We are designing a system that needs to operate at 90% recovery due to brine disposal restrictions. My feedwater has a pH of 8 with 0.5 ppm aluminium. What is your recommended antiscalant to inhibit aluminum fouling of the membranes?
Aluminum is extremely insoluble in water in the neutral pH range (6-8 pH), especially in natural water sources. A concentration of 0.5 ppm Al at pH 8 is very unlikely. Below is aluminum pH vs. speciation diagram. Even though Al is about 85X...
What is the role of circulation in membrane cleaning?
Circulation flushes dissolved foulants away from the membrane surface, and replenishes depleted cleaning chemical. The higher the rate of circulation, the more energy the chemical molecules will have, and the faster the rate of cleaning...
Should I wait until the target CIP solution temperature is reached before starting membrane cleaning?
Increasing the temperature gives energy to molecules, making them bombard the foulant more frequently – this increases the rate of reaction between the cleaning chemicals and the foulants. During soaking, warmer temperature increases the...
Should increase in differential pressure be used as the sole indicator of membrane scaling/fouling?
Differential Pressure (∆P) alone should not be used as an indicator of membrane scaling/fouling. Increases in differential pressure (∆P) across a stage indicate that a foulant has growth thick enough to interfere with flow through the ...
Are American Water Chemicals (AWC®) products PFAS free?
Yes. At AWC® all the ingredients used in the manufacturing of our chemicals are PFAS free because of the extra precautions we take in our manufacturing process. But first, what are PFAS and why are they bad? Per- and polyfluoroalkyl substa...
Under which conditions can antiscalants cause RO membrane fouling?
Reverse Osmosis Antiscalants can cause membrane fouling in Reverse Osmosis systems under the following conditions: Fungal growth in the antiscalant – some antiscalants contain impurities that can provide the necessary nutrients and ...
Can I use citric acid to descale/clean a reverse osmosis (RO) Membrane?
Citric acid is an organic acid that is often used for removal of calcium carbonate scale and is often mistakenly believed to be effective at dissolving iron fouling. It actually has only marginal impact on iron hydroxide deposits, and is ...
When do we know if the cleaning of our Reverse Osmosis plant was successful?
Once the RO membrane system is placed back online after CIP, you can get a relatively good idea by comparing post-cleaning feed pressures and differential pressures for each stage to pre-cleaning values. The most reliable method would be ...
What is the best post-CIP flushing procedure in Reverse Osmosis systems? How do we know when flushing after a cleaning is done?
Always flush your membranes with RO permeate until the pH measured at the concentrate end is within a pH range of 5 – 9. You can then proceed to flush with feed water until the pH of the water exiting the RO membrane system is similar t...
Can we send the CIP solution to our deep injection well after cleaning our Reverse Osmosis membranes?
No, if a high pH RO cleaning solution is mixed with RO brine, it would result in severe scaling. Always consult with your hydrogeologist before sending any solution to the deep injection well. See also: What is the procedure for cleaning ...