What is recycling?
Recycling is the process of converting waste into new materials and objects, thus making them reusable again. In contrast to conventional waste disposal, recycling saves material and reduces greenhouse gas emissions. Also, recycling reduces the consumption of fresh, new materials, energy usage, air pollution and water pollution. Many kinds of glass, paper, cardboard, metal, plastic, tiers, textiles, batteries and electronics are recycable. Also, composting or other reuse of biodegradable waste counts as recycling.
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How is glass recycled?
To recycle glass, it first needs to be crushed into the so called cullet. Then it gets separated into recycable and unrecycable glass. The unrecycable cullet is called "Internal cullet", the recycable glass is called "External cullet". The external cullet then gets purified and cleaned of contamination, like paper, stones, metal and heat resisting glass. Depending on the end use and local processing capabilities, it might have to be separated into different colours. Thats becaus glass retains its colour even after recycling. Not separating it can lead to unwanted colour shifts or instability. After this process is finished, the glass gets melted and remanufactured.
Glass is ideal for recycling, because the material isn´t degraded by normal use.
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How is paper recycled?
Paper is recycled by mixing used or old paper with water and chemicals. This breaks the paper down after which it´s chopped up and heated. This breaks it down even more. The paper now has the form of strands of cellulose. This so-called "pulp" is strained through screens to remove plastic or glue that may still be in the mixture. After that it´s cleaned, de-inked, bleached and mixed with water. It can now be re-manufactured.
There are three different types of paper scrap. "Mill broke" is scrap material from paper production. "Pre-consumer waste" is paper that left the Paper mill but got discarded before usage. "Post-consumer waste" is used scrap paper like newspapers or old magazines.
Most of the time, paper scrap is manufactured into moulded pulp, a typical packaging. It can also be manufactured into plates and bowls.
Cardboard has the same recycling process.
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How is metal recycled?
Metal scrap is treated a little bit differently depending on size. Bulky and difficult to process metal pieces first have to be downsized. For this they are brought to the "scrap shears", which cut the pieces. Depending on whether the metal was from electronic or mechanic scrap, the metal isn´t brought to the shredder but is cannibalized for batteries and other reusable parts. All fluids are drained and the metal is shredded into fist sized pieces. Those are separated into heavy and light metal by a special technique using air. The heavy metal comes down while the light metal is pushed to the top. The material is then separated into magnetic and unmagnetic metal using a big magnet. Material density, colour and conductivity are used to separate non-ferrous metals. The material gets crushed into small pieces and is sorted out with a specific system involving dunking the scrap.
After the different metals are separated, they are brought to the right smelters and melted for re-manufacturing.
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How is plastic recycled?
Roughly, there are two different ways of plastic recycling. The first way is the mechanical way, called "chop and wash". The plastic is washed and grounded into powder. After this, the powder is melted. The second way is to break the plastic down into its basic components, using various chemicals.
Most of the time, the plastic is sorted due to plastic tending to form different layers if mixed together with other plastics. Methods range from manual picking to complex spectrophotometric distribution technologies.
After sorting, the plastic is shredded and undergoes a process to eliminate impurities. The shreds are melted and poured in the form of small pellets. Those are send to re-manufacturing.
The major downside of recycling plastic is that you can´t recycle them unlimited times. After one or two times, most plastics are too low of quality. Also, new plastic has to be added every time.
Exeptions exist were the plastic can be broken down into its chemical building blocks. Those plastics can be recycled hundreds of times.
Biodegradable plastics are used for short-lived packaging applications and can be recycled in industrial composting.
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How are tires recycled?
The recycling of tires starts, like so often, with reducing the size of the waste. After shredding, the parts are cooled to extremely low temperatures causing them to become brittle. After that they are pulverized and screened for large chunks of rubber or polymer. The remains are separated into fibers and magnetic material. This is done by using a magnetic and a vibrational separator. After that the materials are recycled on their own.
This environmental friendly process allows the recources to be used unlimited times.
But the tires often aren´t turned back into tires but are used as "Secondary fuel" in cement manufacturing.
Tires hold flammable parts like carbon black, rubber and polyester. The iron in the tires replaces iron ore or blast furnace slag wich is needed for cement.
Another way to recycle tires is to separate them into their ingredients. Tires hold 67% rubber, 18% steel, 14% textile and 1% rest and stones from the profile. Each ingredient is then recycled on its own.
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How are textiles recycled?
In textile recycling, yarn or fabric is recovered and then transformed into useful products. Those products can vary from production of energy and chemicals to new textiles. Like in paper/cardboard recycling, there is a mechanical and a chemical way to recycle textiles.
The more common, mechanical way first separates the cotton from the remaining components. The raw material then is sorted by colours to avoid the need to bleach and re-dye. The following process involves shredding and separating the material by fibers. Before the product can be re-spun, the fibers have to be aligned. Due to recycled cotton fibers being shorter and lower in quality virgin cotton fibers have to be added. The recycled material can now be re-manufactured into sellable products.
Another material that is regained out of cloths is polyester. Due to polyester and PET plastic bottles being made out of "polyethylene terephthalate" they share their recycling process.
Polyester can also be recycled using chemicals. Like in plastic recycling, the material is broken down and recreated using different chemicals. This removes all unwanted components, making it decontaminated. It´s re-polymerized and used to produce textile products. This process doesn´t require new fiber to be added to the material.
The process of recycling nylon and cellulose based fibers uses different chemicals.
Sorting is organized in 6 classes. First there are diamonds, being used on designer clothing. Most of the time they are the most profitable.
Second comes "Incineration for energy". Textiles that are unprofitable to recycle are used to produce energy. Their calories are comparable with oil.
After that comes "Wiping and polishing cloths", where the unwearable material is re-manufactured into cleaning articles.
The fourth layer is called "Conversion to new products". The textiles that are unable to be resold are recycled and turned into new products.
Fifth is "Second hand clothing exportation markets" where already used clothing is collected and resold.
Last comes "Crude sorting". Many clothes still in good shape are thrown away because they aren´t as pricy or "In" as they used to be. In crude sorting, waste items are separated into distinct categories and are put back into the market.
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How are batteries recycled?
At the moment, there is no cost-neutral way to recycle batteries. Despite this,there are some battery types that get recycled very frequently, like lead–acid or lithium-ion batteries.
Lead-acid batteries are mainly used in automotives industry, powering vehicles. They are recycled by grinding, neutralizing the acid and separating the remaining parts from the lead. The regained recources are then used to create a variety of products, including new batteries.
Silver oxide batteries contain mercury, more commonly known as quicksilver. The focus during recycling is to regain the mercury due to it being very toxic. If not disposed properly, it could lead to water and ground pollution. Silver oxide batteries are used in watches and toys.
Lithium ion batteries require a more complicated recycling process. They contain valuable metals and rare earths. This makes it very important to recycle them in the most effective way.
To recycle a lithium ion battery, it first has to be discharged and disassembled. After that, the parts undergo a process of crushing, sorting and sieving. Lastly the remaining ores are heat treated and obtained.
Other than Lithium-ion batteries, Pouch cells are particularly easy to recycle.This leads to some people ,despite safety issues, salvaging the included copper .
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How are electronics recycled?
During e-waste recycling, electronic devices are disassembled and salvaged of valuable recources. Re-using, donating or repairing is not listed as recycling. The waste comes from not functioning devices or devices that got replaced.
The main goal is to retain valuable recources, built into the device. The waste is disassembled, striped of plastic and purified to eliminate any contamination. The material then is resold or used in new devices.
Recycling electronics can also be cannibalized for still functioning parts. Other than the former mentioned process, this can be done at home. The still functioning parts can be reused and sold, reducing replacement costs. The not working parts then can be recycled by e-waste recycling.
The circuit boards used in electronic devices are also recycled. They contain a high proportion of copper, some times gold and other metals. In theory, the plastic covering the metal could also be recycled. Of course, if not unusable, still functioning circuit boards can be reused.
Electric wires can also be recycled. Most of them are made out of copper, wrapped in an isolating layer. If defect, the copper can be regained or the still working cables, again, can be reused.
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How is biodegradable waste recycled?
In general, biodegradable waste is organic matter. The waste is broken down into carbon dioxide, water, methane or simple organic molecules. This is done by micro-organisms and other living things. This process happens during composting, aerobic digestion, anaerobic digestion or similar processes.
In waste management, there also are some inorganic materials that can be decomposed by bacteria. Examples are gypsum and other simple organic sulfates. Those materials won´t be recycled by private households, but by professionals.
