Oil is collected in cubies and let to settle for a while until a distinct clear level is seen above the sludge. Clear oil is poured through a 200 micron drum screen. When the 55 gallon drum is full it's heated to 120*F by a band heater then pumped through three sediment filters in series (20- 5 - 1 micron nominal) into a 275 tote for long term settling. When I want to de-water a 55 gallon batch I pump out 55 gal from the top of a tote into my de-water drum, an insulated 55 gal steel drum with two drains, one at the bottom for sludge and a standpipe drain 6 inches from the bottom. It's heated to 160*F by a band heater and let to s-l-o-w cool for 72 hours. It's during the slow cooling that the water drops to the bottom and once cooled down I drain the water. Then I drain a sample from the standpipe drain and do a hot pan test to verify it's water free.