The HPR and HY of the immobilized Klebsiella sp. TR17
increased with the decrease of HRTs under non-sterile conditions in UASB reactors using crude glycerol as the substrate.
However, the glycerol conversion rate tended to decrease as
the HRTs decreased from 12 to 2 h. At 4 h HRT, HPR and HY
reached their maximum values of 242.15 mmol H2/L/d and
44.27 mmol H2/g glycerol consumed at 30 g/L and 10 g/L
respectively. Decreasing HRT and glycerol concentration
resulted in the decrease of soluble metabolites, in which 1,3-propanediol was the main product. From the FISH