Hello BESTers,

  This article discusses an interesting but I believe erroneous
idea. It claims that using households food waste disposers is a
"green" method of handling food waste. The argument is that
sewage treatment plants which receive the ground-up food waste is
using anaerobic digestion to generate biogas and biofertilizer
from the waste. This sounds almost too good too be true,
especially since most of us already have a food waste disposer in
our house, but I'm afraid this argument is over-stated. While
certainly there are treatment plants using anaerobic digestion to
capture energy, they are a very small minority. The article
states that insinkerator.co.uk claims that 60-70% of treatment
plants in the UK use anaerobic digestion (a minority of plants use
AD in the US). However, just because a plant is using AD does not
mean it is capturing energy. In fact the vast majority of those
that are using AD in the US simply flare the gas. This does
nothing to offset the high energy demand to treat the waste in the
plant. In addition, plants that use AD are treating the waste
activated sludge not the raw sewage. Meaning the food waste must
still go through the energy-intensive aerobic process prior to
generating this sludge. On top of that food waste has an organic
strength roughly 500-1000 times that of sewage, which takes even
more aeration energy to treat. With all that said, I agree that
if a treatment plant to treating the raw sewage anaerobically and
using the biogas for energy production, that food waste disposers
are an excellent option for disposing food waste, but I'm afraid
this idealistic vision is just not true for the large majority of
municipalities in the US. In the mean time, I believe composting
and vermicomposting are currently the best option outside of true
food waste digestion.
As always any responses or rebuttals are welcome on the
listserve.

Have a great weekend,
Ryan

http://www.guardian.co.uk/environment/2010/oct/17/not-easy-being-green-food-waste-anaerobic-digestion-landfill

Can I throw out food and be green?
Lucy Siegle
The Observer
October 17, 2010