Reactors were continuously mixed (magnetic stirrer; 300 rpm) and sampled with widebore 50 mL serological pipets at 0, 10, 20, 40, 60, 90, 120, 150, 180, and 240 min (PBRs were also sampled at 300 min and 360 min). The aqueous fraction of samples was immediately separated from the solids through centrifugation at 4,200 x g for 5 min at 4 °C (5804R Eppendorf centrifuge; Enfield, CT, USA) and then filtered through 0.22 µm (MF-Millipore™ Membrane Filter, 0.22 μm, item no. GSWP02500; MilliporeSigma). The solids pellet and filtered aqueous samples were stored separately at -20 °C prior to lyophilization (solids samples) and analysis (solids and aqueous samples). TSS and volatile suspended solids (VSS) were quantified at 0, 120, and 240 min (as well as 360 min for the PBRs). The reactor pH was maintained between 6.8 and 7.5 to avoid pH inhibition; adjustments were accomplished with 2 M HCl. The alkalinity of PBR samples -determined via titration of 100 mL samples to pH 4.5 (Mettler Toledo DL55 titrator) -was initially 600 mg•L -1 as CaCO3 and maintained above 200 mg•L -1 as CaCO3 through NaHCO3 addition to avoid carbon limitation.