1 Introduction
1.1 E-waste and e-waste recycling
Electronic waste (e-waste) is a popular, informal name for electronic products nearing the end of their "useful life" (California Department of Resources Recycling and Recovery [CalRecycle], 2018), such as computers, televisions, and printers. With rapid advancements in technology over the past few decades, and short lifespans of electronics of only 5 years (Ala-Kurikka, 2015), old electronics are quickly being replaced and thrown out, leading to a rise in production of e-waste in recent years. In 2016 alone, 44.7 million tonnes of e-waste had been generated worldwide, and it is projected to rise to above 50 million tonnes by 2021 (Figure 1). One of the strategies to reduce the amount of e-waste present is e-waste recycling.
Figure 1: Increasing trend in the estimated amount of e-waste produced annually
(https://www.itu.int/en/ITU-D/Climate-Change/Pages/Global-E-waste-Monitor-2017.aspx)
E-waste recycling refers to the separation and extraction of rare precious metals, as well as plastics and glass from old electronic parts. This process is complex as electronic parts contain many materials which need to be separated before extraction. A common way to separate the precious metals is to use acids like hydrochloric acid to dissolve the metals into a solution. E-waste recycling occurs around the world, but most prominently in China. 70% of e-waste produced worldwide (Watson, 2013) is exported from developed nations, like the United States, to China alone (Greenpeace, 2009), due to low labour costs.
1.2 Improper E-waste Recycling: An Environmental and Health Crisis in Guiyu
1.2.1 Place of Focus: Guiyu
Guiyu is a town located in Chaoyang district of Guangdong province in China, and is currently one of the biggest e-waste recycling sites in the world, with 1.6 million tonnes passing through Guiyu in a single year (Figure 2) due to the fact that the town has the capability, unlike most countries, to recycle e-waste on a very large industrial scale. Evidently, the town has about 80,000 residents working in the recycling sector or about 61.5% of its population of 130,000 (Kor, 2015). As such, the e-waste industry is very important to the economic life of this town.
Figure 2: Amount of e-waste passing through Guiyu yearly (as of 2015)
(https://www.straitstimes.com/asia/east-asia/chinas-gadget-graveyard)
1.2.2 Improper E-waste Recycling: Environmental Crisis
E-waste from old computer parts like CPUs and monitors with Cathode Ray Tubes (CRTs), contain harmful metals, such as lead, which harms the growth of the brain and nervous system in children. This also increases the chances of adults acquiring high blood pressure and kidney failure (World Health Organization, 2018). Therefore, the large scale use of acids (Figure 3), such as hydrochloric acid, or burning of the e-waste, will result in large amount of harmful metal pollutants released, such as toxic fumes and heavy metals, into the atmosphere (Watson, 2013). Similarly, the e-waste burning also causes polychlorinated dioxins to be released into the atmosphere. These dioxins and metal pollutants
Figure 3: Picture of a woman in Guiyu recycling E-waste which is producing toxic fumes
(http://ecomerge.blogspot.com/2014/12/the-need-for-e-cycling-done-right.html)
1.2.3 Effects of Environmental Pollution: Health Crisis
The town has the highest level of cancer-causing dioxins in the world. The burning of e-waste such as cable wires has led to extremely high levels of dioxins (12419 ng TEQ) per kilogram of waste input and 15610 ng TEQ/kg, according to two separate tests, which are about 1000 times higher than that of the amount of dioxins generated by the open burning of household waste (Leung, Cai & Wong, 2006).
Most local children suffer from an extremely high rate of lead poisoning (Moskvitch, 2012) because they are particularly vulnerable to lead poisoning as they absorb 4–5 times as much ingested lead as adults from a given source (World Health Organisation, 2018) (Figure 4). In a population-based study between children in Guiyu and Haojiang during 2011-2013, Children living in Guiyu had significant higher blood lead levels (7.06 µg/dL) than the quantity (5.89 µg/dL) of Haojiang children (Guo et al., 2014).
Figure 4: Picture showing that 88% of children in Guiyu had lead poisoning in 2010 and its effects
(http://www.chinadaily.com.cn/cndy/2011-11/16/content_14101761.htm)
If a child, age under 18 (Figure 5), contains a high percentage of lead in the blood either by inhalation of lead particles produced by burning of e-waste or the spreading of lead from the bone of a mother to her developing foetus. The lead can potentially attack the brain and central nervous system, leading to coma, convulsions and even death. Children who survive severe lead poisoning may be left with intellectual disability and behavioural disorders (World Health Organization, 2018).
Figure 5: A family (mother and 4 children) living in Guiyu contaminated with high levels of lead
(http://www.ban.org/give-removed/)
This issue has been going on in Guiyu for more than a decade and in addition, it had been highlighted by many news reports, articles and documentaries (Figure 6). The Chinese government and local authorities has made efforts to curb the pollution. Although this is showing some success in cleaning up the environment, the productivity of recycling is significantly affected (Zhuang, 2017). As Guiyu’s economy is dependent on this sector for the local people to make a living, overcoming this problem of pollution while maintaining the economy has been a challenge for the government. Despite several efforts made by the government to resolve the health problems associated with e-waste, they were not very successful because the government has to tackle the problem of both the environmental impact and the benefits incurred by the recycling of e-waste as one without the other would disrupt the balance.
Figure 6: Screenshot of South China Morning Post article about the e-waste situation in Guiyu
(https://www.scmp.com/news/china/society/article/2112226/chinas-most-notorious-e-waste-dumping-ground-now-cleaner-poorer)
1.3 Current Measures and their Limitation
1.3.1: Construction of an Industrial Park in Guiyu
The construction of a 1.5 billion yuan (US$233 million) centralized industrial park (Figure 7) by order of regional authorities consolidated 1,243 e-waste workshops that had existed at that time into 29 larger enterprises, and moved the hazardous work away from the town (Figure 8) (Zhuang, 2017). The park’s constant regulation meant that the amount of pollution in the area had decreased. This has allowed residents to live in a cleaner area with better air quality as they live away from the park.
Figure 7: Image of Guiyu Circular Economy Industrial Park
(http://www.recyclingtodayglobal.com/article/ban-guiyu-industrial-park-visit/)
Figure 8: Map of Guiyu (icon indicating where the Industrial Park is built)
(https://ejatlas.org/conflict/guiyu-national-circular-economy-industrial-park)
Limitations: However, stricter regulations has significantly lowered the productivity from 1 million to 150,000 tonnes of recycled e-waste annually (Zhuang, 2017). Additionally, a daily quota is set by the government that limits the production, making e-waste recycling less profitable within the industrial park and forcing some families to recycle illegally in their backyards to earn more money, leading to air pollution. In other words, this ironically leads to the creation of informal recycling activities, which the industrial park was supposed to prevent. Similarly, there would also be pollution created within the industrial park itself, both of which continue to contribute to the pollution.
Thus there is a need to improve the efficiency and convenience of e-waste recycling so that illegal recycling factories will be more encouraged to join the industrial park to reduce their release of pollutants. Hence, productivity can be improved without compromising on the environment.
1.3.2: Licensing of Recycling Centres
Many informal recycling factories in Guiyu are not regulated by the government, resulting in them not adhering to the environmental policies set by the government when they recycle e-waste on their own properties. Hence, the government licensed formal recycling for companies with proper recycling methods and apply tax cuts, while those recycling without license face greater taxes on production depending on the scale. Despite the higher taxes faced by the informal recycling factories, they still recycle illegally as they are able to operate at a larger scale, which increases total profit compared to formal recycling due to selling larger quantity of metals.
Limitations:
However, the relationship between the informal and formal sectors is difficult for the government to take control. If the informal sector is not brought under control, it is futile to build up the formal sector, as there will be very little amount of e-waste sent to the formal sector due to majority of e-waste being sent to informal recyclers as it is cheaper. Consequently, taking jobs away from the informal sector will be just as difficult because producers are profit-driven and it is not beneficial for them to transfer to the formal sector as productive capacity is lower, leading to lower to lower profits which will lead producers to stay in the informal sector.
1.4 Links between Case Study and Existing Measures
Owing to limitations with the existing measures, it can be inferred that inefficient e-waste recycling due to strict regulations and lack of benefit for using a greener method for recycling by informal recyclers are the main factors that continues the pollution through crude e-waste recycling. These issues are addressed in the Case Study, by changing the method used for recycling to balance productivity and environmentally-friendly production.
1.5 Case Study: E-waste crisis in India
As of 2007, India faced a high amount of pollution from improper e-waste recycling due to the informal recycling sector thriving in small peripheral towns. The people of India lack sufficient knowledge and overlook the harmful effects of improper e-waste recycling had led to 95% of the e-waste recycling being carried out by informal recycling centers (Bhattacharya, 2017). Furthermore, the lack of proper technology causes inefficient recovery of metals from e-waste (Chatterjee, n.d.).
Attero is a recycling company that focuses on recycling electronics reaching their end of their lives (e-waste) to extract reusable materials, ensuring that e-waste is processed in an environmentally friendly manner, with high efficiency and lowered carbon footprint, and at the fraction of the costs involved with setting multibillion dollar smelting facilities. (Attero, n.d.)
Thus, with an objective of leveraging technology for a clean and green environment, India’s first integrated, end-to-end electronic waste (e-waste) recycling facility was set up in Roorkee, and became the first e-waste recycler to be registered with the Central Pollution Control Board (CPCB) and Ministry of Environment & Forests, of India. By enforcing zero-dumping on its factories, Attero was able to largely mitigate pollution in Roorkee through its end-to-end e-waste recycling facility (Mehta, 2011).
Lessons learnt: Setting up zero-dump recycling factories proved an important factor in Attero’s success in addressing the e-waste issue in India. This can be applied in our project as we are looking to solve a similar issue of e-waste pollution in Guiyu.
1.6 Source of Design Inspiration: Chromobacterium violaceum bacterium
From the problem identified, we recognise the need to introduce a more productive, environmentally-friendly method of e-waste recycling. Through research, we discovered that scientists from the National University of Singapore (NUS) (Figure 9) have re-engineered Chromobacterium violaceum bacteria to give it the ability to create enzymes that can dissolve useful metals such as gold, from e-waste instead of using acids or melting, which are then recovered through electrolysis. This form of bioremediation not only does not produce toxic metals and chemicals, it is also easy and cheap to reproduce and stays effectively in use for 3 months (Boh, 2016).
Figure 9: Scientists from NUS who are part of the Chromobacterium violaceum research
(https://www.straitstimes.com/singapore/environment/bacteria-used-to-extract-precious-metals-from-e-waste-in-nus-study)
1.7 Derivation of key features in Proposed Solution: Aligning Current Measures, Case Study and Source of Design Inspiration
Gaps from Existing Measures
Learning Points from Case Study
Source of Inspiration
Key Features in Solution
Lacks in providing a cleaner method of recycling rather than restricting e-waste recycling
In order to achieve so many goals, need an integrative system.
Recycling process does not release lead, use of bioremediation.
Pollution is minimised through use of bioremediation in the Bacterium Tank.
Lack in efficiency and productivity of e-waste recycling causes informal recycling factories to sprout.
Use of conventional technology in the recycling processes will be able to help increase efficiency per unit area and convenience.
Bacteria can be produced and multiplied rapidly. Thus, factories will always have constant supply of bacteria.
Bacteria is highly reusable and large amounts can be produced quickly. Hence, bacteria can be used to recycle the e-waste in a clean and efficient manner.
Table 1: Table on application of lessons learnt
2 Aim and Objectives
2.1 Aim
The problem we are tackling is the improper recycling of e-waste in Guiyu, China, and our solution, MicroBactory (a combination of the words ‘bacteria’ & ‘microfactory’), tackles the problem by introducing a form of bioremediation through the use of bacteria to recycle the e-waste cleanly, and includes a compact series of modules in a microfactory that is able to mostly run automatically without much manual work and maintenance. This will allow Guiyu to recycle e-waste without polluting the environment, while minimising the negative impact on economy.
2.2 Objectives
To draw up a detailed proposal for MicroBactory and improve upon it.
By interviewing Dr Jamie Hinks, Senior Research Fellow of Singapore Centre for Environmental Life Sciences Engineering (Refer to Annex A), we plan to ascertain:
a) The effectiveness of the bacterium tank in dissolving metals on an industrial scale operation
b) The effectiveness and durability of the bacterium
c) The feasibility of the collection method of materials produced
To review our proposal for MicroBactory based on all the data we have collected.
3 Proposed Solution: MicroBactory
3.1 Overview of solution
Our product, MicroBactory, is a modified e-waste recycling plant to be used in factories that makes use of bioremediation in the e-waste recycling process. This product consists of several phases (Figure 10): the shredding of e-waste (Phase 1), followed by dissolving of metals (Phase 2) and collection of metals, glass and plastic (Phase 3). The product also contains a supporting element for the production of bacteria.
Figure 10: Overview of MicroBactory
3.2 How MicroBactory reduces pollution in Guiyu
Our product serves as a effective measure in reducing water & air pollution caused by e-waste recycling by minimising the amount of pollutants released into the environment without compromising the productivity of e-waste recycling sector as much as possible. Hence, sustainable e-waste recycling can be achieved. Moreover, Chromobacterium violaceum is easily reproducible, hence the cost of recycling e-waste will be significantly reduced in the long run, making e-waste recycling more profitable.
3.3 Phase 1: Shredding of e-waste
The Waste Shredder (Figure 11) consists of a shredder which shreds by crushing large pieces of e-waste between rotating gears with 0.28m radius and 0.08m thickness (Figure 12) into smaller pieces, increasing the surface area of metals in contact with the bacteria, hence increasing the rate of metal dissolving in the Bacterium Tank (Phase 2). The mouth of the shredder (2.3m by 1m) will be large enough for common e-waste, such as computer monitors or televisions. Then, the shredded e-waste will be transported to the Bacterium Tank (Phase 2).
Figure 11: Sketchup diagram of the Waste Shredder
Figure 12: Gears in the Waste Shredder (0.08m thick, 0.28m radius each)
3.4 Phase 2: Bacterium Tank
The Bacterium Tank (Figure 13) is filled with modified Chromobacterium violaceum solution and shredded e-waste, and also consists of a thermostatically controlled water jacket set at 30°C (Castro et al., 2015). The modified Chromobacterium violaceum bacteria in the Bacteria Tank will dissolve the metals in e-waste, which will then be separated later.
Figure 13: Sketchup diagram showing the overall design of the Bacterium Tank
3.4.1 Thermostatically controlled water jacket
In order to keep the temperature inside the tank constant, a thermostatically controlled water jacket (Figure 14) will surround the tank so as to keep the temperature relatively constant at around room temperature (Castro et al., 2015) in order for the bacteria’s enzymes to carry out the dissolution of metals efficiently. This will be done so through conduction and convection of heat in the water jacket, which is kept constant at 30°C, allowing heat to enter or escape the tank accordingly, keeping its temperature relatively constant.
Figure 14: Sketchup diagram showing the components of the Bacterium Tank
3.4.2 Modified Chromobacterium violaceum: optimal conditions for its application
Chromobacterium violaceum (Figure 15) performs best at 30–35 °C, in a neutral pH and nutrient-rich solvent (water), though it is extremely adaptable to changes in environmental conditions (Castro et al., 2015), it produces the largest amount of enzymes under such conditions so to maximise the overall efficiency of dissolution of metals (30% recovery in 16 – 20 hours). This modified bacteria produces enzymes that can accelerate the breaking down (decomposition) of metals (Boh, 2016) into their separate ions without being chemically unchanged. Thus, the bacteria can be reused in the tank. Eventually, the metals from e-waste will end up dissolved into the bacteria solution (Boh, 2016) in their ionic forms, while pieces of plastics and glass remain unchanged in the container.
Figure 15y: Chromobacterium violaceum bacteria seen under a microscope
(http://microbe-canvas.com/Bacteria.php?p=900)
3.5 Phase 3: Separation and Collection of Materials
3.5.1 Separation of Metals and Non-Metals
After dissolving the metals in the Bacterium Tank, the plastics and glass can be collected as there will be a filter layer (Figure 16). The holes in the layer will only be big enough for bacteria solution and dissolved metals to pass through. Thus, the tank will contain the glass and plastics from e-waste left over from filtration. These will be manually collected and sent to their own respective recycling plants. The metals, which are still dissolved into the bacteria solution, will then be converted into solid pieces on its own (Boh, 2016) in the separation tank and separated according to their melting points.
Figure 16: Separation of materials
3.5.2 Separation of Different Types of Metals
In the Separation Area (Figure 17), metals will be separated using their different melting points: aluminium (660.3°C), silver (961.8°C), gold (1064°C), copper (1085°C), iron (1538°C), palladium (1555°C), platinum (1768°C) and rhodium (1964°C). This is done through liquation, in which the mixture will be heated in a sloping pipe. Metals with lower melting points will turn into their liquid forms and filtered out through separate pipes while remaining metals continue through the pipe with increasing heat until their melting points are reached. Rhodium will be collected last as it has the highest melting point.
Figure 17: Separation of metals
3.6 Collection
The plastics and glass remains in the tank are manually collected by carrying the plastics and glass onto a wooden decking and transported by people (Figure 16) onto a truck. The plastics and glass are not left as waste products as they are sent to their respective recycling centers for sorting which they will then be recycled by converting them into new plastics and glass products. Meanwhile, the separated metals are collected from the separation area and rinsed under cold water to clean and cool the metals down. After that, the metals are transported to the market to be sold for the production of new metal products.
Figure 18: Image of plastics being transported
(https://recyclinginternational.com/plastics/portugal-embracing-hi-tech-sorting-systems-for-plastics/)
3.7 Supporting element: Fermentation Tank
The Fermentation Tank (Figure 19) provides an environment for the bacteria to reproduce, so that the bacteria in the bacterium tank can be automatically replaced every three months (Boh, 2016). This is done by using a timed mechanism which opens up a pipe connecting the fermentation tank to the bacterium tank every 3 months. Meanwhile the bacteria that has been used to dissolve the metals may be reused again by circulating back to the bacterium tank. A similar thermostatically controlled water jacket is used to keep temperature constant at about 30-35°C.
Figure 19: Fermentation tank
The links between these four phases is shown in the flowchart (Figure 20) below:
Figure 20: Flowchart showing how our proposal works and their outputs
3.7 Stakeholders
Even though the government in Guiyu (Figure 21) has chosen to prioritise environment over the local economy, if given the choice, they would rather have both benefits. This is because it will not only increase their revenue, but also help the environmental pollution issue, which is evident from the building of the industrial park. Hence, MicroBactory, which can satisfy the best of both worlds, will appeal to the local government. Furthermore, with the Guiyu industrial park only solving the environmental issue but harming the local economy in the process, it is likely that the local government will have to begin looking for ways to improve the local economy in the future. Thus, the government in Guiyu would likely implement our product.
Figure 21: Government overseeing Guiyu Town
4 Review of Proposal
4.1 Overview of Improvements
The new system will consist of 3 phases, the Waste Shredder (Phase 1), the Bacterium Tank (Phase 2), and the Collection Area (Phase 3). After going through these few phases, the metals in the electronic waste will be separated from the plastics and glass, and ready to be sold. Meanwhile, the plastics and glass will be transported to other plastic or glass recycling factories to be further recycled separately.
[add new overview sketchup diagram here] (Figure 22)
Figure 22: New overview of MicroBactory
4.2 Components of Bacterium Tank (Phase 2)
4.2.1 Change in Bacteria
Chromobacterium violaceum produces cyanide compounds (CN-) which are very toxic, and is a safety hazard (Helmenstine, 2018). Hence, we will be replacing it with Bacillus megaterium (Figure 23) to reduce the safety hazard, since Bacillus megaterium produces lesser amounts of cyanide, is non-pathogenic and thus easier to handle (J. Hinks, personal communication, 10 August 2018). This increases the safety of the MicroBactory making it more user-friendly for industrial use, while maintaining the effectiveness of the bacteria.
Figure 23: Bacillus megaterium bacteria as seen under a microscope with 1000x zoom.
(https://www.flickr.com/photos/occbio/6414376363)
4.3 Improvements in Collection Phase
4.3.1 Separation system
The Filtering System will be replaced with a sedimentation tank (Figure 24). This is because the filter needs to be replaced regularly as plastics and glass pieces may get stuck on the filter, causing a blockage. This will result in the filtration system to be very costly in the long run due to maintenance need and so infeasible (J. Hinks, personal communication, 10 August 2018). Besides, the sedimentation process need no regular replacement, reducing the maintenance cost of MicroBactory
After the bacteria is mixed with the shredded e-waste for 1 day, the ‘sludge’ is then pumped into the Sedimentation Tank where heavier bacteria and solid plastic and glass will sink to the bottom of the tank leaving water and metals ions nearer to the surface of the tank. The solution nearer to the surface is collected for metal recovery while the sludge is collected and filtered to separate out the bacteria for reuse and solid plastics and glass to be sold.
Figure 24: Sedimentation Tank
4.3.2 Recovery of Metals
The collection of separated metals is changed from melting the metals to electrolysis (Figure 25). This is because we have confirmed that the metal ions will not turn back into the solid state by itself (Boh, 2016) and requires external energy (J. Hinks, personal communication, 10 August 2018). Also electrolysis will produce metals with greater purity than separating the metals by their melting point, it is also easier to handle as heating is not involved.
Figure 25: Sketchup diagram of Electrolysis Tank
The metals can be separated using their standard electrode potential as different metal ions get reduced back into their base metals at different voltages. Hence, we can start recovering metals requiring the lowest voltage and increase the voltage progressively.
4.3.3 Improvements in collection of plastics and glass
The collection of plastics and glass is changed from manual collection to collection area (Figure 26). The ‘sludge’ is deposited onto a conveyor belt with small holes that allows the bacteria solution to flow through. Water is sprayed on to the sludge to wash off all the bacteria which is then collected via a drain and reused. The plastics and glass pieces is then dried and sold to other recycling centres for further recycling. This automates the collection of plastics and glass, thus minimising the contact between workers and bacteria. This minimises the chance of bacteria spreading outside the MicroBactory which might be dangerous as it might dissolve away metal building structures.
Figure 26: Diagram showing the components of the Collection Area after change
Figure 26: Diagram showing the collection area before change – to combination inside the microsoft words!!!!!
4.4 Removal of Fermentation Tank
The Fermentation Tank is removed as the bacteria can reproduce from within the Bacterium Tank itself (J. Hinks, personal communication, 10 August 2018), thus removing the need of another tank to produce the bacteria. This will cause the overall cost of MicroBactory to be drastically reduced as the construction and maintenance of the Fermentation Tank is no longer needed.
The flowchart below (Figure 27) summarises the 4 phases in the reviewed MicroBactory:
Figure 27: Flowchart showing how our reviewed proposal works and their outputs
5 Conclusion
5.1 Strength
The main strength of our project would be the use of bioremediation in order to reduce the pollution caused by e-waste recycling and provide a cleaner way to recycle e-waste. This is because bioremediation is a way that can let nature heal itself, and is also a completely natural way of cleaning up contaminants without producing any toxic substances or pollutants (Waste2Water, n.d.). Therefore, bioremediation is a very clean and efficient way to recycle e-waste. We have made use of bioremediation as the main principle of our project, MicroBactory, as it provides us with a method of recycling e-waste that is effective and safe for both the environment and the health of the locals.
5.2 Limitation
A limitation of our project is that although our project provides a cleaner and more efficient method of recycling e-waste, it does not address the root cause of the pollution caused by e-waste, the increasing trend in the amount of e-waste produced in recent years. With an increase in demand of e-waste recycling, it is still unknown whether MicroBactory is able to cope with the increasing demand of e-waste recycling. Hence, another strategy such as public education needs to be implemented for our project to be truly effective.
5.3 Future Developments
Our project can be further extended to the recycling of plastics because there are a huge amount of plastics being wasted. Out of the 8.3 billion tons of plastic produced, 6.3 billion tons of plastics have been turned into waste (Parker, 2017). Since our current project involves the use of bioremediation by using bacteria to break down metals, we can adopt the same idea for the breaking down of plastics. There is a bacterium called Ideonella sakaiensis 201-F6 which secretes enzymes (protein that can speed up chemical reactions) known as PETase which splits certain bonds (esters) in polyethylene terephthalate (PET) into smaller molecules for the bacteria itself to absorb (Flashman, 2018). Hence, we can make use of the same concept as MicroBactory in order to break down certain plastics and reduce the plastic waste problem.