My FIL is a waste water treatment officer at our local water authority, he hates disposable flushable LINERS with a passion as he has to fish them out by hand when they clog up the whole system. Same as stupid flushable panty liners they are bringing out now. Its just ridiculous. Yeah they may be flushable but that does not mean they dissapear never to be seen by anyone again. If its not you putting them in the bin its people like my FIL after they have clogged everything up.
I use sposie nappies and no I dont scrape the poo into toilet, the poos are too runny at the moment when they become more solid I might re assess the situation.
My brother is a commercial diver and spent quite a bit of time dealing with that kind of stuff down in the sewers. They call them rag monsters They had to hack one apart at Bondi full of you- don't- want- to- know- what!

I never knew about it being illegal when I used sposies either but I'm enlightened now If we use them for whatever reason I shake them off in the loo.