A Novel Aeration Method for Submerged Membrane Bioreactors
Paper ID : 1366-MST2015-FULL
Necati Kayaalp *1, Gokmen Ozturkmen2, Tamer Bagatur2, Fevzi Onen2
1Dicle University/ Engineering Faculty/ Civil Engineering Dept./ Division of Hydraulics
2Dicle University
Submerged membrane bioreactors (MBRs) have been aerated by a blower, which is a common method of aeration for biological wastewater treatment. Since aeration of MBRs is done for multi-purpose, namely for biological oxygen supply and membrane surface cleaning, it comprises more than 80% of the operating costs. A technique that can reduce the air requirement will also reduce the operating costs of the submerged MBRs.
When a fluid is circulated through a venturi device, air enters from the suction port of it due lower pressure than the atmospheric pressure that occurs at the throat of the device. In this study, an integration of a venturi device to a submerged MBR was done for the first time to supply the air required for both the biological treatment and the membrane surface cleaning. Two aeration rates were tried in the scope of the study; 3 L/min and 6 L/min. The venturi device achieved much higher gas transfer efficiencies than the blower aeration system. At 5500–6500 mg/L MLSS concentration and in different fluxes tried in the study, while the average dissolved oxygen concentration in MBR was 0.76 mg/L (0.6–1.5 mg/L) with blower aeration system at the aeration rate of 6 L/min, it was 7.75 mg/L (7.5–8.2 mg/L) with venturi aeration system at the same aeration rate.
Also the high-velocity air–water mixture exiting the venturi device was directed to the membrane surfaces by a porous diffuser system for a better membrane surface cleaning. While there was no difference at low flux (18 L/m2.h), venturi system cleaned the membrane surface better than the blower system at medium (32 L/m2.h) and high (50 L/m2.h) fluxes.
membrane bioreactor (MBR), aeration, venturi device
Status : Paper Accepted (Oral Presentation)