The role of fouling mechanisms in a submerged membrane bioreactor during the start-up

The role of fouling mechanisms in a membrane bioreactor.

The present study has aimed to quantify the role of pore blocking and cake layer in a laboratory scale hollow fibre membrane module in submerged configuration. The membrane reactor (MBR) was fed with raw wastewater, only screened with a 2-mm sieve, collected from the Palermo WWTP. The MBR was characterised by an operating volume of 190 L and equipped with an aeration system located on the bottom of the reactor. The MBR operated for 65 days. The permeate was extracted by imposing a constant flux through the membrane (21 Lh−1m−2). The results confirm the importance of pore blocking control during start-up. In particular, it provides a rapid irreversible fouling that takes place at the beginni…

Air lift relevance in a side-stream MBR system

Nowadays, two main MBR configurations are developed in wastewater treatment (Fig. 1a and b). The former is based on a side stream membrane module position, it is generally developed for the industrial wastewater treatment because of its compactness even if it requires more energy due to the necessity of using high suspension flow rate recycles throughout the membrane module to minimise fouling rates [1]. With this configuration the membrane maintenance is easy because of the side stream position of the membrane module relatively to the bioreactor. The second configuration is based on the immersion of membrane module directly inside the bioreactor. This configuration is more extensive becaus…

Particle size distribution and biomass growth in a submerged membrane bioreactor

Submerged membrane bioreactors (MBR)associate in a single treatment unit a process ofbiological treatment and a phase of solid/liquidseparation by membrane filtration. Due to reduced membrane porosity, suspendedsolids and large amount of bacteria and virusesmay be retained in the reactor; consequently, highbiomass concentration is generally established inthe system. Indeed, this latter circumstance leadsto obtain a system able to operate with a low F/Mand high SRT and hence, as a result, a low sludgeproduction. In technical literature, the definition of fou-lants in MBR systems is a controversial task.More specifically, the influence of TSS onmixed liquor filterability has not been yet full…

Start-up with or without inoculum? Analysis of an SMBR pilot plant.

This study analysed a submerged membrane bioreactor (SMBR) start-up with the purpose of determining the best conditions to carry it out. In order to do this, a hollow fibre membrane module was installed in a submerged configuration in a pilot aerobic reactor. The experiment was then divided in two phases, lasting 65 days each. During phase 1, the pilot plant was started-up without inoculum of activated sludge and no sludge, withdrawal was performed. Conversely, in phase 2, the MBR pilot plant was started-up with sludge inoculum and the sludge concentration was kept constant. In both phases, the volumetric loading rate applied to the pilot plant was kept constant. The authors analysed the di…