How High-Capacity Shredders Might Help Divert Waste from Landfills

With landfill space at a premium and tip fees on the rise, solid waste professionals are looking at new options to save money and space. Lindner Recyclingtech America, a subsidiary of Austria-based Lindner Group, hopes to capitalize on this trend with its waste shredders.

Lindner has sold thousands of them worldwide, largely in Europe where landfill space is nearly nonexistent. But North America is relatively new territory. The company has sold 90 in the continent, most recently to Salt Lake County, Utah’s landfill, to Richmond, Ind.’s landfill and to a plastics recycler.

“Shredding is a way to keep waste out of the landfill and at the same time recover thermal energy from the material to make alternative fuel. This process requires sorting so that only materials are shred that are safe to burn,” says Andreas Schwarz, general manager Lindner Recyclingtech America waste division.

Most of the waste, which can be shred to one-inch or two-inch pieces, goes to cement kilns or lime kilns to burn with coal or oil. A few operations leverage the end product to feed gasifiers or pyrolysis systems.

The shredders handle most solid materials other than rocks and steel.

The process entails a primary shred to break down materials and an initial sort of recyclable and nonrecylables. Materials go on to a separator to remove remaining unwanted materials like metals, glass and batteries. There may be a secondary shred to further reduce material.

Primary and secondary setups typically process 50,000 or more pounds an hour. Though Lindner’s models, customized for volume and waste type, manage anywhere from 1,000 pounds to 100,000 pounds an hour.

Whether a primary shred is sufficient or two steps are required depends on capacity.

“If someone needs to process five tons an hour they can buy a big shredder and make the product in one shredding step. If they need to process 20 tons an hour to a smaller size, they need to do a primary and secondary shred, with the secondary configured to make smaller product at high capacity and high speed,” says Schwarz.

Salt Lake County looked at shredders because of a fairly high contamination rate in the yard waste it collected curbside.

“We needed to have a machine more robust than some grinders that have a hard time managing heavy contaminants. What we liked about the Lindner equipment was the dual shaft and size of the machine. The small footprint for the power it has was advantageous,” says Ashlee Yoder, sustainability manager for Salt Lake County’s landfill.

Its machine can process about 22,000 tons of the 44,000 tons of green waste the site receives each year. It processes to a smaller particle size than many shredders and is adjustable to moderate the size of the output.

“This is helpful because occasionally we put material directly into compost windrows," Yoder says. "When we do that, we can’t change up. If the material is too big when it goes in the windrow, the composting process won’t work as well. But we can somewhat control this by shredding it."

While most of Lindner’s customers are in the fuel business, processing more than 10 tons an hour of waste, a handful are in other waste niches and do smaller volumes, such as Winco Plastics in North Aurora, Ill. The line, customized for Winco, includes a pre-shredding system and grinder to boost its plastics-handling capacity.

A conveyor belt feeds into the pre-shredder and two successive belts with a metal detector are used to feed the grinder.

The system handles high-density polyethylene (HDPE) pipes, HDPE sheets, polyethylene, polypropylene and polyethylene terephthalate, as well as lighter-weight materials.

“One major reason for our decision to purchase Lindner’s regrinding line was its ability to handle the wide variety of size, weight and form of the expected input material coming from different suppliers,” Tim Martin vice president of sales for Winco Plastics said in a statement.

Landfilling is still cheaper than shredding and grinding. But Schwarz anticipates that this method will become increasingly popular in the U.S., driven by the push for diversion and to extend landfill life.

“In some parts of the country [accumulating waste] has more of an impact, mainly because of population density, such as in California and the Northeast. New York exports all its waste. Meanwhile, municipalities are banning some materials and restricting others," Schwarz says. "Those who take the trash are forced to do something with it. This gives them an option to not only mange it, but make something from it. And it’s cleaner fuel.”