Journal Article

Evaluation of Different Methods for the Determination of Maximum Heterotrophic Growth Rates

Stasinakis, Athanasios S., Paraskevas, Panayotis A., Mamais, Daniel, Lekkas, Themistokles D.

2003

Overview

This work evaluated the most commonly used methods for determining maximum heterotrophic specific growth rates ($\\mu _{m}$) in batch reactors. Parallel batch experiments were conducted under various initial substrate-to-biomass ($S_{0}/X_{0}$) ratios and values of the solids retention time ($\\theta _{c}$). The maximum specific growth rate,$\\mu _{m}$, was determined simultaneously according to measurements of oxygen consumption (i.e., oxygen uptake rate, OUR) and volatile suspended solids (VSS) increase. The$S_{0}/X_{0}$) ratio was found to significantly influence$\\mu _{m}$values. Under high$S_{0}/X_{0}$ratios (= 20), fast-growing bacteria seemed to gain a competitive advantage resulting in higher$\\mu _{m}$values than those obtained under low$S_{0}/X_{0}$ratios (= 1.5). The OUR-based estimate of$\\mu _{m}$($\\mu _{m({\\rm OUR})}$), under certain circumstances, is differentiated from$\\mu _{m}$that is based on exponential bacterial growth ($\\mu _{m({\\rm VSS})}$), and seems to be more a measure of substrate oxidation than a measure of bacterial growth. At high$S_{0}/X_{0}$ratio and low$\\theta _{c}$,$\\mu _{m({\\rm OUR})}$was significantly higher than the$\\mu _{m({\\rm VSS})}$, indicating that considerable uncoupling between anabolism and catabolism was occuring under these conditions. Batch experiments conducted at high$S_{0}/X_{0}$ratios seemed to be a more sensitive method for determining$\\mu _{m}$values in the presence of an inhibitor than tests conducted at low$S_{0}/X_{0}$ratios.

• Publisher: Water Environment Federation,Blackwell Publishing Ltd
• Subject: ACTIVATED SLUDGE / Applied sciences / Bacteria / Bacteria - growth & development / Bacteria - metabolism / BACTERIAL KINETICS DETERMINATION / BATCH METHODS / Batch reactors / Biological and medical sciences / Biological treatment of waters / Biomass / BIOMASS GROWTH / Biomass production / Bioreactors / Biotechnology / Environment and pollution / Evaluation Studies as Topic / Exact sciences and technology / Fundamental and applied biological sciences. Psychology / General purification processes / Industrial applications and implications. Economical aspects / Kinetics / Models, Biological / Oxygen / Oxygen Consumption / Oxygen uptake / Pollution / Ratios / Research Note / Respiration / Retention time / Sewage - microbiology / SUBSTRATE‐TO‐BIOMASS RATIO / Suspended solids / Wastewater / Wastewaters / Water treatment and pollution