Selecting the right coagulant is a critical decision for any water treatment process, impacting both efficiency and cost. Two of the most commonly used inorganic coagulants are Polyaluminium Chloride (PAC) and Aluminum Sulfate (Alum). Both serve to remove suspended solids and impurities from water, but they differ significantly in their chemical properties, performance, and application suitability. NINGBO INNO PHARMCHEM CO.,LTD., a leading chemical supplier, breaks down these differences to help you choose wisely.

Understanding Aluminum Sulfate (Alum)

Aluminum Sulfate, often referred to as Alum, has been a workhorse in water treatment for decades. It is an acidic salt that hydrolyzes in water to produce aluminum hydroxide flocs, which entrap impurities. Alum is generally more cost-effective on a per-unit basis and is effective in a wide range of raw water conditions. However, its performance can be less optimal in cold or low-turbidity waters. Furthermore, Alum requires alkaline conditions to function effectively and can significantly lower the pH of treated water, often necessitating the addition of alkaline chemicals like lime or soda ash to buffer the water, which adds to the overall cost and complexity of the treatment process.

The Advantages of Polyaluminium Chloride (PAC)

Polyaluminium Chloride is a more advanced inorganic polymer coagulant. It is essentially a pre-hydrolyzed aluminum salt with a higher molecular weight and a more stable polymeric structure. This advanced chemistry offers several distinct advantages:

  • Higher Efficiency: PAC generally produces larger and denser flocs more rapidly than Alum, leading to better sedimentation and filtration. This improved performance is particularly noticeable in challenging water conditions like low temperatures and low turbidity.
  • Wider pH Range: PAC can operate effectively over a broader pH range (typically 5-9) compared to Alum, often requiring less pH adjustment. This can significantly reduce chemical consumption and operational costs.
  • Lower Chemical Dosage: Due to its higher efficiency, PAC typically requires a lower dosage rate to achieve the desired treatment results, further contributing to cost savings.
  • Reduced Sludge Production: The denser flocs formed by PAC can sometimes lead to less sludge volume, simplifying sludge handling and disposal.
  • Lower Alkalinity Consumption: PAC consumes less alkalinity in the water compared to Alum, leading to less impact on the treated water's pH.

When to Choose Which Coagulant?

For general water treatment where cost is the primary driver and water conditions are moderate, Aluminum Sulfate can be a viable option. However, for applications demanding higher purity, greater efficiency, and better performance under challenging conditions, Polyaluminium Chloride is the superior choice. If you are seeking to buy PAC, especially for drinking water purification or industrial effluent treatment where performance and minimal operational adjustments are key, our high-purity white powder PAC is an excellent option. As a leading manufacturer and supplier in China, we offer both PAC and Aluminum Sulfate to cater to diverse needs.

Making the right choice of coagulant can significantly enhance your water treatment outcomes. Consult with your chemical supplier to determine the best fit for your specific requirements.