Effect of FOG (fat, oil, and grease) and antifoam

Effect of FOG on membrane fouling

To be continued

Effect of antifoam on membrane fouling

While there are little hard evidences published, it has been widely believed from the early days in 1990’s that any oil or hydrocarbon based antifoams expedite membrane fouling. Perhaps this notion stems from the fact that hydrophobic oils can cover membrane surface much more strongly than the water molecules. Or, possibly the superior antifoaming performance of oil based antifoams expedites the returning of the hydrophobic debris accumulated in the foam layer back to water phase and thereby membrane fouling can be accelerated as the suggested mechanism here. As a result, cost effective antifoams based on silicone oil and hydrocarbons have been prohibited to date by membrane manufacturers.

Without revealing the experimental data, Zenon published a list of approved and banned antifoams (Zenon, 2003). The criteria used appears that all the oil and the hydrocarbon based antifoams and the antifoams containing large polymers are banned, while alcohol based water soluble antifoams containing glycerins and polyether polyols are allowed. Following are the lists of approved and banned antifoams for GE’s ZeeWeed® membranes.

Table 1. Approved and banned antifoams (Zenon, 2003)

Approved Banned
Nalco, 60096*
Nalco, 7465
Nalco, 76028
Dow, Polyglycol 45-200
Dow, Polyglycol FR-530
Dow, Polyglycol P-1200
Dow, Polyglycol 112-2
Betz, Foamtrol AF1660
Betz, Foamtrol AF3550
Betz, Foamtrol AF3551Surpass Chemical Co., NOFOME AK
Surpass Chemical Co., NOFOME AK
Ultra Additives Inc., FOAMTROL WT-2
Ultra Additives Inc., FOAMTROL WT-73
Ultra Additives Inc., FOAMBAN MS-5

* Replacement of Nalco IL08

 

© Seong Hoon Yoon