Water-stingy street sweeper

By STEVE ALEXANDER, Star Tribune

Mike Caruso is living a cleaning company’s worst nightmare — he’s running a pressure-washing business in Georgia during a drought.

“We’re doing work for companies that won’t let you clean their parking garage unless you’ve got some kind of water-reclamation system,” said Caruso, a partner in the pressure-washing company Clean Up Georgia, based in Marietta, Ga.

But he’s found a solution: a truck-size power-washer that retains and reuses most of its water, managing to be clean and green at the same time. The cleaning machine — informally called a Cyclone — is being marketed by Nilfisk-Advance, a Plymouth-based unit of $1.2 billion Danish cleaning equipment company NKT.

Cyclones cost $100,000 to $250,000, and clean concrete surfaces (such as parking ramps and airport runways) with water jets squirting at pressures of 2,000 to 4,500 pounds per square inch. That’s a pounding so intense that it can clean without detergent, said Christian Cornelius-Knudsen, executive vice president of Nilfisk-Advance, which has 1,100 employees in North America, including 400 in Plymouth.

Instead of letting water run off to storm drains, as most pressure washers do, the Cyclone is able to keep most of its water inside an enclosure on the bottom of the truck, then recycle the water 500 to 600 times for more washing, Cornelius-Knudsen said. That saves 70 percent of the water that normally would be used in a cleaning job, he said.

There’s also an anti-pollution aspect to the water recycling. As the Cyclone purifies and reuses the water, it retains the oil and other pollutants the water washed off the surfaces, preventing them from being dumped down public storm drains, Cornelius-Knudsen said. Some of the oil residue recovered by the Cyclone can be reused as road paving material or heating oil, he said. Nilfisk-Advance got the cleaning technology as part of its May acquisition of Cyclone Environmental Technologies of Tempe, Ariz., which sold the Cyclone for airport runway cleaning for about five years.

But there’s more than one way to be a green cleaning machine, says Factory Cat Co., a Golden Valley cleaning equipment manufacturer. Factory Cat competes with the Cyclone using machines that replace water washing with a combination of compressed air and brushes, spokeswoman Kathryn Lovik said. Only one of its outdoor cleaning machines uses water, and then only a fine mist to control rising dust, she said.

But even in drought-plagued Georgia, Caruso is happy with the water-using Cyclone. For a typical job — cleaning 20,000 to 25,000 square yards of concrete in four to five hours — the Cyclone uses about 250 gallons of water compared with 50,000 to 100,000 gallons for machines that don’t recycle water, he said.

“We’re recycling close to 95 percent of the water,” he said.