The applications of polyacrylamide (PAM) in water treatment are highly specialized and diverse. Its core mechanism of action is based on the adsorption bridging, charge neutralization, and net-capturing sweeping effects of its polymer chain structure.
Eight Water Treatment Applications of Polyacrylamide
1. Polyacrylamide in Water Treatment
The goal of water treatment is to remove impurities from water through appropriate treatment and purification methods to meet standards for domestic or industrial water. Polyacrylamide’s applications in water treatment primarily encompass the treatment of both low-turbidity and high-turbidity water.
Research experiments have shown that the addition of polyacrylamide to the treatment of low-turbidity water with aluminum sulfate can improve treatment capacity. When the aluminum sulfate concentration is between 3 mg/L and 9 mg/L and the polyacrylamide concentration is between 0.0008 mg/L and 0.0125 mg/L, the turbidity of the treated water is below 3 degrees.
The study found that the simultaneous addition of polyaluminum and polyacrylamide to low-turbidity water significantly enhances turbidity removal. In experiments, when polyacrylamide was added at a concentration of 0.03 mg/L, the sedimentation time was shortened to half that of using polyaluminum alone, and the amount of polyaluminum used was reduced by 22%.
Research has shown that when treating highly turbid Yellow River water, the combined addition of polyaluminum chloride and polyacrylamide can both save costs and improve effluent quality. Currently, most water plants in my country use polyacrylamide when producing drinking water from high-turbidity water.
2. Polyacrylamide for Domestic Wastewater Treatment
The primary pollutants in urban domestic wastewater are organic matter, resulting in eutrophication, as well as pathogens and inorganic salts. It is characterized by high chemical oxygen demand (COD), turbidity, total phosphorus (TP), and total nitrogen (TN), dark water color, and an odor.
For complex water compositions, single-component flocculants often fail to meet water treatment requirements, making composite flocculants a focus of research. Composite flocculants not only retain the advantages of each component but also overcome the shortcomings of single-component flocculants, achieving a synergistic flocculation effect.
There are three types of composite flocculants: organic, inorganic, and organic-inorganic composite flocculants. The most commonly used are organic-inorganic composite flocculants. Initially, an inorganic flocculant is added to the wastewater for initial treatment. Then, an organic polymer flocculant such as polyacrylamide is added to further enhance flocculation through its adsorption and bridging effects.
Research has shown that using liquid polyaluminum ferric chloride and polyacrylamide as coagulants and filter aids in flocculation treatment of urban domestic sewage can increase total phosphorus removal by 14.51%, from 75.61% to 90.12%. Similarly, using polyaluminum ferric chloride as a coagulant in combination with polyacrylamide as a coagulant aid, aerodynamic flocculation was used to treat simulated polluted urban river water, achieving excellent results.
Of course, polyacrylamide can also be modified to produce modified derivatives for standalone use in domestic sewage treatment. Thermally modified attapulgite and acrylamide were in situ polymerized to create an attapulgite composite polyacrylamide flocculant, which was used to treat polluted river water, achieving 66.3% turbidity removal and 45.6% COD removal.
3. Polyacrylamide for Flocculation and Sedimentation
PAM acts by electrically neutralizing suspended matter in water and through adsorption and bridging, causing fine particles to aggregate into larger flocs. This accelerates sedimentation, effectively removing suspended matter, turbidity, and some organic matter from the water, improving water clarity.
4. Polyacrylamide for Drinking Water Purification
PAM is used in drinking water treatment to remove suspended particles, organic matter, and microorganisms, ensuring the safety and sanitation of drinking water.
5. Polyacrylamide for Industrial Wastewater Treatment
It is widely used in wastewater treatment in the chemical, papermaking, printing and dyeing, electroplating, and metallurgical industries. Choosing the right type of polyacrylamide based on the characteristics of different industrial wastewaters can effectively remove pollutants and ensure compliance with discharge standards.
6. River and Waterbody Restoration
Polyacrylamide is used in river sewage and waterbody treatment. It can quickly flocculate pollutants, improve water clarity and quality, and contribute to the restoration of the aquatic ecosystem.
7. Oilfield Produced Water Treatment
During the oil extraction process, polyacrylamide can be used to treat oily wastewater in produced fluids, achieving oil-water separation and water purification, thereby improving the quality of reinjection water.
8. Polyacrylamide for Mine Tailings Water Treatment
PAM is used to separate solids from liquids in mine tailings water, accelerate the settling of tailings particles, improve return water utilization, and reduce environmental pollution.
