Tackling plastic pollution with a potentially profitable recycling solution

22 Mar 2019

Dr Nien-Hwa Linda Wang with oil produced from plastic using her chemical conversion process. Image: Purdue Research Foundation/Vincent Walter

Purdue University’s Dr Nien-Hwa Linda Wang has developed a chemical conversion process that can turn plastic into useful products such as fuel.

“My father was a chemist. Growing up, I was always interested in using chemistry and engineering to make useful products,” said Dr Nien-Hwa Linda Wang, a professor in the Davidson School of Chemical Engineering at Purdue University.

Wang is now living her childhood goal as a chemical engineer conducting research and development that is generating truly useful results. Her latest project is exploring how to convert plastic waste to oils, which could have further useful applications.

‘We hope that this conversion technology will create a driving force to reduce the rapidly accumulating plastic waste and the associated risks to the environment’

Future Human

Wang’s war on plastic

While researching how to recover polycarbonates from electronic waste for a major plastics producer, Wang realised that this represented just 1pc of total plastic waste. This total has been growing exponentially for decades, and Wang explained that mere fractions are recycled (9pc) or incinerated (12pc). “Most of the waste is accumulating in landfills or is scattered in the oceans,” she said.

The United Nations has ‘declared war’ on plastic pollution in the world’s oceans, and it’s a colossal adversary to be up against, with an estimated 8m tonnes flowing into the oceans each year.

Growing concerned at the potential damage of plastic pollution to our ecosystems and to human health, Wang set about researching and developing cost-effective chemical and engineering solutions to shrink the world’s plastic waste stock.

The result, so far, is a new chemical conversion process to transform polyolefin waste into products such as clean fuels. Wang and her team focused on polyolefins (plastic types 2, 4 and 5) because they represent the vast majority of plastic waste.

Applying this chemical conversion process to plastic shopping bags, the researchers first turned the plastic into pellets and then into oil. Using distillation, that oil was then separated into a gasoline-like fuel and a diesel-like fuel. “Since [polyolefins] have a high energy content, converting them into oils or fuels can be a cost-effective solution to reduce the waste,” Wang explained.

“We first studied individual virgin polyolefins to gain fundamental understanding of the conversion processes. We then applied the knowledge to design processes for the conversion of actual polyolefin waste.”

Why you should clean and sort your recycling

With limited research funding, Wang has delivered encouraging results, but more funding and industrial partners are now needed to develop economical large-scale processes. “I am looking for investors with a long-term vision and partners in industry or government agencies who are passionate for the environment,” she said.

‘Our research shows that clean, sorted waste can be converted into valuable and useful products with higher potential profits for industry’

However, there are many challenges ahead for scaling this project. Wang’s research shows that clean, sorted plastic waste can be converted into high-quality, high-value products with low processing costs – but clean, sorted waste is not widely available. Only 14pc of plastic waste is currently collected, and this represents a mix of all seven plastic types.

“Sorting and cleaning the plastic waste will add additional costs, making many otherwise technically feasible solutions not economical. If plastic waste is thrown into trash and mixed with other solid waste, the cost for retrieving the plastic waste from the trash alone is similar to the costs for producing virgin plastics from crude oil. Thus, unless the supplies of crude oil become insufficient, it is not economical to separate and process plastic waste from landfills,” Wang explained.

“Our research shows that clean, sorted waste can be converted into valuable and useful products with higher potential profits for industry. I hope that this information will motivate consumers to help with the collection of clean, sorted plastic waste. More profit for industry in turn may accelerate the reduction of plastic waste and the associated risk to the environment,” she added.

Act now to save in the long run

Should the solution be optimised, the potential impact of Wang’s research is major. “Converting the plastic waste into oils or fuels can save the petroleum crude that would have been used for producing fuels or other chemicals. The oils produced from the waste can be further refined or converted into many other useful chemicals,” she explained.

“We hope that this conversion technology will create a driving force to reduce the rapidly accumulating plastic waste and the associated risks to the environment.”

Indeed, this conversion technology could be profitable for the recycling industry, and Wang believes financial incentives are “critical” to encourage adoption of environmentally conscious techniques.

“If there are special financial incentives (tax credits, tipping fees, subsidies), they will of course encourage industry to adopt new technologies. But even if there are no special incentives, it is still worthwhile converting plastic waste into useful products to diminish the potential impact of slowly degrading waste in the environment. In fact, the costs of cleaning the oceans and waterways in the future will be much higher than any special financial incentives provided now.”

Although she is one of the people helping to find solutions for our global environmental issues, Wang is “not very hopeful” for a widespread turnaround on actively tackling these issues. “However, as people and governments become more familiar with the seriousness of this problem, this projection may change,” she added.

“We have no choice but to act soon if we want to prevent further damage to our environment. If we do not tackle the problem of plastic pollution within the next one or two decades, it will be much more difficult and more expensive to restore our environment.

“New technologies such as ours may provide a driving force for recycling. However, the public, the policymakers, the plastic producers and the recycling industries must work together to address the growing challenges of the mounting plastic waste.”

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Elaine Burke is the editor of Silicon Republic