Polyamine is a highly effective cationic organic polymer widely used in industrial water treatment, wastewater clarification, sludge dewatering, and mineral processing operations. As a water-soluble cationic coagulant, polyamine works primarily by neutralizing the negative surface charge of suspended particles and colloids in water. Once the surface charge is neutralized, these particles can aggregate, forming larger flocs that settle rapidly or are more easily filtered or separated. Because of this mechanism, polyamine has become one of the most important primary coagulants and charge neutralizers in modern water and wastewater treatment systems.

In the field of drinking water treatment, polyamine is used as an efficient coagulant to clarify raw surface or groundwater that contains suspended solids, organic matter, and fine colloids. When added to the raw water, polyamine neutralizes the negatively charged colloids such as clay, humic substances, and organic contaminants. These neutralized particles then aggregate into larger flocs that can be removed through sedimentation or filtration. Compared with traditional inorganic coagulants such as aluminum sulfate or ferric chloride, polyamine generates less sludge, has a wider effective pH range, and does not increase the salinity of treated water. As a result, it is often used either alone or in combination with other coagulants in potable water production systems.

In industrial wastewater treatment, polyamine serves as a versatile cationic coagulant that effectively treats effluents from chemical plants, textile dyeing, food processing, paper manufacturing, and petroleum refining industries. Many industrial wastewaters contain negatively charged suspended solids, color bodies, emulsified oils, or dissolved organic substances that are difficult to remove by simple sedimentation. Polyamine, with its strong cationic charge density, neutralizes the electrostatic repulsion among these particles and bridges them into larger flocs. This process reduces color, turbidity, and chemical oxygen demand (COD) in the treated effluent. In textile wastewater, for example, polyamine reacts with anionic dye molecules, breaking color bonds and producing clear water suitable for reuse or discharge. In food or beverage plants, polyamine assists in clarifying wastewater containing organic matter, fats, and proteins, significantly improving downstream biological treatment efficiency.

Polyamine also finds extensive use in sludge conditioning and dewatering processes. After primary or secondary treatment, wastewater produces large amounts of biological or chemical sludge that contain a high proportion of water and fine solids. Dewatering this sludge efficiently is crucial for reducing disposal costs. When polyamine is added as a pre-treatment agent, it enhances particle aggregation and water release properties, allowing mechanical dewatering equipment such as belt presses or centrifuges to achieve higher solids content in the cake. In this application, polyamine is often combined with high-molecular-weight cationic polyacrylamide (CPAM) flocculants to obtain synergistic effects. The polyamine provides charge neutralization and particle destabilization, while the polyacrylamide supplies bridging and strengthening of the flocs.

Another important industrial application of polyamine is in paper and pulp manufacturing. In this sector, polyamine serves as a retention and drainage aid as well as a pitch control agent. It improves the retention of fine fibers, fillers, and pigments on the paper sheet, reducing losses and improving product quality. Furthermore, polyamine can effectively control pitch and resin deposits by neutralizing the negative charge of colloidal materials, thus preventing fouling of paper machine parts. When used in conjunction with anionic microparticles or other cationic polymers, polyamine enhances drainage, leading to higher machine speed and improved energy efficiency.

In oilfield and petroleum operations, polyamine plays a significant role in oily water treatment, crude oil dehydration, and produced water clarification. The polymer destabilizes oil-in-water emulsions by neutralizing the charges on oil droplets, facilitating coalescence and separation. This process leads to faster oil-water separation and improved water quality for reinjection or disposal. Polyamine is also used as a demulsifier in crude oil processing and as an additive in desalting systems to improve efficiency and reduce corrosion risk.

In mineral processing and mining, polyamine is used as a flocculant or coagulant aid to clarify process water, recover fine mineral particles, and treat tailings. Many mining effluents, such as those from coal washing, phosphate beneficiation, or bauxite processing, contain ultrafine suspended solids that are difficult to settle. Polyamine, with its strong cationic charge, neutralizes these negatively charged mineral particles and promotes rapid sedimentation. In tailings management, polyamine can also assist in water recycling by improving the clarity of recovered water, thereby reducing freshwater consumption and improving the sustainability of mining operations.

Polyamine is also widely employed as a coagulant aid in systems using anionic polyacrylamide (APAM) or other flocculants. When used together, the polyamine acts first to neutralize the negative surface charge of suspended solids, while the anionic polyacrylamide performs the bridging and floc strengthening function. This two-step mechanism enhances floc formation, resulting in faster sedimentation rates, clearer supernatant, and reduced polymer consumption. The synergy between polyamine and anionic flocculants is especially beneficial in treating high-turbidity water, mining slurries, and complex industrial effluents.

In desalination and membrane treatment systems, polyamine is used as a pretreatment chemical to reduce colloidal fouling of reverse osmosis (RO) membranes. By removing fine suspended solids and organic colloids before the membrane stage, it minimizes fouling and extends membrane service life. In such applications, polyamine’s low residual metal content and high efficiency make it preferable to inorganic coagulants, which could otherwise leave deposits or scale on membrane surfaces.

In swimming pools and recreational water systems, polyamine can be applied as a clarifier to remove fine suspended materials and improve water transparency. Its non-metallic nature avoids issues associated with alum-based clarifiers, such as pH changes or staining.

From an operational perspective, polyamine offers several advantages: it functions effectively over a broad pH range (typically pH 4–10), performs well in both cold and warm water, and produces low amounts of sludge. It also dissolves rapidly, can be easily metered in liquid form, and maintains stability over long storage periods. Its cationic nature makes it compatible with most anionic flocculants but incompatible with strongly anionic surfactants or dispersants, which could hinder coagulation performance.

In summary, polyamine is an indispensable cationic coagulant and charge neutralizer used across many industries. Its ability to destabilize negatively charged particles, reduce turbidity, remove color, and enhance solid-liquid separation makes it vital in water treatment, sludge dewatering, papermaking, mining, and oilfield operations. By optimizing dosing and combining polyamine with complementary flocculants such as anionic polyacrylamide, users can achieve superior clarity, lower operating costs, and improved environmental compliance. Through its versatility and high efficiency, polyamine continues to play a central role in modern water and wastewater treatment technologies.