Shellfish waste holds opportunities for recycling

Absorbing seafood waste into the circular economy

SOUTH AFRICA: The seafood industry produces mounds of chitinous waste from its shellfish every year that scientists at the Council for Scientific Research (CSIR) are aiming to recycle into eco-friendly products.

According to Prof Suprakas Sinha Ray, scraps from lobster, prawns and other shellfish have promising applications and that chitin derivatives can be used in fireproof fibres and plastics, which could be incorporated into firefighter gear and building materials. 

Chitin is a hardy biological molecule that fortifies the exoskeletons of crustaceans and insects.  

Through chemical engineering, chitin can be converted into chitosan, a polymer that can be woven into other common synthetic polymers, such as those used to produce fabrics or PVC pipes. 

Ray says the chemical conversion of chitin to chitosan is well-established and that scientists already know about chitosan’s fire deterrent properties: its unique structure can block oxygen and therefore combustion, and when it does burn, it turns into char, stopping fire in its tracks. 

Currently working on how to extract chitin from shellfish waste and how to incorporate chitosan into useful products, Dr Lucia Steenkamp’s team at the CSIR’s Industrial Biocatalysis Hub in Pretoria has developed a method to isolate chitin from waste collected at seafood production facilities.

They have also optimised a commercial method of chitosan production using less chemicals, with less waste and ten-fold less water. 

“We already have some samples produced from shellfish, using crustacean waste received from Mozambique,” says Steenkamp. “We first made the chitin and then different chitosans. Langoustines, for example, yield a slightly different product than prawns, and the down-stream process yields different chitosans.” 

Collaborating with other research institutes and industry, the CSIR plans to develop chitosan-based products and seek approval for viable ones from the South African Bureau of Standards.  

One of the products they are exploring is fire-retardant materials. Ray says they will test the market for fire-retardant products, but he is confident that sustainable alternatives to existing products are in demand. 

“In most countries, conventional chemicals used in fire retardants, like bromide, are banned,” he says. “But our challenge here is that there is no alternative yet. So, our goal is to develop a local, high-value product that is produced cleanly from waste streams and does not harm human health or the environment.”  

While Ray describes chitosan-based fireproofing as a circular economy project that is still in its infancy, many other green materials developed by the CSIR, including an agricultural mulch film, antimicrobials and bio-packaging for foods, are already at advanced stages for commercialisation. 

President makes new appointment to stabilise authority Mauritius positions itself as a bunkering hub