Effects of Substrate Concentrations on the Growth of Heterotrophic Bacteria and Algae in Secondary Facultative Ponds
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Date
2003
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
This paper presents the effect of substrate concentration on the growth of a mixed culture of algae and heterotrophic
bacteria in secondary facultative ponds (SFPs) utilizing settled domestic sewage as a sole source of organic carbon. The
growth of the mixed culture was studied at the concentrations ranging between 200 and 800 mg COD/l in a series of
batch chemostat reactors. From the laboratory data, the specific growth rate (m) was determined using the modified
Gompertz model. The maximum specific growth rate (mmax) and half saturation coefficients (Ks) were calculated using
the Monod kinetic equation. The maximum observed growth rate (mmax) for heterotrophic bacteria was 3.8 day 1 with
Ks of 200 mg COD/l. The mmax for algal biomass based on suspended volatile solids was 2.7 day 1 with Ks of 110 mg
COD/l. The mmax of algae based on the chlorophyll-a was 3.5 day 1 at Ks of 50 mg COD/l. The observed specific
substrate removal by heterotrophic bacteria varied between the concentrations of substrate used and the average value
was 0.82 (mg COD/mg biomass). The specific substrate utilization rate in the bioreactors was direct proportional to the
specific growth rate. Hence, the determined Monod kinetic parameters are useful for the definition of the operation of
SFPs.
Description
Keywords
Heterotrophic bacteria, Half saturation coefficient, Maximum growth rate, Secondary facultative pond, Specific substrate removal
Citation
Kayombo, S., Mbwette, T.S.A., Katima, J.H.Y. and Jorgensen, S.E., 2003. Effects of substrate concentrations on the growth of heterotrophic bacteria and algae in secondary facultative ponds. Water Research, 37(12), pp.2937-2943.