Abstract: A fermenter and a method of fermentation in a U-shape and/or nozzle U-loop fermenter (100) comprising a U-part having an essentially vertical down-flow part (101), an essentially vertical up-flow part (102) and a substantially horizontal connecting part (103), which connects the lower ends of the down-flow part (101) and the up-flow part (102), a top part (104) which is provided above the U-part and has a diameter which is substantially larger than the diameter of the U-part, means for creating liquid circulation in U-part of the fermenter, and one or more gas injection points (110) for the introduction and dispersion of the gas(ses) into the fermentation liquid. The pressure may be controlled differently in certain zones of the fermenter by pressure controlling devices (105, 106, 108) e.g.

Abstract: A method for improving biomass production and/or growth rate of a microorganism in a fermentation process is shown, and includes: (i) providing one or more microorganisms; (ii) providing a fermentation substrate suitable for fermenting the one or more microorganisms; (iii) mixing the one or more microorganisms and the fermentation substrate providing a fermentation broth; (iv) adding the fermentation broth to a fermentation tank; (v) injecting at least one gaseous substrate into the fermentation broth; (vi) running the fermentation process for a fermentation period of at least 1 hour; wherein the at least one gaseous substrate comprises one or more greenhouse gases, such as carbon dioxide (CO2).