This Week's Top Stories About Antiscalant For Ro Membrane

How do antiscalants work in reverse osmosis water treatment applications?

Antiscalants are pretreatment agents that are injected into the water before the feedwater enters the reverse osmosis membrane. Its presence delays the reaction of calcium, magnesium, and bicarbonate. The result is that scale does not form when RO purifies water. The relatively short duration of the treatment process in the membrane system prevents scale formation.

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What are the dose rates and injection methods for Flucon Stopper?

Dose rate.

The amount of Flucon required to inhibit scale formation depends on the insoluble salts’ saturation at the highest concentration point in the system. Excessive saturation depends on the concentration of ionic species in the water supply, the total salinity of the water supply, the water supply’s temperature, the water supply ratio for permeate recovery, and the type of membrane applied.

Dosing Method.

Flocon should be added to the membrane system before the last cartridge filter. If media filtration or activated carbon is used, Flocon should be applied after these treatment stages.

Flocon must be delivered to the water supply via a dosing pump from the dilution tank, directly from the drum or bulk storage facility at a rate determined by the size of the membrane system, the recommended dosing rate, and the delivery range of the dosing pump. It is recommended to adjust the dosing pump by the stroke length while maintaining the stroke frequency as much as possible to achieve a uniform distribution of Flocon in the membrane system feed water.

Caution - Biological Activity.

Flocon contains preservatives that are effective in dilutions of Flocon to 15 system permeate waters. Periodic cleaning of the dosing system is recommended as part of the planned maintenance program.

What is the difference between Flocon260 Antiscalant/Dispersant and Coagulant?

Flocon260 Antiscalant is used to prevent hardness precipitation in water during reverse osmosis treatment. Antiscalant also contains dispersant, preventing iron or aluminum in the water from reacting with the antiscalant and failing.

The coagulant has the opposite effect. Their role is to coagulate and precipitate suspended solids that may be present in the water. By coagulation, we mean that excellent suspended particles come together into large pieces and easily precipitate smaller suspended particles. Small suspended particles in water usually have an electrical charge. The coagulant facilitates the removal of the electrical charge and causes the particles to coagulate and settle. In short, coagulants are used to remove suspended solids.

In membrane processes, coagulants are used only in rare cases. Many coagulants are harmful to membranes. Coagulants are widely used in municipal water treatment systems.

In short, antiscalants are used to address hardness, which is dissolved in the water, and coagulants are used to manage suspended solids.

Can excess antiscalant foul membranes?

Excessive antiscalants can cause fouling of membranes. This fouling can be cleaned by washing the membrane with water with a pH of 2-3.

Antiscalant (organophosphate) and AM-88 (dechlorinated sodium metabisulfite) are sometimes used for pretreatment. In this case, will there be a chemical reaction that causes fouling on the membrane?

There is no chemical reaction between these two chemicals.
In our desalination RO pretreatment system, we add a cationic coagulant before sand filtration. Also, Flocon 260 (anionic) is added after sand filtration. I would like to know if these two chemicals will react and cause fouling of the RO membrane.
Flocon260 is usually not compatible with cationic polymers. If we know what kind of polymer you are using, we can give a definite answer. We can use other anti-quaternary ammonium salts (FLOCON40), but a complete water analysis is needed to determine if they are useful.

Under what circumstances can denitrifiers cause RO membrane fouling?

1、Fungal growth in antiscalants - Some antiscalants contain impurities that can provide the necessary nutrients and carbon for biological evolution. It is not uncommon to find fungal growth in polymer-based antiscalants—barrel growth seeds growth on the membrane surface. Reputable manufacturers produce higher purity products with NSF approved antimicrobial preservatives to prevent these problems.

2、The dosing point is too close to the acid dosing point - pH is usually adjusted by concentrated sulfuric acid. Without good mixing, the acid and water densities are very high, temporarily forming separate phases. Adding antilithic agent immediately after adding acid point will be hydrolyzed away by strong acid. Some polymer-based anti stone agents are prone to this decomposition.

3, incompatibility with water quality - Some anti stone agents have a low tolerance to iron and aluminum. This anti-sedimentation agent forms an insoluble bond with these metals and precipitates on the RO membrane’s surface.

4, high hardness or foulant dosage - foulants carry a higher load than typical foulant anions such as carbonate and phosphate, which have a potent charm for calcium and magnesium. During threshold control, this attraction to calcium/magnesium leads to the adsorption of forming clusters and interferes with stable nuclei formation. However, when the hardness concentration is high, the antiscalant itself forms insoluble calcium antiscalant salts. This is a problem because once the active inhibitor precipitates, and the other scales will also precipitate. Hardness affects all antiscalants, whether polymer or phosphonate based. Proton antiscalant prediction software from AWC can predict such salts’ formation and, therefore, maximum recovery for a given temperature and pH.

5、Quality Control Issues - In some cases, manufacturing issues can lead to the formation of insoluble gels on the membrane surface for certain polymer-based antiscalants. Therefore, it is vital to use only counter-dialyzers produced by reputable suppliers.