Flocculation – Flotation Pretreatment Improves Operation of MBR Installed to Treat Snack Food Manufacturing Wastewater

Large food manufacturing company has facilities to produce their well known brand
name dairy based products in rural Indiana. As is commonly case with dairy wastewater,
significant amount of proteins, sugars, oil and some suspended solids are present.
Company installed membrane bioreactor (MBR) System to treat such wastewater for
possible reuse.
The MBR performed poorly due to membrane fouling. Manufacturer suggested that in
addition to screen other primary pretreatment is needed to reduce FOG and organic TSS
as low as possible prior to MBR treatment. Classical DAF and advanced hybrid
centrifugal – dissolved air flotation (GEM) were pilot tested. Both systems performed
well, but GEM removed FOG and TSS to lower amount and produced drier sludge. The
full scale GEM System has been installed in June 2010. Dual high molecular weight
flocculants and GEM flotation remove TSS below 50 mg/l, FOG below 2 mg/l and
produce sludge with 20% solids. Data are currently collected to evaluate how such
pretreatment improves operation of the MBR.