Garbage In, Garden Out: Trash Processing Goes High Tech

Wired recently had a short, graphical, article, on the new trash processing facility in Sydney, Australia that was built by Global Renewables in its effort to shrink the millions of tons of recyclables that end up in landfills every year. A high-tech marvel of a processing plant that uses technology that includes wind sifters, optical scanners, magnets, and electrical currents, it is capable of diverting 75% of a city’s waste stream to recycling. This significantly cuts down on landfill space requirements, methane production (from rotting garbage), and greenhouse gas emissions.

The 6-step plus process, depicted in the graphic linked through the thumbnail below, is quite ingenious.

  1. Robotic Arms open the trash-bags (to prevent workers from injuring themselves on dangerous or hazardous materials) and then workers remove contaminants and toxic materials for safe disposal. The rest of the trash is allowed to proceed on a conveyor belt.
  2. A vacuum separates paper and plastic, which are separated by optical scanners.
  3. Electrical eddy currents subject the trash to a magnetic field which makes the nonferrous metals actually ‘jump’ into a bin.
  4. Electromagnets attract ferrous metals and a small belt channels the material into a separate chamber for compacting and resale as scrap.
  5. A computer-guided camera tracks paper and plastic and air jets blow the refuse into appropriate bins.
  6. What’s left is fed into a percolate tank and washed with warm water to dissolve readily soluble carbon and other organic compounds. The liquid enters a digester which turns the dissolved carbon into bio-gas to power the plant. A composting hall ferments everything else into fertilizer.