Glass: a successful case study

Glass is an inorganic material that is obtained mainly from silica sand (SiO2, around 70%[1]), calcium carbonate (Ca2CO3, around 15%), limestone (CaCO3, approximately 10%) and other additives, by melting at about 1,500 ºC (2,732 ºF).

According to different sources, glass was first manufactured around the year 3500 a.C. in Egypt other sources indicate its origin to be2500 a.C. in Mesopotamia[2]– as a decorative element, and its different uses have evolved. Thus, glass has been used to manufacture vessels, windows and nowadays, above all, for packaging, specifically for liquids, since it’s a type of packaging that neither interferes nor alters the taste of its contents. We have been manufacturing glass for the last 4,500 years, at least.

Glass is a material that can be fully recycled in an unlimited manner, meaning that you can repeat the process as many times as you want without altering its properties. The color of the glass depends on the type of additives that are put in. You can usually find it in 3 different colors: green, topaz or amber and transparent. Separation or triage by colors can be carried out before starting the recycling process. However, this triage is optional. In facilities such as Barcelona, for example, the bottles are usually crushed or fragmented with the 3 types or colors mixed together. The crushed material is called cullet, which is taken to the bottling factories to be melted in an oven in order to obtain new glass bottles. 60-70% of the glass bottles on the market are green – wine, cava, champagne. Some factories use up to 95% of cullet to manufacture new glass bottles.[3]

The glass is crushed, melted and reused to make glass bottles. The process can be repeated infinitely

In countries like Germany or Ireland, glass is separated by colors. Other countries have even chosen to climb one step higher on the recycling pyramid that we saw in the previous chapter, and instead of recycling glass, they reuse the glass packaging through a deposit-refund system (or DRS).

Around 8% of the household and commercial garbage that we generate is glass.[4]

In 2012, a total of 169,222 tons of glass (the equivalent of 646 million bottles) were recycled (collected separately in green containers) in Catalonia.[5] In Spain,[6] 726,729 tons (2,774 million bottles) and in Europe,[7] 15,700,000 tons (almost 60 billion bottles), more recycling data.

Of the total amount of glass generated in 2012 in Catalonia[8] 70% was recycled(recovery, which includes glass recovered from Ecoparks), along with 69% of the glass generated in Spain[9] and 73% in Europe. There’s no doubt about it, this is excellent recycling data, especially if we compare it with the other fractions, as we will see afterwards.


GLASS recycled (Tn/year)




BOTLLES recycled (millions/year)

646 2774


70% of the glass produced is recycled. A success story that began in 1982

Judging from these numbers, we could say that the history of glass recycling is a success story that has not yet come to an end and that continues to thrive. Little wonder, as the selective glass container was the first one to be placed on the streets, back in 1982, as part of the first recycling campaign in Barcelona.

Want to know more?

 The book Stop garbage. The truth about recycling, Alex Pascual, February 2019

► Recycling glass. Agència de Residus de Catalunya (MUSICAL)

i Recycling data in different regions in Spain (CAST)

i Information about the DRS system (Deposit Refund System) (ENG /CAST)

[1, 2 and 3].“Recycler le verre d’emballage. Porquoi?”Verre Avenir, Chambre Syndicale des Verreries Mécaniques de France
[4]. My compilation from different studies: op. cit.
[5].Generalitat de Catalunya Statistics

[6]. Annual report 2013 Ministerio de Agricultura, Alimentación y Medio Ambiente, Spanish Government.
[7]. EUROSTAT. Official statistics. European Union.
[8]. My compilation from different studies. Official data for Catalonia is 64% but from General prevention and waste management Program in Catalonia 2013-2020
[9]. EUROSTAT. Official statistics. European Union.

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  1. Pingback: The importance of recycling plastic and metal – Stop Garbage

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