How does polyaluminium chloride improve water purification through efficient flocculation?
Publish Time: 2025-06-19
In the field of water treatment, polyaluminium chloride (PAC) is a highly efficient flocculant, and its excellent performance plays a vital role in improving water purification. Through its unique and efficient flocculation, polyaluminium chloride can not only effectively remove suspended matter, colloids and certain soluble pollutants in water, but also significantly improve the transparency and sensory quality of water quality, providing people with a cleaner and safer water source.First of all, polyaluminium chloride has a strong charge neutralization ability, which is the basis for achieving efficient flocculation. When added to the water to be treated, polyaluminium chloride quickly dissociates into positively charged polynuclear hydroxyl complexes. These positive ions can interact with the negatively charged colloidal particles in the water, effectively neutralizing their surface charges and reducing the electrostatic repulsion between colloids. Once the colloidal particles lose their stable charge barrier, they begin to approach each other and aggregate together to form larger particles or flocs. This process not only accelerates the sedimentation rate of particles, but also improves the efficiency of subsequent filtration steps, thereby greatly improving the overall water purification effect.Secondly, polyaluminium chloride has an excellent bridging effect, which further enhances the flocculation effect. In addition to charge neutralization, polyaluminium chloride molecules can also connect multiple colloidal particles through their long chain structure to form large flocs in a three-dimensional network. This bridging mechanism allows polyaluminium chloride to exhibit significant flocculation performance even at low concentrations. Compared with traditional coagulants, the flocs generated by polyaluminium chloride are denser and easier to precipitate, reducing the risk of secondary dispersion and completing the solid-liquid separation process in a shorter time. Therefore, in practical applications, the use of polyaluminium chloride can significantly shorten the treatment cycle and improve the working efficiency of water treatment facilities.Furthermore, polyaluminium chloride has strong adaptability under different pH conditions, which makes it possible for its wide application. Many traditional coagulants are sensitive to the pH of the water body and often require strict control of the pH value to achieve the best effect. However, due to its special chemical composition, polyaluminium chloride can maintain good flocculation performance over a wide pH range. This means that whether in acidic industrial wastewater or near-neutral drinking water sources, polyaluminium chloride can work stably, without frequent pH adjustment, simplifying the operation process and reducing operating costs.In addition, polyaluminium chloride also performs well in removing organic matter and heavy metal ions. In the water treatment process, some natural organic matter and artificial synthetic compounds may pollute the water quality and are difficult to completely remove by conventional means. Polyaluminium chloride can wrap these organic substances in flocs through adsorption and bridging, and settle with the flocs, thereby effectively reducing the organic matter content in the water. At the same time, for heavy metal ions in water such as lead, mercury and other harmful substances, polyaluminium chloride can also fix them in flocs by co-precipitation, preventing them from dissolving into the water again, ensuring water safety.It is worth noting that the use of polyaluminium chloride can also bring environmental benefits. Due to its efficient flocculation characteristics, ideal treatment effects can be achieved at lower dosages, thereby reducing the amount of chemicals used and their potential impact on the environment. In addition, the amount of sludge produced by polyaluminium chloride is relatively small and easy to dehydrate, which reduces the cost and difficulty of subsequent sludge disposal. This is of great significance for promoting the development of green water treatment technology and building a sustainable water resources management system.From a practical operation perspective, the ease of operation and stability of polyaluminium chloride are also its major advantages. The solid form of polyaluminium chloride is easy to transport and store, and it will not deteriorate and become ineffective due to temperature changes like some liquid coagulants. During the addition process, it only needs to be dissolved in water in a specific proportion and can be put into use without complicated pretreatment steps. In addition, polyaluminium chloride can take effect quickly after addition, and obvious improvement in water quality can be observed in a short time, which is particularly important for responding to sudden water pollution incidents, and can respond quickly and restore the normal operation of the water supply system in time.Finally, polyaluminium chloride has a wide range of applications and is suitable for various types of water treatment scenarios. Whether it is an urban water plant, a sewage treatment plant or an industrial circulating cooling water system, polyaluminium chloride can be used for effective water purification. Especially in the treatment of high turbidity raw water, low temperature and low turbidity water, and industrial wastewater containing complex pollutants, polyaluminium chloride has become the first choice of many water treatment experts due to its excellent flocculation ability and adaptability. It can not only ensure that the effluent water quality meets the corresponding standard requirements, but also reduce the pressure of subsequent deep treatment processes to a certain extent and optimize the entire water treatment process.In summary, polyaluminium chloride has significantly improved the water purification effect through its strong charge neutralization ability, excellent bridging effect, wide pH adaptability, and outstanding performance in removing organic matter and heavy metals. Its application not only simplifies water treatment operations and reduces operating costs, but also plays a positive role in environmental protection. With the continuous advancement of technology and changes in market demand, polyaluminium chloride will continue to play an important role in the future water treatment field and contribute to the protection of global water resources. Whether in daily water supply guarantee or emergency treatment, polyaluminium chloride will be one of the indispensable key materials.
