Measurement of kinetic parameters in a submerged aerobic membrane bioreactor fed on acetate and operated without biomass discharge

The objective of this work was to study the biological performance of a submerged membrane bioreactor working with complete sludge retention that is susceptible to induce high biomass concentration and consequently low F/M ratio. A synthetic organic influent was used and the biological behavior of the system was studied for three different volumetric organic loads. In spite of continuous increase in the VSS concentration, a steady state in terms of removal efficiency and respiratory activity was achieved. High organic matter removal efficiency and no decline of the membrane performance were observed. Cycles of biomass synthesis and biomass loss by predation, lysis and decay could be considered so that a reduction of the biomass production seemed to be possible while keeping high treatment efficiency. Most of the cells were assumed to stay in a physiological state in which cell division was not favored, and the degraded substrate was essentially used to ensure maintenance requirements and storage products synthesis.