The process: The waste is first sorted (manually!) to remove any contaminants. Currently it’s very low as most people do the right thing and don’t put the wrong items in the bin – under 1% - if that number increases it can become unviable and then the whole lot ends up in landfill – so follow the rules! The most common contaminant is the small plastic tubs that plants come it.
"most people do the right thing and don’t put the wrong items in the bin".
It’s then stacked up and the pile is covered in mulch. Under the piles are a series of pipes that introduce air into the piles via a fan that blows for 3 seconds every 30 seconds – this creates aerobic composting.
The temperature and oxygen content of the piles is monitored – once the material has been at over 55 degrees for 3 days then all the nasties will have been terminated such as pathogens and seeds.
The piles are moved over a period weeks until a very usable compost emerges from the final pile. This is finally screened ( a large sieve) to remove any items that have not broken down.