2.3. Content of FOG in grease trap waste
According to the Standard Methods for the examination of
water and wastewater 5520 B (APHA et al., 2005), acidified samples
of waste (10 g) were extracted 3 times with 30 ml portions
of n-hexane/methyl-tert-butyl ether (4:1, by volume). The extracts
containing FOG were combined and dried with anhydrous Na2SO4
and the organic solvent was removed by evaporation (water bath
at 85 C). Heating of the residue at 101 C for 30 min periods was
repeated until constant weight (within less than 0.05%) was
achieved. The content of FOG was calculated from the weight of
the residue recovered