Selecting the optimal coagulant is a critical decision for any water treatment facility. While alum has been a staple for decades, newer generations of inorganic polymer coagulants like Polyaluminum Chloride (PAC) and Aluminum Chlorohydrate (ACH) offer enhanced performance and efficiency. Understanding the distinctions between these advanced coagulants is key to making an informed purchasing decision. This guide, from a dedicated chemical supplier, compares ACH and PAC to help you choose the best fit for your water treatment needs.

Understanding the Basics: Al2O3 Content and Basicity

Both PAC and ACH are aluminum-based coagulants that operate on the principle of charge neutralization and sweep flocculation. However, they differ significantly in their chemical structure and performance characteristics:

  • Al2O3 Content: This refers to the total amount of aluminum oxide present in the product. ACH typically boasts a higher Al2O3 concentration (around 23-24% in liquid form, and up to 46-50% in solid form) compared to most standard PAC products, which generally range from 10-17% Al2O3. Higher Al2O3 content means a more concentrated product, potentially leading to lower dosage requirements.
  • Basicity: Basicity is a crucial parameter that describes the degree of neutralization of the aluminum chloride by hydroxide ions. It is expressed as the ratio of [OH]- to [Al]. Higher basicity indicates a more polymerized aluminum structure with a greater positive charge. ACH generally exhibits higher basicity (75-90%) than most PAC products (around 50-70%). This higher basicity is a primary driver of ACH's superior performance in many applications.

Performance Comparison: ACH vs. PAC

The differences in Al2O3 content and basicity translate into distinct performance advantages:

  • Coagulation Efficiency: Due to its higher cationic charge density stemming from high basicity, ACH is generally more effective at destabilizing and removing a wider range of contaminants, including very fine particles and dissolved organic matter. This often results in better turbidity removal and clearer finished water.
  • Sludge Production: ACH typically generates less chemical sludge compared to PAC. This is a significant advantage, as sludge handling and disposal represent a substantial operational cost and environmental consideration. Furthermore, ACH-produced sludge often dewaters more efficiently.
  • pH Impact: ACH's high basicity means it has a less significant impact on the water's pH compared to PAC or traditional coagulants like alum. This reduces the need for pH adjustment chemicals, simplifying the treatment process and lowering chemical costs.
  • Dosage Requirements: Owing to its higher efficiency, ACH often requires lower dosage rates than PAC to achieve comparable or superior treatment results, leading to further cost savings for procurement.
  • Range of Application: While both are versatile, ACH's robust performance across varying temperatures and pH levels makes it particularly advantageous in challenging water conditions.

Making the Right Choice for Your Facility

When deciding between ACH and PAC, consider your specific water quality challenges, operational costs, and desired treatment outcomes. If you are seeking maximum efficiency, reduced sludge, and minimal pH impact, ACH is often the superior choice. If you are looking to buy PAC or ACH, sourcing from a reputable chemical supplier in China can provide access to high-quality products at competitive prices. Understanding these differences empowers you to make the most cost-effective and performance-driven selection for your facility.