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Clean and efficient recycling of electronic waste

The level of recycling of electronic waste is very lower than the level required in order to reduce its impact on the environment and human health, this is in light of the fact that it is not economically viable. Researchers from Japan are trying to change this situation

Electronic waste dump. Photo: shutterstock
Electronic waste dump. Photo: shutterstock

[Translation by Dr. Moshe Nachmani]

While the amount of electronic devices in our world is increasing, finding effective methods for recycling electronic waste is becoming an increasingly significant problem. Almost fifty tons of e-waste is produced every year, with only twenty percent of it being recycled. Most of the remaining eighty percent end up in landfills, where this waste can become an environmental problem. Today, recycling of electronic waste involves the use of mechanical shredders and toxic chemical solutions, two expensive methods that also require skilled personnel, and which can cause significant problems in terms of human health and the environment if they are not carried out properly. Following this situation, researchers from a university in Japan are trying to utilize the method of explosive electrical discharge in order to develop a more efficient and cleaner recycling method. Pulsed power has been proven to be a successful method in the processing of a variety of waste materials, from cement to polluted water.

A picture of a plasma discharge in the first second showing the effect of the discharge on the metal layer (blue color) and the plastic layer (orange color) [courtesy of Prof. Hamid Hosano].
A picture of a plasma discharge in the first second showing the effect of the discharge on the metal layer (blue color) and the plastic layer (orange color) [courtesy of Prof. Hamid Hosano].
In order to test the ability of this method to be used in the recycling of electronic waste, the researchers tested its effectiveness in separating components found in one of the most common types of electronic waste - CDs. In their previous study, the researchers showed that complete separation of the metal from the plastic occurs using thirty pulses of energy of 35 joules per pulse (at the current rate of electricity in Tokyo, this supply of energy amounts to 0.4 yen for the recycling of 100 CDs).

In order to examine the mechanism of the separation of the materials using this method, the researchers performed additional analyzes within the framework of observations of the plasma discharge using an extremely fast camera, while obtaining images that will help in measuring the movement of the various segments. Images of the initial phase of the electrical discharge showed two distinct light emissions: blue-white light (metal) and orange light (plastic). These emissions indicate electronic excitation of aluminum and the upper protective plastic layer, respectively. After the plasma was dispersed, pieces of metal and plastic were seen ejected from the CD sample.

Images were obtained during the process and revealed that the most destructive shock waves developed around the two electrodes. The waves created a pressure of over 3.5 MPa near the ends of the electrodes and immediately decreased to a pressure lower than 0.8 MPa. "Electronic waste constitutes one of the most important recycling problems we face every day, due to the comprehensive and comprehensive nature of this waste," explains the chief researcher. "Our research demonstrates the importance of surface waves for peeling and separation in electronic waste recycling processes. We believe that our research data will be important in the development of future recycling projects." The research findings were published in the scientific journal Waste Management.

Abstract for the article

The news about the study

A picture of a plasma discharge in the first second showing the effect of the discharge on the metal layer (blue color) and the plastic layer (orange color) [courtesy of Prof. Hamid Hosano].

6 תגובות

  1. Dear Tzah,
    You raised an obvious question, although it is indeed a "complete question":
    1. Do you really want to concentrate all the toxic metals (hexavalent chromium, and indium, mixing different types of strong oxidizing acids, radioactive substances, carcinogenic and deadly corrosive substances, transition metal ions such as mercury and lead, normal biological waste - in addition to all consumer product waste the home ones, and more and more...) at the exact same point?
    2. What about the enormous ecological damage in the event that an eruption of such a polluted volcano takes place? After all, you emphasized in your question that all waste must be thrown into an active volcano...
    3. Further to the first argument: Do you intend to evacuate tens of millions of people, all of whom live on the slopes of volcanoes and in their surroundings (not only the Europeans but also - and even mainly - all the rural residents who live around the "Ring of Fire" in the Pacific Ocean)?
    4. What about the (inevitable) pollution that will be caused in the transportation routes for all types of transportation (trucks, ships, trains, containers, etc.) in residential areas and rural areas due to accidents and leaks of various kinds?
    5. I must point out that I can't even imagine the costs of transporting the waste!
    6. The logistics of transporting waste from 192 countries that exist today to tens of thousands of carefully selected sites around the world will require the use of supercomputers and/or quantum computers of enormous dimensions that have not yet been invented!
    7. Why do you think that countries (like Italy in Europe and Hawaii in the USA), where there are active volcanoes, would agree to store the waste of the rest of the world (or even part of it) in their territory?
    8. And finally - the winning argument, which dwarfs all the other arguments against Tzach's proposal: the difference between the orders of magnitude of the amounts of human waste produced in the entire world compared to the number of volcanoes where the waste is deposited is simply incomprehensible: even if we assume that there are 10,000 in the entire world - or even 100,000 - volcanoes that could be used as "dumps" for human waste - after all, within a few days or weeks they will be filled! what will you do then In my opinion, the logic behind your approach to the destruction of human pollution will lead to the fantastic solution in which "septic tanks" with a diameter of hundreds of meters and a depth of hundreds of kilometers will be drilled, in order to introduce the waste into the mantle or even the core of the earth - where everything will burn and decompose.
    In short: Let's call your plan "Plan T" - that is, the absolute last resort for destroying waste, after all other other ideas - and no matter what they are - fail.

  2. Your question is over. Why don't all types of garbage, plastics, electronics, etc. be deposited in active volcanoes. Transportation is problematic, but a permanently active volcano will recycle everything,

  3. This is indeed a nice article dealing with separating the plastic from the aluminum in CDs. I agree with Rafi that it works well in the laboratory, but it is not certain that an industrial plant could use such a technique due to the high cost of the inert electrodes (made of rare metals, which are usually made of pure platinum) and the need to renew and replace them frequently), of course the cost of the electricity consumed in the process must be added , and above all: the difficulty of transferring this technology from the laboratory (where, in my estimation, no more than a few grams are separated each working day) - but the factory will have to separate no less than thousands of kilograms of plastic from the aluminum each working day.
    But the most important reason for the lack of interest in this method is that nowadays CDs are hardly used - after all, the disk-on-key can store huge amounts of information in a smaller volume compared to CDs and is also less fragile than them. In fact, almost every laptop you want to buy today no longer has CD/DVD drives but only USB connections of various types. In other words, the problem of having to recycle CDs was solved with elegant simplicity: we just stopped using them! ?

  4. It is not clear how the described process will assist in large-scale e-waste recycling.

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