Domestic wastewater hydrolysis and lipolysis during start-up in anaerobic digesters and microbial fuel cells at moderate temperatures

Raw wastewater hydrolysis rates during start-up in microbial fuel cells (MFCs) and anaerobic digestion (AD) systems, seeded with a mesophilic inoculum from a digester, were compared at moderate temperatures (27.5 ℃ and 8 ℃). Temperature drop affected both the lipids and carbohydrates hydrolysis rates but not necessarily the protein removal rates (temperature-independent rates of MFC), which were significantly influenced from treatment alteration (AD to MFC). MFC showed robust proteolysis at low temperature compared to AD; the latter seems to have a higher potential at warmer conditions. A lipases activity assay showed that although at 27.5 ℃ both AD and MFC are likely to hydrolyse lipids, the latter has a higher lipolysis potential at low temperatures. Preliminary community structure analysis showed that the switch from AD to MFC alters the bacterial community by 15% with the MFC showing higher diversification; temperature decrease, though, alters the community by 40%. Key organisms that appear to be favoured at the MFC set-ups are Geobacteriaceae, taxa likely related to the hydrolytic capacity of this set-up.