Performance of ceramic micro- and ultrafiltration membranes treating limed and partially clarified sugar cane juice

The performance of ceramic membranes with pore sizes of 0.02, 0.05 and 0.10 μm in clarifying limed and partially clarified raw sugar cane juice was investigated under different operating conditions. For the 0.10 μm membrane, the increase in transmembrane pressure (TMP) from 1 to 3 bar increased the initial flux by 15.5% and increased the average flux over a period of 4 h by 11.9%. The initial flux of the 0.10 μm membrane increased dramatically at a TMP of 1 bar when the membrane underwent a chemical cleaning with 1% NaOH and NaOCl equivalent to 3000 ppm free chlorine for 1 h and the average flux over a period of 4 h was also increased. Among the three membranes tested 0.05 μm membrane performed better than the other two membranes and yielded higher initial and average fluxes. Out of the four fouling models used to fit the experimental data, the cake filtration model predicted the initial fluxes of 0.02 and 0.05 μm membrane more accurately. On the other hand, the combination of external and progressive internal fouling model predicted the performance of 0.10 μm membrane better compared to the others. Intermittent air back flushing improved the performance of 0.10 μm but did not have any effect on the performance of the other two membranes. However, all the membranes produced high quality filtered juice.