2. Evaluation of Pre-treatments on the first stage of an anaerobic digester
2.1. Experimental
Two reactors (R1 and R2), made of borosilicate glass, clear, with round bottom, were used for the
experiments. The reactors have a total volume of 12 L, with a working volume of 10 L (sludge) and 2 L
headspace volume (biogas). Two point nine liters of inoculum (sludge) for the reactors (R1 and R2) were
taken from the anaerobic digester of the Wastewater Treatment Plant for Research and Education
(LFKW) at the University of Stuttgart (Germany). The anaerobic digested sludge (ADS) or inoculum was
diluted to 7.2% Total Solids (TS) concentration and strained through a 10 mm sieve to eliminate coarse
material that could interfere with further analysis.