Aluminum Chlorohydrate (ACH) is a high-basicity aluminum-based coagulant used in drinking water purification, municipal wastewater treatment, and industrial water treatment. It helps destabilize suspended particles and colloids so they can form larger flocs and be removed through sedimentation or filtration.
Compared with conventional aluminum coagulants, ACH has a high charge density and can provide effective coagulation at relatively low dosages. Its performance also makes it useful when water quality changes during the treatment process.
For water treatment chemical buyers, however, choosing ACH is not simply about looking at the product name. Dosage, basicity, Al₂O₃ content, water quality, pH, and treatment objectives all affect the final result.
This guide explains how aluminum chlorohydrate works, its main benefits, typical dosage considerations, and where ACH is commonly used.
What Is Aluminum Chlorohydrate (ACH)?
Aluminum Chlorohydrate, commonly abbreviated as ACH, is a group of water-soluble aluminum complexes containing aluminum, chloride, and hydroxide. PubChem describes ACH as a group of water-soluble aluminum complexes with the general formula AlₙCl₍₃ₙ₋ₘ₎(OH)ₘ. It is also used as a coagulant in water purification.
ACH is closely related to other aluminum-based coagulants, including polyaluminum chloride (PAC). In fact, ACH can be considered a highly basic and highly charged aluminum polymer used for coagulation applications.
Commercial ACH is available in different forms, including liquid and powder. The appropriate form depends on the treatment system, storage conditions, transportation requirements, and dosing equipment.
For example, liquid ACH can be fed directly into a water treatment system, while powder ACH offers advantages for storage and long-distance transportation.
Key ACH properties include:
- High basicity
- High cationic charge density
- Good coagulation performance
- Low water-insoluble content in suitable grades
- Available in liquid and powder forms
- Suitable for drinking water and wastewater treatment
The exact specification should always be selected according to the intended application rather than using one grade for every water treatment process.
How Does ACH Work in Water Treatment?
The main function of ACH in water treatment is coagulation.
Many suspended particles and colloids in water carry negative surface charges. Because particles with similar charges repel each other, they can remain suspended for a long time instead of settling naturally.
When ACH is added to water, its positively charged aluminum species interact with these negatively charged particles. This reduces the repulsive forces between particles and destabilizes the suspension.
The destabilized particles can then come together and form small aggregates, or micro-flocs. During the following flocculation stage, these particles can grow into larger flocs that are easier to remove through sedimentation, flotation, or filtration.
A simplified treatment process looks like this:
Raw Water → ACH Addition → Charge Neutralization → Floc Formation → Sedimentation/Filtration → Treated Water
This is why ACH is often used as a primary coagulant rather than as a simple filtering chemical.
EPA documents also identify aluminum chlorohydrate and other aluminum-based coagulants as chemicals used in coagulation processes for removing turbidity, color, and suspended materials from water.
Main Benefits of Aluminum Chlorohydrate in Water Treatment
ACH offers several practical advantages for water treatment plants and industrial users.
1. High Charge Density
One of the key characteristics of ACH is its high charge density. This allows it to efficiently destabilize suspended particles and colloids. As a result, ACH can achieve effective coagulation without necessarily requiring a high chemical dose.
2. Effective Coagulation at Relatively Low Dosage
ACH is often selected when operators want strong coagulation performance while keeping chemical consumption under control. However, there is no universal ACH dosage. The required amount depends on turbidity, suspended solids, organic matter, alkalinity, pH, temperature, and the treatment target.
A laboratory jar test is therefore recommended before determining the operating dosage.
3. Good Performance Across Different Water Conditions
ACH has relatively high basicity compared with some conventional aluminum salts. This can help maintain coagulation performance across changing water conditions.
Still, a wider operating range does not mean that pH can be ignored. Water chemistry remains one of the most important factors when selecting and dosing a coagulant.
4. Dense and Fast-Settling Flocs
When the treatment conditions are suitable, ACH can produce compact flocs that are easier to separate from treated water. This can improve clarification and filtration performance, particularly in systems where fast solid-liquid separation is important.
5. Lower Sludge Generation in Some Applications
Because ACH can work efficiently at relatively low dosages, it may help reduce the amount of chemical sludge compared with some conventional treatment approaches.
The actual sludge reduction depends on the raw water and the complete treatment process. It should therefore be confirmed through application testing rather than assumed for every project.
Aluminum Chlorohydrate Dosage: How Much ACH Should You Use?
One of the most common questions from water treatment buyers is:
What is the correct ACH dosage?
There is no single dosage that works for every water source.
The optimum ACH dosage depends on factors such as:
- Raw water turbidity
- Suspended solids concentration
- Organic matter
- pH
- Alkalinity
- Temperature
- Color
- Phosphorus concentration
- Treatment process
- Required final water quality
For this reason, dosage should normally be determined through a jar test or other application testing.
EPA guidance also emphasizes that coagulant dosage should be determined according to raw water characteristics and treatment conditions rather than relying on one fixed dose.
A practical approach to ACH dosage testing
A water treatment operator can prepare several test samples and add different ACH concentrations to each sample. After rapid mixing and flocculation, the samples can be compared for:
- Floc formation
- Floc size
- Settling speed
- Water clarity
- Turbidity reduction
- Residual aluminum
The best dosage is not necessarily the highest dosage. Overdosing can increase chemical consumption and may negatively affect treatment performance. Therefore, jar testing is one of the most useful tools for optimizing ACH dosage.
Applications of ACH in Water Treatment
ACH is used in several water treatment applications. The most relevant applications for industrial buyers include drinking water treatment, municipal wastewater treatment, and industrial wastewater treatment.
1. Drinking Water Treatment
ACH can be used as a coagulant during drinking water purification. It helps remove suspended particles, colloids, turbidity, and some organic matter by promoting coagulation and floc formation.
A typical treatment process may include:
Coagulation → Flocculation → Sedimentation → Filtration → Disinfection
The exact treatment train depends on the raw water source and the local drinking water requirements. ACH has also been used in real drinking-water treatment systems as a coagulant before filtration.
For potable water applications, buyers should pay particular attention to the applicable drinking-water standard and the certification or documentation required in their market.
2. Municipal Wastewater Treatment
ACH can also be used in municipal wastewater treatment.
Its coagulation action helps destabilize suspended particles and improve solid-liquid separation. Depending on the wastewater characteristics and treatment process, aluminum-based coagulants can also support phosphorus removal.
ACH may be applied before sedimentation, flotation, or filtration. In some advanced treatment systems, it can also be used to improve the quality of secondary effluent before further treatment.
3. Industrial Wastewater Treatment
Industrial wastewater can contain high levels of suspended solids, color, colloids, and other pollutants.
ACH can be considered for wastewater from industries such as:
- Textile and dyeing
- Paper and pulp
- Food processing
- Chemical manufacturing
- General industrial production
For example, coagulation can help remove fine suspended particles and color from difficult wastewater streams.
However, industrial wastewater varies significantly from one factory to another. Therefore, ACH should be evaluated together with the wastewater composition and the complete treatment process.
4. Sludge Dewatering
ACH may also be used as part of sludge treatment and dewatering processes.
By destabilizing charged particles and helping form denser flocs, a suitable coagulant can improve the separation of water from sludge. In practice, ACH may be combined with an organic flocculant such as polyacrylamide (PAM), depending on the sludge characteristics and equipment.
The final chemical combination should be optimized through testing rather than applying the same formula to every sludge system.
ACH vs. PAC vs. Alum
ACH, PAC, and aluminum sulfate (alum) are all aluminum-based coagulants, but they are not identical.
| Coagulant | Main Characteristics | Floc Formation | pH Impact | Typical Applications |
|---|---|---|---|---|
| Aluminum Chlorohydrate (ACH) | High basicity, high Al₂O₃ content, low sludge production | Fast and dense flocs | Relatively low | Drinking water, municipal wastewater, industrial water treatment |
| Aluminum Sulfate (Alum) | Cost-effective and widely available | Good floc formation, especially with suitable alkalinity | Can lower pH | Drinking water, wastewater, general coagulation |
| Aluminum Chloride | Strong coagulation performance, but less commonly used than PAC or ACH | Rapid floc formation | Can affect pH | Industrial wastewater and specific water treatment processes |
| Polyaluminum Chloride (PAC) | Pre-hydrolyzed inorganic polymer coagulant | Fast, strong, and adaptable floc formation | Generally lower pH impact than alum | Drinking water, wastewater, industrial water treatment |
The EPA identifies aluminum chlorohydrate as a highly concentrated and highly charged form of polyaluminum chloride used as a coagulant or flocculant in water treatment.
So, the question is not simply whether ACH is “better” than PAC or alum. The right choice depends on the water chemistry, treatment target, equipment, dosage, and total operating cost.
How to Choose ACH for Water Treatment
For B2B buyers, product selection should go beyond price per ton.
Before purchasing ACH, it is useful to check the following specifications:
Al₂O₃ Content: Indicates the concentration of aluminum oxide in the product and is an important commercial specification.
Basicity: Affects the hydrolysis behavior and coagulation performance of the product.
Water-Insoluble Matter: Lower insoluble content can be important for consistent dosing and treatment performance.
pH: The pH specification can help buyers understand the chemical characteristics of the supplied grade.
Physical Form: Choose liquid or powder according to the dosing system, storage conditions, transportation method, and project requirements.
Application Grade: Drinking water, industrial wastewater, and other applications may require different specifications and documentation.
Packaging: Common options include bags, drums, IBCs, and bulk containers, depending on the product form and order volume.
For example, HOO CHEMTEC currently lists ACH products in liquid and solid forms, including water-treatment and drinking-water grades with different specifications.
Conclusion
Aluminum Chlorohydrate (ACH) is a high-performance aluminum-based coagulant with applications across drinking water purification, municipal wastewater treatment, industrial wastewater treatment, and sludge treatment.
Its high charge density and high basicity make it attractive for applications that require efficient particle destabilization and strong coagulation performance. However, ACH dosage should not be selected by a fixed formula. Raw water quality, pH, turbidity, alkalinity, treatment targets, and process conditions all need to be considered.
For buyers, the most important step is to match the ACH grade with the actual treatment application. Checking Al₂O₃ content, basicity, insoluble matter, physical form, packaging, and required certifications can also help ensure consistent supply and treatment performance.
HOO CHEMTEC supplies water treatment chemicals for customers in different industrial applications. Its ACH product range includes liquid and powder forms for water treatment and related applications, with specifications available according to the intended use. HOO CHEMTEC also supplies other water treatment chemicals, including PAC, aluminum sulfate, ferric chloride, PAM, PolyDADMAC, and other coagulation and flocculation products.
If you are sourcing Aluminum Chlorohydrate for a water treatment project, sharing your application, water quality, required grade, estimated quantity, and delivery destination can help the supplier recommend a more suitable product specification.
FAQ
Is Aluminum Chlorohydrate a coagulant?
Yes. ACH is used as an aluminum-based coagulant in water purification and wastewater treatment. It helps destabilize suspended particles and colloids so they can form removable flocs.
What is ACH used for in water treatment?
ACH is mainly used for coagulation in drinking water treatment, municipal wastewater treatment, industrial wastewater treatment, and related clarification processes.
What is the typical ACH dosage?
There is no universal ACH dosage. The required dose depends on turbidity, suspended solids, pH, alkalinity, organic matter, temperature, and treatment objectives. Jar testing is recommended to determine the appropriate dosage.
Is ACH the same as PAC?
No. ACH and PAC are closely related aluminum-based coagulants, but their basicity, composition, charge characteristics, and commercial specifications can differ. ACH is generally associated with highly basic, highly charged aluminum chemistry.
Can ACH be used for drinking water?
Yes, ACH can be used as a coagulant in drinking water treatment. However, the product grade must meet the applicable requirements and certifications for potable water use in the target market.
Can ACH be used with PAM?
Yes. In some treatment systems, ACH can be used as the primary coagulant while PAM is used as a flocculant or coagulant aid. The combination and dosage should be optimized through jar testing or plant trials.
