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My Thesis! Or Everything You Wanted to Know about Anaerobic Digestion

I haven’t posted here regularly for a year now, but school is officially over, so I can jump back in again. If you’re interested in (part of) what I’ve been doing all this time, check out my thesis: Municipal Development of Anaerobic Digestion/Combined Heat and Power in Massachusetts.

If you just want the CliffsNotes version, anaerobic digestion is basically breaking down organic materials (like food) with bacteria in an environment without oxygen. Composting is aerobic digestion, meaning it does roughly the same thing with oxygen. But with anaerobic digestion, we can collect the gas that’s produced (roughly half methane) and use it to generate energy. This happens in landfills, anyway, and there are some landfills that have gas capture systems, but if we control the process ourselves we can tweak it to be faster and generate more methane, and we can make sure the methane doesn’t escape into the atmosphere (very important, since methane is a greenhouse gas).

Anaerobic Digestion


There are a few places already doing this in Massachusetts. There are six wastewater treatment plants with anaerobic digestion and three farms. Manure and wastewater are both reliable feedstocks, but if you mix food waste with them it’s even better, generating more biogas, reducing the volume of the sludge, and making the process more stable. The three farms are adding food waste to the mix, but the wastewater treatment plants aren’t yet. However, Deer Island—the wastewater treatment plant that serves most of us in the Boston area—is planning a pilot food waste project for the fall.

Anaerobic Digestion in Massachusetts


Here in Massachusetts this is especially relevant, because we have a commercial organic waste ban coming up in October. This only applies to entities that generate a ton or more of food waste per week, not residents. But some towns are  considering doing residential food waste pickup, too. Hamilton has been doing so for about a year now, and Cambridge is doing a pilot project in one neighborhood. Anaerobic digesters are a great place for all that food waste to go.

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