In August I did a mini-eco tour of the DC area. I biked to a coal plant, a waste water treatment plant and a recycling plant. The recycling plant was the Prince George's County Materials Recycling Facility (MRF) which has been open since October of '93. I went there during break time so I didn't get to see the single-stream machinery at work, but I got a neat tour.
The first thing you need to know about any recycling plant is who separates the recyclables? Generally areas with single stream plants (where they separate, not the customer) have higher recycling rates than other areas as consumers don't have to figure out which bin to drop which thing in, thus making things easier for them. Now the PG county MRF is a single stream plant, but before November 2007, it was a dual-stream system and all paper products had to be collected separately. Also, Prince George's County is the only county in Maryland that has a single-stream recycling center. In your face Montgomery and Frederick!
The tour started out in the dump room which is a massive empty room where the recycling trucks dump all their load. Then bulldozers push the stuff to a big conveyor belt in the corner of the room. The conveyor belt brings all the stuff up and flings it into the next room over and the heavy cardboard falls into a lower container. The recyclables continue on the belt and there is this spinning gear thing that kicks everything up and the various types of paper sift out to the bottom and due to weight and density differences they fall into different containers. Now there are just plastics and metals left on the belt. To separate the metals they have a rotating electro-magnetic disk and half of which gets magnetized while it's over the belt and it picks up the steel. The disk spins and when the half with steel is over a container it demagnetizes and the stuff gets dropped in another container.
To separate the aluminum cans they run an electric current through the belt and the cans fly off of the belt and into their own container. I feel Magneto would be very good at this.
The coolest part by far was how they separated all the types of plastic. The conveyor belt passes the plastic under a laser beam which scans the bottles and determines their density (and thus their recycling number). This information gets sent to small air jets which then shoots air at the bottles, launching them into their proper containers.
And that is how your mixed recycling gets sorted, and it only requires about 30 people (15 per shift).
Some fun facts:
They recently expanded their program to include plastic bags, so if you live in Maryland's PG county or DC (including Georgetown townhouses, but not dorms) you can drop your bags in your recycling bins. However, the machine isn't designed to separate them so workers remove them by hand.
They can handle plastic bottles with numbers from 1-8 which is also pretty sweet and rare.
They recycle about 9,000 Tons a month. By weight it is 55% newspaper, 30% cardboard, and aluminum (which is the most valuable per pound) is less than 1%.
It only cost about $8 million in capital costs to upgrade to single stream.
Prince George's county has a 45% recycling rate which is well over the national average.
And in case you want your very own, go to TiTech's website and check out their PolySort.
It was a cool experience, and I encourage all of you to go out into your communities and see how your infrastructure works. For a tour of the PG county MRF contact them at (301) 499-1707, they are located at 1000 Ritchie Road in Capitol Heights, Maryland. Tours are available Monday through Friday 8am- 3pm.