eaux grasses

CONT: [...] l'utilité des récupérateurs de graisse se manifeste surtout dans les cuisines de grands établissements [...] Les eaux grasses traversent une capacité cloisonnée en partie haute pour retenir les graisses qui surnagent.

CONT: Greasy waste is liquid waste that is generated by a commercial business as a result of food preparation, cooking and cleaning activities, which is then dischargedthrough the sewerage system.
OBS: Waste is considered to be an uncountable noun. However, it is often found in the plural form (wastes), particularly when speaking of different types of waste.