In this work, the effect of wastewater feed composition on the membrane
fouling rate of 5 and 20 kD ultrafiltration ceramic membranes was investigated
using statistical analysis of the experimental results (two way factorial design),
with particular regard to the protein (meat extract and peptone), sodium
alginate and calcium chloride components. A mathematical model was used
to determine the major membrane blocking mechanisms and the effect of
different feed components concentration on the blocking mechanisms.
Polysaccharides are the major fouling compounds in extracellular polymeric
substance (EPS), while protein compounds are an important part of EPS
membrane fouling, their effect increases in the presence of polysaccharides.
Sodium alginate calcium solutions fouled the membrane more severely,
causing twice the increase of resistance (on average) than did meat extract
calcium solutions. This study showed that irreversible fouling was the major
fouling type in alginate calcium filtration experiments, while less of the fouling
in the meat extract calcium filtration experiments was irreversible.
The effect of changing the artificial wastewater components concentration on
the fitting accuracy of the blocking models for the 20 kD pore size membrane
was almost the opposite of the 5 kD pore size membrane. Increasing the
calcium concentration increased the predication accuracy of the intermediate
and complete blocking models, while the increase in alginate concentration
reduced the cake filtration model prediction accuracy.
After each experiment, the membrane was cleaned using different cleaning
chemical concentrations. The best cleaning was achieved with increasing
sodium hydroxide concentration in the cleaning solution. In general higher
cleaning temperature and increasing cleaning time improved the membrane
recovery, nevertheless; the effect was not as noticeable as the effect of
increasing sodium hydroxide concentration.
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.