Selecting the optimal coagulant is a critical decision for any water treatment facility. Among the advanced inorganic polymer coagulants available, Aluminum Chlorohydrate (ACH) and Polyaluminum Chloride (PAC) are frequently considered. Both offer advantages over traditional coagulants like alum, but they possess distinct characteristics that can influence their effectiveness and suitability for specific applications. Understanding these differences is key for engineers and procurement specialists when deciding where to buy their next supply of coagulant.

Understanding the Chemistry: Basicity and Polymerization

The primary distinction between ACH and PAC lies in their chemical structure and properties, particularly their basicity and degree of polymerization. Basicity refers to the ratio of hydroxyl groups to aluminum atoms in the molecule, which influences the charge density and stability of the aluminum species.

  • Aluminum Chlorohydrate (ACH): Typically exhibits a higher basicity (often 80-85% or higher) and a more highly polymerized structure. This translates to a higher cationic charge density. Its chemical formula can be represented as Al2(OH)5Cl.
  • Polyaluminum Chloride (PAC): Generally has a lower basicity, commonly ranging from 40-70%. While still a polymerized aluminum compound, its structure is less complex than that of ACH.

These chemical differences lead to significant performance variations:

Performance Comparison: ACH vs. PAC

  • Coagulation Efficiency: Due to its higher basicity and charge density, ACH often demonstrates superior performance in coagulating smaller, more challenging particles and achieving lower turbidity levels. It tends to form denser, faster-settling flocs.
  • Dosage Requirements: ACH typically requires lower dosages than PAC to achieve comparable or better results. This lower dosage translates into reduced chemical consumption, lower chemical costs, and less generated sludge, which is a significant economic and environmental benefit.
  • pH Impact: ACH’s high basicity means it has a much gentler impact on water pH compared to PAC and traditional coagulants. This often reduces or eliminates the need for costly pH adjustment chemicals (alkalis), simplifying operations and further lowering costs. PAC, while better than alum, still tends to depress pH more than ACH.
  • Temperature Tolerance: ACH often performs more consistently across a wider range of water temperatures, particularly in colder conditions where traditional coagulants can become less effective.
  • Impurity Removal: Both ACH and PAC are effective at removing a range of impurities like color, heavy metals, and TOC. However, ACH's higher efficiency can sometimes lead to more complete removal at lower doses.

When to Choose ACH: Key Considerations for Buyers

Consider sourcing Aluminum Chlorohydrate (ACH) when:

  • Your water source has challenging turbidity or requires efficient removal of very fine particles.
  • You aim to minimize chemical usage and sludge production to reduce operational costs.
  • Controlling pH fluctuations and reducing alkali consumption is a priority.
  • You are seeking the highest possible level of performance and efficiency in your coagulation process.

While PAC is a capable coagulant and often more cost-effective upfront, the long-term operational savings and superior performance of ACH can make it the preferred choice for many advanced water treatment applications. When looking to buy Aluminum Chlorohydrate, remember to source from reputable manufacturers in China who can guarantee consistent quality and competitive pricing for this high-performance coagulant.