Abstract: An apparatus for biologically treating lipid-containing waste water comprising a waste water introducer, a biological treatment constituted by a carrier holding a fixed lipid-assimilating, and a discharge for discharging the treated waste water. The carrier has a shape of string, lace, mat, sheet, fiber, sponge or film which facilitates the lipid-assimilating yeast to cling thereto. The apparatus may also be provided with backwashing for the biological treatment carrier, and an aerator for aerating the waste water. It is possible to directly treat lipid-containing waste water without producing any harmful matter and to efficiently reduce the concentration of the lipid (n-hexane extract) to not more than 30 mg/1. Furthermore, the maintenance of the apparatus is easy.

Abstract: A process for high-load treatment of carbohydrate-containing waste water comprises the steps of separating a yeast appearing in the waste water, subjecting the separated yeast to large-quantity culture, and treating the waste water by a high-load operation using the cultured yeast as a seed fungus under the conditions of a volume load of 10 to 80 kg-BOD/m.sup.3 .multidot.day and a yeast load of 1.0 to 5.0 kg-BOD/kg-yeast.multidot.day, whereby it is possible to treat the high-concentration waste water efficiently with a small volume for treatment. To obviate the conflict between the yeast and bacteria, it is recommendable to add Cl.sub.2 to a reservoir in an amount of 10 to 50 mg/l. Upon the treatment of the waste water, a surplus of yeast is generated, which contains proteins and vitamins in high contents and, therefore, is capable of being taken by a fodder company as fodder or fertilizer; thus, the disposal cost associated with the surplus yeast is saved.