DBPapers
DOI: 10.5593/SGEM2016/B31/S12.021

CLEANING BY PHYSICAL METHODS OF MEMBRANES USED FOR DRINKING WATER TREATMENT – A CASE STUDY FOR HOLLOW FIBER MEMBRANES WITH DIFFERENT MOLECULAR WEIGHT CUT-OFF

A.Ciocanea, C. Dumitrescu, R.Sauciuc, L. Dumitrescu, C. Cristescu
Wednesday 7 September 2016 by Libadmin2016

References: 16th International Multidisciplinary Scientific GeoConference SGEM 2016, www.sgem.org, SGEM2016 Conference Proceedings, ISBN 978-619-7105-61-2 / ISSN 1314-2704, June 28 - July 6, 2016, Book3 Vol. 1, 153-160 pp

ABSTRACT
Two pairs of hollow fiber membrane modules used for water drinking treatment by ultrafiltration (outside-in permeate flow direction) were tested for assessing the efficiency of cleaning by physical methods. The two hollow fiber membranes were of polypropylene type, of different molecular weight cut-off (MWCO): 0.097 m and 0.047 um respectively. For each module pairs, there were provided same water flow rate and inside cylinder pressure. One of the hollow fiber membranes has been subjected to relaxation, backflushing procedure, and strong shear force, while for the other module, no treatment was provided for comparison reasons. All modules were horizontally positioned for the tests. The results highlight that for membranes of smaller MWCO, relaxation and backflush procedures were effective. For membranes of large MWCO, backflushing was effective, but poor results were registered for reversible fouling. Therefore, a reduced time interval between backwashing is needed, if one uses membranes at large MWCO. Using of small bubble jets at different velocities in order to enhance turbulent flow regime did not provide relevant results. A composite index is proposed, by computing the ratio of the inside cylinder pressures and the feed pump power consumption, at the same outlet flow rate. For membranes of smaller MWCO the index is greater that 1, indicating that inside cylinder pressure can be yet efficiently increased - ratio for increased pressure is higher that power consumption ratio.

Keywords: ultrafiltration, fiber, cleaning, hollow, physical methods