Innovations in the inhibition and cleaning of reverse osmosis membrane scaling and fouling

Scaling and fouling of membranes are an on-going performance issue for most plants This presentation outlines innovations in speciality chemicals designed to inhibit membrane scaling and fouling and to clean membranes where deposition has occurred. There is an increasing trend to treat recycled waste water and use it as a feed supply to RO plants. Resulting high levels of phosphate can cause rapid scale formation in the membranes. This paper discusses phosphate chemistry and field trails of a new antiscalant which overcomes the need for acid dosing. Specialised nanofiltration membranes, have been developed for the removal of sulphate from seawater in offshore wells, reducing scale formation and souring in the well-head. The membranes are subject to barium/strontium sulphate scaling. This section discusses the processes and products developed to inhibit scale formation. Clay is a common-place foulant and very difficult to remove from membranes. The paper also describes the mechanisms and products developed to remove clay effectively. A number of case studies are described.

In order to support the world’s requirement for clean pure water, there has been a necessary acceptance of reverse osmosis technology. Innovations in engineering and a desire to minimise environmental impact by optimising plant performance have resulted in new challenges to maintain membrane performance and longevity. This paper has identified a number of new antiscaling and fouling speciality chemicals and techniques to improve plant operation. C Waste water reuse/recycling reverse osmosis plant can operate without having to dose large quantities of acid to reduce feed pH to control calcium phosphate scale by using a new antiscalant, Genesys PHO, which uses advanced threshold inhibiting mechanisms to raise the solubility of calcium phosphate 150 times. C Barium and strontium sulphate scale formation can form in off-shore oil rigs using SR90 membranes for sulphate removal. Genesys DW is a new antiscalant designed to prevent all forms of scale formation and iron fouling whilst being compatible with the nanofiltration membranes. C Clay fouling of a reverse osmosis membrane has historically resulted in failure and replacement. A new powdered high pH cleaner, Genesol 703, has shown to be effective in clay removal through a combination of detergent and surfactant mechanisms combined with osmosis from the permeate to the concentration boundary layer which assists in dislodging particles. C