Reverse osmosis sanitization

Ball and butterfly valves are also commonly used in water treatment systems. Diaphragm valves should be used downstream from the unit that removes dissolved solids (reverse osmosis unit or deionizer), however, because of their inherent ease of sanitation. 

Plants are cleaned, sanitized, and rinsed immediately after processing, and right before processing to ensure satisfactory initial process conditions from microbiological standpoint [3]. Because chlorine is freely permeable to most membranes that it is able to sanitize the permeate side of the system as well as the retentate side, using solutions of sodium hypochlorite containing 100-200 ppm of active chlorine is a common sanitation technique for many membranes, except cellulose acetate reverse osmosis membranes, which can only tolerate brief exposure to chlorine at 10-50 ppm level [3]. 

Municipal water systems usually contain 5-50 EU/ml of endotoxin. Pharmaceutical waters are treated by ultrafiltration, distillation, or reverse osmosis to separate endotoxin from water.f The principal source of endotoxin is bacteria within a water system in the form of biofilm or colonies entrapped in resin beds, etc. A water system will be contaminated unless there is an ongoing sanitization program. The endotoxin limit for Water for Injection was set at 0.25 EU/ml because it is a critical vehicle and a major source of pyrogens. 

The equipment required for water treatment will be determined by the quality of the incoming water. Typically, a USP pharmaceutical grade system will require pretreatment (filters), deionization, reverse osmosis, and potentially a polishing step such as continuous deionization. Many systems now incorporate UV filters for sanitization, which kill micro-bials and also eliminate ozone. 

A. CoUentro, M. CosteUo, G. Zoccolante, Hot water sanitization of reverse osmosis systems for pharmaceutical water production, Ultrapure Water 17 (10) (2000) 1-6. 

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