Reduction of membrane fouling by innovative method (injection of air jet)

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 maintenancecosts such as membrane damage and replacement of membrane. membrane fouling is attributed to thephysicochemical interactions between the bio fluid and membrane. in order to decrease the fouling inbioreactors there are common anti fouling strategies such as operation at low flux, optimization of aerationflow-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 foulingon membrane surface by injection of parallel air jet on membrane bio reactor. this is a new idea and fundamentalstudy about the influence of wall jet on fouling of membrane surface. this study is included both experimentaland numerical investigations. in order to polarize the stream path on the surface of the membrane, four symmetricnozzles were implemented at the bottom of the membrane surface upon the sparger. the changes in the foulingresistance were experimentally measured at five various jet velocities and all of them recorded by a computersystem. in addition the effect of air jet velocity and shear stress on fouling resistances was also investigated bycomputational 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 flowat the membrane surface. when the velocity of air jets increase, the permeate flux increase too. also, resultsillustrate 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 shearstress. the resistances of the cake are removed by the jet velocity changes, from 20% in lower jet velocity up to40% in higher jet velocity.