Executives at Brightmark, a company that wants to build a massive plant in Macon that will turn plastic into diesel fuel and chemicals, say they plan to push ahead with their plans, despite losing the support of the city’s mayor.

Macon-Bibb Mayor Lester Miller told The Atlanta Journal-Constitution he is concerned about pollution from the plant and Brightmark’s ability to deliver on its promises to cleanly turn waste plastic into useful products in the timeframe it promised. The project also has drawn opposition from resident and environmental groups.

Miller said he will not sign documents approving $500 million in exempt facility bonds proposed by the Macon-Bibb County Industrial Authority to fund the land purchase and construction. He also said he doesn’t believe the bonds can go forward without his signature.

“We wish them well,” Miller said. “But it’s not the right fit for Macon and Bibb County.”

However, a spokesman for the authority said it would abide by agreements signed with the company, though he declined to elaborate.

The state Department of Economic Development, which recruited Brightmark to Georgia, declined to comment.

The company said its plans have not changed.

“Given Brightmark’s commitment to the environment and economy of Macon-Bibb County, we look forward to continuing our engagement with Mayor Miller and the community at large,” Brightmark founder and CEO Bob Powell said in a written statement. “We’re eager to demonstrate the overwhelmingly positive effects of plastics renewal technology, along with the immediate- and long-term economic growth that this project will drive for Macon-Bibb County. We are confident that this project will continue to move forward, comply with all environmental permitting requirements and demonstrate its positive impact on the environment in this community.”

Brightmark, one of a number of companies working to try to recycle plastics, announced last June it would build a plant and employ more than 100 workers. It uses a process called pyrolysis — turning plastics into liquids by vaporizing them with heat in air-tight processors. The liquids can be refined into wax, diesel fuel and naphtha. The company hopes to be able to turn those liquids back into plastics in the future.

Recycling plastic has been a brass ring that many companies are trying to grab, but there have been few successes. Many types of plastic are difficult or impossible to recycle.

The world has a huge problem with plastic waste. The Environmental Protection Agency estimated that the U.S. produced 35.7 million tons of plastic in 2018 — the amount increases each year — but only 9% got recycled. About 5.6 million tons were burned to create energy, releasing greenhouse and toxic gases. And 27 million tons were buried in landfills or ended up in gutters, rivers and oceans.

Jessica Wahl, with Environment Georgia, helped organize opposition to the plant.

“It’s just a green-washing tactic,” she said, giving companies who use Brightmark’s products cover of being environmentally friendly.

Macon residents began speaking out against it in public meetings last year. Wahl said people are concerned about air pollution, such as benzene and toluene, that the process creates.

Wahl said Brightmark’s first plastic plant in Indiana has had problems, including a significant fire last year. Because of that and other issues, Miller said, the 18-month-old plant has not been able to get to full production, one of the reasons he withdrew support.

We are thrilled that this is a serious step back for Brightmark’s plans to build in Macon,” Wahl said.