ABSTRACT: The feasibility of a biological augmentation approach to
eliminate oil and grease in the wastewater of a large bakery was
evaluated and experimentally tested. The approach, based on
approximation of a treatment tank with a model of a continuous culture
of bacteria (chemostat), was eval~ated first. Bacteria appropriate for use
in biological augmentation were selected according to theoretical
requirements. Results of subsequent field tests corresponded fairly well
to predicted values, although oil and grease content in the outflow was
still greater than the allowable level. To further increase cell
concentration in the treatment tank, a solid support for bacterial growth,
a biological filter, was added next and was successful.
As a result, a bioremediation scheme was devised that included pH
adjustment and mixing-aeration systems, an external biological reactor
system for production and periodic injection of the appropriate bacteria
to the treatment tank, and a biological filter. A dramatic reduction of oil
and grease in the bakery waste from approximately 1.5 gIL to less than
0.03 gIL, which is thiee times less than accepted regulatory limits,
resulted. Reliable functioning of the bioremediation system has been
observed during an extended period of time (20 months). Water
Environ. Res., 72, 141 (2000).