Rajesh Kumar Gera: PET Trends, challenges and opportunities with a focus on enzymatic recycling

The PET recycling industry had a turnover of Rs 5,000-crore in 2020-21. This has increased to Rs 7,000 crore plus in 2023-24. Today, India has one of the highest PET recycling rates at 92% which competes with the best nation-states globally. The Indian recycling industry consists of unorganised and organised recyclers.

In addition, there are value-added recycled products made from rPET. Today the Indian PET recycling industry is projected to grow at 15-20 % p.a. in the coming years. It is estimated that the Indian PET recycling industry will have a turnover of Rs 10,000 crore plus in the next 2-3 years’ time. In addition to traditional mechanical recycling, there is an interest in chemical and biochemical (Enzymatic) recycling for difficult-to-recycle PET packaging and other polyester materials like textiles.

The Indian ecosystem
Although PET is a relatively new packaging material, its versatility, affordability and convenience is contributing to its rapid growth in India. It is putting increasing pressure on the recycling infrastructure. India is on a learning curve in terms of the usage, handling and disposal of PET packaging.

The Indian industry is benefitting through better management of PET waste, including difficult-to-recycle PET packaging and polyester textile materials through chemical and enzymatic recycling systems. Simultaneously, India has been introducing more rPET items in the system including those for direct food-contact applications.

Advanced recycling
The demand for rPET resin in the long run can’t be met solely by mechanical recycling. There is a growing interest in non-mechanical PET recycling globally. This is true in India, too. This includes both chemical recycling and bio-chemical recycling technology for PET recycling. Today, chemical recycling is being done in a small way in India. The bio-chemical recycling will help to power both the PET bottle and textile recycling and circularity.

One of the technology suppliers (Carbios) has done a successful alliance of polymer science and enzymology.  The process enables the enzymatic recycling of PET and results in virgin-like monomers. It will have high purity and consistent rPET quality allowing for direct food contact applications.

Opportunities in enzymatic recycling of polyesters
Enzymatic recycling is a fast-emerging technology globally and with huge latent potential in India. It is an incredible opportunity, as it allows recycling of waste which is not recycled. All these wastes could be recycled on a large scale tomorrow, and thus the potential of these end-of-life materials is enormous in India. It gives scope to leverage on far more economical feedstock, as one can use all types of waste polyester textiles along with PET bottles in this process.

The PET mechanical recycling industry is well established globally, including in India. However, there is a need for chemical and bio-chemical recycling (enzymatic) processes for difficult-to-recycle polyester materials. These include coloured PET bottles, trays, laminates and polyester-rich textiles.

Enzymatic recycling is a fast-emerging technology globally. Likewise, it has potential in India. The development of bio-chemical recycling to reinvent the life cycle of PET packs and polyester textiles is meeting challenges to move from end-of-life to end-of-cycle models.

The enzymatic recycling process
It is important to understand the basic principle of enzymatic recycling. The depolymerisation technologies break down plastics like PET/polyesters into monomers (PTA and MEG), so that they can be transformed back into new plastics (PET resin). This process breaks molecular chains and decomposes plastics into monomers and once purified, they can be used to form new high-quality plastics (PET). The enzymatic depolymerisation process is quite promising, as it uses enzymes as catalysts to decompose polymers.

The different steps involved in enzymatic recycling are pre-treatment (including sorting, washing etc.), surface preparation, enzymatic depolymerisation (from polymer to monomers), filtration steps, separation of TA (Terephthalic acid) and MEG (Mono ethylene glycol), followed by purification of TA and MEG. It results in monomers of virgin-like quality. These can be re-polymerised into PET of a quality equivalent to that of virgin PET, as obtained from the fossil route. The process enables the enzymatic recycling of PET and results in virgin-like monomers. It has high purity and constant rPET quality allowing direct food-contact usage.

This technology has matured from a demonstration plant stage to an industrial scale and is set to enter the commercial plant stage. These chemical enzymatic recycling processes will have a higher differentiated CAGR for PET/polyester recycling soon.

Enzymes are deployed in many everyday applications (detergents, biofuels, food, textiles and paper). Interestingly enough, using enzymes for the degradation and thus enabling the recycling of both plastics and textiles for industrial purposes was not considered in the past. These enzymes have been developed to optimise polymer degradation activity. Their activity, including thermostability, is required for efficient and competitive implementation in the industrial recycling processes. These optimised enzymes are used in enzymatic recycling (both for PET packaging and textiles) and also in the production of biodegradable plastics (like PLA).

Advantages of the enzymatic depolymerisation recycling process
The enzymatic depolymerisation recycling process helps to produce high-quality plastics without the use of petroleum. It allows the recycling of ‘difficult to recycle polyester materials’ (both packaging and textiles), to produce new materials. 

It has enhanced circularity (more cycles with constant rPET quality), soft biological process (solvent-free, water-based and low-temperature depolymerisation resulting in virgin-like quality) and high-standard LCA (less CO 2 emissions versus the virgin PET resin from fossil fuels). It results in circularity per industry (packaging to packaging textiles to textiles) and it gives flexibility to the polyester recycling industry to use cheaper feedstocks.

Opportunities in the enzymatic recycling process
The rPET resin/end-products from the enzymatic recycling process find applications in the packaging, both for direct food contact and also for non-food contact end-uses. There is a huge latent potential for the recycling of ‘textiles to textiles’, which is presently not happening. 

The use of this recycled polyester allows the brands to be "circular" and it will attract a premium over their regular products. A faster market penetration will be thus enabled by the active collaboration between all the stakeholders, including PET and/or Polyester raw material manufacturers, machinery and technology suppliers, along with the brand owners.

Conversion of plastic waste
The conversion of plastic waste into resources is one of the main thrusts of the circular economy. Enzymatic recycling is an opportunity, as it allows recycling of those 'difficult to recycle polyester waste' which is not recycled, such as cosmetic packaging, mixed packs, coloured bottles, multi-layer food trays etc. and also polyester textiles.

All these wastes could be recycled on a large scale tomorrow, and thus the potential of these end-of-life materials is enormous. These bio-chemical recycling plants need to be multiplied globally under a licensing model to enable local supplies and recycling, including in India. It will create a sustainable ecosystem to meet both consumer demands and strategically contribute to the recycling economy.

Plastic and textile waste is a precious raw material, enabling the circular economy to become an industrial reality. Partnering at 360° among different stakeholders will lead to faster innovations, unique solutions, enhanced sustainability and the creation of value-added businesses in India.

Rajesh Kumar Gera is a packaging and recycling consultant and was AVP at Reliance Industries’ PET division.