I think its possible, depends on the filters. The body fat is help in suspension in the waste water.
You would need to aquire the water and distill the juices to get the fat. 5kg may need alot of water, as a bye product you should get enough hair for a couple of wigs.
A better idea would be to look underneath a sauna bench,
you can scrape the fat of them, not bad on a bit of toast by all accounts.
Enjoy.