Rare earth elements’ waste management for smartphones’ touch screens by system dynamics modelling

Abstract

Developments in smartphones’ technology affect mobile phone use rates in the world. Increasing use of internet in the last 10 years parallelly force people to use smartphones not only in the work but also in their private lives. This high amount of consumption brings together the problem of excessive amount of waste, and also raises environmental concerns about how to treat them in the end-of-life phase of the smartphones. It is known that a classic smartphone, which is composed of battery, electronics, case part and touch screen, can be dissembled and recycled even though less than 20% of smartphones are going through reusing and recycling in the world. One of the problematic parts of the smartphones’ waste management is the touch screen. Rare earth elements used in touch screens are scarce sources, which are mainly silver, gold, palladium, indium, gadolinium, terbium, yttrium and lanthanum, and these elements cannot be easily substituted. In case they are not reused or recycled, they will be lost forever. In this paper, it is aimed to propose a system dynamics model for rare earth elements’ reuse and recycling in smartphones’ touch screens by a closed loop supply chain view. The design of the system dynamics modelling is operated and simulated by Anylogic and Stella simulation softwares which give perspective to observe how to better manage rare earth elements’ closed loop supply chain in order to increase the rate of reuse and recycling by considering important and relative factors of waste management system.

Full text

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Rare earth elements’ waste management for
smartphones’ touch screens by system dynamics
modelling
Aziz Kemal Konyalıoğlu (  konyalioglua@itu.edu.tr )
Istanbul Technical University - Ayazaga Campus: Istanbul Teknik Universitesi https://orcid.org/0000-0002-
2443-5063
Ilke Bereketli
Galatasaray Üniversitesi: Galatasaray Universitesi
Research Article
Keywords: system dynamics, smartphones, rare earth elements, closed loop supply chain, waste
management, simulation
DOI: https://doi.org/10.21203/rs.3.rs-458455/v1
License:   This work is licensed under a Creative Commons Attribution 4.0 International License.  Read
Full License

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Abstract
Developments in smartphones’ technology affect mobile phone use rates in the world. Increasing use of
internet in the last 10 years parallelly force people to use smartphones not only in the work but also in their
private lives. This high amount of consumption brings together the problem of excessive amount of waste,
and also raises environmental concerns about how to treat them in the end-of-life phase of the smartphones.
It is known that a classic smartphone, which is composed of battery, electronics, case part and touch screen,
can be dissembled and recycled even though less than 20% of smartphones are going through reusing and
recycling in the world. One of the problematic parts of the smartphones’ waste management is the touch
screen. Rare earth elements used in touch screens are scarce sources, which are mainly silver, gold,
palladium, indium, gadolinium, terbium, yttrium and lanthanum, and these elements cannot be easily
substituted. In case they are not reused or recycled, they will be lost forever. In this paper, it is aimed to
propose a system dynamics model for rare earth elements’ reuse and recycling in smartphones’ touch
screens by a closed loop supply chain view. The design of the system dynamics modelling is operated and
simulated by Anylogic and Stella simulation softwares which give perspective to observe how to better
manage rare earth elements’ closed loop supply chain in order to increase the rate of reuse and recycling by
considering important and relative factors of waste management system.
Introduction
Development in network and working technologies, together with consumerism make smartphones widely
used all around the world. (Geyer and Blass, 2010). Although a mobile phone lifetime is stated as
approximately 10 years, the average usage period of a typical mobile phone is 3 years and 2 years in
developing countries and in developed countries respectively, which implies that the duration reaching the
end-of-use for smartphones are far shorter than expected (Huang et al., 2009, Soo and Doolan, 2014).
Parallel to that, mobile phone waste has been rising up because of dramatically increasing rate of production
and consumption (Sarath et al., 2015). It is stated that 75% of mobile phone users generally throw their
phones away to the garbage without any waste treatment method, and only less than 20% of smartphones
are reused and recycled yearly (URL1).
Figure 1 shows the waste management process of smartphones. Smartphones include many recyclable
materials, although most of them is not reused or recycled actually. Moreover, a typical mobile phone is
made up of different types of materials including plastics, glass, ceramic, ferrous and non-ferrous metals,
rare and precious elements which are also included in other electronic devices.
It is mostly known that rare elements are crucial for every electronic device, for some parts of the
smartphones, especially their touch screens (Jowitt et al., 2018). In touch screens of smartphones,
palladium, gold, silver, lanthanum, terbium etc. are used (URL2). They are categorized under rare earth
elements and considered as the very important ones compared to other earth elements. Regarding this fact, it
is very problematic that approximately only 1% of rare earth elements are recycled.
In this study, it is aimed to propose and design a closed loop supply chain model by a system dynamics
approach in order to increase the reusing and recycling ratios of rare earth elements in touch screens of

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smartphones considering different rare earth elements, such as Gold, Silver, Yttrium, Lanthanum, Indium,
Terbium and nally Palladium. An ecient and effective waste management system’s behavior of rare earth
elements in smartphones can be observed by the relative factors changes in system dynamics, which is
suitable for modelling. The originality of the study comes from the fact that, although these rare earth
elements in smartphones can be recycled in a proper way and they are becoming a scarce resource, there is
not any study in the literature focusing on that problem and combining the system dynamics approach and
rare earth elements’ waste management in smartphones’ touch screens.
Literature Review
2.1 System Dynamics in Waste Management
In the literature, there are studies applying system dynamics approach in the waste management area, WEEE
and other types waste processing, especially in the last 10 years (Cai et al., 2016). Dhanshyam and
Stivastava (2021) applied system dynamics approach in order to observe the policy eciency of plastic
waste management in India and tried to reach the most effective roadmap for proposing to policymakers.
Another study in solid waste management by a system dynamics approach is illustrated by Lu et al. (2021)
considering the interaction between the generation of municipal solid waste, greenhouse gas emission,
economic and environmental impact and life cycle assessment of these types of waste per capita in China
versus Gross Domestic Product (GDP). In municipal solid waste management area, Pinha and Sagava
(2020) assessed a system dynamic modelling for promoting the awareness of managers in order to reduce
costs by a view of zero budget balancing. At the same year, Liu et al. (2020) used system dynamics
modelling as an environmental assessment modelling for demolition and construction waste in Guangzhou
and analyzed three main impacts of these types of waste consisting of environmental, social and economic
impacts. Phonphoton and Pharino (2019) evaluated ooding effects on municipal solid waste management
by a system dynamics approach and analyzed waste collection and transfer processes in vulnerable areas in
Thailand. Lee et al. (2018) used a system dynamics modelling in different scenarios for investigating
policies of food waste in Hong Kong and considered interrelated factors affecting food waste management
policy’s eciency in order to suggest the details for how to improve the current policy.
Sukholthaman and Sharp (2016) evaluated the effects of source separation on solid municipal waste in
Thailand by a view of system dynamics and envisaged the source separation dynamic effects by a scenario
analysis in a 120-month periods. In Waste of Electric and Electronic Equipment (WEEE) area, Ardi and Leisten
(2016) assessed a system dynamics modelling for informal recycling sector affecting WEEE management
system dynamics as a secondary market. Additionally, Dace et al. (2014) analyzed eco-design policies of
packaging waste management by the aid of system dynamics methodology in order to observe if policies
are effective on recovery rates and material eciency in Latvia. Ciplak and Barton (2012) evaluated
healthcare waste generated by healthcare sector including hospitals, clinics and medical centres in Istanbul
by system dynamics with the aim of supporting a decision system, planning and simulating the waste
amount until 2035 and concluded that a high amount (77%) of healthcare waste would be possible with
modern treatment technologies. In the area of household waste management, Inghels and Dullaert (2011)
used system dynamics modelling for the aim of analyzing household waste management policy underlying

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the dynamic factors affecting GDP and collection rates in Flanders. The study of Pinha and Sagava also
considers nancial aspects in Brasil. Hao et al. (2008) proposed a decision tool for construction waste in
order to better manage demolition waste by a system dynamics approach and to understand relative factors
affecting and causing dynamic waste problems.
2.2. Waste Management of Smartphones
In smartphones area, there also exist some studies but there is not any study including system dynamics for
evaluating rare earth elements waste management in smartphones. Firstly, In China, He et al. (2020)
performed a life cycle cost analysis for high-tech minerals in mobile phone waste and while analyzing, they
divided into two groups including simple phones and smartphones for extracting various high-tech minerals.
Gu et al. (2019) analyzed recovering materials of mobile phone waste and the latest technological
developments by reviewing articles and identied material recovery processes of mobile phone waste. Yao et
al. (2018) evaluated environmental effects of smartphones waste management in China by using system
dynamics methodology including life cycle assessment of smartphones. On the other hand, Sinha et al.
(2018) studied and identied product systems including material ows of smartphones and also collection
systems and policies of mobile phone waste by the aid of system dynamics modelling. Xu et al. (2016)
compared China’s policies and technology for not only waste management system of smartphones but also
other electric and electronic waste management systems with other developing countries. Thavalingam and
Karusena (2016) evaluated the process of identication, public contribution in Sri Lanka and legislation of
mobile phone waste and also analyzed if people are aware of mobile phone waste management importance.
Yla-Mella et al. (2015) investigated the perception in Finland towards reuse and recycling of smartphones’
waste, included in electronic waste and the advertisement and publicity effects on public awareness, which
is aimed to increase public awareness.
In China, Yin et al. (2014) studied on consumers’ behaviour towards mobile phone waste recycling with a
questionnaire and surveying, and formed a metric of consumer behaviour about mobile phone. The crucial
result of this study is that most consumers are willing to pay 0-5% of recycling cost and the affecting factors
are education, region and monthly income. Jha et al. (2013) tried to investigate lithium and cobalt recoveries
in the smartphones’ batteries and studied on dissolution lithium and cobalt mechanism. Another study in
Czech Republic done by Polak and Drapalova (2012) estimated smartphones end-of-life generation, which
assigns the targets for mobile phone waste collection, and they are only reached if the target is more
realistic. Ongondo and Williams (2011) surveyed the incentives for smartphones waste collection and
concluded that incentives highly support take-back operations of smartphones effectively and create
awareness of collection mobile phone waste. Another survey study has been done by Nnorom et al. (2008)
investigating the willingness of Nigerian citizens to recycle mobile phone waste and to pay more for green
smartphones.
Methodology And Modelling
System dynamics and causal loop diagrams are very useful tools to see the system behavior and affecting
factors which change system behavior. In this study, we aim to observe how the reuse and recycling rate

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change in time according to different collection approaches. Therefore, these two methods t well with our
proposed methodology.
3.1. Methodology Description
System dynamics can be dened as the methodology to understand the complex system’s behavior by the
time. (Forrester, 1993). The system, as a whole, includes stocks, feedback mechanisms, negative or positive
relationships, dynamics variables in order to understand the relation between interrelated variables and how
a change of a variable in the complex system affects on the other variable in the system. In order to start
analyzing the system, rstly it is essential to understand if the existing system is suitable for being a system
or not as the system dynamics methodology is based on cause-effect relationship between variables
(Forrester, 1961). As Forrester (1994) stated, system dynamics has some conceptual parts, which are factors
of the system, feedbacks and causalities, stocks, dynamic variables and ows.
Richardson (2020) dened the basic structure of system dynamics, which also called as state- determined
system, as follows (1)see formula 1 in the supplementary les section.
, where is a vector, which belongs to stocks or state variables, is a non-linear vector-valued function and is
dened as set of parameters.
3.2. Model Description
3.2.1 Causal Loop Diagrams (CLD)
Causal Loop Diagram (CLD) is vital for observing system behavior, especially in closed loops, considering
feedbacks which forms a basis for a system dynamics mentality. Also, CLD indicates the mapping of cause-
effect relationships between variables. (Sterman, 2010). A loop of feedback includes two or more causalities
between related variables. In the relationship between two or more variables, negative or positive relationship
may be possible. The positive relationship between two variables indicates that they are proportionally
affected which means one related variable increases when the other one increases. As an example, if there
exists an arrow positively (+) signed at the end, starting from A and coming to B, it indicates that if A
increases, B also increases. Inversely, if there is a negative relationship between two variables having cause-
effect relationship, an increase in A causes a decrease in B assigned as a negative (-) sign at the end (Bala et
al., 2016).
For increasing amount of rare earth elements, different factors are taken into consideration to observe the
behavior of the system. Since the relative factors of Causal loop differently affect the ratio of reusing and
recycling ratios of rare earth elements in smartphones’ touch screens, the total effect can be mainly positive
only if technology development in waste collection centers, governmental and municipal incentives are
applied in the Causal loop diagram.
3.2.2. System Dynamics Modelling and Simulation of Rare Earth Elements in Smartphones
The system dynamics modelling for rare earth elements in smartphones’ touch screens has been designed in
three main aspects. All inputs can be seen in table 1. The inputs have been simulated in kilogram(kg) and

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milligram(mg) as some information is found in different measure forms. The average mobile phone weigh is
taken as 140 gram (URL3) and it is accepted that 350000 smartphones are thrown away in a day, which is
equal to 152 million devices thrown away yearly. The inputs indicated in table 1 are applied in Anylogic
simulation software by system dynamics approach given in Figure 4 as a closed loop supply chain. The
maximum collection rate is accepted as 25% as given in URL1 and the rest, 75% of smartphones, is thrown
away without any collection, reusing or recycling process. As a classical closed supply chain, raw materials
have been also fed with reused and recycled rare earth elements in the simulation. The main parts in the
simulations are respectively governmental and municipal collection centres operated by government and
municipalities.
Table 1. Description of system dynamics modelling parts and input names in simulation

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Input Name in the model Description
MunicipalIncentiveEffect Incentive(rate) given by municipalities for increasing
collection of smartphones
GovernmentalIncentiveEffect Incentive given by government for increasing collection
of smartphones
Indium,Lanthanum,Gold,Silver,Terbium,Yttrium
and Palladium Amount (mg) of each rare earth elements existing in
smartphones in the stocks after disassembly and
collection
Refurbishment Refurbishment process for disassembly and reuse of
smartphones
IncinerationandGarbage Amount of rare earth elements in smartphones’ touch
screens for not being reused or recycled but going
through for incineration and garbage stocks
TouchScreens Weight (gr) of touchscreen in smartphones taken
according to the weight distribution given in Table 2.
ReuseorResale Number of Smartphones not going through recycling
process
Export Number of Smartphones to export without recycling
GovernmentalCollectionCenter Number of Smartphones being collected in
Governmental Collection Center.
WasteCollectionCenter1 Rare earth elements’ amount (mg) after recycling
process
RawMaterial Raw Material Stock in order to reuse recycled
components and elements of smartphones and
manufacture new smartphones
MunicipalCollectionCenter Number of Smartphones being collected in Municipal
Collection Center.
DisposalStock Stock of not reused or recycled rare earth elements
after recycling process
Battery,AerialofPhones,Microphone,
BatteryConnectors,TouchScreens
Weight of each part in stocks before the process of
going through waste collection center
ThrowAway Number of mobile phone waste without recycling
On the other hand, a smart contains 7 main parts and the distribution of weights in the simulation model
changes based on Table 2. (Singh et al.,2018). Table 2 shows the weight distribution of the mobile phone
components for a classical smartphone. The weights in the model are distributed and assigned as given in
Table 2.
Table 2. Component distributions of smartphones based on their weights (Singh et al.,2018)

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Mobile phone components Weight distribution (%)
Speakers 2
Screws 5
Aerial of phones 10
Battery connectors 35
Circuit boards 15
LCD screens 30
Microphones 3
Furthermore, as seen in Table 2, touch screens or LCD screens of smartphones have 30% of total weight.
Given that a total weight of a smartphone is approximately equal to 140 g., touch screen is nearly 42 g. Also,
these LCD screens include very crucial and rare earth elements, which becomes a scarce source. Table 3
shows some important rare earth elements weights found in smartphones touch screens which requires to
be functional and operative.
Table 3. Important Rare Earth Elements’ weight in smartphones (Singh et al., 2018 & Jowitt et al., 2018 &
Weng et al., 2013, Silviera et al., 2015)
Rare earth elements in smartphones touch
screens Weight (mg) of rare earth elements in smartphones per
1 kg
Silver 1732.9
Gold 190.9
Palladium 40.16
Indium 636
Terbium 1.58
Yttrium 1.39
Lanthanum 1.61
According to the table 2 and table 3, the weights and distributions are proportionally taken place in the
system dynamics modelling operated by Anylogic and these elements are accepted to be collected in Waste
Collection Center except thrown away rare earth elements coming from not-recycled or not reused cell
phones. Additionally, only 1% of rare earth elements are recycled in recycling process (Jowitt et al., 2018) and
in the model, the scenarios are differently evaluated. In the modelling; rst scenario is 1% of recycling of rare
earth elements without any incentives, which is the current scenario in the current waste recycling process.
For the next scenario, it is 4% of recycling of rare earth elements in smartphones touch screens with an
effective and ecient supply chain management and incentives, which is future state and put in incentive
sections as scalar for designed model simulation. Moreover, the part of collection centers, refurbishment and

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reuse or resale, e-waste recycling and export of supply chain are the general parts of smartphones’ waste
management as seen in the Figure 4 (Jang and Kim, 2010).
Results And Discussions
In the model, the recycled rare earth elements are directly sent through the raw material and production
process. Figure 5 shows the current state of recycling of rare elements’ weights (mg) in smartphones’ touch
screens after 45 years without any incentives and at a very low rare (1%) recycling operation.
In the model, there exist two incentives, which are governmental collection incentives supporting
governmental collection point for increasing the collection and municipal collection incentives for public
awareness. Governmental incentive and municipal incentive taken into consideration (Ylä-Mella et al., 2015)
are respectively put in the model at a rate of 10% and 5%.
Figure 6 shows the future state of recycling of rare elements’ weights (mg) in smartphones’ touch screens
after 45 years with incentives and at a rate of (3%) recycling operation with two separate collection points.
By the aid of incentives and effective collection points, which are governmental collection points and
municipal collection points, the recycled rare earth elements in smartphones’ touch screens can increase up
to 4.13% of total wastes by stating that only 1% of rare earth elements is recycled and reused actually.
Conclusion
Increasing use of smartphones parallelly increase mobile phone waste. Taking into consideration the fact
that mobile phone reuse and recycling rate is only 25%, this rate threaten environmental, social and
economic sustainability. Moreover, rare earth elements found in almost every part of smartphones are
considered as recyclable waste and the majority of these can be reused in production process. However, due
to insucient waste management and effective policy deciencies, rare earth elements in smartphones’
screens are recycled at a rate of only 1% and the rest is thrown away or incinerated. In the proposed system
dynamics model for these elements, which face to an increasing risk of extinction, 7 rare earth elements,
which are gold, palladium, lanthanum, silver, terbium, yttrium and indium, have been evaluated and an
effective closed loop supply chain management has been proposed for these elements in touch screens of
smartphones, along with an effective mobile phone waste management. The proposed closed loop supply
chain model has been designed with system dynamics. By the aid of incentives and different collection
points, these elements can be recycled up to 4.13% with the proposed model while only 1% of these elements
are actually recycled. In future studies, different policies can be examined for all countries in the world and a
separate model can be designed for each country based on its policies. On the other hand, since the waste
management policy of each country is different, the current situation of these policies and the future
situation can be discussed according to the developments. Also, for further researches, if data is available,
other rare earth elements can be evaluated by a system dynamics approach.
Declarations

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Authors’ contributions
Both of authors (Aziz Kemal Konyalıoğlu and İlke Bereketli) have been equally included in the research and
worked equally.
Aziz Kemal Konyalıoğlu and Ilke Bereketli should be respectively AKK and IB.
Funding There is no funding for this research.
Data availability Research data can be obtained from the corresponding author through email.
Compliance with ethical standards
Ethical approval We certify that the manuscript titled. “Rare earth elements’ waste management for
smartphones’ touch screens by system dynamics modelling” (hereinafter referred to as “the Paper”) has been
entirely our original work except otherwise indicated, and it does not infringe the copyright of any third party.
The submission of the Paper to Environmental Science and Pollution Research implies that the paper has
not been published previously (except in the form of an abstract or as a part of a published lecture or
academic thesis), that it is not under consideration for publication elsewhere, that its publication is approved
by all authors and that, if accepted, will not be published elsewhere in the same form, in English or any other
language, without the written consent of the Publisher.
Copyrights for articles published in Environmental Science and Pollution Research are retained by the
author(s), with rst publication rights granted to Environmental Science and Pollution Research.
Consent to participate- We arm that all authors have participated in the research work and are fully aware
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Consent to publish- We arm that all authors have agreed for submission of the paper to ESPR and are fully
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Competing Interests- The authors declare that they have no conict of interest.
References
Ardi, R., & Leisten, R. (2016). Assessing the role of informal sector in WEEE management systems: A System
Dynamics approach.Waste management,57, 3-16. https://doi.org/10.1016/j.wasman.2015.11.038
Bala B.K., Arshad F.M., Noh K.M. (2017) Causal Loop Diagrams. In: System Dynamics. Springer Texts in
Business and Economics. Springer, Singapore. https://doi.org/10.1007/978-981-10-2045-2_3
Cai, Y., Yue, W., Xu, L., Yang, Z., & Rong, Q. (2016). Sustainable urban water resources management
considering life-cycle environmental impacts of water utilization under uncertainty.Resources, Conservation
and Recycling,108, 21-40. https://doi.org/10.1016/j.resconrec.2016.01.008

Page 11/18
Ciplak, N., & Barton, J. R. (2012). A system dynamics approach for healthcare waste management: a case
study in Istanbul Metropolitan City, Turkey.Waste Management & Research,30(6), 576-586.
https://doi.org/10.1177/0734242X12443405
Dace, E., Bazbauers, G., Berzina, A., & Davidsen, P. I. (2014). System dynamics model for analyzing effects of
eco-design policy on packaging waste management system.Resources, Conservation and Recycling,87,
175-190. https://doi.org/10.1016/j.resconrec.2014.04.004
Dhanshyam, M., & Srivastava, S. K. (2021). Effective policy mix for plastic waste mitigation in India using
System Dynamics.Resources, Conservation and Recycling,168, 105455.
https://doi.org/10.1016/j.resconrec.2021.105455
Forrester, J. W. (1994), System dynamics, systems thinking, and soft OR. Syst. Dyn. Rev., 10: 245
doi:10.1002/sdr.4260100211
Forrester J.W. (1961), Industrial Dynamics, The MIT Press, Cambridge, Massachusetts.
Forrester, J. W. (1993). System dynamics and the lessons of 35 years. InA systems-based approach to
policymaking(pp. 199-240). Springer, Boston, MA
Geyer, R., & Blass, V. D. (2010). The economics of cell phone reuse and recycling.The International Journal of
Advanced Manufacturing Technology,47(5-8), 515-525.
Gu, F., Summers, P. A., & Hall, P. (2019). Recovering materials from waste smartphones: Recent technological
developments.Journal of Cleaner Production,237, 117657. https://doi.org/10.1016/j.jclepro.2019.117657
Hao, J. L., Hill, M. J., & Shen, L. Y. (2008). Managing construction waste on‐site through system dynamics
modelling: the case of Hong Kong.Engineering, Construction and Architectural Management.
https://doi.org/10.1108/09699980810852646
He, P., Feng, H., Hu, G., Hewage, K., Achari, G., Wang, C., & Sadiq, R. (2020). Life cycle cost analysis for
recycling high-tech minerals from waste smartphones in China.Journal of Cleaner Production,251, 119498.
Huang, E. M., Yatani, K., Truong, K. N., Kientz, J. A., & Patel, S. N. (2009). Understanding mobile phone
situated sustainability: the inuence of local constraints and practices on transferability.IEEE Pervasive
Computing, (1), 46-53.
Inghels, D., & Dullaert, W. (2011). An analysis of household waste management policy using system
dynamics modelling.Waste management & research,29(4), 351-370.
https://doi.org/10.1177/0734242X10373800
Jang, Y. C., & Kim, M. (2010). Management of used & end-of-life smartphones in Korea: a review.Resources,
Conservation and recycling,55(1), 11-19.
Jha, M. K., Kumari, A., Jha, A. K., Kumar, V., Hait, J., & Pandey, B. D. (2013). Recovery of lithium and cobalt
from waste lithium ion batteries of mobile phone.Waste management,33(9), 1890-1897.

Page 12/18
Jowitt, S. M., Werner, T. T., Weng, Z., & Mudd, G. M. (2018). Recycling of the rare earth elements.Current
Opinion in Green and Sustainable Chemistry,13, 1-7.
Lee, C. K. M., Ng, K. K. H., Kwong, C. K., & Tay, S. T. (2019). A system dynamics model for evaluating food
waste management in Hong Kong, China.Journal of Material Cycles and Waste Management,21(3), 433-
456. https://doi.org/10.1007/s10163-018-0804-8
Liu, J., Liu, Y., & Wang, X. (2020). An environmental assessment model of construction and demolition waste
based on system dynamics: a case study in Guangzhou.Environmental Science and Pollution
Research,27(30), 37237-37259.
Lu D, Iqbal A, Zan F, Liu X, Chen G. Life-Cycle-Based Greenhouse Gas, Energy, and Economic Analysis of
Municipal Solid Waste Management Using System Dynamics Model.Sustainability. 2021; 13(4):1641.
https://doi.org/10.3390/su13041641
Nnorom, I. C., Ohakwe, J., & Osibanjo, O. (2009). Survey of willingness of residents to participate in electronic
waste recycling in Nigeria–A case study of mobile phone recycling.Journal of cleaner production,17(18),
1629-1637.
Ongondo, F. O., & Williams, I. D. (2011). Mobile phone collection, reuse and recycling in the UK.Waste
management,31(6), 1307-1315.
Phonphoton, N., & Pharino, C. (2019). A system dynamics modeling to evaluate ooding impacts on
municipal solid waste management services.Waste Management,87, 525-536.
https://doi.org/10.1016/j.wasman.2019.02.036
Pinha, A. C. H., & Sagawa, J. K. (2020). A system dynamics modelling approach for municipal solid waste
management and nancial analysis.Journal of Cleaner Production,269, 122350,
https://doi.org/10.1016/j.jclepro.2020.122350
Polák, M., & Drápalová, L. (2012). Estimation of end of life smartphones generation: the case study of the
Czech Republic.Waste management,32(8), 1583-1591.
Richardson, G. P. (2020). Core of System Dynamics.System Dynamics: Theory and Applications, 11-20.
URL1: Kennedy, M. (2013). Cell Phone Recycling
https://www.wastecare.com/Articles/Cell_Phone_Recycling.htm. Accessed 19 February 2021
URL2: Compound Interest (2014) Elements of a Smartphone,
https://i1.wp.com/www.compoundchem.com/wp-content/uploads/2014/02/The-Chemical-Elements-of-a-
Smartphone-v2.png?ssl=1 . (Accessed 19 February 2021)
URL3: (2018) Weekly poll results: the ideal weight for a phone is between 140g and 170g,
https://www.gsmarena.com/weekly_poll_results_the_ideal_weight_for_a_phone_is_between_140g_and_170g-
news-29934.php. (Accessed 19 February 2021)

Page 13/18
URL4: https://earth911.com/eco-tech/20-e-waste-facts/ (Retrieved on 7th of May, 2020)
Sarath, P., Bonda, S., Mohanty, S., & Nayak, S. K. (2015). Mobile phone waste management and recycling:
Views and trends.Waste management,46, 536-545.
Silveira, A. V. M., Fuchs, M. S., Pinheiro, D. K., Tanabe, E. H., & Bertuol, D. A. (2015). Recovery of indium from
LCD screens of discarded cell phones.Waste Management,45, 334-342.
https://doi.org/10.1016/j.wasman.2015.04.007
Singh, N., Duan, H., Yin, F., Song, Q., & Li, J. (2018). Characterizing the materials composition and recovery
potential from waste smartphones: A comparative evaluation of cellular and smartphones. ACS Sustainable
Chemistry & Engineering, 6(10), 13016-13024.
Sinha, R., Laurenti, R., Singh, J., Malmström, M. E., & Frostell, B. (2016). Identifying ways of closing the metal
ow loop in the global mobile phone product system: A system dynamics modeling approach.Resources,
Conservation and Recycling,113, 65-76.
Soo, V. K., & Doolan, M. (2014). Recycling mobile phone impact on life cycle assessment.Procedia cirp,15,
263-271.
Sterman, J. (2010).Business dynamics. Irwin/McGraw-Hill c2000...
Sukholthaman, P., & Sharp, A. (2016). A system dynamics model to evaluate effects of source separation of
municipal solid waste management: A case of Bangkok, Thailand.Waste Management,52, 50-61.
https://doi.org/10.1016/j.wasman.2016.03.026
Thavalingam, V., & Karunasena, G. (2016). Mobile phone waste management in developing countries: A case
of Sri Lanka.Resources, Conservation and Recycling,109, 34-43.
Weng, Z. H., Jowitt, S. M., Mudd, G. M., & Haque, N. (2013). Assessing rare earth element mineral deposit
types and links to environmental impacts.Applied Earth Science,122(2), 83-96.
Xu, C., Zhang, W., He, W., Li, G., & Huang, J. (2016). The situation of waste mobile phone management in
developed countries and development status in China.Waste management,58, 341-347.
Yao, L., Liu, T., Chen, X., Mahdi, M., & Ni, J. (2018). An integrated method of life-cycle assessment and system
dynamics for waste mobile phone management and recycling in China.Journal of cleaner production,187,
852-862.
Yin, J., Gao, Y., & Xu, H. (2014). Survey and analysis of consumers' behaviour of waste mobile phone
recycling in China.Journal of Cleaner Production,65, 517-525. https://doi.org/10.1016/j.jclepro.2013.10.006
Ylä-Mella, J., Keiski, R. L., & Pongrácz, E. (2015). Electronic waste recovery in Finland: Consumers’
perceptions towards recycling and re-use of smartphones.Waste management,45, 374-384.

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Figures
Figure 1
Classic illustration of smartphones’ waste management (Jang and Kim, 2010)
Figure 2
System Dynamics methodology (Richardson,2020)

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Figure 3
The Causal loop and affecting factors of reusing and recycling ratios of rare earth element in smartphones

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Figure 4
System dynamics modelling in Anylogic software for waste management of rare earth elements in
smartphones’ touch screens

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Figure 5
The current state of rare elements’ weights (mg) in smartphones touch screens

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Figure 6
The future state of rare elements in smartphones touch screens
Supplementary Files
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formula.docx