Teru Talk Newsletter

Volume IV, Issue 8, February 24, 2014 

Teru Talk by Michael Theroux (pronounced "Terú")  

Ah, the joys of Rot! But ah, the difficulties … like so many things in life, the very characteristics that make something appealing also cause problems. Rot is like that. Food needs to break down, and rather quickly, or eating it serves little purpose. Yet the faster it breaks down, the more likely it is that there will be Waste. Not all food rots at the same rate: those lettuce leaves turn to green slime in their baggie within a matter of hours, but the core of that head of lettuce will sit happily in my composter for a couple of weeks before giving up nutrients to my pet microbes, grubs and worms. In management of meat waste, problems multiply: the things that eat waste meat also tend to eat us, as well.

All of this rotting to goopy matter is temperature dependent, so weather plays its part. Those parts of the country not frozen solid are instead experiencing a dry, early Spring. When the outside air is warmer than refrigerator temperature, that natural break-down process accelerates dramatically. On the average, during warm weather we have about three days for Food Waste to become rotten goopy. Three days to rot: that's the general definition of "putrescible" waste, and that timing dictates much of how we manage our trash tsunami.

Once-a-week trash pick-up is just barely frequent enough to get it into the landfill before real Rot sets in. When that same tub-o-trash goes instead to a Materials Recovery Facility (MRF) to pick out the valuables before final disposal, things get a bit sloppy. Yet Food Waste is valuable; it can make great compost when digested by air-breathing microbes, grubs and worms. When we train no-air, or "anaerobic" microbes to do that digestive happy-dance, they can produce methane and similar substances that are the building blocks for so many of our fuels and chemicals. When an anaerobic digester at a sewer treatment plant or at a dairy is properly bolstered with food waste slurry, it can produce up to twice as much biogas, and that cuts the cost of handling the regional poop and manure over-supply.

But let's go back to this three-day rule. Since food starts to break down as soon as it warms up, it also starts to lose the nutrients necessary for humans to use as food. In the same way, it loses the basics needed for the best biogas production. If you are counting on that extra biogas production to make money from recovering and converting food waste, you want to quickly control that breakdown to get the most return on your money. You need to figure out a way to intercept the stuff as soon as it becomes waste, not wait for the MRF to serve it up for you as slop-in-a-baggie. This is the current challenge around the globe: Waste less, Reuse more, and Convert the rest back to goods. For Food Waste to Biogas, there should be no surprise: it just means knowing your Business, and being quick about it.