A 6 MGD reverse osmosis plant in South Texas that was using chlorine to oxidize arsenic for improved membrane rejection was experiencing severe membrane fouling. The ferrous ions in the well water were being oxidized by the chlorine, resulting in ferric hydroxide fouling of the cartridge filters and membranes throughout the system. Despite numerous cleanings, the productivity of the system would not recover even while differential pressures would return to normal. A membrane autopsy revealed that the ferric hydroxide was seeding silica polymerization on the membrane system, so that even while the ferric hydroxide was removed, the silica scaling was continuing to grow. A description of the chemistry behind the scale formation and cleaning methods to impede the scale formation are discussed.
This presentation is available to AMTA Members only.
- Mo Malki
- American Water Chemicals, Inc.
- AWWA/AMTA Membrane Technology Conference, Las Vegas, NV
- AWWA/AMTA Membrane Technology Conference
- Ferrous Ion Oxidation, Silica Scaling, Reverse Osmosis (RO), CIP