The Missing Link: Chains Are a Smart Move for Tyrolean Food Waste Recycler

If the experience of one Tyrolean farm in the village of Schlitters, Austria is any indication, food waste recycling is in for a big step up.  The farm just added a biogas plant to its operations, using a new design that can boost methane yields from biogas by 30%.  The secret?  That’s where the missing link comes in.

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Food Waste Recycling Starts with a Good Shredding

The farm takes in agricultural waste from around the area, restaurant waste from the tourist industry, and packaged foods that have passed their expiration date.  To handle the mixed food waste, it installed recycling machinery produced by the German company MeWa Recycling, called the Querstromzerspaner, or QZ for short.  Conventional shredding blades are not ideal for mixed food waste, because it contains packaging materials, misplaced cutlery and other non-organic items.  The QZ uses chains to mash the waste instead of slicing it.

Chains Beat Blades for Biogas, Too

The mashing action of the chains has a second benefit, even more important than the first.  Mashed food has a much greater surface area than sliced food, so it provides a more efficient environment for bacteria in biogas production.  According to the manufacturer, the methane gas yield was 30% higher in a conventional blade shredder after it was retrofitted with chains.

Beyond Food Waste Recycling

Composting and biogas production relieve landfills and incinerators from a shocking amount of usable waste.  It’s important to keep in mind, though, that food waste recycling is only the front end of a bigger problem: the scale of overproduction that permits some countries to throw out a significant proportion of their food supply, and the consequent effect on water supply.

Image: Clearly Ambiguous at flickr.

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