Is Polyvinyl Alcohol biodegradable? (3 stages of PVA treatment) 

This article will explain the biodegradability status of PVA. Other covered aspects will be: 

  • Is PVA biodegradable?
  • Is PVA eco-friendly?
  • What is PVA made of?
  • How does PVA affect life (if any)?
  • Can PVA be recycled?
  • How is PVA treated?
  • What are eco-friendly alternatives to PVA?
  • FAQs

Is Polyvinyl Alcohol biodegradable?

PVA is a type of water-soluble plastic which is biodegradable under very certain conditions. Since biodegradability usually means breakdown by microbes in a natural setting, PVA is regarded as non-biodegradable. 

However, PVA is better off than conventional plastics because it is a water-soluble plastic. This means that it goes from a polymer (Bulk form) to a monomer (smaller parts) when combined with water which makes it possible for microbes to degrade. 

It is also possible to recycle PVA. However, the process of recycling PVA could be energy intensive because of its water-soluble nature. 

Why is PVA biodegradability often confused?

No, it is generally considered non-biodegradable due to certain factors. Polyvinyl Alcohol or PVA is a plastic which is water-soluble. PVA is used mainly in wrappings especially in the detergent industry so it mostly ends up in wastewater.

In the US alone, it is reported that over 17500 metric tons of PVA is produced and ends up in wastewater where only 65% of the total wastewater goes through wastewater treatment plants or WWTPs.

PVA is biodegradable under very specific conditions which are specific types of bacteria that are able to degrade PVA. It also requires certain enzymes to aid in the degradation process and a specific amount of time. All of these conditions are extremely specific which makes it very difficult to degrade PVA.

Most WWTPs in the US do not have the proper setup that would degrade PVA during wastewater treatment so most of it ends up in the eventually in oceans which finds its way back to our table through bioaccumulation, meaning the fish that consumes PVA through water creates a bridge between humans and PVA. 

Is Polyvinyl Alcohol sustainable? 

Yes, it is considered sustainable (or at least it is marketed as such). However, the question of the sustainability of PVA is very broad and certain things need to be understood before coming to any conclusion.

PVA is a petroleum-based polymer so it is technically a plastic and plastics generally are known to be non-biodegradable and harmful to the environment and humans as well. But PVA is a water-soluble plastic: a property not very common among other types of plastics.

A water-soluble plastic can eventually be degraded naturally due to the fact that it goes from a polymer (Bulk form) to a monomer (smaller parts) when combined with water which makes it possible for microbes to degrade it but it may require certain conditions as discussed earlier and those conditions might take a day, month, year or years to fulfil.

So it comes down to the question of the rate of production vs the rate of degradation. At the current rate of production, PVA might become a very serious environmental risk, especially for marine life because biodegradable as it might be, still, the rate of biodegradation of PVA is no way near its rate of production which it will accumulate in the environment over years to come.

In which materials PVA is present?

PVA is mainly used as a packaging material and has broad uses in the textile, paper, and food industries due to its low manufacturing cost, high strength and thermal stability. It is considered safe for packaging food and has been approved by the FDA to be used as food packaging.

So the next time you go shopping you’ll find many products that are packaged using PVA. Laundry pods are covered using a thin layer of PVA so that the detergent remains intact and due to its water solubility it gets quickly dissolved during washing.

PVA is also present in many biomedical products, especially medicine pills which are covered in a thin layer of PVA as it keeps the medicine safe until it gets dissolved in the body so it helps in drug delivery.

Due to its water-solubility, PVA is becoming the number one choice for packaging consumer products in almost every sector and its apparent low environmental impact brings a good image to the manufacturer for which they had to use other high-strength plastics which are surely unsustainable so its use is increasing day by day.

How does Polyvinyl Alcohol affect life (animals, humans and plants)?

If PVA is completely degraded during wastewater treatment then it does not impact the lives of animals and plants in any way. However, not all of the WWTPs have a proper capacity for the biodegradation of PVA hence most of it ends up in oceans and farms.

PVA is converted into a monomer when it comes in contact with water hence it takes the form of microplastics. When it reaches the oceans, it moves up the food chain through marine animals and then eventually ends up on our plates. 

Although PVA is generally regarded as safe by the FDA meaning it does not affect normal human functioning when ingested but FDA has set a limit for its consumption which is often breached when marine animals such as fish and lobsters are eaten which have accumulated PVA from the oceans. 

A similar process is followed in agriculture where water from rivers and canals is used to irrigate crops and this way PVA eventually ends up at our table. The problem is evident, PVA itself is not dangerous until it is not properly treated, due to which it reaches dangerous levels.

Can you recycle Polyvinyl Alcohol?

Yes, polyvinyl alcohol is 100% recyclable as it is a petroleum-based product but there are a few problems that need to be solved.

Firstly, once PVA has been dissolved in water it becomes very difficult and costly to take it out to be recycled and since most products that use PVA packaging are designed for them to be dissolved i.e., laundry pods, so most of the PVA becomes unrecyclable.

Secondly, it requires tough processes in order to recycle PVA, which means adding it to a sulphuric acid bath which breaks into a concentrated form of acetate which can then be used to recycle PVA but this process requires energy. Still, the environmental benefits of recycling PVA outweigh the energy requirement. 

How Is PVA treated? (3 stages of PVA treatment) 

We understand the process of recycling above but how PVA is treated in wastewater treatment plants. In the US, wastewater treatment is done in three stages and we’ll see how these stages affect PVA.

During the primary treatment, large solids are separated from the wastewater but as we know that PVA is water soluble, hence it is not possible to separate PVA from water at this stage so it moves onto the next stage without any type of treatment.

In the secondary treatment, PVA comes in contact with different bacteria and microbes. It is at this stage that specific bacteria are required to degrade PVA and if those are present then PVA is easily degraded but most plants in the US do not have these specific types of bacteria which mean most of the PVA passes this stage as well.

During the last stage, filtration and disinfection are done. It is possible to degrade PVA at this stage as well but the process and technology are costly hence most WWTPs do not have it. 

What are eco-friendly alternatives to PVA?

There are many eco-friendly alternatives to PVA. Most plant-based plastics which are made from sugar cane, cornstarch and soybean are less durable but more eco-friendly than PVA but there is a problem with using plant-based plastics.

Plant-based plastic is an emerging concept which offers a wide range of environmental benefits but it put a lot of pressure on the agriculture supply chain. 

If plant-based plastics were to be used for everything instead of PVA then the resources required to maintain the packaging requirements would put more pressure on the agricultural supply chain shifting from one problem to another and potentially causing more damage to the environment through deforestation, overgrazing etc. 

Conclusion

It is concluded that PVA is a type of water-soluble plastic which is biodegradable under very certain conditions. Since biodegradability usually means breakdown by microbes in a natural setting, PVA is regarded as non-biodegradable. 

However, PVA is better off than conventional plastics because it is a water-soluble plastic. This means that it goes from a polymer (Bulk form) to a monomer (smaller parts) when combined with water which makes it possible for microbes to degrade. 

It is also possible to recycle PVA. However, the process of recycling PVA could be energy intensive because of its water-soluble nature. 

Frequently Asked Questions: Is Polyvinyl alcohol biodegradable?

Is PVA toxic or non-toxic?

PVA is generally regarded as a non-toxic material and there are no known health impacts of it. It is even stated small amounts of PVA ingested should not be a problem as such. 

Why is PVA recycling challenging?

PVA has been dissolved in water so it becomes very difficult and costly to take it out to be recycled since most products that use PVA packaging are designed for them to be dissolved i.e., laundry pods, so most of the PVA becomes unrecyclable.

References

  • Jain, N., Singh, V. K., & Chauhan, S. (2017). A review on mechanical and water absorption properties of polyvinyl alcohol based composites/films. Journal of the Mechanical Behavior of Materials, 26(5-6), 213-222.
  • Chai, W. L., Chow, J. D., Chen, C. C., Chuang, F. S., & Lu, W. C. (2009). Evaluation of the biodegradability of polyvinyl alcohol/starch blends: A methodological comparison of environmentally friendly materials. Journal of Polymers and the Environment, 17(2), 71-82.
  • Baker, M. I., Walsh, S. P., Schwartz, Z., & Boyan, B. D. (2012). A review of polyvinyl alcohol and its uses in cartilage and orthopaedic applications. Journal of Biomedical Materials Research Part B: Applied Biomaterials, 100(5), 1451-1457.
  • John Mascari. What is PVA and What are its environmental impacts? Retrieved from https://www.blueland.com/articles/what-is-pva-and-its-impact-on-the-environment 

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