we have a mini wheely bin for our nappy bin - never noticed any smells coming out but then we do give our nappies a very good rinse before they go in the bin. I also air it when its emptied and pop a few drops of orange oil in the bottom of it.

It does not seal tight so its probably not what your after but it works well for us, it sits in a corner of our bathroom/toilet area.

Nae x