Membrane life in a seeded-slurry reverse osmosis system

Abstract

Membrane replacement can be a major operating cost of a membrane plant. During the development of a novel desalination technique (the SPARRO process) for treating calcium sulphate scaling mine waters the expected life of tubular cellulose acetate membranes operating in the seeded-slurry mode was investigated. During four operating phases of the plant over a five-year period more than 9 000 h of operating data were obtained. Performance data showed that each operating phase was dominated by either membrane fouling or membrane hydrolysis. Membrane fouling was observed to begin near the front-end of the membrane stack and proceed towards the back. Hydrolysis, on the other hand, occurred first in the tail end of the stack and moved backwards towards the front end modules. Although two detailed membrane autopsies were carried out no definitive statement can be made in respect of the causes of either membrane hydrolysis or membrane fouling.

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