Research On Strategies For Membrane Fouling Control During MBR Operation

The widespread application of the membrane bioreactor is constrained bymembrane fouling, searching for the strategy and method for fouling control is themain aspect of research in this field, also is the object of this research.An innovation of membrane pretreatment by hydrate colloid was put forward in thisresearch and the optimal operation parameters were determined. By 213 days ofparallel experiment, the pretreatment showed some profits on fouling control.Meanwhile, a great deal of experience of MBR operation was gained during the longterm experiment.Aerobic granular sludge was not only better than traditional activated sludge in sizedistribution, but also in the aspects of hydrophobicity and filterability, which relatedto the membrane fouling. A method for aerobic granular sludge culturing wasexplored in the research. Though, there were no macroscopic granules harvested inthe end of the experiment, but the SVI dropped from 152 mL/g of the beginning to 69mL/g in the end, which showed satisfying tendency of granulation. The relativehydrophobicity of activated sludge was determined by salt aggregation test and it rosewith the dropping of SVI, which suggested that hydrophobicity is a driving force inthe aggregation process of activated sludge.Sub-critical operation is especially important to prevent macroscopic depositing ofactivated sludge onto membrane surface. An orthogonal experiment was conducted inthis research to study the impacts of aeration and the sludge concentration on thecritical flux which determined by the flux-step test. Test data were analyzed with theSAS software——PROC ANOVA and PROC REG and the result shows that aerationinfluences the critical flux more significantly. Also, a linear regression equation on thecritical flux was achieved in which aeration and the sludge concentration wereindependent variables. With the help of the regression equation, the relative efficiencyfor fouling control of different intermittent ratios were determined and the sequencewas 8:2>10:2>15:5>13:2.