Paper recycling

Paper is the most recycled material in the world. We recycle more paper than plastic, glass and aluminum combined. In some countries, where recycling is still not very wide-spread, people still recycle paper. Recycling 1 kilogram of white (printing or copier) paper saves slightly more than 2 kilograms of wood. At the same time recycling 1 kg of gray paper (i.e. paper used for printing newspapers) saves about 1 kg of wood. On many sources you can find a relation of kilograms of recycled paper with the amount of saved trees. This comparison is, however, rather meaningful. Tree sizes vary significantly, therefore, such a comparison can result in very different outcomes. It has, however, been estimated that recycling half of the paper currently used by humanity, would save around 81,000 km² of forestland [1].

Paper recycling

What can recycled paper turn into?

Have you ever heard the following phrase: “Paper has seven generations”? This phrase refers to the amount of times it can be recycled. The quality of paper is defined by the length of its fibers. The longer the fibers – the higher the quality (or grade). Usually, the more times the paper has undergone the recycling procedure – the shorter its fibers. Therefore, a general “rule of thumb” is: the grayer the paper – the more recycling cycles it has been through. For example, newspapers and paper-towels represent the lower grades, since they usually make use of recycled paper. White paper for the printers is, on the other hand, usually of the highest quality – not yet recycled at all. After five to seven recycling cycles, the fibers become too short to make new paper and addition of new fibers is necessary to create paper.

One of the most popular usages of recycled paper is pulp or molded fiber packaging. However, various other usages of scrap or recycled paper exist. Among them the previously mentioned newspapers and paper towels, as well as egg cartons or grocery bags.

Recycling procedure.

The process of paper recycling consists of several stages.

  1. The first stage is paper collection. The biggest amount comes in a form of used paper from the consumers. However, paper trimmings from the manufactures also end up in the recycling process. Furthermore, some paper is discarded after it left the production site  but before it reaches the customer. That paper usually ends up collected for recycling as well.
  2. The second stage is sorting the paper according to its grade. As discussed above, the length of the fibers defines the grade of the paper.
  3. After sorting comes storing in the recycling facility or “recycling mill”.
  4. Consequently, some chemicals are added to the paper to remove the leftover admixtures. These admixtures can include aluminum, ink and other contaminants.
  5. Then special machines cut the paper into small pieces and heat these pieces up. This breaks paper down further into fibers. The resulting mixture has the name of pulp, or slurry. Dedicated screens then remove any impurities that may still be in the mixture. Then the mixture is cleaned, de-inked, bleached, and more water is added to it.

 

 

 

[1] EarthWorks Group. 1990. “The Recycler’s Handbook”. Berkeley, CA: The EarthWorks Press

Types of plastic: part 2

In Part 1 of Types of plastic you can find information about the three most used types – PET, HDPE and PVC. The provided information includes the most common uses, the dangers, ways to recycle and, finally, our advice on whether it is safe to use. This post will give similar information on four other relatively wide-spread plastic types.

plastic trash

4. LDPE -Low Density Polyethylene

LDPE plastic

Similar to HDPE (and also belonging to polyethylene family), this type of plastic is considered one of the safer ones. You can find LDPE in various bags – grocery and garbage bags, frozen food or dry cleaning.  Coatings for paper milk cartons and hot & cold beverage cups also contain LDPE rather often. Among the more rare uses are wire and cable covering.

As mentioned above, LDPE is one of the safer plastics, due to the fact that it is relatively stable. However, some studies demonstrated a possibility of leaching estrogenic chemicals (also similar to HDPE). The chances of chemical release increase under the influence of ultraviolet radiation – a.k.a. sunlight.

Recycling of this plastic is rather rare as well, due to the fact that the procedure is expensive and inefficient.

Conclusion: relatively safe.

5. PP – Polypropylene

polypropylene plastic

Polypropylene has similar applications as polyethylenes – mainly food packaging. This plastic is considered to be more heat resistant, therefore, it is used to pack warm food. like takeout meals. Among other uses of PP are yoghurt containers and medication packs.

Due to the high heat resistance PP is unlikely to leach chemicals. Despite that common consideration, at least one study has demonstrated the opposite. The study considered PP in the labware for scientific experiments. Therefore, it is not exactly clear what the release probability is from your everyday yoghurt container.

Polypropylene is often mixed with other resins, therefore, it is difficult to separate and recycle it. Recycling rates are thus very low.

Conclusion: relatively safe. Only one study showed leaching of chemicals, and that only when used in scientific experiments.

6. PS – Polystyrene

PS - Polystyrene - plastic

Another popular name of polystyrene is Styrofoam. Among the widespread uses are food containers and egg cartons, as well as disposable cups and bowls. Bike helmets and disposable cutlery are among the more rare uses, alongside with house smoke detectors and dvd cases.

Polystyrene is known to leach styrene, which is a human carcinogen. Moreover, it can damage your brain and nervous system. These effects can take place when PS is part of a food container composition. The styrene release becomes more pronounced when PS contacts warm foods, therefore, take-away food packages or coffee-mugs are the worst! Despite that fact polystyrene is often used for these applications exactly. If we still haven’t convinced you, note that styrene is also present in second-hand cigarette smoke.

Recycling rate of PS is very low due to the fact that it is difficult to recycle.

Conclusion: Better to avoid it altogether.

7. Other

Image result for plastic 7 other

This category does not refer to any plastic in particular. Sometimes it stands for a mix of previously discussed plastics, sometimes – for other compounds, including bioplastics. Very often PC – Polycarbonate is marked with 7, however, that is not exactly correct, since PC is just one example. Without going into too much detail we can advise you to avoid PC, since it leaches bisphenol A (BPA).