Design considerations for biological ion exchange drinking water filters: Resin selection, backwash, and regenerations

• Published in: AWWA water science Vol. 5; no. 5
• Main Authors: Zimmermann, Karl, Chen, William Szu‐Wei, Wright, Jaycee, Mohseni, Madjid
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.09.2023
• Subjects: Backwash; Dissolved organic carbon; Drinking water; Filter media; Filters; Ion exchange; Resins; Scour; Water filters
• ISSN: 2577-8161; 2577-8161
• DOI: 10.1002/aws2.1356

Abstract Two pilot studies provide insights into the design and operations of biological ion exchange (BIEX) drinking water filters. A lab‐scale pilot with strong‐base anionic (SBA) and weak‐base anionic (WBA) resins demonstrated 35% and 31% removal of dissolved organic carbon (DOC) up to 30 months, until secondary ion exchange exhaustion. While the WBA resins exhibited 14% less removal of DOC, their larger capacity doubled the duration until filter exhaustion. WBA filters were less affected than their SBA counterparts by sulfate‐containing inlet waters. In a second pilot, while water with high DOC yielded rapid exhaustion of SBA resins, air scouring increased the breakup of filter media and improved solids removal by 30× compared to hydraulic backwash alone. Significantly, DOC removal improved by 36% for a week following air scour. Key recommendations include the use of WBA resins to extend operating life while implementing air scouring can dramatically improve short‐term DOC removal.