ACH Water Treatment

What is Aluminum Chlorohydrate (ACH)?

Chemical name: Aluminum Chlorohydrate, sometimes written "ACH" or "Aluminum chlorhydrate". IRO Polymer+2North Star Chemical+2
Formula (general): Al₂(OH)₅Cl - 2H₂O (for the hydrated form) IRO Polymer+1
ACH is a hydrated aluminum compound with chloride and hydroxide. IRO Polymer+2North Star Chemical+2
It dissolves in water and forms a solution that has a high (positive) cation charge. IRO Polymer+2North Star Chemical+2

Role of ACH in Water Treatment

ACH is used in the coagulation/flocculation process to help settle suspended particles, organic matter, colloids, and impurities in water. Some of its advantages and characteristics:

Function / Advantages	Explanation
Coagulant / Flocculant	ACH helps combine (coagulate) small particles into larger flocs that are easy to filter or settle. IRO Polymer+3North Star Chemical+3IRO Polymer+3
Lower dosing efficiency	Due to its high positive charge, ACH dosage can be lower than other aluminum compounds such as alum (aluminum sulfate) or some types of PAC. YunCang Chemical+3Waterworld+3IRO Polymer+3
Impact of low pH	The use of ACH tends to lower the pH of water less than other aluminum coagulants, so often the need for pH correction (alkalis) can be reduced. North Star Chemical+2Waterworld+2
Wide working pH range	ACH is still effective in a fairly wide pH range compared to some other coagulants. North Star Chemical+2IRO Polymer+2
Reduced sludge/chemical solids production	Due to lower dosage and more efficient coagulation, less sludge load can be produced. North Star Chemical+1

Example in Water Treatment Process

In a drinking water treatment system:

Raw water is added with ACH solution.
Suspended particles, organic matter, and colloids are destabilized and form flocs.
The flocs are then filtered or settled, making the water clearer.
After that, filtration, disinfection, and final pH adjustment may be performed.