Using effective membrane cleaning schemes to maintain designed permeability is one of the
key factors that determine the long-term productivity of a microfiltration (MF)/ultrafiltration (UF) membrane plant. This
paper presents the results from a membrane performance testing program conducted by the
Minneapolis Water Works for the selection of membrane supplier for its new 70-mgd UF
membrane plant. During this six-month testing program, two membrane manufactures
utilized different chemical cleaning concepts to maintain membrane performance. One
manufacturer used the conventional cleaning-in-place (CIP) approach, in which the
membranes were chemically cleaned when the operating transmembrane pressure reached the
maximum allowable level, while the other manufacturer adopted a new "chemical enhanced
backwash" (CEB) cleaning regime that applied frequent, low-dosed, periodical chemical
cleaning. Although membrane fouling is a very complicated process and can be affected by
many operating conditions, the testing results indicated that the CEB procedure with a 16-
hour low-dose cleaning cycle could effectively control the fouling and the performance was
much more stable than the other system that used the conventional CIP approach. This result is
consistant with findings from other research that demonstrated that interrupting fouling accumulation at an
early stage could prevent the formation of an aggregated massive fouling layer that could be
very difficult to remove even by chemical cleaning. A membrane autopsy study was
conducted at the end of the testing program. Various surface analysis techniques were used
to identify the composition of the fouling material. The microscopy images suggested that
most of the majority of the fouling material was powdered activated carbon, which was used
in the pretreatment processes for taste and odor control.
Includes tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 710 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 13 |
| Published : | 11/01/2002 |
