Last year, the CSIR received the UN’s highest environmental honour when it was named one of five Champions of the Earth for 2023 for its efforts to develop and apply solutions to plastic pollution. Photo by Delwyn Verasamy
The medical diagnostic kit prototype that Maya Jacob John held looked identical to its throwaway plastic counterpart. Except hers was entirely compostable.
Conventional diagnostic kits are made from ABS, a petroleum-based polymer, which takes “forever to degrade”, according to John, principal researcher at the Council for Industrial and Scientific Research (CSIR).
“These [diagnostic kits] are single-use plastic products, so once you use it, you just throw it away … But they can be replaced using this compostable kit, which is a plant-based compilation. After use, you just bury it in your garden in a home compost and it will disappear within six to seven months.”
At their state-of-the-art labs in Pretoria, John and her team of scientists are developing compostable products to replace single-use products that are not recycled.
This includes products in the biomedical, agricultural and food packaging sectors.
“For all those products, which cannot be recycled because it’s contaminated with some sort of waste, compostable plastics are a really good option.”
These environmentally sustainable products are partially made from local biomass resources, such as starch and cellulose, and are biodegradable in home or industrial composting conditions.
“In this particular case [compostable diagnostic kits], a biomedical company was quite interested and they did further testing, which was quite successful. The company wants us to change the colour to green and we’re working on that.”
Highest honour
In October, the CSIR received the UN’s highest environmental honour when it was named one of five of the 2023 Champions of the Earth for its efforts to develop and apply solutions to plastic pollution. It was awarded in the science and innovation category for its use of “cutting-edge technology and multidisciplinary research to develop innovations to tackle plastic pollution”.
“It is a pioneer in identifying sustainable alternatives to conventional plastics, establishing opportunities for local manufacturing and economic development and testing plastic biodegradability,” the UN Environment Programme said (Unep).
In 2022, the CSIR was the first to use Pathways, a software application developed by The Pew Charitable Trusts and the University of Oxford to evaluate local strategies to reduce plastic pollution, Unep said.
Its findings contributed to a report aimed at policymakers, which found that South Africa could slash plastic pollution by 63% by 2040 with interventions across the value chain. Those include limiting the demand for plastic, using alternative materials and increasing waste collection.
Plastic toll
CSIR data has found that South Africa’s rising population and increased consumption means that, without urgent action, plastic pollution is set to almost double to 865 000 tonnes in 2040 from 491 000 tonnes in 2020.
Globally, more than 8 million tonnes of single-use plastics are dumped in landfills or the oceans each year, where they persist for hundreds of years.
According to the CSIR, bio-based materials, derived from renewable sources, present a solution to plastic pollution, reducing greenhouse gas emissions and contributing to a circular plastics economy.
“It’s been shown that the greenhouse gas emissions when it comes to plant-based polymers is about 75% less than conventional plastics,” John said.
While more expensive than traditional plastic, “we go to the companies making these [conventional plastic] products and ask them to do runs on our materials to show them these can be made on the industrial line you have, that you don’t need to make any changes or any Capex investments to adopt this material”.
Agricultural advances
In the agricultural sector, farmers who plant seeds for strawberries, lettuce and sweetcorn, for example, lay down plastic mulch film, to help crop growth and to reduce evaporation, among others.
“The problem is, after the crop is harvested, the farmers have to physically remove this and then prepare the field for the next cycle. That’s quite expensive.
“What we thought of was mulch films from plant-based biopolymers that are soil biodegradable so that, after your crop is harvested, that mulch film will biodegrade into the soil, so then the farmers don’t have to go through the process of additional labour of getting this all out and being ready for the next cycle.”
John said plastic agricultural mulch films are thin and can slowly disintegrate, forming microplastics that can pollute the soil, and because they’re light, they can be easily transported elsewhere.
She and her team went a step further. “Crops have different life cycles. Some biopolymers might biodegrade eight months in the soil and, if your crop is a short-term crop and gets harvested within three months, then it doesn’t serve its purpose.
“We have developed mulch films with additives that can actually accelerate or retard the biodegradation, depending on the life cycle of the crop. If it’s a short-term crop, like three or four months, then you have a mulch that will also biodegrade at the same time.”
The CSIR is working with the Agricultural Research Council and the University of Nigeria, who are doing field trials.
‘Greenwashing’
Last year, the UN Industrial Development Organisation (Unido) and the government of Japan donated biodegradation assessment laboratory equipment to the CSIR. It hosts the only laboratory in Africa equipped to test and verify imported or locally produced products that are being touted as biodegradable.
“The Unido-funded testing laboratory is capable of establishing the conditions and timeframes for the biodegradation of materials,” John said. “Tests can be performed under different conditions — aerobic (compost, soil, freshwater and marine) and anaerobic.”
Several products are being marketed as more environmentally friendly alternatives to conventional plastics.
“Without evidence from testing and life-cycle analyses, businesses can misguide consumers. Industries can use the CSIR facilities for this purpose.”
The CSIR is working with the South African Bureau of Standards to develop national standards for home compostability.
There is no mandatory legislation specific to the material properties of biodegradable and compostable plastics in South Africa, according to a 2020 review of biodegradable and compostable packaging.
“We test if a product is really biodegradable because some people just spread lies to claim that their products are biodegradable,” said senior researcher Asanda Mtibe, who explained that they use internationally developed standards. “For example, for home compostability, there’s a standard that was formulated in Australia, so we are testing based on the available standards.
“If you’re claiming that your material can compost in industrial compost, then we follow that standard, which says that in six months, 90% of your material should have biodegraded. So, if you’re claiming that your material is compostable, but when we are testing it here, and 90% of material does not biodegrade in six months, then that is a false claim.”
Conditions of biodegradation
John said that the CSIR’s compostability assessment comprises mineralisation, chemical characterisation, disintegration and eco-toxicity tests.
There are different aspects to biodegradation. “There’s disintegration where a material disintegrates into smaller fragments; then there’s mineralisation where the carbon in the material, 90% of carbon as Asanda is saying, should be converted to carbon dioxide and that’s what we measure in this equipment here.”
The eco-toxicity tests determine that “whatever is left behind after biodegradation does not contain any toxic elements and it is suitable for plant growth … These are the three aspects that we need to do to claim that a material is biodegradable.
“What we see right now is that most people do the disintegration, where it’s just fragmenting into smaller particles, and they don’t do the mineralisation because they don’t have the capability to do it, and then they claim that it is biodegradable.”
But disintegration is not biodegradation. “It just disintegrates into smaller particles and leads to the formation of microplastics and nanoplastics. It is not environmentally friendly because this can accumulate in the food chain and gets transported into different environments. Now, you have all of these reports finding microplastics in human blood.”
John cited a specific class of materials called oxo-degradables, which are plastics to which certain additives are added to enhance disintegration. Biodegradation does not happen.
“These oxo-degradable materials are in the process of being banned in Europe and what we now see is that a lot of it is being imported into Asian and African countries, where it is being promoted as compostable and biodegradable.”
There is a misconception, too, that compostable and biodegradable materials can be “discarded anywhere and it will biodegrade”. This is not the case.
“Biopolymers biodegrade under specific conditions and that depends on the type of biopolymer it is. When something is biodegradable, you have to follow it up with two more aspects.
“One is the conditions of biodegradation — does it biodegrade in soil, in compost or in water — and also, the timeframes. How long does it take to biodegrade? Without this information, to say something is biodegradable is actually an incomplete sentence,” she said.