Hello BESTers,

Using in-sink food disposals (in this article called garburators) can 
be a divisive issue.  In fact, the City of Vancouver is currently 
debating whether to ban their use due to the excess strain that food 
waste (which has a much higher organic loading than sewage) puts on the 
sewage treatment plant.  A common question is whether it is better to 
send food waste to the landfill or sewage treatment plant.  The obvious 
answer is neither (compost and anaerobic digestion are much better 
options); it is a no-win decision between the landfill and treatment 
plant, as both options have major downsides.

However, Insinkerator, a major manufacturer of disposals, has been 
pushing that disposals are a sustainable option for processing food 
waste.  Their rationale is that anaerobic digesters at the treatment 
plant treat the food waste that is sent to the plant via disposals.  
While this will make disposals more sustainable than without a digester, 
most sewage treatment plants in this country do not have a digester.  
Furthermore, those that do often treat the sewage sludge that results 
after the aerobic treatment process has already occurred, meaning it is 
still an energy intensive process, even if offset with biogas.  Also, by 
digesting food waste with sewage, the resulting fertilizer can be 
contaminated and unsuitable for food crop production.  One option that 
is touched on in this article, is to have several disposals flow to a 
centralized vat that is then used as a feedstock slurry for digestion.  
While this would be most appropriate for commercial operation, there may 
be potential for this in high-density residential housing areas, where 
composting is also more difficult.  I believe the in-sink food disposal 
can play an important role in solving food waste, especially for on-site 
small scale anaerobic digestion.

Have a great weekend,

Ryan

http://www.theglobeandmail.com/news/british-columbia/cities-looks-at-new-ways-to-use-garburator-food-waste/article20611130/

Metro Vancouver enters garburator food waste debate
The Globe and Mail
Frances Bula
September 15, 2014