Trace 1310 gc tcd

TS, VS, TAN and TKN were measured using APHA's Standard Methods (APHA, 2013) and pH values with PHM99 LAB pH meter. Sulphate concentration in wastewaters was measured using Spectroquant® Sulphate Cell Test (Merck, Denmark). The wastewater samples were previously filtered at 0.45 µm with Millex-HV13 Filter Unit (Merck, Denmark). The total VFA concentrations of the inoculum and the wastewaters were the sum their individual VFA concentrations (i.e. acetate, propionate, iso-butyrate, butyrate, iso-valerate, valerate and hexanoate), which were determined with a gas-chromatograph (HP 5890 series II, Hewlett Packard, US) equipped with flame ionization detector and a FFAP fused silica capillary column, (30 m x 0.53 mm i.d., film thickness 1.5 µm), and nitrogen as a carrier gas. The biogas composition was measured with a gas-chromatograph (Trace 1310 GC-TCD, Thermo Fisher, Denmark) equipped with Trace PLOT TG-BOND Q 26004-6030 column (30 m x 0.32 mm I.D., film thickness 10.0 µm; Thermo Fisher, Denmark) and helium was used as carrier gas for both methane, carbon dioxide, and hydrogen sulphide.

Methane accumulation in the headspace of the batch reactors was determined by a gas chromatographer (Trace 1310 GC-TCD, Thermo Fisher, Denmark) equipped with a
TracePLOT TG-BOND Q 26004-6030 column (30 m x 0.32 mm I.D., film thickness 10 μm) (Thermo Fisher), and helium was used as carrier gas (Tian et al., 2017) . The pH of each reactor was measured with PHM99 LAB pH meter (Radiometer TM).