Off-site membrane cleaning

Off-Site Membrane Cleaning On-Site Membrane Cleaning (CIP)  

Off-site membrane cleaning involves removing membrane modules from the pressure vessels and shipping them off site for cleaning by a 3 party. If the RO must remain in operation, a second set of membranes is used to replace those sent out for cleaning (one of the shortcomings of off-site cleaning). 

Chapter 13.2 discussed techniques and chemicals used for cleaning of RO membranes. This section discusses the merits of on-site verses off-site membrane cleaning. Table 15.4 summarizes the advantages and limitations of on-site and off-site membrane cleaning. 

Off-site membrane cleaning involves removing membrane modules from the pressure vessels and shipping them off site for cleaning 

For example, higher temperature and pH may be used to address biofilms and lower pH and higher temperature may be used to remove calcium carbonate scale (refer to Table 13.1). 

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Table 15.4 Merits of on-site versus off-site membrane cleaning.

Off-site cleaning offers expert service. Personnel specifically trained for that purpose clean membranes. Experience goes a long way when it comes to membrane cleaning, because cleaning can be as much an art as it is a science. 

Membrane manufacturers at times give special variances to off-site cleaning operations to use conditions outside the normal cleaning recommendations for membranes, as listed in the membrane specifications. 

Off-site cleaning costs more than on-site cleaning. Quotes should be obtained form specific vendors, but pricing can be as high as 150 or greater per membrane 8-inch diameter module. 

A two-stage, 500-gpm RO skid can be cleaned is about 2 days. Off-site cleaning can take a couple of weeks to turn around the membranes. 

CIP is less expensive that off-site cleaning. Depending on the chemical(s) used, an 8-inch diameter membrane module can be cleaned for anywhere from 5 to 25 each. 

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