High-tech composting at Unimelb

At the University of Melbourne Student Union (UMSU) various food services generate lots of food waste. A significant amount of this food waste is composted in an aerobic digester to produce compost. Although it is small scale and highly efficient, this aerobic digester is not a system that I would suggest to anyone because of its high cost and energy requirement. However, the machine is ingenious and is worth to know more about it.

Aerobic digester

The aerobic digester is fed daily with 150 kg of food waste. Air and heat (45 °C) are injected into the chamber where food waste is continuously turned with an endless screw. The impressive thing is that while typical composting systems produce compost in two months at least, this aerobic digester produces compost in just one week.

The food waste after one week

According to the IPCC, composting is a carbon neutral process. This means that despite composting emits carbon dioxide; these are not counted in the greenhouse gas inventory because its carbon dioxide emissions come from biological sources. However, the fact that this aerobic digester requires electricity cancels the carbon neutral characteristic of the process. In energy terms, is this process better than sending the food waste to a landfill? That is a research question yet unknown. For UMSU, this system is perfect because they obtain discounts from the manufacturer, saves space, part of the energy used comes from renewables (favours carbon neutrality), do not generate odours and divert waste from landfills.

This machine can has as a target audience groups of food services. Take a look at this new:

http://www.abc.net.au/news/2016-06-03/recycling-food-waste-melbourne-precinct/7474714