WIT Press

Monitoring The Biomass Content In The Aerobic Digestor Of A WWTP: Correlation Between Gravimetric And Optical Methods


Free (open access)

Paper DOI






Page Range

401 - 408




3,233 kb


M. Salaverría, A. Elías, A. Iturriarte, L. Gurtubay & S. Paunero


The aim of this work is to develop reliable and quick methods to quantify the amount of active biomass in the aerobic reactor of a Wastewater Treatment Plant (WWTP). The removal of pollutants contained in wastewaters is carried out by several processes involving physical, chemical and biological treatments. The biological treatment renders the elimination of the organic matter and takes place in aerobic reactors. A constant concentration of microorganisms in the reactor system ensures a high degradation performance, since an inappropriate biomass amount would hinder the process efficiency. Although the most used method to control microorganisms’ growth is based on the measurement of the solids content in the mixture, this simple determination has several drawbacks. First, it is a tedious procedure, which requires more than 24 h-performance, delaying the decision-making and proper control of the sludge recirculation rate. The second disadvantage is the lack of a standardized method for result calculation. Finally, high solids content is not directly related to a big amount of active biomass. In this study, absorbance and turbidity have been selected as additional parameters in order to obtain a reliable correlation between those optical parameters and dry weight measures. A quick measurement of absorbance or turbidity, related to the quantity of solids in the sample, makes the decision-making easier in the everyday operation of the plant. Keywords: WWTP, biomass, solids content, absorbance, turbidity, correlation.


WWTP, biomass, solids content, absorbance, turbidity, correlation