charged depends on
the freight’s volume or weight. The unit
transportation cost change is due to the different
product (or component) rate of weight and volume.
The recycling process leads to the total transportation
cost changes. A simple product is used to be a
sample to illustrate the variation of the transportation
cost more clearly. Figure 2 is a disassembly tree of
product , and the transportation cost related with
each component
.
Figure 2. Disassembly tree of product
Product is being transported from collection
sites to disassembly sites; the unit transportation cost
is 40 dollars. At the disassembly site, product
will be disassembled into four parts (component ,
component , sub-assembly , disposable item
). For component , it is a shell of product ,
the volume is equal to the original volume, although
the weight is less than product , it is still be
charged by the volume, which is 40 dollars. In the
case of component , sub-assembly , disposable
item , they are all charged by weight. And sub-
assembly will be transported to extraction sites
for further treatment, after which extraction process
material and hazardous material are generated.
The transportation cost of these two types of material
is also charged by weight.
3. Recycling system network model
Based on the recycled goods processing
sequence mentioned in the previous section, a
recycling system network configuration model was
constructed for solving recycling management
problems. A mixed integer programming model is
proposed to create an optimal reverse logistics system
for recycling EOL products
.
Figure 3.Recycling System Network
There are four layers of sites in this recycling
system network: collection site, disassembly site,
extraction facility, and termination site. The arcs
represent the flow of resource waste, sorted waste
and regenerated material, and hence there are arcs
between each adjacent level. In our problem, m kinds
of products are to be transferred from a set of
collection sites to a set of Termination sites (Disposal
site and reuse/resell site) (see figure 3). The objective
is to minimize the total cost as well as the income
from selling the reclaimed materials.
This research addresses the problem of
efficiently transporting multiple types of recycled
products from multiple sources and in the process
satisfying the demand on the recycled items at a
number of destinations. The recycling system
problem can be formulated as follows:
Given:
(a) Locations of each site (collection,
disassembly, extraction, termination).
(b) Capacities of these disassembly sites and
extraction facilities.
(c) Processing efficiency of these extraction
facilities.
(d) Cost structures (transporting, processing,
operating, and disposal costs).
(e) Availability of reusable material for each
reuse/resell site.
Find:
Which facility should be used and how the
recycled goods should be delivered so that the total
cost of the system is minimized.
The mathematical formulation of the model
follows while explanation of the notations is included
in the next section.
3.1 Assumption and Notations
The optimization model of the recycling
network is based on the following assumptions:
1. All recycled products must enter the
recycling system through collection
sites.
2. The recycled product at the collection
site must be recyclable, reusable or
recoverable.
3. The capacities of disassembly and
extraction facilities are limited.
4. The transportation cost is linearly
related to distance.
5. The location of collection sites,
disassembly sites, extraction facilities
and termination sites are fixed
Following notations to formulate the recycling system network problem:
Number of collection sites;
Number of disassembly sites;
Number of extractions sites;
Number of reuse/resell sites;
Number of disposal sites;
Number of product types;
Number of sub-assembly types;
Number of directly reuse parts;
Number of disposable items;
Number of regenerated materials;
Number of non-recyclable materials;
The amount of components or material of type n necessary to produce every unit of product
type m. .
The unit transportation cost. For different product or component types m.
The distance between outgoing site i and incoming site j,
The extracted rate at extraction facility for .
The unit operation cost at site j (disassembly and extraction) for product type (or component)
m. ,
Maximum storage and processing capacity of handling product m at disassembly site j=
for , for .
Maximum storage and processing capacity at extraction facility for
for handling integral sub-assembly m,
Unit cost of dispose of disposable item and non-recyclable material
. For the revenue of directly
reusable components and material fractions per unit,
.
The supply at collection site i for recycled product m.,
0-1 variable, =1 represents reuse/resell site j has the demand for component part m or
=0. ,
.
If site (collection or extraction) can handle product(or sub-assembly) type m, =1;
otherwise =Z;
Note: Z is set to some arbitrarily high value.
Decision variables:
The unit of product(or component) type m is transported from outgoing site i to incoming site j
; i,j ,
3.2 Model Formulation
In this section, we formulate the problem of
minimum cost of the recycling system. The system
which considered transportation cost, capacity and
operating cost of disassembly sites and extraction
facilities, and the demand of the secondary market.
This formulation is based on the single objective of
minimum cost of transporting cost, operating cost,
and disposal cost
.
Total cost = Transportation cost+ operation cost+ disposal cost- revenue of sell reclaimed materials and
components.
(1)
Eq. (1) represents the objective functions. The objective function is constrained by various requirements,
which will be addressed individually. To ensure that all the recycled products leave the collection site, Eq. (2) is
imposed as follows.
for ,
(2)
This means all recycled products collected at the collection site will be processed through the entire recycling
system.
To ensure the flow balance between each site, Eq. (3) to (7) is imposed as follows.
(3)
(4)
(5)
(6)
(7)
Eq. (3), (4), and (5) ensures the incoming flow of recycled products at the disassembly site j multiple is
equal to the outgoing flow from disassembly site to extraction site, reuse/resell site, and disposal site respectively .
Eq. (6), and (7) ensures that the outgoing flow from the extraction facility j is equal to the incoming flow from the
disassembly site i multiple and extraction rate .
To ensure the reuse/resell site has the demand for different components and materials or not, Eq. (8) and (9) is
imposed as follows.
(8)
(9)
=1 represents reuse/resell site j has the demand for component part m or =0.
To ensure the capacity of each site will not be exceeded, Eq. (10) and (11) is imposed as follows.
(10)
(11)
Eq. (10) limits the units sent from collection site i through disassembly site j to the capacity of disassembly
site j. Eq. (11) limits the unit which is sent from disassembly site i to extraction facility j to the capacity of extraction
facility site j.
Eq. (12) deals with non-negative decision variables. Eq. (13) means all types of products, integral sub-
assemblies, directly reusable parts, and directly disposable items are integers.
for all m, i , j. (12)
as an integer. (13)
4. RFID at collection points:
Supply in reverse logistic is typically considered as a
fluctuant factor since the timing, quality, quantity of
returned products may be difficult to control.
Uncertainty is an important characteristic of returned
product so this issue should be additional research
effort. Lee (2009) mention that the information of
returned product was estimated by forecasting and
simulation in the past. However, those methods lack
for accurate and efficient information which leads to
the higher reverse logistic cost. Therefore, RFID
technology is utilized to manage the amount and
quality of returned product that can provide real data
to improve shipment schedule from collection points
to collection facilities of recycling network
The steps of returned products from collection points
to collection facilities are shown in the figure 4.When
returned products from customers are arrived at
collection points such as retailers or permanent drop-
off sites, RFID tags are attached to the items,
containing the information of items such as product
name, the returned address and the status of returned
product. Information on quality and types of returned
items stored at collection point is transmitted to the
database by RFID readers. With the collected data,
recyclers will prepare a collection schedule which
will be stored in database. Then returned products are
put into the cartons with RFID attachment and the
information data on a carton label consists of the type
of items, amount of items and destination
Then, cartons are put in trucks and RFID readers are
installed there to detect and transmit the good
information to database that help managers to know
the quantity of returned to have efficient routing and
supply to collection facility. They keep track of the
inventory level in each collection point as well.
Figure 4. The steps of returned products from collection points to collection facilities
5. Conclusions:
In this paper, the reverse logistic network design
problem for WEEE has built. A mixed integer
programming model has established to minimize the
total costs while operating the reverse logistic
network and used AMPL to get an optimal solution.
The model considers fourth stages such as collection
sites, disassembly sites, extraction sites and
termination Sites
Compare to existing researches on reverse logistic,
this paper has attempted to apply the recycling
network with analyzing detailed treatment and final
stage for multi-type WEEE. Moreover, the
transportation cost of each type is estimated related to
its characteristic as well. Besides, the RFID
technology is suggested to keep track the quantity
and quality of return goods to increase shipment
route efficiently from collection points to collection
facilities.
MÔ HÌNH TỐI ƯU HÓA CHI PHÍ CHUỖI CUNG ỨNG NGƯỢC CHO VIỆC XỬ LÝ
PHÊ PHÂM THIÊT BI ĐIỆN VÀ ĐIỆN TỬ
Đoàn Thị Trúc Linh 1, Nguyễn Thị Lệ Thủy 2, và Trần Thị Mỹ Dung 3
Bộ môn Quản lý Công Nghiệp, Đại học Cần Thơ, Việt Nam.
Tom tăt: Phê phâm thiêt bị điện và điện tử đa và đang đươc đươc quan tâm nhiêu trong thập kỷ qua kể từ khi sư
phat triển công nghệ ngày càng cao và việc mở rộng thị trường của cac sản phâm điện và điện tử. Để ngăn chặn tac
động tiêu cưc của cac loai phê phâm này đối với môi trường, con người, và cac tài nguyên có gia trị mà có thể
đươc sử dụng lai, cac phê phâm này cần phải đươc xử lý, tai sử dụng, tai chê, tai sản xuất hoặc đươc xử lý hơp lý
đung quy định. Dưa trên phân tích tính chất của phê phâm thiêt bị điện, bài bao này trình bày mô hình tai chê với
chi phí tối ưu cho nhiêu sản phâm trong hệ thống chuôi cung ưng ngươc. Những nhân tố đươc xem xét trong mô
hình gồm có chi phí sản xuất, chi phí xử lý, lơi nhuận thu đươc từ việc tai chê, chi phí vận chuyển tùy theo những bộ
phận khac nhau của phê phâm. Đặc biệt, mô hình đê xuất đươc giải bằng một ngôn ngữ lập trình toan học. Mô hình
tối ưu này sẽ xac định số nhà may cần xây dưng và số lương phê phâm từ nhà may này đên nhà may khac trong
chuôi cung ưng ngươc một cach tốt nhất Ngoài ra, công nghệ tần số vô tuyên (RFID) đươc đê nghị để quản lý thông
tin của phê phâm tai cac tram thu gom điêu này có thể giup cac nhà quản lý nâng cao hiệu quả của hoat động hậu
cần.
Từ khoa: tai chê, chuôi cung ưng ngươc, phê phâm thiêt bị điện và điện tử, công nghệ tần số vô tuyên
References
1. Fleishmann, M., M. Jacqueline, M. Bloem-hof-Ruwaard, R.Dekker,E.V.Lann,J.V.Nunen and L.V.Wassenlove, “Quantiative models for reverse logistics: a review,” European Journal of Operational Research, 101, 1-17 (1997)
2. Fleischmann, M., Krikke, H.R., Dekker, R., Flapper, S.D.P., (2000). “A characterization of logistics networks for product recovery”. Omega 28, 653-666.
3. Fleischmann, M., Beullens, P., Bloemhof-Ruwaard, J.M., van Wassenhove, L.N., (2001). “The impact of product recovery on logistics network design” Production and Operations Management 10 (2):156-173.
4. Fleischmann M., (2001). “Quantitative Models for Reverse Logistics” Springer, Berlin, Germany.
5. Liu , Z.F.,X.P.Liu,S.W.Wang and G.F.Liu,” Recycling strategy and a recyclability assessment model base on artificial neutral network,” Journal of Materials Professing Technology, 129, 500-506 (2002)
6. Thierry, M.C,M.Salomon, J.V.Nunen and L.V.Wassehove, “Strategic production and operations management issues in product recovery management,” California management Review, 37, 114-135 (1995)
7. Q.Seng, X.Li, and S.Zeadally, “Enabling Next-Generation RFID Applications: Solutions and Challenges”, IEEE computer, Vol.41,No.9, September 2008.
8. T. Spengler, M. Ploog, and M. Schroter, “Integrated planning of acquisition, disassembly and bulk recycling: A case study on electronic scrap recovery,” OR Spectrum, vol. 25, pp. 413–442, 2003.
9. I-Hsuan Hong, Tiravat Assavapokee, Jane Ammons “ Planning the e-Scrap Reverse Production System Under Uncertainty in the State of Georgia:A Case Study” IEEE Transactions on electronics packaging manufacturing, Vol.29,No 3, 2006.
10. Realff MJ, Ammons JC, Newton D. Carpet recycling: determining the reverse production system design. The Journal of Polymer–Plastics Technology and Engineering 1999;38(3):547–67
11. Lee, C.-H., Chang, S.-L., Wang, K.-M. & Wen, L.-C. (2000) Management of scrap computer recycling in Taiwan. Journal of Hazardous Materials,A73, 209–220
12. Liu, X., Tanaka, M. & Matsui, Y. (2006) Electrical and electronic waste management in China: progress and the barrier to overcome. Waste Management & Research, 24, 92–101
13. Th. Spengler, H. Püchert, T. Penkuhn and O. Rentz (19997)” Environmental integrated production and recycling management” European Journal of Operational Research ,97, 308-326
14. C.K.M Lee, T.M.Chan (2009) “Development of RFID-based reverse logistics system”, Expert Systems with Applications, 9299-9307