Cycle analysis and batch experiments
To characterise one cycle, product and biomass concentrations were measured in parallel to H2 and CO2 in the off-gas. Sampling and off-gas analysis were carried out as described above. The biomass concentration was determined spectrophotometrically at 660 nm (OD660) and this value was correlated to the three previous measurements of VSS.
A batch test with lactate and a batch test with H2, and CO2 was performed in the complex medium enrichment. This went by adding the peptides and B vitamins and peptides together with the N, P, S, trace elements, and either 11 mmol of lactate or 0.46% of H2 and 1.00% of CO2. Sampling was conducted as in a cycle measurement.