The lipids were converted into FAMEs (biodiesel) through acid catalysed esterification/transesterification using a modified version of Christi's method [4], i.e., with hexane instead of toluene. This method was chosen because of the high amount of FFAs in the sludge lipid fraction. The FAMEs were analysed by GC-FID according to Agilent ApplicationNote228–398usingaHP-INNOWaxcolumn(19091N-133).For the calibration of the method, a 37 component FAME standard mixture was used (Supelco: 47885-U). The samples were also subjected to GS–MS analysis (G1099A/MSD5973) using a HP-FFA column (19091F-433).The results of theGC-FID were used to estimate the amount of saponifiable (esterifiable) material in the lipid fraction and hence the maximum mass of biodiesel(FAMEs) that could yield.The compounds which could not be identified by GC-FID are presented as others. The other compounds identified by GC–MS are described in Section 3.4