Indianapolis may be the next American city to usher in a garbage-sorting MRF, though a number of recycling companies and groups are hoping to push the municipality in a different diversion direction.

The Indianapolis Business Journal reported earlier this week New Jersey-based Covanta has submitted a proposal for the construction of a facility that would accept household waste and then sort out recyclable material (such facilities are often referred to as dirty MRFs). Residents would be instructed to place all material – trash and recyclables – in a single curbside receptacle.

It would be the first such operation in the U.S. developed by Covanta, a company that currently runs a waste incineration plant in Indianapolis. However, it would continue what some see as recent nationwide momentum for the “dirty” MRF concept. Montgomery, Alabama earlier this year unveiled a facility that sorts recyclables from curbside-collected municipal solid waste. Houston and Cleveland leaders have been debating the merits of the strategy for some time.

The idea of such a strategy gaining traction, however, raises serious alarms for many in the recycling industry. Detractors argue dirty MRFs yield far less usable material than facilities that take in only recyclables from curbside programs. Opponents to mixed waste facilities also say some materials may not get recovered at all at the operations, and the Indiana Business Journal story in fact indicated the proposed Covanta facility would not sort out glass from the waste stream.

Beth Schmitt, global manager of sustainability and recycling at aluminum manufacturer Alcoa, told Resource Recycling dirty MRFs may not provide Alcoa with clean recycled material.

“While Alcoa applauds all efforts to recycle, we have concerns that a single-stream dirty mixed waste processing facility could cause the aluminum cans to become contaminated by solid waste and hinder the ability to turn them into new cans,” she said. “Aluminum is a valuable component of the circular economy. Because it does not rust, decay, or lose its quality, it can be recycled repeatedly without loss of properties. But, in order to truly maximize that value we need to separate materials for recycling.”

The Indiana Recycling Coalition (IRC) this April submitted a letter to the office of Indianapolis Mayor Greg Ballard, echoing Schmitt’s concerns and requesting a six-month delay on any consideration of Covanta’s proposal.

“We believe it would set recycling back in Indianapolis and central Indiana for decades to come, despite providing limited improved recycling rates in the near term,” Carey Hamilton, the group’s executive director, states in the letter. “We are confident, based on those of us representing the commodity markets, that the Covanta proposal will provide lower quality and lower quantity material compared to a true curbside recycling program.”

In a separate letter sent to Mayor Ballard and obtained by Resource Recycling, Ron Gonen, the CEO of the Closed Loop Fund, proposes the city use a zero-interest loan to invest in and develop curbside recycling. “Please accept this letter as confirmation that the Closed Loop Fund is interested in providing a zero-interest loan to Indianapolis to support the deployment of a curbside recycling program,” the letter reads.

The state of Indiana has set a recycling rate goal of 50 percent and Indianapolis, as the state’s largest city, will likely be viewed as a key momentum-builder toward reaching the goal.