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It's in the Timing PUBLIC ACCESS

Clean, Fast, and Compact, a Means of Destroying Dangerous Medical Waste Went Years Without Takers. That May be Changing Now.

[+] Author Notes

Executive Editor

Mechanical Engineering 128(07), 42-43 (Jul 01, 2006) (2 pages) doi:10.1115/1.2006-JUL-4

Abstract

This article discusses about latest developments in handling medical wastes. The article highlight features of Ecolotec, which is a large autoclave equipped with a system of blades to churn and chop the waste. The waste treatment system is in its final stages of testing and could be on the market soon. Currently, Ecolotec is studying blades of SAE 4140 chromium-molybdenum steel. The blades are sharpened daily with a belt sander, and the company may package one with the system when it reaches the market. Computer control is provided by an Allen-Bradley programmable logic controller (PLC) with a waterproof keyboard. The PLC has a wireless Internet card so, if a customer chooses, Ecolotec will be able to diagnose equipment from its headquarters. Ecolotec's executives say that, at an operating cost of 11 cents a pound, their machine costs considerably less than a waste disposal service.

Article

We all know the saw about building the better mousetrap. Here’s a new twist on that idea.

It may not catch mice, but a machine that destroys medical waste without polluting the atmosphere serves a health purpose at least as important as ridding your house of pests. However, when he was issued a patent for his “process for disposal of medical waste,” the inventor, Wolf von Lersner, found that nobody wanted to build it. Potential investors just didn’t see people beating a path to the door.

The system was fast and clean, but there were other, cheaper ways of handling medical waste. People would cart it away, for instance, and burn it up for you. But at a time when gasoline at $3 a gallon sounds like a bargain, that kind of service gets costly.

So now, 13 years after the patent was issued, a group of people is betting that conditions are ripe for von Lersner’s mousetrap.

Back in 1987, medical waste was being routinely dumped into the Atlantic Ocean for disposal. At the time, you were permitted to sink trash and forget it. Things that float, though, have a way of coming back to haunt sea dumpers.

Medical waste—things like surgical dressings, disposable gloves, and used hypodermic syringes—started washing up on the beaches of New Jersey and Long Island. At the time, von Lersner had a vacation home in Avalon, on one of the south Jersey barrier islands.

He said his house backed on the bay, so the trash didn’t literally land in his backyard, but it appears nonetheless that the problem hit home. Unlike most of his neighbors, von Lersner had an edge. At the time, he was director of engineering at Campbell Soup Co.

He understood methods of sterilization and systems using heat, and was familiar with devices for food handling and disposal of food waste. He worked with a company in Hameln, Germany, to devise an environmentally sound method of dealing with hospital waste. The company, Stephan Machinery GmbH, manufactures machinery and plants for food processing. A Stephan machine for sterilizing and reducing kitchen waste is cited in von Lersner’s patent.

The collaboration resulted in Ecolotec, a large autoclave equipped with a system of blades to churn and chop the waste.

In 1993, when von Lersner received his patent, ocean dumping had been curbed, but at that time, many hospitals were burning their biohazards in incinerators on site. So no one stepped up to put Ecolotec into commercial production.

The latest configuration of Ecolotec (above) stands 8 feet high and has a footprint of less than 6 square feet. A food-handling equipment company in Germany (opposite) manufactures the machine.

Grahic Jump LocationThe latest configuration of Ecolotec (above) stands 8 feet high and has a footprint of less than 6 square feet. A food-handling equipment company in Germany (opposite) manufactures the machine.

Even in 1997, when the U.S. Environmental Protection Agency under the Clean Air Act ordered hospitals to reduce emissions from their incinerators, von Lersner’s idea was still a tough sell. The hospitals could not bear the cost of adding the necessary emissions control equipment, so they shut down their incinerators. Waste disposal services in many states, however, outfitted central, state-of-the-art, and fully compliant incinerators, and then hired out their services to hospitals.

Now, a small company in Alabama is betting that rising costs in general, and of fuel in particular, will keep haulers’ fees sufficiently high to make Ecolotec an attractive method of waste disposal.

David Allen, president of the company, Ecolotec LLC in Huntsville, Ala., said the waste treatment system is in its final stages of testing and could be on the market later this year. There is a test bed at Huntsville where the system is being run at a cost of 10.8 cents a pound for utilities, tipping fees, and labor.

The price of the system hasn’t been decided yet, Allen said, but is expected to be around $280,000. Tests indicate that it is possible in some areas of the country to achieve a payback in 16 months, he said.

The machines will be made by Stephan, which built the ones being tested. A Canadian company, Eco Concepts Inc. of Guelph, Ontario, is leading a marketing effort.

Inside the machine, a batch of waste is directed to a jacketed vessel and exposed to steam heated to 270°F, or about 130°C, at a pressure of more than 45 psi. Blades called knife hammers rotate at 1,500 rpm to churn and shred the material.

The action of the blades exposes more of the trash to the steam at one time and makes sterilization quicker. According to the company, trash in the hopper will reach complete sterilization in less than 10 minutes, if the blades are working, and the system can process 200 pounds of waste an hour. In the Huntsville test, an Ecolotec system is treating more than 2,000 pounds every day in a two-shift operation, approved by the Alabama Department of Environmental Management, the company reported.

There is a provision built into the system to expose waste to the hot steam for a longer time if the blades should fail to activate.

The blades serve a second purpose. The sterilized waste must be reduced to an unrecognizable mass. That isn’t so much to respect the concerns of the squeamish as it is to prevent accidental injury from sharps or blades. It also makes it impossible for anyone to recycle a syringe or a scalpel from the trash.

When the batch has been sterilized, the vessel vents through a condenser and filter. Venting reduces pressure in the vessel and a vacuum pump kicks in to reduce it more and to remove moisture. Only when the material inside has reached a safe handling temperature, around 165°F, will the vessel open to be emptied.

According to Ecolotec, the chopping can reduce overall volume of waste by as much as 80 percent, and the sterilized mass coming out is ready for disposal in a conventional landfill.

According to von Lersner, the best-performing blades that have been tried in the system were of S7 tool steel, but that’s too expensive for a commercial machine. Right now, Ecolotec is studying blades of SAE 4140 chromium-molybdenum steel. “They’re looking pretty good,” von Lersner said.

The steel is hardened Rockwell 54. “But we’re going back on that—closer to 50—so they don’t get too brittle,” he said.

The blades are sharpened daily with a belt sander, and the company may package one with the system when it reaches the market, von Lersner said.

Water consumption is about 15 gallons per cycle. A 40- horsepower motor drives the tools, and there’s a 1.5 hp motor in the lid. There is also a 1 hp vacuum pump.

Exhaust is triple-filtered, passing through a mechanical prefilter, a HEPA filter, and an activated carbon filter. The system stands 8 feet high and has a footprint of just under 6 square feet. There are monitoring strips in the machine to test for sterilization after each batch.

Computer control is provided by an Allen-Bradley programmable logic controller with a waterproof keyboard. The PLC has a wireless Internet card so, if a customer chooses, Ecolotec will be able to diagnose equipment from its headquarters.

Medical waste disposal is regulated by state governments. In New Jersey, the state most hurt by the wash-up of medical waste in the late ’80s, the Department of Environmental Protection says there are about 19,000 sources, including hospitals, that dispose of an estimated 89,000 tons of medical waste every year.

According to “Guidance Document for Regulated Medical Waste,” published on the DEP’s Web site, there are 30 or so facilities in New Jersey registered to destroy their own regulated medical waste on-site. They process a portion of the medical waste generated in the state.

Most of the waste is shipped out of state because New Jersey has no commercial treatment facilities to process it.

Ecolotec’s executives say that, at an operating cost of 11 cents a pound, their machine costs considerably less than a waste disposal service. Prices vary around the country. Ecolotec says its research has found that haulers are charging large-volume customers 21 to 29 cents a pound. Smaller hospitals may pay more per pound.

A hospital in New Jersey told Mechanical Engineering that its medical-waste hauler charges a little more than $1,400 for every 4,700-pound container of medical waste that it takes away. That comes out to about 30 cents a pound, providing that the container is at full weight when it is picked up.

You can’t always predict what the world is going to buy. Or where it will beat a path. You’d expect that, all things being equal, the cheapest mousetrap would win. But we know that isn’t always so. And all things are rarely equal, if ever. But being competitive on cost gives you a good shot.

The people at Ecolotec now have the opportunity to take theirs.

Copyright © 2006 by ASME
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