Microbial population shifts during disturbance induced foaming in anaerobic digestion of primary and activated sludge

An extensive experiment involving six replicate laboratory-scale continuous stirred-tank reactors (CSTRs) was conducted. CSTRs were fed with a mix of primary sludge and waste-activated sludge over 24 weeks. After nine weeks of stable operation, foam was intentionally induced in three of the six replicates through organic overloading with glycerol. High frequency 16S rRNA marker gene profiling was performed to identify potential biomarkers of the foaming event.