Fig. 2. Volatile suspended solids (VSS) content ( ) and ash content ( ) in the biomass at the end of a cycle in the glycerol SBR and VSS content ( ) and ash content ( ) in the biomass at the end of a cycle in the acetate SBR. The content is expressed as % on total suspended solids (TSS). Initiation of the C/N ratio of 15 induced intensive biofilm growth. On day 63, the reactor was cleaned and reinoculated with sieved biomass (