Biomass Concentration by Density Measurement: Activated Sludge and Membrane Bioreactor

Grégory Cano, Adil Mouahid, Emilie Carretier, Philippe Moulin



In waste water treatment plant using biological treatment, the treatment efficiency strongly depends on the biomass concentration which controls the mass transfer in the bioreactor for activated sludge and the level of membrane separation for membrane bioreactor. This study shows the possibility of determining the total suspended solids concentration in a short time on activated sludge process or membrane bioreactor using density measurement for urban and industrial effluent. A linear relationship between density and total suspended solids concentration is obtained with a high value of R2 (between 0.924 and 0.9996). The influence of the density-meter measurement modes (fast and slow equilibrium mode), clearly shows that the fast equilibrium mode is adjusted for biomass which can easily settled in the measuring cell. If a very good relation is obtained for each WWTP (Waste Water Treatment Plant), a general linear relation which is determined only for urban effluent and three WWTP is given to determine the total suspended solids concentration without calibration by measuring its density at 20°C.

Keywords: Density; total suspended solids; activated sludge; waste water treatment plant; biomass concentration