Author/Authors :
Amiraftabi، Maryam-Sadat نويسنده School of Chemical Engineering, College of Engineering, University of Tehran, Tehran, Iran , , Mostoufi، Navid نويسنده , , Hosseinzadeh، Mostafa نويسنده , , Mehrnia، Mohammad Reza نويسنده Biotechnology Group, School of Chemical Engineering, College of Engineering, University of Tehran, Tehran, Iran ,
Abstract :
Background: One of the most important challenges about the Membrane Bio Reactors is membrane fouling.
Fouling has been at the centre of a globe debate for more recent years. It leads to high operational and maintenance
costs such as membrane damage and replacement of membrane. Membrane fouling is attributed to the
physicochemical interactions between the bio fluid and membrane. In order to decrease the fouling in
bioreactors there are common anti fouling strategies such as operation at low flux, Optimization of aeration
flow-rate and Physical and chemical cleanings. However, often they are not effective.
Methodology: This work deal with fouling crisis by a new and innovative method in order to reduce of fouling
on membrane surface by injection of parallel air jet on membrane bio reactor. This is a new idea and fundamental
study about the influence of wall jet on fouling of membrane surface. This study is included both experimental
and numerical investigations. In order to polarize the stream path on the surface of the membrane, four symmetric
nozzles were implemented at the bottom of the membrane surface upon the sparger. The changes in the fouling
resistance were experimentally measured at five various jet velocities and all of them recorded by a computer
system. In addition the effect of air jet velocity and shear stress on fouling resistances was also investigated by
computational fluid dynamics at the similar conditions.
Results: It was revealed that the permeate flux and resistance of fouling can be related to shear stress of air flow
at the membrane surface. When the velocity of air jets increase, the permeate flux increase too. Also, results
illustrate that jet injection can partially remove the cake which was formed on the surface of the membrane.
Conclusions: Correlations were developed for estimating each resistance of the membrane surface via the shear
stress. The resistances of the cake are removed by the jet velocity changes, from 20% in lower jet velocity up to
40% in higher jet velocity.
