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Fed-batch and continuous cultivation of Thiosphaera pantotropha (GB 17) 91.89

This paper presents a segment of our work on the development of a process for simultaneous nitrification and denitrification conducted in a horizontal rotating tubular bioreactor (HRTB) by a facultative chemolitotrophic bacterium Thiosphaera pantotropha. The process has to be started as a two-stage process where the first stage is used for biomass cultivation of bacterium Thiosphaera pantotropha (GB 17) 91.89 in a homocontinuous chemostat, and in the second stage both nitrification and denitrification are conducted in HRTB. Due to low substrate-to-biomass conversion coefficient (YX/S) Thiosphaera pantotropha regularly grows in low concentrations. Therefore in this work we tried to optimise the first stage of the process i.e. to explore the possibilities to conduct the chemostat operation with a relatively high biomass outlet concentration. For that purpose we carried on the aerobic fed-batch cultivation followed by the continuous mode of operation with a high substrate concentration in the inlet feed. At the end of experiment maximum biomass concentration of 8.1 g/L was achieved, but YX/S decreased dramatically from 0.36 g/g in a batch phase to 0.017 g/g in a continuous operation.

Thiosphaera pantotropha; aerobic cultivation; high biomass concentration

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