Effective contaminant removal using MF/UF processes assumes that there is no feed water bypassing
the membrane through defects in the membrane module. One of the important issues in the practical
application and proper regulatory acceptance of these processes involves the methods of monitoring
membrane integrity. This manuscript evaluates data collected in pilot and full-scale evaluations of
integrity monitoring tools in the context of the requirements of the Long Term 2 Enhanced Surface
Water Treatment Rule (LT2) specific to continuous indirect integrity monitoring.
The current draft of LT2 stipulates minimum membrane integrity monitoring methods. A maximum
direct integrity monitoring interval of 24 hours and continuous turbidity monitoring are required. The
document also calls for an action limit for direct testing, based on a maximum filtrate water turbidity of
0.15 NTU. In certain cases, this limit might be only indicative of a major membrane system failure. In
the case of a major integrity failure occurring between integrity tests, it is feasible that the maximum
filtered water turbidity would not be exceeded, but required log removal may not be met. Two pilot-scale evaluations were performed. The first involved
a single, full-scale membrane module mounted on a pilot-scale plant was operated under a protocol
approved by the California Department of Health Services. The membrane, provided by Westech Engineering (Salt Lake City, Utah), was an outside to inside flow, polysulfone membrane operating in
deposition mode. The module contains 1227 square feet of active membrane surface area, is rated at a
nominal pore size of 0.01 microns by the manufacturer (Polymem). Challenge testing was performed at
United Water Idaho's Marden Water Treatment Plant. The testing took place in three phases that included: MS-2 bacteriophage challenge testing; surrogate evaluation of Cryptosporidium removal; and, integrity evaluation. The second pilot-scale evaluation involved a single, full-scale membrane module mounted a pilot-scale plant was operated under a protocol
approved by the California Department of Health Services. The membrane, provided by inge Americas
(Northbrook, IL), was an inside to outside flow, polyethersulfone membrane operating in deposition
mode. The module contained 485 square feet of active membrane surface area, was rated at a nominal
molecular weight cutoff of 100-150 kD by the manufacturer (inge, AG). Challenge testing was
performed at the City of Redlands' Horace Hinckley Water Treatment Plant. The testing involved four phases that included: MS-2 challenge testing; microsphere challenge testing; compromised membrane challenge testing; and, operational characteristics. The testing of various integrity monitoring techniques in this work was performed on a single full-scale
membrane rack at selected water treatment plants. Four of
the participating plants are located in the U.S., while the remaining two are located internationally. The
concentrated full-scale testing at each participating plant was performed for a period of two months.
The plants participating in this project were selected to represent the existing range of commercially
available membrane systems and manufacturers. Direct methods tested included the pressure decay test
and online sonic testing. Indirect monitoring methods tested included particle counting at various
sensitivities, index based particle monitoring, count based particle monitoring, turbidity monitoring,
laser turbidity monitoring, multi-sensor laser turbidity monitoring. Includes 4 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 360 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 11 |
| Published : | 06/17/2005 |
