Comparing two start-up strategies for MBRs: Experimental study and mathematical modelling

Performance of membrane bioreactor (MBR) systems for the treatment of shipboard slops: Assessment of hydrocarbon biodegradation and biomass activity under salinity variation

“…During experimental Phase II, the fouling tendency showed a behaviour similar to that of EPS production, in agreement to what already proposed in the technical literature [21,47] even if, as observed above, the relationship between the total polymeric substance concentration and membrane fouling deserves further investigation since it is subject to discussion, as pointed out by Lin et al [67]. Indeed, in the experimental Phase II it was not possible to analyse a rational mathematical relationship between fouling resistances and EPS or SMP because only 4 data are available (one for each physical cleaning).…”

“…hydraulic washing). The superficial cake deposition (irreversible or reversible, see [47]) can be then evaluated by calculating a series of flux and transmembrane pressure (TMP) data that are obtained before and after cake layer removal from the membrane surface. In agreement with previous experimental activities [32,39], it is possible to define the membrane fouling as being constituted by different contributing factors:…”

“…Furthermore, it is also possible to define an irreversible resistance (R irr ) as the sum of deposits due to pore blocking and cake deposition that are not removable by the ordinary cleaning action or periodical backwashing. On the other hand, the reversible resistance (R rev ) can be defined as the fouling amount that is removable by ordinary washing actions, represented by ordinary backwashing in the case of hollow fiber modules (and that is almost coincident with R C,rev ) [47].Regarding the evaluation of the biokinetic parameters of the suspended biomass, respirometric batch experiments were conducted by means of a "flowing gas/static-liquid" type batch respirometer. Before running each test, the biomass samples were moved into the batch respirometer and aerated until endogenous conditions were reached, as suggested by the oxygen uptake rate (OUR) values.…”

Foaming in membrane bioreactors: Identification of the causes

“…The membrane allows the retention of all solids that are larger than 0.01 (Ultrafiltration)-0.1 (Microfiltration) mm, so free swimming bacteria are retained. Unfortunately, there are some disadvantages, such as membrane fouling and biological foaming (Di Bella et al, 2010;Mannina and Di Bella, 2012). In fact, the tank in which the membrane module is submerged may become a "foam trap" and the recirculation of trapped foam make foaming worse (Wanner, 1994;Jenkins et al, 2004).…”

Bacterial community structure and removal performances in IFAS-MBRs: A pilot plant case study

“…In this context, membrane bioreactors (MBRs) may represent a useful solution, since they enable to disconnect the efficiency of the biological processes from the biomass settling properties. In particular, MBRs generally feature high quality effluent, small footprint and low sludge production rates compared to conventional activated sludge (CAS) systems (Stephenson et al, 2000;Mannina and Di Bella, 2012). Therefore, in the last years the integration of BNR process with MBRs has been proposed for wastewater treatment, in order to increase the effluent quality, including such BNR processes as University of Cape Town (UCT) process, anoxic/oxic (A/O) process and anaerobic/ anoxic/oxic (A2O) process (Hu et al, 2014).…”