Thought it might be interesting to post about this here as some of us guys in the UK are halving our 'waste-by product' by acidulating the by-product after de-methylating to form roughly a 50/50 split of FFA oils and a purer form of glycerol.

The FFA recovered burns very cleanly and could be used for heating as some here in the UK do. Its also a way to halve the stuff needing to be disposed of. The FFA is a thin oily fluid that is Coke/Pepsi coloured and roughly the same viscosity as BioDiesel.

The purer glycerine will be an amber colour, and will contain any water left over from the reaction as well as any methanol and other impurities left too.

--I guess a soft-soap could be made from this purer glyc, More appealing than the 'orrible brown soap made from un-treated Bio by-product...

If Sulphuric acid is used to acidulate, then Sodium Sulphate will also be precipitated at the very bottom.

Just thought I would mention it for anyone to make use of....