Week 8: Field Trip!!!

This past week we met with Nancy Clay and Al Greek from the South Bend WWTP to get a tour of the anaerobic digesters. During our tour we discussed the feasibility, convenience, and effectiveness of managing the dining hall's food waste by sending it all through the wastewater stream, with the help of a large food grinding machine. Nancy reassured us that the anaerobic digesters at the South Bend WWTP would definitely be able to process approx 1 ton of food waste from ND each day. She also showed us that the biogas collected at the anaerobic digesters is filtered and then burned to fuel the digesters. Pretty cool. But, more gas is produced in the digesters than the digesters need, so the excess gas is just burned off. :(

They are looking into the possibility of using the extra gas to power a nearby office building, but that is still in the works.

After our tour of the WWTP's anaerobic digesters, we drove to the South Bend Organic Resource Facility, where the city manages and composts yard waste. We had considered this site as a possible location for building a food waste composting facility, but Nancy indicated something that we did not notice until we arrived at the site: the South Bend airport is adjacent to this site. This means that there are strict regulations about what kinds of waste management can occur, because vector attraction (i.e. birds) is a safety hazard for airports. That is why this composting center does not take food waste, and only manages yard waste, which doesn't attract seagulls. So, its starting to look like this site won't be a very good option for a food-waste composting facility.

When we were driving back to campus we started talking about how incredibly convenient the WWTP digester option seemed. Could it be that simple? Just grind up all your food waste in the dining halls and send it away through the wastewater stream? The price seems right: invest in a couple food grinders and save money on fewer landfill truck pickups too. What's the catch? Is this the best way to manage food waste? Currently, the South Bend WWTP doesn't use all the biogas it produces, and that makes us hesitant to label this design option as sustainable.

A big concern about mass-disposal of food waste in the wastewater stream is that meals made with unsaturated fats solidify at lower temperatures and potentially clog sewage piping. If ND switches over to grinding up its food waste and sending it down the wastewater stream -- 1 ton of food waste per day -- how much of that food will contain unsaturated fats?

It would be too much to ask the dish cleaners in the dining hall to separate out meals made with unsaturated fats, so likely all food would need to go down the drain if we choose this method of food waste management. So, this option of food waste management could increase the risk of clogged sewer pipes. Quite unpleasant.

We could still consider the option of trucking the food waste to the South Bend WWTP and grinding it up there, but our plan is to do more research about the environmental/sustainability arguments for garbage disposal as a large-scale form of food waste over composting. Tbh, we are a bit skeptical... We'll do research on it this week and see what we find.

http://www.treehugger.com/kitchen-design/is-my-in-sink-garbage-disposal-eco-friendly.html

http://www.slate.com/articles/health_and_science/the_green_lantern/2008/09/should_we_dispose_of_disposals.html http://www.wickedtastyharvest.com/wicked_tasty_harvest/2009/05/runoff-compost-vs-garbage-disposal-vs-trash.html