Standard Operating Procedure - Ultrafiltration - Department of ...

Membrane PreservationIf the system is to be down for an extended length of time – more than 6 hours - themembranes should be stored in a preservative. The normal preservative will be a 0.5 to 1-percent solution of Ultrasil MP. Add enough preservative to get a pH of 3 to 4. Thesolution should be circulated every 3 to 4 days and flushed once a week. If a new solutionis required, a caustic wash should precede the addition of fresh preservative.The Scepter module should be fully CIPed and removed from the system to dry if it willnot be used for an extended length of time.CIP (Clean in Place)Proper CIP of the system is critical to the operation of the Model L. While not terriblydifficult, proper attention to detail is a must. Specified pH’s and temperatures arerequired and inflexible. Due to the nature of membranes, chemical strength is limited,and thus efficiency must be maximized. Maintain pH’s where instructed, use thespecified amount of chemical, and complete the log sheets daily.System CIP is manual. When CIP temperature setpoints have been reached, chemicals canthen be added. CIP profiles need to be set up according to the CIP procedures specifiedby the membrane manufacturer.While RO/NF elements are intolerant of oxidizers such as chlorine or peroxide, UF elementswill use some chlorine with the caustic wash step to increase the efficacy of the caustic.The absolute limit for UF membranes is 200 ppm chlorine and the wash procedures arelimited to 150 – 180 ppm. Always add the caustic to the system before adding chlorine!As with the RO/NF elements, these elements are also intolerant of any silica-based defoamers,even those labeled for food grade use. Use of defoamers will result in permanent fluxloss and void membrane warranty!42