Could prawn shells become part of the solution to plastic waste? — Suriani Ibrahim

SEPTEMBER 11 — The next time we peel prawns at the dinner table, the shells will probably go straight into the bin. We rarely give them another thought. Yet those discarded shells contain a natural material that researchers are exploring as a possible ingredient for biodegradable plastics.

At Universiti Malaya, researchers from the Faculty of Engineering have investigated how prawn shell waste can be converted into chitosan, a natural biopolymer, and subsequently used to produce biodegradable plastic films. The work offers an interesting example of the circular economy in practice: taking something usually treated as waste and giving it another useful life.

Biopolymer developed from prawn shells by the author’s research group.

This matters because Malaysia faces two waste problems at the same time. Food waste makes up a substantial proportion of municipal solid waste, while plastics remain another major component of what we discard. The seafood industry also generates large amounts of biological waste, including shells that have relatively little value once the edible portions have been removed.

Prawn shells, however, are not entirely useless. They contain chitin, a naturally occurring substance that can be processed into chitosan. Chitosan has attracted considerable scientific interest because it is biodegradable, biocompatible and versatile. It is already being studied for applications ranging from food packaging and agriculture to biomedical and environmental technologies.

In our study, chitosan was extracted from discarded prawn shells through several chemical treatment stages. The resulting material was then combined with starch and formed into thin bioplastic films using a solution-casting process.

But producing something that looks like plastic is only part of the question. If the aim is to develop a more environmentally friendly material, we also need to know what happens to it after it is discarded.

To examine this, the researchers buried the bioplastic films in soil and observed them for four weeks. After three weeks, visible changes began to appear. The films became smaller, their colour changed and their texture started to deteriorate. By the fourth week, substantial degradation could be observed.

Prawn shell waste can be processed into chitosan and used to produce chitosan-starch films capable of degrading under soil burial conditions. — Pexels pic

These findings demonstrate that prawn shell waste can be processed into chitosan and used to produce chitosan-starch films capable of degrading under soil burial conditions. The significance lies not simply in producing another type of bioplastic, but in connecting two environmental challenges that are usually considered separately.

Waste from one industry could potentially become a raw material for another.

There is, of course, still a considerable distance between producing a promising material in the laboratory and replacing the plastics we use every day. Bioplastics must meet requirements involving strength, durability, moisture resistance, safety, cost and large-scale manufacturing. Further research is therefore needed before materials derived from prawn shells can become commercially viable alternatives for specific applications.

Nevertheless, studies such as this encourage us to reconsider what we call waste. Prawn shells may appear to have reached the end of their usefulness once the meal is over, but their chemical components may still have value.

The broader lesson of the circular economy is precisely this. Solving our waste problem does not always begin with finding somewhere else to put what we throw away. Sometimes it begins by asking whether what we are throwing away could become the starting material for something new.

* The author is an Associate Professor at the Department of Mechanical Engineering, Faculty of Engineering, Universiti Malaya, and may be reached at [email protected] 

** This is the personal opinion of the writer or publication and does not necessarily represent the views of Malay Mail.