Water treatment polyacrylamide significantly improves suspended solids removal rates in seawater desalination pretreatment through its unique flocculation effect, providing stable, low-turbidity feed water conditions for subsequent membrane treatment or distillation processes. Its core mechanism lies in utilizing the adsorption bridging and charge neutralization effects of its polymer chains to rapidly aggregate dispersed micro-suspended particles, colloids, and organic matter in seawater into large-volume flocs, thereby accelerating sedimentation or filtration separation efficiency. This process not only solves the problem of treating high turbidity and high salinity seawater but also further enhances the removal effect of suspended solids through optimized process parameters and composite technologies.
The molecular chain structure of water treatment polyacrylamide is key to its improved suspended solids removal rate. After its linear polymer chains fully extend in water, they can simultaneously adsorb multiple suspended particles, forming a "bridging" effect that connects the originally dispersed micro-particles into visible flocs. These flocs, due to their increased volume and weight, settle rapidly under gravity, significantly shortening the settling time. For example, in seawater pretreatment, the removal rate of suspended solids may be limited when using inorganic flocculants (such as polyaluminum chloride) alone. However, the addition of water treatment polyacrylamide allows its polymer chains to further encapsulate inorganic flocs, forming a denser structure and preventing floc breakage or secondary suspension, thereby improving overall removal efficiency.
Category neutralization is another important mechanism by which water treatment polyacrylamide treats suspended solids in seawater. Suspended particles (such as clay and algae) and colloids in seawater are usually negatively charged and maintain a stable dispersed state due to the repulsion of like charges. The positively charged groups on the molecular chains of cationic polyacrylamide can actively adsorb these negatively charged impurities, neutralizing their surface charge and weakening the electrostatic repulsion between particles. After charge neutralization, the collision frequency between particles increases, making it easier for them to aggregate and form large flocs. This characteristic makes cationic polyacrylamide particularly effective in treating seawater containing negatively charged colloids, effectively reducing effluent turbidity and meeting the stringent requirements of subsequent membrane treatment for influent suspended solids content.
The combined use of water treatment polyacrylamide and inorganic flocculants can significantly improve the removal efficiency of suspended solids. Inorganic flocculants (such as iron salts and aluminum salts) generate polynuclear hydroxyl complexes through hydrolysis, which have a rapid coagulation effect on large suspended solids in seawater. However, the resulting flocs are loose and easily broken. The addition of water treatment polyacrylamide can overcome this deficiency: its polymer chains can wrap around the surface of inorganic flocs, enhancing the mechanical strength of the flocs and preventing them from breaking during stirring or transportation. Simultaneously, the adsorption bridging effect of polyacrylamide can further capture residual small particles, forming "inorganic-organic" composite flocs and improving overall settling performance. This composite process is widely used in seawater desalination pretreatment, significantly reducing the risk of contamination in subsequent membrane treatment.
Optimization of process parameters is crucial for polyacrylamide to improve the suspended solids removal rate. During the dissolution process, the water temperature must be controlled below 40℃ to avoid molecular chain breakage due to high temperatures; the dissolution time must be at least one hour to ensure the polymer chains are fully extended. In terms of dosage sequence, inorganic flocculants are typically added first for initial coagulation, followed by polyacrylamide for deep flocculation, resulting in larger and denser flocs. The dosage needs to be determined through small-scale tests based on seawater quality (e.g., suspended solids concentration, pH value). Excessive dosage may lead to "colloidal protection" of the flocs, thus reducing the removal rate.
Polyacrylamide also exhibits good adaptability in seawater desalination pretreatment. For the high salinity of seawater, salt-resistant polyacrylamide has been developed, which enhances its solubility and flocculation activity in high-salt environments by adjusting its molecular structure (e.g., introducing sulfonic acid groups), avoiding the decrease in flocculation effect caused by salt ion compression of the electric double layer. Furthermore, the addition of polyacrylamide can reduce seawater corrosion of pretreatment equipment, extend equipment lifespan, and reduce long-term operating costs.
From an application perspective, polyacrylamide can significantly reduce effluent turbidity in seawater desalination pretreatment, providing a stable guarantee for subsequent membrane treatment. For example, in reverse osmosis seawater desalination, the suspended solids content in the pretreated effluent needs to be controlled below 2 mg/L. The addition of polyacrylamide ensures this standard is met, preventing membrane fouling that could lead to decreased permeate flow or shortened membrane life. In distillation-based seawater desalination, the flocculation effect of polyacrylamide reduces the tendency of suspended solids in the raw water to cause scaling on the heating elements, thus improving distillation efficiency.
Water treatment polyacrylamide, through its unique flocculation mechanism, optimized composite process, and improved salt resistance, achieves highly efficient removal of suspended solids in seawater desalination pretreatment. Its application not only improves the overall efficiency of seawater desalination but also provides key technical support for ensuring the stable operation of membrane treatment systems and reducing long-term maintenance costs, making it an indispensable chemical agent in seawater desalination pretreatment processes.
