Sludge reduction via biodegradation of the endogenous residue (X): experimental verification and modeling.

The feasibility of sludge reduction via the X biodegradation process was explored both experimentally and through modeling, where the main focus was on determining the value of the b parameter (first order degradation of X) from a continuous process. Two activated sludge (AS) systems (30 L) were operated in parallel with synthetic wastewater during 16 months: a conventional activated sludge (CAS) system and a modified low-sludge production activated sludge (LSP-AS) process equipped with a side-stream digester unit (DU). First, the long term data of the CAS reactor (1 year) were used to calibrate the ASM model and to estimate the heterotrophic decay constant of the cultivated sludge (b = 0.