Fast food restaurants typically produce a low volume grease-containing wastewater,
generated by their daily kitchen activities, for which there is currently no acceptable
treatment technology. This paper describes the performance of a novel bioreactor, the
weir tank reactor, for the treatment of fast food restaurant wastewater at an organic loading rate
(OLR) of 5 kg wastewater m
± 3 d
± 1
. Two different mixed microbial cultures (one designated
MC1, the other an activated sludge), were used together with fast food grease residues from
two different sources (Woking, Surrey, and Birmingham, West Midlands). The reactor
achieved a high (84±96%) removal of FOG (fats, oils and greases) irrespective of the microbial
inoculum, the source of the FOG or the alkalinity (low or high) of the water. This high
performance was attributed to a combination of the effective mechanical mixing regime and
the periodic removal of a portion of microbial solids from the weir tank reactor liquor, in the
form of an ef¯ uent, during the weir tank reactor studies.
Keywords: fats; oils; grease; biological treatment; fast food restaurants.