Waste Treatment - Literature Review - Alex Skempris

8/8/2019 Waste Treatment - Literature Review - Alex Skempris

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Skempris Alexios, 20059088 Literature Review

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PEME5451M – Waste Treatment & Disposal Module Professor: Paul Williams

Coursework 1: Literature Review

Topic selected: The recycle of electrical and electronic equipment (EEE)

Skempris Alexios, 20059088

School of Process Environment and Materials Engineering, Leeds University

The Recycling of EEE

Abstract

On this paper a literature review will be made on the recycling of Electrical and

Electronic Equipment, otherwise known as EEE. When it comes to the recycling of EEE

there are several factors to be taken into account, most important of which are the materials

and the processes that are hazardous to the environment as well as the techniques used for

recycling that are the most efficient. This essay will focus on these two based on the research

that has already been conducted and some discussion on the existing techniques will be made.

Introduction

Recycle is the process through which used materials are reformed in order to be able

to be used again. By recycling we reduce the consumption of raw materials as well as energy

usage and therefore the environment is spared a great deal of implications. Additionally a

considerable amount of resources is saved as the processed material is suitable for reuse.

Finally recycling is a key component to the “hierarchy of waste management”, a plan

developed by the EU as a guideline to its member states to optimize their waste treatment and

disposal strategies. [1]




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Figure 1: Hierarchy of waste management (Source: [1]).

In this review the recycle process of Electrical and Electronic Equipment waste is to

be studied. The new applications of EEE are increasing significantly and the production of

electrical and electronic equipment is one of the fastest growing sectors of industrial

production in the world. This development, however, makes the Waste of Electrical and

Electronic Equipment (WEEE) as one of the most critical categories of waste.

With the present evolution and development rate, electronic technology has an

increasingly short lifespan. As a result, the waste of electronic equipment becomes larger and

larger and therefore raising the concern of the EU and public as to its damaging effects to the

environment. Electrical and Electronic waste was found to have several hazardous

components and the need for proper recycle was urgent. As the EU retains a leading role in

environment protection policies, the directive 2002/96/EC otherwise known as WEEE, was

legislated by the European Council in order to meet the environmental needs. [2]

In this review a short introduction of the WEEE directive will be made and based on

the research that has been done so far on the recycling of the EEE the actual danger the “end-

of-life” electronic parts are posing will be discussed. Also recycle processing techniques will

be briefly introduced and a comparison will be made between the different recycling

methods.




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The WEEE directive

The WEEE directive is important to be mentioned because it’s the directive under

which all manufacturing industries should apply to. Essentially it obligates them to have a

recycling facility and to put it in use. WEEE stands for Waste of Electrical and Electronic

Equipment and is concerning the electrical and electronic equipment that is no longer usable

and has been deemed as waste. It directs the percentage of the equipment that goes to landfill

as well as set targets for the percentage that is to be recycled [3]. Each member state is

responsible for its own WEEE and has to apply inspections to ensure the directive is applied

properly [2].Under the WEEE directive, all manufacturers of electrical and electronic

equipment are enforced by law to keep a separate site for their electronic waste and are also

responsible for accepting the waste of the consumers. It is noteworthy that the consumers can

return their “end-of-life” electronic equipment for recycling free of charge [2]. From there

they should process the waste material and recycle whatever is possible before sending it to a

landfill.

Wastage of raw materials and energy in EEE

Obviously, the increased production of EEE bounds significant quantities of raw

materials and energy, while using several chemicals. The increasingly fast wastage involves

significant losses of raw materials, but also a loss for all the energy consumed for those

materials to be mined. In addition, electrical and electronic products contain valuable

materials such as various metals, plastics, glass, etc.

According to Ching-Hwa Lee et al. when constructing a computer (hard drive, screen,

keyboard and mouse) a great number of materials is used including plastic, magnetite and

components of integrated circuit boards like iron, copper and resin [4]. Furthermore, the work

of Martin Goosey et al. adds that each construction of a new computer consumes amounts of

crude oil and natural gas [6]. The most interesting though when it comes to the waste of EEE

raw materials is the work of Li-Teh Lu et al. which presents a table of the materials and

chemical substances found in notebook computers [17]. As notebook computers are one of

the fastest growing industries of our days the danger of its increased production and need for

recycling hardly needs to be stated. Table 1 shows the composition of a notebook computer

by material and by their average weights.




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Table 1: Composition of NB computer (Source: [17])

In May 2003 on a seminar in Copenhagen Denmark, a study was presented about the

quantity of several raw materials in electronic boards. Table 2 shows the variety and quantity

of material found in each ton of electronic boards.




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Material contained in a tonne of electronic boards

Component Kg/t Component Kg/t

Plastic 273 Cadmium 0,36

Copper 130 Tantalum 0,17

Iron 41 Molybdenum 0,14

Bromine 26 Palladium 0,11

Tin 20 Cobalt 0,08

Nickel 18 Cerium 0,05

Antimony 10 Platinum 0,03

Zinc 4 Lanthanum 0,03

Silver 0,45 Mercury 0,01

Gold 0,45

Table 2: Variety and quantity of material found in each ton of electronic boards (Source: [7])

Hazardous substances in WEEE

Many of the problems of environment and health caused by the current management

of Waste Electrical and Electronic Equipment (WEEE) are linked to the existence of

hazardous substances in such products.

Each electrical or electronic product consists of a combination of multiple structural

units. The works of Martin Gousey et al. and Jae-Chun Lee et al. seem to agree on a

composition of the basic building blocks common to EEE. These include: assembly of printed

circuit boards, cables and wires, plastics containing flame retardants, mercury switches and

breakers, components used in displays such as cathode ray tubes and liquid crystal displays,

batteries and electric data, data storage, light generators, capacitors, resistors, relays, sensors

and links[6],[8].

Furthermore Jae-Chun Lee et al. also notes that among the substances contained in

these components, the most environmentally problematic are the heavy metals, such as

mercury, cadmium and chromium, halogenated substances such as chlorofluorocarbons

(CFC), polychlorinated biphenyl (PCB), polyvinyl chloride (PVC) and brominated flame

retardants, as well as asbestos and arsenic.[8]




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Noteworthy are the results of Hedemalm et al. on studies on EEE hazardous

materials which were presented recently at the Council of Ministers of the Nordic countries

[9]. It was concluded that high levels of dangerous substances were contained in

proportionally few parts of the apparatus.

Specifically:

Mercury is used in percentage more than 90% in batteries and sensors. It is estimated

that 22% of the mercury consumed annually worldwide is used in electrical and

electronic equipment.

Lead: also used in 90% in batteries and less in PBAs, and fluorescent light bulbs.

Cadmium: over 90% is used in rechargeable batteries.

Hexavalent chromium: is used mainly as a corrosion inhibitor in cooling systems of

refrigerators.

Printed Circuit Boards (PCBs): 90% of PCBs is used in capacitors.

Brominated flame retardants: 80% of those is used in circuit boards, cables and

plastic covers of computers, while a small percentage is used in televisions and

household appliances in the kitchen.

Tetrabromobisphenol A (TBBPA): 90% of those are used in PBAs, PWBs (Printed

Wiring Boards) and their components.

Chloroparaffins: 90% of those is used in PVC cables.

Copper: small waste of electrical and electronic goods is the source of 40% of the

copper content in bottom ash from incineration of solid.

Polychlorinated Naphthalene (PCN): used for impregnation of the paper casing of

the cables and the capacitors.

Liquid crystals: more than 2000 components, many of which are poisonous, can

form liquid crystals.

Optical materials: Contain indium, gallium, arsenic and cadmium

(Source: [9])




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Types of WEEE recycling techniques

In the first half of the last decade [11], the interest of the majority researchers have

focused on planning for the “end-of-life” EEE (Design for End-of-life) and analysis of the

costs of dismantling that would lead to more accurate results for design from the outset. The

main reason was probably that research in this area was launched by the developments in

machine designs [11]. It seemed therefore logical that the solution to environmental concerns

was dismantled.

An alternative or complementary treatment technology such as cutting and then

separating materials for recycling had not received special attention for several years. [10].

Later, researchers realized that the factors of cost in and the opinion of the manufactures and

the public play an important role.

It should be noted that the international academic literature does not attach special

importance to the exact process of how the recycling is made. But the researchers of

recycling companies that aim to attract more and more customers covered this area morethoroughly. It is noted however that in Europe, the process of cutting is currently dominant

[11].

For the “end-of-life” of the devices studied, there are 3 essential techniques for

recycling of WEEE [10]:

• Cutting-Separation

• Metal processing

• Controlled Disassembly

the three techniques will be briefly described in order to identify vulnerabilities and

make comparisons.




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Cutting – Separation

According to the work by Seliger et al. [12] the basic principle of this technique is:

cutting the devices in very small pieces and then separating the different materials through

the appropriate processes (recovery of materials). One can characterize this as uncontrolled

disassembly. The procedure is as follows: The device is inserted into a cylindrical container

(sometimes compressed at presses first), where they are minced by rotating hammers until

they reach the appropriate size (usually 10 – 100mm) [12].

Figure 2: Shredder (Source: [14])

Metallurgical processing

Zussman et al. best describe this process and state that it’s an alternative to cutting

[15]. This technique mostly uses the non-metallic material products as fuel to liquefy and

recover metals. The method isolates the liquids, removes the valuable materials and the rest is

compressed and driven into the blast furnace. In the melting furnace, metals are properly

separated in order to avoid the creation of unwanted alloys. This treatment is highly

dependent on the requirements of the recycled materials. Especially in copper, many

applications are at various levels of purity. [15]

Nevertheless, criticism of the method indicates that the non-ferrous metals such as

copper can form alloys from the molten steel and significantly reduce its value, because the

copper is almost impossible to remove from alloys of steel.

Some researches argue, however, that the total energy benefit that is gained is

preferable to the one gained from disassembly [13]. Others see this process as a disguised

method of waste incineration [12].




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Disassembly

Gupta S.M.et al. [16] argue that this is the best technique for the recycle of EEE.

“Disassembly is the process of systematic removal of unwanted components from an

electronic device, ensuring that no parts are worn out in the process”. [16] As this is a purely

theoretical definition of dismantling a more practical version would be that disassembly can

be defined as a controlled process that aims to, by any means, separate and recover a desired

subset of the product.

Types of Dismantling [16]

According to Gupta S.M.et al. the process of disassembly can be distinguished in the

following types, depending on the level of recovery achieved:

Non-destructive, without damaging any subset of the product (i.e. loosening screws,

disconnecting links).

Partially destructive (partly destructive), with destruction of selected parts (i.e.

flame cutting, laser cutting) to achieve our goal.

Destructive, with uncontrolled destruction of the structure product (i.e., cutting).This

is the most extreme case of disassembly.

Selective disassembly: The process proceeds until a desired depth which is called

disassembly depth. This happens when estimations indicate that further dismantling is

not particularly beneficial to the environment and increases costs disproportionately.

The type of disassembly that is selected will depend on many factors. The goal is to

minimize costs and to automate the process [16]. The following figure shows the three major

trends of the solution structure of the products (cutting, manual and automated disassembly)

and some characteristics of each.




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Figure 3: solution structure of EEE (Source: [16])

Discussion

On the field of recycling EEE the fact that there is imminent danger to the

environment from mass production of devices appears to be common knowledge both for the

researchers and the public. The legislation of the WEEE directive serves as additional

evidence of that. Regarding the materials existing in most of the electrical and electronic

equipment, the majority of the researchers seem to agree on their analysis of the raw matter

used and also make valid points about the dangers they pose to the environment. However,

the recycling techniques, even though the descriptions of the processes were of limited detail,

give some room for comparison and discussion.

Regarding the cutting separation technique even though it is the most widely used

there are some shortcomings that appear. The nature of the technique is such, that the

complete reuse of a specific device is impossible. This means that there will always be a

percentage of raw materials that is wasted and not recycled. This could qualify as the main

disadvantage as the most environmental damage is done during the process of production.




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The metal processing technique appears to be basically a melting of the products until

the metallic parts can be extracted. As we saw earlier, the most of the EEE equipment

consists of more than just metals and therefore the same problem with the cutting separation

arises since plastic and other components are melt. Additionally through the process of

melting there’s bound to be pollutants released in the atmosphere so the argument that this is

a method close to incineration [12] is not invalid.

The disassembly technique appears to be the most effective when it comes to

environmental concerns since it can help it in several ways. Initially, easier access to subsets

will be possible fact which will deem repairs easier and increase the lifetime of the products.

By having a better access to the retrieval of subsets, the materials used are much easier to be

separated and ranked, resulting in the recycling process being much more efficient. Finally

it’s the only technique that has some potential to achieve a complete reuse of a specific

product or material. However, as the disassembly is obviously the slowest process of the

three it can result in low recycling productivity as well as a bigger cost to be achieved. This is

probably the reason why, even though it’s the most envir onmentally conscious method, it is

not so widely used.

Conclusions

On this Essay a review of the existing literature was presented on the topic of EEE.

The importance of proper recycling has already been research and the concern of the

scientific community has already led to several breakthroughs in recycling techniques.

However, economic impacts play an important role to the choice of the best recycling

technique for the EEE. Some studies were also presented on this review for they showed

particular interest as they concerned every day products. Room for further research does exist

as a technique efficient from both economic and environmentally conscious viewpoints has

yet to be discovered.




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References

1. Williams P.T, 1998. Waste Treatment and disposal

2. Directive 2002/96/EC of the European parliament and of the council of 27 January 2003

on waste electrical and electronic equipment (WEEE) available at http://eur-

lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2003:037:0024:0038:en:PDF

3. Electronic Waste Management, R E Hester (Editor), R M Harrison “ Introduction and

overview” Martin Goosey available online at

http://0-www.rsc.org.wam.leeds.ac.uk/publishing/ebooks/2008/9780854041121.asp

4. An overview of recycling and treatment of scrap computers Ching-Hwa Lee, Chang-Tang

Changb, Kuo-Shuh Fanc, Tien-Chin Changd available at www.sciencedirect.com

5. C.-H. Lee, S.-L. Chang, K.-M. Wang, L.-C. Wen, Management of scrap computer

recycling in Taiwan, J. Hazard. Mater. 73 (3) (2000) 209 – 220.

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Electronic Waste Management , R E Hester (Editor), R M Harrison “ Materials used inmanufacturing” Martin Goosey and Gary C. Stevens available online at


7. Boks C.: How research institutions can contribute towards research progress in true

operationalisation of ecodesign. CIRP seminar on life cycle engineering Copenhagen,

Denmark May 2003 engineering for sustainable development - an obligatory skill of the

future engineer.

8. Present status of the recycling of waste electrical and electronic equipment in Korea Jae-

Chun Lee, Hyo Teak Song, Jae-Min Yoo available at www.sciencedirect.com

9. Hedemalm, P., Carlsson, P. & Palm, V. (1995). Waste from Electrical and Electronic

Products - A Survey of the Contents of Materials and Hazardous Substances in Electric

and Electronic Products.

http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2003:037:0024:0038:en:PDF





http://www.sciencedirect.com/

















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10. Huisman J., Boks C., Stevels A.: Quotes for environmentally weighted recyclability

(QWERTY): concept of describing product recyclability in terms of environmental value .

Iint. J. Prod. res., 2003, vol. 41, no. 16, pp: 3649 – 3665.

11. Rose, C. M., Stevels, A.: Lessons Learned from Applying Environmental Value Chain

Analysis to Product Take-Back . Submitted to 7th CIRP - Life Cycle Engineering

Conference, Tokyo, Japan, November 2000.

12. Seliger, G., Zussman, E., Kriwet, A.: Integration of Recycling Considerations into

Product Design – a System Approach. Presented at the NATO ARW, Italy, 1993.

13. Boks, C., The relative importance of uncertainty factors in product end-of-life Scenarios,

Delft University of Technology, 2002

14. Artech. Recyclingtechnik GmbH ) http://www.recyclingtechnik.de/

15. Zussman, E., Kriwet, A., Seliger, G.: Disassembly-Oriented Assessment Methodology to

Support Design for Recycling. Annals of the CIRP, Vol. 43/1/1994, pp: 9-14.

16. Gupta S.M., Brennan L. and Taleb K.N.: Operations Planning Issues in an

Assembly/Disassembly Environment . International Journal of Operations & Production

Management, Vol. 14 No. 9, 1994, pp. 57-67.

17. Li-Teh Lu , Iddo K. Wernick, Teng-Yuan Hsiao, Yue-Hwa Yu, Ya-Mei Yang, Hwong-

Wen Ma Balancing the life cycle impacts of notebook computers: Taiwan’s experience

available at www.sciencedirect.com

http://www.recyclingtechnik.de/








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