The rotten side of sustainability

It is the fate of all living things to eventually die and rot away. Before I get too existential let me be clear: I’m talking about compost.

Humans have composted for centuries but the earliest of early adopters probably never dreamt of the ways it could be used.

Compost can be made from anything that was once alive. That doesn’t mean that all compost is created equal; different grades have different standards, with the highest quality stuff used on agricultural land. Makes sense.  I don’t like the thought of human biosolids from the water treatment plant being spread over my tomatoes, thank you very much. A lot of the municipal compost produced in Canada is used in its own operations—in parks, as erosion control or in the landscaping around municipal buildings—or sold to landscape companies and individuals.

The Bubbetorp Composting Plant in Karlskrona, Sweden composts residential organics in a closed system. It’s first heated in a box for 55°C for three weeks, then to 65°C for another week to kill germs and weeds.

The Bubbetorp Composting Plant in Karlskrona, Sweden composts residential organics in a closed system. It’s first heated in a box for 55°C for three weeks, then to 65°C for another week to kill germs and weeds.

It’s then transferred to open bins and mixed. After hanging out there for four weeks, it’s finally transferred to an open pile and given a turn ever week or so to aerate it (as anyone who composts at home knows, if you don’t turn your compost or poke some air holes in there once in a while, it can get a bit stinky). Finally, the compost is chopped up and sold.

It’s then transferred to open bins and mixed. After hanging out there for four weeks, it’s finally transferred to an open pile and given a turn ever week or so to aerate it (as anyone who composts at home knows, if you don’t turn your compost or poke some air holes in there once in a while, it can get a bit stinky). Finally, the compost is chopped up and sold.

Compost or biosolids are the precursors of biogas, which is just a fancy term for the methane—a greenhouse gas with 23 times the GWP of CO2—that is produced during decomposition. Lots of places all over the world capture methane from landfills and use it to generate electricity, power vehicles or produce heat.

A Linköping city bus fuels up on biogas.

A Linköping city bus fuels up on biogas.

Linköping, a city of about 100,000 in Sweden uses biogas to power its transit vehicles. The gas is produced from, among other things, local slaughterhouse waste.

BKW Compost goes in

The BKW biogas plant in Fürstenwalde, Germany produces electricity, heat, compost and liquid fertilizer from residential, restaurant and grocery store waste.

BKW Between the digesters

In between the biogas digesters. Close up, parts of the plant stank like a diarrheic monkey but only a few steps away the air was fresh and clear thanks to those microorganisms.

The waste is first separated and shredded then pumped into anaerobic (without air) digesters where it goes about its business decomposing.  Inside the airless vats, microorganisms go to work eliminating pathogens and odours.

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One response to “The rotten side of sustainability

  1. Pingback: World Organic News·

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