TSS, VSS, N–NH4+and dissolved COD (d-COD) were determined according to Standard Methods [27].
For the quantification of volatile fatty acids (acetate, propionate, butyrate) acidified samples with H2SO4(20% v/v) were analyzed on a Varian CP-3800 gas chromatograph equipped with a flame ionization detector(FID) and a HP-FFAP (Agilent technologies INC. 30 m × 0.53 mmI.D. × 1.00 m film) capillary column.
For soluble carbohydrates determination, a colored sugar derivative was produced through the addition of l-tryptophan, sulphuric and boric acid which was subsequently measured colorimetrically at 520 nm (MILTON ROY-Spectronic 601) [28].