To view the table associated with this story click here (191KB PDF)
Canadian municipalities can take advantage of advancements in automated optical sorting technology to help lower the collection and processing costs of their municipal curbside programs. The types of automated optical sorting systems used today by leading-edge municipal recovery facilities (MRFs) deliver high throughputs and accuracy rates.
Automated sorting technology is already widely used for fibres, but with the advent of optical sorting sensors, advanced automation is now cost-effective for containers as well. The equipment uses optical sensors to sort a stream typically composed of commingled plastics and paperboard (aseptic, polycoat). Other containers, like metal cans and glass, have usually been removed through mechanical or other means. Purity levels of 90 to 99 per cent can be attained with such systems, depending on the technology.
To help municipalities and waste management companies gain a better understanding of optical sorting technology and of the different types of equipment available, the Environment and Plastics Industry Council (EPIC) has released an updated version of its Review of Automated Sorting Technology to Sort Plastics & Other Containers and has made it available free of charge on its websitewww.plastics.ca/epic.These technologies generally involve the use of one or more sensors placed over conveyor belts of mixed containers.
There are several main players involved in automated sorting technology for plastic bottles. The list is as follows:
* MSS Inc., based in Nashville, Tennessee, produces the Aladdin and Sapphire models. Website: www.magsep.com
* National Recovery Technologies (NRT), based in Nashville, Tennessee, offers the MultiSort IR and MultiSort ES Systems. Website: www.nrt-inc.com
* TiTech is based in Norway but has ties to LUBO USA in Stamford, Connecticut. The company produces the AutoSort system. Website: www.titech.com or www.lubousa.com
* Rofin Australia Pty. Ltd., based in Australia, offers the Rapidsort systems. Website: www.rofin.com.au
* Pellenc Selective Technologies (PST) is based in France but has a local partner in Montreal called Machinex. PST produces the Mistral and Sirocco systems. Website: www.pellencst.com or www.machinex.ca
* S&S Separation and Sorting Technology is based in Germany but has formed a joint venture with Tectron Engineering of Laguna Hills, California. S&S produces the Varisort series of machines. Website: www.ss-metal-detection.com
A brief synopsis of their equipment, including throughput capacity and estimated cost, can be seen in the chart.
A case of action
Metro Waste Paper Recovery Inc. owns a MRF in Ottawa, Ontario. When the MRF was awarded the contract to handle the City of Ottawa’s container stream (about 18,000 to 20,000 tonnes per year), it decided to use automated optical plastic sorting technology.
“We were awarded the contract to process the Ottawa’s fibre stream back in 1999,” says Peter McMahon, senior vice president of the company. “We built a state-of-the-art facility to do that. In 2004, we were awarded the contract to process their container stream and we decided that we wanted to come up with the best technology available to process it.”
To do so, McMahon began investigating the various automated optical sorting equipment on the market.
“We have dealt with a number of manufacturers through our operations spread across North America,” comments McMahon. “In the end, we decided to go with Pellenc equipment. We had worked with their distributor, Machinex, in the past on different fibre lines and we were confident in their ability to provide good service and a good support network.”
The new container sortation facility is about 35,000 square feet in size and was initially designed to handle a long list of materials: clear and coloured glass bottles and jars; steel cans; aluminum cans, plates and pans; plastic bottles; polycoat milk containers and aseptic juice boxes. By adding a single automated optical sorting sensor, Metro Waste Recovery is able to sort both PET and HDPE bottles. This sensor cost $250,000, but saves the equivalent of four manual sorters or 160 man hours each week.
“If you were running a real tight shop, you could probably try to do this with three workers but our priority has always been on quality so we would have required four people to do the job,” McMahon says.
Metro Waste Recovery currently runs only one shift per day, five days a week for a throughput of five to 10 tonnes per hour. But that can change. As it is, McMahon suggests that the optical sensor will pay for itself in about three years. If, however, he ends up adding another shift, then that pay-back period will be likely cut in half. And the chances of adding another shift look good, as there is significant excess capacity to handle the container streams of nearby municipalities. McMahon is already in discussions with some neighbouring municipalities.
“Freight is sometimes an issue but I think we can work things out for most municipalities near us,” he says, adding that automated sorting technology has come of age. “I don’t think there is any other way to go.”
The new container facility began operations in December of 2004.
“In general, the number one advantage of the Pellenc system is that, under optimal conditions, it operates at a 90 per cent plus efficiency rate,” says McMahon. “With our cold winters, we found that we didn’t always have optimal conditions but Pellenc has been very good at responding and adapting their equipment to our needs.”
Since the company made its deal to handle Ottawa’s container stream, the city has decided to re-instate plastic tubs and lids to its blue box collection system. The automated optical plastic sorting sensor already works with plastic bottles, and it can also be programmed to sort by molecular structure and by size and shape as well. McMahon plans to add another sensor to the line to handle the tubs and lids as one stream. Polycoat milk cartons and aseptic juice boxes will be sorted as another stream.
“I think the City of Ottawa is extremely pleased with the system,” concludes McMahon. “The mayor has been by several times. Everyone who comes by is smitten with the facility. Although it’s not an example of a public/private partnership, it certainly feels like it’s one.”
Cathy Cirko is the director general of the Environment and Plastics Industry Council (EPIC), a council of the Canadian Plastics Industry Association. Contact Cathy at email@example.com