A high strength industrial wastewater was treated in a
bench-scale activated sludge reactor modified by the
addition of biomass support media to the aeration tank. Two
experimental biomass support systems (BSS) and one
conventional activated sludge system were operated at
different mean cell retention times (mixed liquor MCRTs).
Three separate media were tested, NOR-PAC and Linpor used as
free-floating supports, and BIONET used as a fixed-bed
support. The effect of the media on substrate and oxygen
utilization, and solid-liquid separation was investigated.
Substantial attached growth did not occur on the NORPAC
and BIONET media. The attached biomass concentration in
the Linpor systems increased with increased media
concentration. The ratio of attached volatile solids to
total volatile solids (attached volatile solids + MLVSS)
decreased with increased mixed liquor MCRT. The advantages
of the BSS would occur at low mixed liquor MCRTs.
Both the BSS and control systems achieved greater than
94% COD removal and substrate utilization rates (mg/h) did
not significantly change during the experiments. Therefore,
both systems were substrate limited. The substrate
limitations caused decreased oxygen uptake rates of the
attached biomass with increased mixed liquor MCRT.
The sludge settling of the Linpor systems was a
function of mixed liquor MCRT, filamentous upsets, and the
presence of the media. Enhanced settling was observed in
the Linpor system only at the 3 day mixed liquor MCRT
experiment.
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