Abstract: This disclosure relates to an installation for treating residual water, particularly residual water resulting from the manufacture of sauerkraut, in order to transform such water into proteinic food products, especially yeasts. The novel installation comprises a fermentation vat, means for supplying said vat with residual water, nutritive salts and oxygen, means for evacuating the contents from the vat, in the form of paste and for feeding the latter to a centrifugal separator, connected to the storage tank for the paste previous concentrated in said separator, said vat further comprising a stirrer in its lower part and a foam separator in its upper portion and a cooling circuit extending through said vat, said installation being also provided with means for adjusting the pH of the medium submitted to fermentation.