Simultaneous removal of phosphorus and nitrogen from sewage using a novel combo system of fluidized bed reactor–membrane bioreactor (FBR–MBR)

Abstract

A FBR-MBR combo system was designed as a novel approach for simultaneous phosphorus and nitrogen removal from sewage. The combo system was evaluated more than 7 months under variable pH (7.5-9.5), hydraulic retention times (HRT=2-10h), intermittent aeration cycles (IAC) (on/off=60/60-15/45 min) and sludge retention times (SRT=10-60 d). Prior recovery of phosphorus as struvite in the FBR enhanced nitrogen and COD removal efficiency in MBR. Under optimum operating conditions (pH=9, HRT=6h and IAC=45/15 min), PO4(3-)-P, NH4(+)-N and COD removal efficiencies were 92.6 ± 4.2, 98.7 ± 1.2 and 99.3 ± 0.5%, respectively. Stable mixed liquor suspended solid concentration (3.0-5.0 g/L); enhanced nitrification-denitrification activity (78-92%) and reduced transmembrane pressure were also achieved. Compared to soluble microbial products, extracellular polymeric substances (EPS) showed strong correlation with fast membrane fouling. Among EPS components, carbohydrate rather than protein was associated with membrane fouling. Except HRT, all parameters considered (pH, IAC, SRT) showed a significant effect on removal efficiency.

Preparation and characterization of antifouling graphene oxide/polyethersulfone ultrafiltration membrane: Application in MBR for dairy wastewater treatment

“…Nevertheless, this phenomenon might have occurred due to reduced efficiency of oxygen transfer provided by incomplete air distributions in a high concentration of biomass and high viscosity of the medium. Therefore, the inner regions of the biological flocs probably did not receive oxygen and transformed to anoxic zones, thus providing favorable conditions for denitrification [49,50]. In such cases, nitrification occurs on the surface of the flocs, whereas denitrification occurs in the internal layers of the flocs due to a dissolved oxygen gradient, therefore simultaneous nitrification and denitrification (SND) take place in the reactor even during aeration [51,52].…”

Effect of Aeration and Recirculation in the Removal of Nitrogen and Chemical Oxygen Demand From Sanitary Sewage in a Structured Bed Reactor

“…These pH values are within the ideal range for the development of nitrifying and denitrifying and heterotrophic aerobic microorganisms (Mayer et al, 2009;Won & Ra, 2011). Guadie et al (2013) did not perceive a significant difference in the COD removal and N-NH4 + from sanitary sewage in a membrane reactor when the pH ranged from 7.5 to 9.5. He et al (2014) evaluated the influence of pH values of 7.5 to 9.0 on SND and observed better reactor performance with pH values lower than 8.0.…”

Membrane bioreactor: A mini review on recent R&D works

“…The detailed study on this mechanism remains lacking. Guadie et al (2013) and Gao et al (2014b) studied a fluidized bed reactor (FBR)-MBR system for simultaneous phosphorus and nitrogen removal from sewage. These authors revealed that the tested system could have enhanced nitrogen and chemical oxygen demand (COD) removal to above 98.7% as phosphorus was removed in the FBR stage.…”