The Role of Synthetic Membrane Pre-Treatment in Influencing Filtration Performance over Multiple Operational Cycles

Abstract

Manufacturers of polymeric membrane filters used for treating food streams routinely recommend that they are chemically cleaned prior to first use. In this paper, two pre-treatment methods are compared for the filtration of a spent sulphite liquor [SSL] (17.8 wt.% dry solids) using a 20 kg mol⁻¹ molar mass cut off (MMCO) fluoropolymer membrane. In an extension of previous work that considered the effect of the application of a pre-treatment protocol over a single operational cycle, this paper reports the effect of pre-treatment protocols over four complete fouling and cleaning cycles. The pre-treatment methods evaluated were the conditioning with water at 60°C only [Protocol 1], and the conditioning with water at 60°C followed by cleaning with 0.5 wt.% NaOH [Protocol 2]. Results are presented that demonstrate that for the system examined, the positive effect of the NaOH pre-treatment protocol diminished after three complete operational cycles, and disappeared after four cycles.

Keywords:

• cleaning
• conditioning
• fouling
• multiple cycles
• spent sulphite liquor
• ultrafiltration

ACKNOWLEDGEMENTS

This study was supported by a Food Processing Faraday/EPSRC studentship. The industrial partners were Alfa Laval (Nakskov) and Nordzucker (Nakskov). We thank both Dr Frank Lipnizki (Alfa Laval) and Mr John Jensen (Nordzucker) for their invaluable technical input and guidance. Alfa Laval kindly donated the membranes used in this study, and also arranged the donation of the SSL.