Function of self-forming dynamic membrane and biokinetic parameters’ determination by microelectrode

The self-forming dynamic membrane coupled bioreactor (SFDMBR), which uses coarse pore-sized material to separate solids and liquids in a bioreactor, has some advantages compared with membrane bioreactor (MBR) using micro-/ultra-filtration membranes such as low module cost and high flux. In this study, we investigate the microbial activity change of a self-forming dynamic membrane (DM) during its bio-fouling process by a microelectrode for O2. At a high flux of 40 L/m2 h, the dissolved oxygen was determined to be depleted at the depth of 1.5–2.0 mm in the self-forming DM. Based on the dissolved oxygen concentration profiles in the self-forming DM, a reliable and simple model and computational procedure were developed to estimate the biokinetic parameters in the self-forming DM. Sensitivity analysis of the model revealed that the dissolved oxygen profiles are sufficiently sensitive to the maximum specific rates of oxygen uptake (q⌢max,20), which were computed to be within the range of 3.8–11.1 mg O2/g SS h. q⌢max,20 decreased sharply in the first 5 days with the development of the bio-fouling process in the surface cake layer of the self-forming DM and then reached a relatively steady state afterwards. The Monod half-saturation coefficient for oxygen (Ko) was computed to be in the range of 0.16–0.75 mg O2/L. In summary, the results gave new experimental evidence on the change of microbial activity in the self-forming DM during its bio-fouling process.