Application of Polyamine Hydrex 3423 and Hydrex 3426

1. Introduction to Hydrex™ Polyamine Series

Hydrex 3423 and Hydrex 3426 are liquid cationic polyamine coagulants developed by Veolia Water Technologies for use in municipal water treatment, municipal wastewater treatment, and industrial effluent clarification. These products belong to the polyamine polymer family, which is characterized by high positive charge density, low to medium molecular weight, and rapid charge neutralization performance.

Polyamines differ from high-molecular-weight flocculants such as polyacrylamide in that their primary function is coagulation rather than bridging flocculation. Hydrex™ 3423 and 3426 destabilize negatively charged colloids, fine suspended solids, emulsified oils, and dissolved organic matter, allowing them to aggregate and be efficiently removed by sedimentation, flotation, or filtration. The two grades are formulated with different charge strengths, enabling selection based on influent water quality and treatment objectives.

2. Municipal Drinking Water Treatment Applications

2.1 Raw Water Clarification

Hydrex™ 3423 and 3426 are widely applied in municipal drinking water treatment plants to clarify surface water, river water, and reservoir water. Raw water typically contains clay, silt, algae, and natural organic matter, all of which carry negative surface charges that keep them dispersed.

When dosed into the rapid-mix zone, Hydrex™ polyamines quickly neutralize these charges, promoting micro-floc formation. This improves sedimentation efficiency and reduces turbidity in clarified water.

• Hydrex™ 3423 is commonly used for low to medium turbidity raw water, where stable and controlled coagulation is required.

• Hydrex™ 3426, with higher charge density, is better suited for high turbidity or high organic load conditions, such as during stormwater runoff or seasonal water quality fluctuations.

2.2 Coagulant Aid for Inorganic Salts

Hydrex™ 3423 and 3426 are frequently used as coagulant aids alongside aluminum sulfate or ferric salts. Their application reduces the required dosage of inorganic coagulants, resulting in lower sludge production, reduced residual aluminum or iron in treated water, and improved filter run times. Their broad pH effectiveness also reduces the need for pH adjustment chemicals.

3. Municipal Wastewater Treatment Applications

3.1 Primary Clarification Enhancement

In municipal wastewater treatment plants, Hydrex™ 3423 and 3426 are used in primary clarifiers to enhance the removal of suspended solids, fats, oils, and grease (FOG). Domestic wastewater contains finely dispersed solids and emulsified oils that do not readily settle without chemical assistance.

Hydrex™ polyamines destabilize these particles rapidly, producing larger flocs with higher settling velocity. Improved primary clarification reduces organic loading on downstream biological treatment systems, helping stabilize activated sludge processes and improve overall plant efficiency.

Hydrex™ 3426 is often selected for high-strength influent, while Hydrex™ 3423 is suitable for more consistent municipal wastewater conditions.

3.2 Sludge Conditioning and Thickening

Hydrex™ 3423 and 3426 are also applied as sludge conditioning agents prior to gravity thickening or mechanical dewatering. By neutralizing the negative surface charge of sludge particles, these polyamines promote aggregation and improve free water release.

They are frequently used as a pretreatment step before cationic polyacrylamide flocculants, reducing overall polymer consumption and improving sludge cake dryness.

4. Industrial Wastewater Treatment Applications

4.1 Paper and Pulp Industry

Paper and pulp mill effluent contains fibers, fillers, inks, and dissolved organic substances. Hydrex™ 3423 and 3426 are effective in this industry due to their strong cationic charge, which neutralizes fines and colloidal contaminants.

Applications include improved fiber recovery, reduced suspended solids, enhanced performance of clarifiers and dissolved air flotation (DAF) systems, and lower turbidity and COD in treated effluent. Hydrex™ 3426 is especially effective in recycled paper and coated paper mills with higher contaminant loads.

4.2 Textile and Dyeing Wastewater

Textile effluents often contain negatively charged dyes and surfactants, resulting in high color and COD. Hydrex™ polyamines neutralize dye molecules, allowing effective color removal through sedimentation or flotation. Hydrex™ 3426 is typically used for high-color wastewater, while Hydrex™ 3423 is suitable for moderate dye concentrations.

4.3 Food and Beverage Industry

In food processing industries such as breweries, dairies, and meat processing plants, wastewater contains proteins, fats, oils, and suspended solids. Hydrex™ 3423 and 3426 destabilize emulsified oils and organic matter, improving oil–water separation and reducing organic load before biological treatment.

5. Oil, Gas, and Petrochemical Wastewater

Hydrex™ 3423 and 3426 are used in the treatment of oily wastewater from refineries, petrochemical plants, and oilfield operations. They assist in breaking oil emulsions and removing dispersed oil droplets, improving the efficiency of API separators, flotation units, and secondary clarifiers. Hydrex™ 3426 is particularly suitable for complex or high-oil emulsions.

6. Operational Advantages

Key advantages of Hydrex™ 3423 and 3426 include rapid coagulation, short mixing time, wide pH adaptability, reduced sludge volume compared with inorganic coagulants, improved downstream dewatering performance, and easy handling as liquid products.