A U-shape and / or
nozzle-U-loop fermentor has a U-part consisting of an essentially vertical downstream part (2), an essentially vertical upstream part (4), a U-shape bend part (3) which connects the lower ends of the downstream and upstream parts, an inline pump (12) placed in the U-part for circulation of
fermentation liquid in the fermentor, a top part (5) which is placed above the upper end of the downstream part,
gas supply members (7, 8, 9, 10) which are provided in the U-part with appending static-mechanical mixing members (13, 14, 15, 16, 17) for the
comminution of the gases introduced into the
fermentation liquid, and supply numbers for water and
nutrient salts (18) and (19), respectively, and in connection with the supply members (7, 8, 9, 10, 18, 19) or in by-pass arrangements in connection therewith one (or more)
ion sensor(s) or
analyser(s) (20, 21, 22, 23) for sensing the concentration of at least one of the
ion species
phosphate,
ammonium,
nitrate and
hydrogen ion,
oxygen sensor(s) for sensing the
oxygen concentration, and at least one thermo phial for sensing the temperature, said sensor(s),
analyser(s) and phial(s) delivering signals to a
data processing system (PC), wherein the signals received are processed and the dosage of feed gases, water, minerals and pH adjustment means via the supply members (7, 8, 9, 10, 18, 19) are calculated and optimised from pre-programmed amounts relative to the results measured.