Fine Tuning

The biggest problem I've had with making our biodiesel has been dirty oil. Though our friendly local restaurant is good enough to give us oil that is pretty clean, some of it is less than crystal clear. Leave it a few days to settle, particularly in warm weather, and the bits of fried food and what I assume to be flour sink, leaving a top layer that is clear to the naked eye.

So far I've been pouring that top layer off into our holding tank, from which it is sent through a 5 micron filter. The filter soon clogs up, but as there's no hurry, it can be left to drip through into a drum as slowly as it likes. The end result is a drum of 'clean' oil that can be tipped into the processor and turned into diesel that is good enough to go straight into the car.

However, that leaves a certain amount of oil that never settles. Often it's only a couple of litres in the bottom of a twenty litre drum. Sometimes though, we get given a drum that barely settles out at all. Up to now, the unsettled oil has just been accumulating whilst I've tried to work out what to do with it.

Thanks to Meare Solutions (http://www.mearesolutions.co.uk/) it looks like I've cracked the problem. They sell 32 inch long 'sock filters' which fit neatly inside a tiny space-saver water barrel that was on discount at our local DIY store. The 'sock' can take at least ten litres of dirty oil at a time, allowing the filtered oil to drip into the barrel through the sock wall and leaving a thick layer of 'dry' debris inside the filter. All I need to do is to top it up each morning. By the following day pretty much all of the usable oil has been extracted and the sock can be topped up again. In only a few days I've got through nearly the entire backlog of dirty oil.

The end result is more oil for biodiesel, and conveniently dry waste that can be much more easily disposed of. The only question remaining is how long the socks will last, and whether they can be reused by tipping out the dry waste.