Poly Aluminium Chloride (PAC) is widely used as a coagulant in drinking water, municipal wastewater, and industrial wastewater treatment. It is available in both liquid and dry powder forms. For buyers who purchase PAC powder, one practical question often comes next:

How do you prepare PAC solution from powder before dosing it into water?

The basic process is simple. Add PAC powder gradually into clean water while mixing. Continue mixing until the powder is well dispersed and dissolved. Then prepare the solution at a suitable working concentration and feed it through the dosing system.

However, good PAC solution preparation involves more than simply mixing powder and water. The solution concentration, mixing method, dosing equipment, water quality, and PAC grade can all affect the final treatment result.

This guide explains how to prepare PAC solution from powder, how to calculate the required amount, how to choose a working concentration, and how to avoid common preparation and dosing problems.

Why Prepare PAC Solution from Powder?

PAC powder is convenient for storage, transportation, and bulk purchasing. Compared with liquid PAC, dry powder can offer advantages when buyers need to ship the product over long distances or store large quantities.

However, PAC powder normally needs to be prepared as a solution before it enters many water treatment dosing systems.

Preparing a PAC solution provides several practical benefits:

• More uniform chemical dosing
• Easier control of PAC dosage
• Better dispersion in the treatment process
• Easier connection with dosing pumps
• More consistent operation
• Convenient adjustment of the chemical feed rate

The preparation process also helps operators control how much PAC enters the treatment system.

For example, the Poly Aluminium Chloride powder concentration and the PAC treatment dosage are two different things. A plant may prepare a 5% PAC solution but only dose a small amount of that solution into the raw water.

Understanding this difference is important for both operators and chemical buyers.

What Do You Need to Prepare PAC Solution?

Before preparing PAC powder solution, prepare the basic equipment and materials.

PAC Powder

PAC is available in different grades and specifications. HOO CHEMTEC supplies both White PAC and Yellow PAC powder for different water treatment applications.

Different PAC products can have different:

• Al₂O₃ content
• Basicity
• Water-insoluble matter
• pH
• Iron content
• Heavy metal specifications
• Application requirements

Therefore, always check the product specification and technical data sheet before preparing the solution. The preparation method may be similar, but the recommended working concentration can vary by product and dosing system.

Clean Water

Use clean water to prepare the PAC solution.

The quality of the preparation water can affect chemical handling and the final solution. In plant applications, it is useful to consider the actual water used by the dosing system and follow the supplier’s recommendations.

The main goal is to avoid introducing unnecessary suspended solids or contaminants into the chemical solution.

Mixing Tank

A suitable mixing tank should provide enough space for:

• Water
• PAC powder
• Mixing
• Safe operation
• Connection to the dosing system

The tank should also be compatible with the chemical solution and suitable for continuous or intermittent mixing.

Agitator or Mixer

A mechanical mixer helps disperse PAC powder throughout the water.

Good mixing is especially important during powder addition. If the powder enters the water too quickly, it may form lumps. These lumps can take longer to dissolve and may create problems for dosing equipment.

Dosing Pump

After preparation, the Poly Aluminium Chloride solution is normally transferred to the treatment system through a dosing pump.

The pump capacity should match:

• Plant flow rate
• Required PAC dosage
• PAC solution concentration
• Operating hours

This means the solution concentration should be selected together with the dosing system, not as an isolated number.

How to Prepare PAC Solution from Powder: Step-by-Step

The preparation process can be summarized as:

Clean Water → Start Mixing → Add PAC Powder Slowly → Continue Mixing → Complete Dissolution → Dose into Treatment System

Each step matters.

Step 1: Fill the Tank with Clean Water

Start by adding clean water to the PAC preparation tank.

Do not fill the tank completely. Leave enough space for the PAC powder and mixing process. The amount of water depends on the required batch size and target solution concentration.

For example, if you need to prepare a small laboratory stock solution, you may use a laboratory container. A larger wastewater treatment plant will normally use a dedicated PAC preparation tank.

The important point is to establish the desired batch volume before calculating the required PAC powder.

Step 2: Start Mixing Before Adding PAC

Start the mixer before adding the PAC powder.

This creates movement throughout the water and helps distribute the powder as soon as it enters the tank. Starting the mixer first also reduces the chance of powder accumulating at one point in the tank.

A simple rule is:

Start mixing first, then add PAC powder gradually.

This is one of the easiest ways to reduce clumping during PAC solution preparation.

Step 3: Add PAC Powder Slowly

Add the PAC powder gradually while the water continues to mix. Do not pour the entire amount into the tank at once.

Rapid addition can create a concentrated layer of powder. The outside of this layer may become wet while the inside remains dry. This creates lumps that are much harder to dissolve.

Instead:

1. Start the mixer.
2. Add PAC gradually.
3. Spread the powder across the mixing area.
4. Maintain continuous mixing.
5. Avoid large amounts of powder accumulating in one location.

HOO CHEMTEC specifically recommends adding PAC powder slowly into water while mixing to help prevent clumping.

This simple step can make a major difference in solution quality.

Step 4: Continue Mixing Until the PAC Is Fully Dissolved

After adding the powder, continue mixing until the solution becomes uniform. Do not stop mixing immediately after the powder disappears from the surface.

Check whether:

• Large particles remain at the bottom.
• Lumps are still present.
• The solution is uniform.
• The dosing line is likely to receive a consistent solution.

The required mixing time depends on factors such as Poly Aluminium Chloride grade, concentration, water temperature, particle size, and mixing equipment. For this reason, it is better to follow the product supplier’s instructions than to use one fixed mixing time for every PAC product.

Step 5: Transfer the Prepared Solution to the Dosing System

Once the solution is properly prepared, it can be transferred to the dosing system. The dosing pump should deliver the PAC solution at a controlled rate.

At this stage, operators should monitor:

• PAC solution concentration
• Pump flow
• Raw water flow
• PAC dosage
• pH
• Turbidity
• Floc formation
• Final treatment performance

This creates a complete control loop:

PAC Preparation → PAC Dosing → Coagulation → Flocculation → Separation → Water Quality Monitoring

What Concentration Should PAC Solution Be?

One of the most common questions is: What is the recommended PAC solution concentration? There is no single concentration that fits every PAC product and every treatment system.

The appropriate concentration depends on:

• PAC grade
• Required treatment dosage
• Dosing pump capacity
• Treatment plant flow
• Storage tank size
• Mixing equipment
• Operating conditions

A working solution in the 5–10% range is commonly referenced for PAC applications, but this should be treated as a practical reference rather than a universal specification. The product supplier’s recommended concentration should take priority.

PAC Solution Concentration vs. PAC Treatment Dosage

These two terms are easy to confuse.

Solution concentration describes how much PAC powder is present in the prepared chemical solution. Treatment dosage describes how much PAC is applied to the water being treated.

For example:

• PAC working solution: 5%
• PAC treatment dosage: determined by jar test

A 5% solution does not mean that the wastewater receives a 5% PAC dose. This distinction is very important when setting a dosing pump.

How to Calculate PAC Powder and Water

PAC solution preparation becomes easier when the concentration is clearly defined.

For simple weight/volume (w/v) calculations:

PAC powder required = Target concentration × Final solution volume

For example, a 5% w/v solution means approximately:

5 g PAC per 100 mL solution

or:

50 g PAC per 1 L solution

Therefore:

100 L × 50 g/L = 5,000 g = 5 kg PAC

So, for a simplified 5% w/v calculation, 100 L of final solution requires approximately 5 kg of PAC powder.

Example PAC Solution Calculation

Target Concentration	PAC Powder per 1 L	PAC Powder per 100 L
2% w/v	20 g	2 kg
5% w/v	50 g	5 kg
10% w/v	100 g	10 kg

These figures are calculation examples based on w/v concentration, not universal PAC preparation recommendations.

For plant-scale preparation, operators should also consider the exact definition of concentration used by the supplier, the final solution volume, and the operating instructions for the PAC grade.

This is especially important when a supplier specifies concentration on a weight/weight basis rather than weight/volume.

How to Calculate PAC Dosing After Preparing the Solution

Preparing a Poly Aluminium Chloride solution is only the first step. The next question is: How much prepared PAC solution should be added to the water?

The answer depends on the required PAC treatment dosage.

A simple relationship is:

PAC solution flow = Required PAC mass flow ÷ PAC concentration

For example, suppose a treatment system requires a certain PAC mass per hour. If the working solution becomes more concentrated, the required liquid volume decreases. If the solution becomes more dilute, the dosing pump must deliver a larger volume.

This is why solution concentration and pump capacity should be considered together.

Factors That Affect PAC Dosage

PAC dosage depends on the actual water being treated.

Important factors include:

• Turbidity
• Suspended solids
• Color
• Organic matter
• pH
• Alkalinity
• Raw water quality
• Treatment target

There is no universal PAC dosage that works for every water treatment application.

Jar testing remains an important method for selecting and optimizing coagulant dosage. EPA water treatment guidance also describes jar testing as a practical way to evaluate coagulant doses.

Common Mistakes When Preparing PAC Solution

Even when PAC is a simple powder product, preparation mistakes can affect the treatment process.

Adding Too Much PAC at Once

This is one of the most common problems. If too much powder enters the water at one time, it may form large lumps. Better approach: add PAC slowly under continuous mixing.

Using the Wrong Solution Concentration

A solution that is too concentrated may create mixing or pumping challenges. A solution that is too dilute may require a larger storage tank and higher dosing flow.

Better approach: select the concentration according to the PAC grade, treatment dosage, and dosing equipment.

Stopping Mixing Too Early

A solution can look mixed while undissolved material remains at the bottom. This can cause inconsistent dosing.

Better approach: continue mixing until the solution is properly uniform.

Using a Fixed PAC Dosage for Every Water Source

Water quality changes. A PAC dosage that works for one plant may not work for another. Even the same plant may need different dosages when raw water quality changes.

Better approach: use jar testing and monitor treatment performance.

Confusing Solution Concentration with Treatment Dosage

This mistake can lead to incorrect dosing calculations.

Remember:

PAC solution concentration ≠ PAC treatment dosage

The first describes the prepared chemical solution. The second describes the amount applied to the treatment water.

How Long Can Prepared PAC Solution Be Stored?

Another practical question is whether PAC solution can be prepared in advance.

The answer depends on:

• PAC grade
• Solution concentration
• Storage temperature
• Storage tank conditions
• Mixing conditions
• Supplier recommendations

PAC solution may change during storage because aluminum species can continue to interact in the solution. Long storage can also create settling or changes in solution consistency. For this reason, freshly prepared solution is often preferred when practical.

HOO CHEMTEC recommends preparing PAC solution at the recommended concentration close to the time of use for best results.

Rather than applying one fixed storage period to every PAC product, operators should follow the supplier’s technical instructions for the specific grade.

If a prepared solution must be stored, monitor it before dosing and make sure the solution remains uniform.

Safety Tips for Preparing PAC Solution

PAC powder and concentrated chemical solutions should be handled with appropriate safety procedures.

Wear Appropriate PPE

Operators should consider:

• Protective gloves
• Safety glasses
• Protective clothing
• Appropriate respiratory protection when handling dusty powder

Always follow the product SDS for detailed handling requirements.

Avoid Direct Contact

Avoid direct contact with the eyes and skin. If powder or solution comes into contact with the body, follow the product SDS and site emergency procedures.

Control Dust During Powder Handling

Poly Aluminium Chloride powder can generate dust during bag opening and feeding. Good ventilation and suitable powder-handling procedures can reduce exposure.

Keep the Preparation Area Clean

PAC powder can become slippery when mixed with water. Clean spills promptly and maintain a safe working area around the preparation tank and dosing equipment.

Quick Reference: PAC Powder Solution Preparation

For operators who need a simple procedure, the process can be summarized as follows:

Step	What to Do
1	Prepare the required amount of clean water
2	Start the mixer
3	Add PAC powder slowly
4	Maintain continuous mixing
5	Continue until the solution is uniform
6	Check the working concentration
7	Transfer the solution to the dosing system
8	Determine PAC dosage through jar testing
9	Set the dosing pump
10	Monitor pH, turbidity, floc formation, and treatment results

The key principle is simple:

Prepare the PAC solution correctly, but optimize the actual PAC dosage according to the water being treated.

Conclusion

Preparing PAC solution from powder is a straightforward process, but good preparation can make a significant difference in chemical dosing and treatment consistency.

The basic procedure is:

Clean Water → Mixing → Slow PAC Addition → Complete Dissolution → Working Solution → Controlled Dosing

The most important points are:

1. Add PAC powder slowly into water while mixing.
2. Avoid adding a large amount of powder at one time.
3. Choose the working concentration according to the PAC grade and dosing system.
4. Do not confuse solution concentration with treatment dosage.
5. Use jar testing to determine the appropriate PAC dosage.
6. Monitor water quality and treatment performance after dosing.
7. Follow the supplier’s technical and safety recommendations.

For water treatment operators and B2B buyers, the goal is not simply to prepare a PAC solution. The goal is to create a stable chemical feed that supports consistent coagulation and efficient water treatment.

HOO CHEMTEC supplies White PAC and Yellow PAC powder for different water and wastewater treatment applications. Buyers can request product specifications, COA, samples, and technical information before placing a bulk order.

If you are looking for Poly Aluminium Chloride powder for water treatment or need help selecting a suitable PAC grade and working solution concentration, contact HOO CHEMTEC to discuss your application and supply requirements.

FAQ

How do you prepare PAC solution from powder?

Add PAC powder gradually into clean water while continuous mixing is running. Continue mixing until the powder is properly dispersed and dissolved. Then prepare the working solution at the concentration recommended for the specific PAC grade and dosing system.

What is the recommended PAC solution concentration?

There is no single concentration that works for every PAC product. A 5–10% working solution is commonly used as a reference, but the appropriate concentration depends on the PAC grade, dosing equipment, required treatment dosage, and plant conditions.

Always follow the supplier’s product instructions when available.

How much PAC powder is needed for 100 liters of water?

It depends on the target solution concentration.

For a simplified 5% w/v calculation, 1 liter contains approximately 50 g of PAC powder. Therefore, 100 liters of final solution would require approximately 5 kg of PAC powder.

This is a calculation example, not a universal PAC preparation ratio. The exact preparation method should follow the selected concentration basis and supplier instructions.

How can I avoid PAC powder from clumping?

Start the mixer before adding PAC. Then add the powder gradually and evenly into the moving water.

Avoid dumping the full amount into one location.

Good mixing and controlled powder addition are the simplest ways to reduce PAC clumping during solution preparation.