Search Bar

In vogue

A first step towards integrating marine plastics into urban recycling

A study by the University of the Basque Country (UPV/EHU) has assessed the technical feasibility of automatically separating marine plastic waste

  • Research

First publication date: 12/12/2024

From left to right Amaia Mendoza, Galder Kortaberria and Cristina Peña. | Photo: UPV/EHU.

The UPV/EHU’s Materials + Technologies research group analysed the possibility of incorporating coastal marine litter into the urban solid waste management system, which would allow it to be subsequently recycled. The results reveal that the efficiency of separating poly (ethylene terephthalate) (PET) bottles –one of the most common types of marine plastics– of marine origin is both effective and successful.

In response to the millions of tonnes of marine litter, mostly plastics, floating on the oceans, the need to manage this waste effectively is more urgent than ever. Faced with this reality, the UPV/EHU’s Materials + Technologies research group decided to take a first step. “We assessed a practical approach: the possibility of integrating plastics collected from the sea into the urban waste system. This pioneering study, which is part of a PhD thesis, explores the possibility of managing this waste efficiently in current urban recycling infrastructures,” explained Cristina Peña, lecturer in the Department of Chemical and Environmental Engineering at the Faculty of Engineering, Gipuzkoa (UPV/EHU) and author of the work.

Unlike municipal solid waste, marine litter does not yet have a systematised management system; it is managed on a very ad hoc basis and within the framework of very specific projects. “It is important to bear in mind that this waste, having been at sea, has a level of degradation that is significantly different from, for example, a bottle deposited in a yellow container under normal conditions. So our starting point and key question was precisely this: Does the level of degradation of marine waste prevent it from being classified in an urban waste management process?” as Amaia Mendoza, a researcher in the UPV/EHU’s Materials + Technologies research group, pointed out.

PET plastic bottles

“In this work,” Amaia Mendoza went on, “we used identical PET plastic water bottles of the same brand to assess the effects of various environmental conditions. We divided the bottles into two batches: the first batch was left in the open air for nine months, simulating exposure on a beach or rocky coast, and the second batch was submerged in the sea for the same period. We saw that the submerged bottles underwent increased chemical degradation, while those exposed to the open air on the “shore” remained in a better state”. This approach allowed them to analyse how the degradation process varies according to marine conditions and how each type of waste responds in different environments.

We then “simulated how these materials would be managed in an urban solid waste treatment plant” by comparing them with the same bottles that had not undergone degradation to see if the automatic separation equipment in these plants would be able to identify and separate the plastic bottles of marine origin. “To find out, we conducted tests using an optical separation system, a type of technology that automatically classifies materials according to their composition,” and they saw that the effectiveness of separating the bottles of marine origin –both those exposed to the open air and those submerged in the sea– “was very high, comparable to that of bottles from urban waste”, said Amaia Mendoza. “These results indicate that the treatment of marine bottles in these plants is feasible and could be successfully implemented. The state of degradation is crucial when determining the feasibility of subsequently recycling them,” stressed the UPV/EHU researchers.

The authors of the work say that “the study has achieved an important breakthrough by demonstrating that PET plastic bottles of marine and urban origin can be separated in a joint process, thus establishing a first step in an area with huge potential for development”. It also “opens up the way to exploring the automatic separation of other plastics present in marine litter, such as polypropylene or polyethylene, in urban waste treatment plants”, added Amaia Mendoza.

The UPV/EHU team stresses that this work set out to evaluate the possibility of upgrading marine litter by making it attractive as a usable raw material. “If we manage to find practical applications and encourage the industrial development of these materials, collecting them will also become attractive. The more efficient and viable the management of this litter is, the greater the incentive to use it and, consequently, the greater the interest in collecting it from the sea,” said Cristina Peña.

Additional information

This study is based on the PhD thesis of Amaia Mendoza-Larrañaga, who belongs to the Materials + Technologies research group of the Department of Chemical and Environmental Engineering at the Faculty of Engineering, Gipuzkoa (UPV/EHU). The thesis was written up under the supervision of Cristina Peña-Rodriguez and Oihane Cabezas-Basurko. Cristina Peña-Rodríguez is a tenured lecturer in the Department of Chemical and Environmental Engineering and director of the University-Business-Society Classroom at the Faculty of Engineering, Gipuzkoa.

Bibliographic reference

Legal information

As Campusa is part of the website of the UPV/EHU-Universidad del País Vasco/Euskal Herriko Unibertsitatea/University of the Basque Country, it is regulated by the said website’s General Conditions of Use that can be accessed at www.ehu.es/es/lege-oharra

The existence of these General Conditions of Use does not exclude the presence of other provisions or conditions of access to the various sections that comprise the UPV/EHU’s website. In this respect, Campusa uses third-party cookies to share content via the social networks facebook, twitter and linkedin. To conduct this content sharing, identification in the relevant social network is required and this entails authorising the social network to store a persistent cookie. This cookie remembers your identification in the service and makes access during subsequent visits much faster.

If you continue browsing, we assume that you accept our Cookie Policy in accordance with the following rules of use:

Cookie policy

This web page uses third-party cookies. Cookies are small text files generated by the web pages you visit and which are stored on your computer or mobile device. They contain data pertaining to your browsing that may be of use on the said web page later on. That way, the web site recalls information about your visit and this can facilitate your next session and make the website more useful for you.

How do cookies work?

Cookies can only store text that on the whole is always anonymous and encrypted. No personal information whatsoever is stored on a cookie and they cannot be associated with an identified or identifiable person.

These data enable a website to maintain its information between pages, and also to analyse the way of interacting with the website. Cookies are secure because the only information they can store is what is provided by the browser, what the user has input into the browser, or what is included when a page is requested. They cannot execute code and cannot be used to access your computer. If a web page encrypts the information of the cookie, only that particular web page can read the information.

Types of cookies

1. According to the organisation that manages them:

Depending on which organisation manages the equipment or domain that the cookies are sent from and processes the data obtained, we can distinguish between:

  • Own cookies: They are the ones sent to the user’s terminal equipment from equipment or a domain managed by the editor itself and from which the service requested by the user is provided.
  • Third-party cookies: They are the ones sent to the user’s terminal equipment from equipment or a domain that is not managed by the editor, but by another organisation that processes the data obtained via the cookies.

The cookies cannot be regarded as own cookies if the information gathered through them is managed by a third party, even though the cookies themselves have been installed from equipment or a domain managed by the editor itself.

2. According to the time during which they remain activated:

According to the time during which they remain activated on the terminal equipment, we can distinguish between:

  • Session cookies: They are a type of cookie designed to collect and store data while the user accesses a web page. They are usually used to store information that is only worth preserving in order to provide the service requested by the user on a single occasion (a list of products purchased, for example).
  • Persistent cookies: These are a type of cookie by means of which the data remain stored on the terminal and can be accessed and processed during a period specified by the organisation responsible for the cookie, and which can range from a few minutes to several years.

3. According to their purpose:

According to the purpose for which the data obtained through cookies are processed, we can distinguish between:

  • Technical cookies: They are cookies allowing the user to browse a web page, platform or application; the use of the different options or services that exist may include the following: monitoring data traffic and communication, identifying the session, accessing the restricted access areas, recalling the elements that make up an order, executing the purchasing process of an order, carrying out requests to enrol for or participate in an event, using security elements during browsing, storing content for the dissemination of videos or sound, or sharing content over the social networks.
  • Personalisation cookies: They are the ones that allow the user to access the service with certain pre-specified features of a general nature depending on a number of criteria of the user terminal such as, for example, the language, the type of browser through which the service is accessed, the regional configuration from where the service is accessed, etc.
  • Analysis cookies: They are the ones allowing the organisation responsible for them to monitor and analyse user behaviour of the web sites to which they are linked. The information gathered through cookies of this type is used to measure the activity of the web sites, application or platform; this is then used to draw up browsing profiles of the users of the said sites, applications and platforms and thus introduce improvements based on the analysis of the data on the use that the users make of the service.

How to manage the cookies on your equipment: disabling and eliminating cookies

All Internet browsers allow you to limit the behaviour of a cookie or to disable cookies within the browser configuration or options. The steps for doing so vary between one browser and another, and instructions can be found in your browser’s help menu.

If you do not accept the use of cookies, this option can be set thanks to your browser’s preferences or settings menu, and this website will continue to function satisfactorily without the use of them.

You can allow, block or eliminate the cookies installed on your equipment by setting the options of the browser installed on your computer:

Through your browser you can also see the cookies that are stored on your computer and delete them as and when you see fit. Cookies are text files, you can open them and read the content. The data inside them are nearly always encrypted with a numerical code that corresponds to an Internet session, so very often they only make sense for the web page that wrote the text. 

Informed consent

The use of this web page implies that you are giving your express, unequivocal consent to the use of cookies, according to the terms and conditions provided for in this Cookie Policy, without prejudice to the measures for disabling and eliminating them that you may adopt and which are referred to in the above section.