FLOPAM AN923 is an anionic polyacrylamide (APAM) flocculant from the FLOPAM range of SNF. It is designed primarily for solid-liquid separation, coagulation/flocculation, clarification, thickening, and dewatering. Published FLOPAM information places AN923 among anionic polyacrylamides with medium charge density, while AN923 grades are available in different molecular-weight variants.

Because the exact performance of an anionic polyacrylamide depends strongly on molecular weight, charge density, wastewater chemistry, pH, suspended-solids concentration, and the presence of inorganic coagulants, FLOPAM AN923 should be regarded as a product grade requiring jar testing or pilot testing rather than a universal flocculant for every application.

1. Municipal and Industrial Wastewater Treatment

One of the most important applications of FLOPAM AN923 anionic polyacrylamide is wastewater treatment. It can be used to improve the separation of suspended solids from water in municipal and industrial wastewater treatment systems.

When FLOPAM AN923 is introduced into wastewater containing suspended particles, its long polymer chains can adsorb onto particle surfaces and bridge several particles together. This produces larger and stronger flocs that settle more rapidly.

Typical applications include:

• Primary wastewater clarification
• Secondary sludge clarification
• Industrial effluent treatment
• Suspended-solids removal
• Clarifier performance improvement
• Dissolved-air flotation pretreatment
• Sludge thickening
• Sludge dewatering

The advantage of using FLOPAM AN923 is that very fine particles that settle slowly can be converted into larger flocs with improved settling characteristics.

For example, research on fish-processing wastewater has demonstrated the use of FLOPAM AN923 SH together with an iron-based coagulant in dissolved-air flotation to remove oil, grease, and solids.

2. Sludge Thickening and Dewatering

FLOPAM AN923 can also be considered for sludge conditioning where an anionic polymer is appropriate.

In sludge treatment, the objective is to separate water from solids. The polymer promotes aggregation of fine sludge particles, producing a more permeable floc structure through which water can escape.

Potential equipment includes:

• Belt filter presses
• Centrifuges
• Screw presses
• Vacuum filtration systems
• Gravity thickeners
• Dissolved-air flotation thickeners

However, an important distinction should be made between anionic and cationic polyacrylamide. Many biological municipal sludges respond better to cationic PAM because the sludge particles often have a predominantly negative surface charge. Therefore, FLOPAM AN923 should not automatically be selected for every municipal sludge-dewatering application. A polymer screening test is normally necessary.

3. Mining and Mineral Processing

Another major application area for FLOPAM AN923 anionic polyacrylamide is mineral processing.

Mining operations generate large quantities of fine mineral particles suspended in water. These particles may be difficult to settle naturally. Anionic polyacrylamide can promote flocculation and accelerate solid-liquid separation.

Applications include:

• Mineral tailings thickening
• Tailings-water clarification
• Ore washing
• Mineral slurry clarification
• Concentrate thickening
• Fine-particle settling
• Process-water recycling
• Tailings dewatering

In a thickener, FLOPAM AN923 can help convert fine suspended mineral particles into larger aggregates. The solids then settle more quickly, while clearer water rises to the surface.

This can increase water recovery and allow more process water to be recycled back into the mining operation.

It can be particularly useful in systems processing ores such as iron ore, copper, gold, coal and other minerals, although the optimal polymer charge and molecular weight must be determined for each ore.

4. Sand Washing and Aggregate Processing

FLOPAM AN923 can be used in sand-washing wastewater where large quantities of fine clay, silt and mineral particles must be separated from process water.

Sand and aggregate plants commonly generate wastewater containing very fine suspended solids. If this water is discharged directly, it can create high turbidity and significant sedimentation problems.

An anionic polyacrylamide can help:

1. Aggregate fine particles into larger flocs.
2. Accelerate settling in a settling tank or thickener.
3. Improve overflow-water clarity.
4. Increase recovery of usable process water.
5. Reduce the volume of solids remaining in suspension.

The recovered clarified water can then potentially be recycled to the washing system.

For sand washing, dosage should be optimized carefully because excessive polymer can produce weak or slimy flocs rather than improving separation.

5. Paper and Pulp Industry

Anionic polyacrylamides have applications in the paper industry as retention, drainage and wastewater-treatment aids.

FLOPAM AN923 or a related grade may be considered for:

• White-water treatment
• Fiber recovery
• Fine-particle retention
• Wastewater clarification
• Sludge dewatering
• Process-water recycling

The polymer can promote aggregation of fine fibers and fillers, making them easier to retain or separate from water.

SNF's FLOPAM product literature also identifies anionic polyacrylamides for paper-retention applications, with specific grades designed for this purpose.

For high-performance papermaking, however, a paper-specific FLOPAM grade may be preferable to selecting AN923 solely on the basis of its anionic character.

6. Chemical and Industrial Effluent Treatment

FLOPAM AN923 can also be used in industrial wastewater where suspended solids require chemical flocculation.

Potential industries include:

• Food processing
• Chemical manufacturing
• Textile processing
• Pulp and paper
• Metal processing
• Mineral processing
• Oil-related industries
• General manufacturing

In these systems, AN923 can work alone or together with inorganic coagulants such as aluminum sulfate, polyaluminum chloride (PAC), or ferric salts, depending on wastewater chemistry.

A common treatment sequence is:

Coagulant → rapid mixing → FLOPAM AN923 → gentle flocculation → clarification/DAF → filtration

The inorganic coagulant destabilizes colloidal particles, while the polymer helps form larger, stronger flocs.

7. Dissolved Air Flotation (DAF)

Another useful application is DAF wastewater treatment.

In DAF, air bubbles attach to suspended particles and float them to the surface. Good floc formation is essential because very small particles may otherwise remain suspended.

FLOPAM AN923-type anionic polyacrylamide can improve particle aggregation before flotation, potentially producing larger flocs that are more readily captured by the air bubbles.

Applications include:

• Food-processing wastewater
• Oil-containing wastewater
• Industrial effluent
• Pulp and paper wastewater
• Slaughterhouse wastewater
• Fish-processing wastewater

The published fish-processing study is a useful example of AN923 SH being incorporated into a DAF treatment process.

8. Drilling and Oilfield Applications

Certain FLOPAM AN923 variants can also have applications associated with drilling. NSF's product listing specifically identifies FLOPAM AN923 SHU QW4 PWG as a well-drilling aid, in addition to listing AN923 PWG and related variants for coagulation/flocculation.

This demonstrates why the exact AN923 suffix is important. AN923, AN923 SH, AN923 VHM, AN923 SHU and other variants should not be assumed to have identical specifications or applications.

Depending on the grade, anionic polyacrylamide can be used for:

• Drilling-fluid treatment
• Solids control
• Cuttings treatment
• Drilling-waste dewatering
• Water clarification

Oilfield use requires consideration of temperature, salinity, hardness, shear, and compatibility with other drilling chemicals.

9. Soil Stabilization and Erosion Control

Anionic polyacrylamide can also be used in soil conditioning, erosion control and sediment management.

When applied appropriately, PAM can bind fine soil particles together and reduce the movement of suspended sediment in runoff.

Potential applications include:

• Construction-site sediment control
• Agricultural erosion control
• Irrigation-channel management
• Dust and soil stabilization
• Runoff clarification

The dosage and application method for environmental land applications are substantially different from wastewater treatment, so a water-treatment dosage should not simply be transferred to soil applications.

10. Advantages of FLOPAM AN923

The principal advantages of FLOPAM AN923 anionic polyacrylamide are related to its ability to promote particle bridging and improve solid-liquid separation.

Its potential benefits include:

• Rapid floc formation
• Improved suspended-solids removal
• Faster settling
• Improved clarification
• Better sludge thickening
• Improved filtration
• Reduced solids carryover
• Improved process-water recycling
• Potentially lower inorganic-coagulant requirements

SNF's published product information confirms that AN923 is an established FLOPAM anionic polyacrylamide grade, while NSF listings identify AN923 PWG among polyacrylamides approved for coagulation/flocculation applications at specified maximum-use conditions.

11. How to Select the Correct Dosage

There is no single universal dosage for FLOPAM AN923.

Actual dosage depends on:

• Suspended-solids concentration
• Particle size
• Particle charge
• pH
• Water temperature
• Alkalinity
• Hardness
• Organic content
• Type of inorganic coagulant
• Mixing conditions
• Required effluent quality

For wastewater clarification, a jar test should normally be performed using several polymer concentrations. The optimum dosage is the lowest concentration that provides satisfactory floc formation, settling and water clarity.

It is also important to prepare the polymer correctly. Anionic PAM should generally be slowly dispersed into water to avoid formation of polymer lumps and allowed sufficient hydration time before dosing.

Conclusion

FLOPAM AN923 anionic polyacrylamide is primarily a solid-liquid separation flocculant. Its most important applications include industrial wastewater treatment, municipal and industrial clarification, mining and mineral processing, tailings thickening, sand washing, DAF treatment, paper and pulp processing, and selected drilling applications.

The product's medium-charge anionic character makes it particularly interesting for systems containing mineral or inorganic suspended solids. However, the best performance depends on matching polymer charge density and molecular weight with the specific particles being treated.

For commercial water-treatment applications, FLOPAM AN923 should therefore be evaluated by jar testing rather than selected solely from the product name. Also, when comparing AN923 with other FLOPAM products such as AN913, AN926 or AN934, the differences in charge density, molecular weight and grade suffix can significantly change flocculation performance.