Inoculum
The reactor was inoculated with anaerobic sludge taken from a full-scale mesophilic anaerobic digester treating the excess sludge of a municipal wastewater treatment plant located in Padova, Italy. The inoculum had a concentration of total (TSS) and volatile suspended solids (VSS) of 12 gTSS L1 and 6 gVSS L1, respectively. Sludge was added on three further occasions during the experiment. Sludge had to be topped up to compensate for biomass loss caused by cleaning of the filtration support due to clogging and by other maintenance procedures.