Sustainable development is both a major challenge and focus worldwide. Addressing the triple bottom line of People-Plant-Profit to meet community and employee needs; reduce environmental impact; yet also deliver company profits, is a fragile balance. Consumers and businesses alike are rethinking current behaviors to specifically address sustainability.
The production and use of plastics are important considerations in sustainability programs, and awareness has grown during the ongoing COVID-19 pandemic. In fact, all sustainability topics have drawn a lot more focus during this time. There is a greater awareness of risk across businesses, and a growing concern about the environment including plastic waste reduction. At the same time, we have seen greater use of single-use plastics to secure food and health during the pandemic.
The recycling of plastics has remained at low levels for many years, and expanding this activity is key to move toward the circular economy. This demanding concept is based upon principles that manufacturing processes move from the current linear lifecycle to integrate waste and by-products and eliminate emissions, while overall reducing impact on the natural environment.
According to the Ellen MacArthur Foundation, only about 14% of plastic packaging is collected for recycling globally and as much as one-third of the volume ends up in the environment. In a recent CERAWeek Conversation, IHS Markit vice president Anthony Palmer estimated that more than 400,000 metrics tons of plastic waste are expected to leak into the environment by 2050.
Consumer companies have ambitious targets to integrate recycled plastic into their final products and packaging, they are challenged to scale recycling and collection processes to address the very large and dispersed volumes.
The good news is that many companies across the plastic value chain are actively working and collaborating to resolve plastic waste issues. And digital capabilities are helping to solve some of the largest challenges in recycling activities.
For mechanical recycling processes, when the plastic is melted to create a new plastic article, it can be difficult to re-integrate the material back into value chain. The variety of plastic types typically identified by the recycling symbols #1 – #6 (as shown in figure 3) often demands different solutions requiring labor-intensive sorting. Many packages are composed of a mix of plastics used, typically marked #7, that can require unique approaches.
Japanese company FP Corporation had complex business and sustainability challenges in its packaging and logistics operations. It successfully applied digital supply chain solutions to optimize its complex production and distribution processes for both profitability and sustainability targets.
Working with partner Time Commerce, the company generates a detailed scheduling plan that integrates its demand plans and warehouse capacity with key cost components for production, inventory and transportation. The plan includes the retrieval of spent containers from consumer locations and the material re-use at production sites, primarily made from polystyrene (PS #6) and polyethylene terephthalate (PET or PETE #1). The company estimates that it reduced landfill waste by 443,000 metric tons and cut carbon emissions by 160,000 metric tons in FY2019, continuing the improvement seen in the previous year.
Digital technologies are also helping to develop and improve new recycling capabilities often referred to as “advanced recycling”. This advanced approach differs from mechanical recycling in that it takes the polymer apart to make the starting monomer or feedstock, or another intermediate that can be used as a feedstock. Advanced recycling provides the opportunity to manage large volumes of plastic waste, and convert it to usable materials. As processes improve, it can also provide more flexibility in the types and variability of plastics that can be recycled.
Pyrolysis is the primary process for advanced recycling of polyethylene (HDPE #2 and LLDPE #4) and polypropylene (#5). Several global companies are working on pyrolysis processes with a focus on digital simulation solutions, such as AspenTech’s Aspen Plus. These solutions model the complex reactions that occur in polymer decomposition so conditions can be optimized for cost and emissions. Pyrolysis can be a helpful first step in a local recycling plan as the liquid product formed is much easier to transport than large volumes of plastic waste.
A recent research study that used Aspen Plus to model the pyrolysis of waste tires highlighted that the simulation model can “serve as a robust tool to respond to market conditions that dictate fuel demand and prices while at the same time identifying optimum process conditions (e.g., temperature) driven by process economics.” Operators can optimize based on local market demand, such as gasoline, diesel and other hydrocarbons. (1)
Digital technology can also aid the next step in the recycling process as the resultant pyrolysis oil is integrated back into operations as a feedstock into steam crackers for olefins production. Scheduling solutions, such as Aspen PIMS, help companies assess unit capability for alternate feed and provide guidance on optimal conditions for processing. As operational experience develops, process analytics can help operators target reliability and maintenance activities, such as furnace decoking, to ensure energy efficiency remains high while balancing operational demands.
The value of plastics in their applications, including increased quality and durability is another focus area across the plastics value chain. Some consumer companies are moving toward more durable packaging that can be re-used while and plastic producers are moving to upgrade the quality of their products, make them easier to recycle, and overall reduce waste in current production.
Simulation of polymer properties and processes accelerates this new product development so producers can deliver new products to the market faster and at lower cost. Dow, for example, was able to speed time to market and reduce batch cycle time for polymer production using dynamic simulation to adjust process conditions. SCG Chemical saved more than $300,000 USD by eliminating plant trials for new HDPE grades.
Plastic value is also tied to production quality, and eliminating the low value material that is often produced in high volume processes. Digital solutions help to optimize current polymer operations to minimize low quality production and reduce energy use. Scheduling solutions can be applied to polymer unit operations to optimize the production schedule and conditions to ensure minimal waste material is produced between high quality products.
Major effort is needed worldwide to resolve plastic waste challenges and make progress toward important sustainability goals. Companies can best target and accelerate their efforts in polymer recycling, optimization and redesign by using digitalization capabilities.
(1) “Pyrolysis of waste tires: A modeling and parameter estimation study using Aspen Plus®.” Hamza Y. Ismail, Ali Abbas, Fouad Azizi and Joseph Zeaiter. Waste Management, Vol 60. February 2017.
Circular Economy requires the integration of process to eliminate waste and emissions
Published : September 16, 2021