Adapting to biodegradable bags takes time and money, says researcher

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The Federal Supreme Court (STF) judges this week a law in the municipality of Marília that came into force in 2012 and prohibits the supply of bags plastic in markets. The idea would be to replace it with biodegradable bags, and encourage the use of cardboard boxes and reusable bags.

The judgment seeks to determine whether a municipal law would have the power to legislate on environmental issues. If the court understands that this is possible, it would have a “general repercussion” character, that is, all municipal laws with the same challenge would be maintained.

Around Brazil, it is possible to find several states and municipalities that have already passed laws to curb the use of plastic bags.

The biggest is the Rio de Janeiro, which approved the measure in 2018, together with states such as Paraná, Espírito Santo, Goiás, Pará and Rio Grande do Sul. At the municipal level, similar laws exist in São Paulo, Joinville, Belo Horizonte and, as of September 2021, Manaus.

The main justification for the projects is to reduce the amount of plastic materials in nature. At the same time, switching to the biodegradable bag is not simple, and affects the sector’s industry to some degree.

The change of bags

Maria Filomena Rodrigues, a researcher at the Technological Research Institute of the State of São Paulo (IPT-SP), says that a common plastic bag stays in the environment for decades without degrading, reaching up to 100 years, and can release toxic materials for animals or in water, for example.

“If it manages to replace it with a biodegradable material, bacteria and fungi attack it, convert it into CO2 and water and it doesn’t remain in the environment for a long time”, he says. However, a key element to this is the bag’s disposal location.

It is necessary that the environment has the proper conditions for this process, which lasts a maximum of six months, especially being a compost area with a certain humidity, allowing the proliferation of bacteria.

In general, however, this is not the reality of waste disposal in Brazil. Without the ideal conditions, the biodegradable material remains in nature for a long time, and the environmental impact is also great.

Despite this, she believes that the great merit of laws such as Marília’s is to encourage the exchange of plastic bags for boxes or cardboard bags and reusable bags, which represents a benefit for the environment.

At the same time, the content of the law is important to analyze its impact. For a plastic to be considered biodegradable, it must follow the composition standards of the Brazilian Association of Technical Standards (ABNT), in this case NBR 15448-2:2008.

Biodegradable material is at least five times more expensive than petrochemical plastic. Today, according to Rodrigues, there is still no biodegradable material for bags that can be produced on a large scale, even with some types already developed, such as the one based on sugarcane made by the IPT.

“The industry takes a long time and needs a lot of investment to adapt to change bags. It needs a biodegradable plastic that is commercially viable with the desired characteristics”, he says.

Another case is that of research at Poli-USP, using cassava. According to professor Carmen Tadini, the production of plastic involves two types of industry, the petrochemistry, which produce the plastic “grains”, and the processor, which receives the grains and transforms them into materials such as bags.

“Petrochemicals are difficult to adapt, the most they can do would be to produce from renewable sources, something that is already happening today and is important, but the product would not necessarily be biodegradable”, he says.

In the case of transformers, research shows that it is possible to transform materials from renewable sources into biodegradable products. However, the professor says that there is a lack of investments to scale this process, that is, to allow production in large quantities. Another problem is that biodegradable materials are still single-use, which increases usage costs.

the most common in supermarkets it is still to find, and pay an additional amount for, plastic bags of renewable origin, but they are not biodegradable, even if sold as such.

Because of this, it is not uncommon to find the bags “Oxidegradable”, which receive an additive in the composition to break up. They are not good for the environment, as the plastic fragments are toxic to animals, but they end up being cheaper.

Tadini says that “the plastic industry still provides many products, economically it shouldn’t harm so much [proibir o fornecimento de sacolas plásticas], even for not having a law at the national level”.

“[A proibição] Generates a loss of money. But it is something necessary thinking about environmental preservation”, says the researcher.

For the teacher, the great advantage of laws such as Marília’s is that they first encourage the use of cardboard materials, such as boxes provided by markets. The use helps markets, which drain a surplus from purchased boxes, and the environment, as the chain of recycling cardboard is already well defined in Brazil.

Another advantage for the municipalities is to reduce the amount of garbage sent to dumps, allowing them to reduce their size and spend less on the area.

“There is no point in having the law without conditions for it to materialize, there is no point in having it mandatory”, says Rodrigues. The researcher believes that it is necessary to have a biodegradable plastic available for exchange, which requires either its import, which is expensive, or to activate a new type of industrial production, which takes time to implement.

“The industry has to go after it, but it is a process that demands investment, focusing on new types of bags”, he says.

“Economics is closely linked to the environment. If you talk about looking at the economic side without looking at the environmental side, it is difficult. When you take action in favor of the environment, you are in a way leveraging the economy. The plastic bags need to finish”, says Tadini.

Reference: CNN Brasil

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