Hey,
I thought about this quite a lot, of how to prevent the bad trash from mixing with the coffee grinds. In some of our cafes we have bins next to the knockout bins but rubbish always ends up with the grinds in a busy cafe. It’s so hard to stop yourself from chucking stuff in there, to brake that habit!
Although it may not be too bad fishing out the contaminants, it’s not that pleasant pulling out dirty dishcloths and baby wipes and it adds risk, so…
A couple ways to prevent or reduce contaminants;
Modify knockout bins so entrance hole is so small it’s annoying to put rubbish in or supply them with ‘knockout tube’ and have rubbish bin adjacent with large opening(people are lazy and will mostly put rubbish in easy target:).
Incentivise them by offering to take there waste and turn it into food, if you plan to grow a lot then maybe you could eventually exchange mushrooms for coffee or give them discounts on mushrooms…
I hope these can help you 🙂
Shaun