How do you mean, I'm not understanding?
A bin lorry doesn't do it's round ...and then head to the incinerator.
They "hub" the waste in another (larger) container.
Then, after several loads are collected, they take just one container. Saves lots of cash.
But to get the most out of that one container, they compact all the waste, so as to get more in.
I checked the Mildenhall "household waste site" and there is a larger container there.
I'm not suggesting that is where they transfer the rubbish. Just that they do use this process.
There is a large industrial complex up in Mildenhall. And several "rubbish" businesses.
Clearly there is "something" the bin lorry went to up there to do, as Bury also has a Biffa base.
Here's a "larger lorry" delivering at that Ipswich plant