PAC and PAM at a Glance

Appearance alone cannot confirm chemical identity, purity or suitability. Check the product label, technical data sheet and batch certificate of analysis.

1. How PAC Works

Fine suspended particles and colloids can remain dispersed because their surface charges prevent them from coming together. PAC introduces positively charged aluminum species that help reduce this repulsion and initiate aggregation.

Depending on the water chemistry and treatment conditions, aluminum hydroxide precipitates can also capture particles through sweep coagulation. PAC performance therefore cannot be explained by a single mechanism alone. Coagulant dose, pH, temperature and mixing all influence the result.

Technical reference: Inorganic coagulants in water treatment.

The practical objective is to establish effective coagulation before evaluating whether a polymer is needed to improve separation.

2. How PAM Works

PAM has long polymer chains that can adsorb onto multiple particles and connect them into larger flocs. This bridging action helps solids separate during settling, flotation, thickening or dewatering, depending on the process.

PAM products differ in ionic character:

• Anionic PAM: Commonly evaluated for mineral suspensions and for flocculation after inorganic coagulation.
• Cationic PAM: Commonly evaluated for sludge conditioning and dewatering, especially where the solids have substantial negative surface charge.
• Nonionic PAM: An option where low-charge polymers provide suitable adsorption and bridging.

These are screening directions, not fixed selection rules. Wastewater pH alone does not determine the correct PAM type. Particle characteristics, charge demand, dissolved salts and the separation equipment also matter.

3. Why PAC and PAM Are Often Used Together

PAC and PAM address different stages of particle aggregation. PAC may establish coagulation, while an appropriate PAM grade can help the resulting particles develop into flocs that separate more effectively.

A common clarification sequence is:

1. Check the incoming water and establish suitable pH conditions.
2. Add PAC with sufficient mixing for rapid distribution.
3. Allow coagulation to develop, checking pH again where necessary.
4. Add a separately prepared PAM solution.
5. Apply controlled flocculation mixing before settling or flotation.

The pH adjustment point, chemical addition points and contact times must be confirmed through trials. Some systems work with PAC alone; some suspensions respond to PAM without PAC. A combined program should demonstrate a measurable benefit.

4. Preparation Matters as Much as Product Selection

Preparing PAC

For powder PAC, use the dilution concentration specified for the selected grade and dosing equipment. Mix until the powder has dissolved sufficiently for reliable feeding. Account for any insoluble material according to the product specification and system design.

A percentage concentration should always state its basis. For example, a concentration expressed by mass is different from grams of product per litre of final solution. Liquid PAC also requires its concentration and density to be considered when calculating pump output.

Preparing PAM

Feed powder PAM gradually into clean water with effective dispersion. Dumping a large quantity into the tank can create gel-coated lumps with dry material inside, reducing the amount of usable polymer in the solution.

Allow the hydration time specified for the grade. Use mixing that disperses and hydrates the polymer without excessive shear after dissolution. Emulsion PAM requires its own make-down procedure and should not be treated as powder PAM.

Prepare solution quantities that match consumption and the supplier's recommended usable life. Temperature, preparation-water quality, contamination and storage conditions can affect solution performance.

5. How Much PAC and PAM Should You Dose?

There is no universal PAC-to-PAM ratio. A dosage that works for one industrial wastewater may perform poorly when the solids concentration, pH or production process changes.

Do not confuse these three quantities:

• Product dose: The mass of supplied chemical added per volume of water.
• Active dose: The mass of active material added per volume of water.
• Make-up concentration: The concentration of chemical in the dosing tank.

Run jar tests to screen PAC grades and doses, then evaluate PAM types and doses under comparable conditions. Record clarified-water quality, separation speed, floc behavior and sludge characteristics. Repeat promising combinations on representative samples before a controlled plant trial.

A Simple Pump-Rate Calculation

When dose and solution concentration are expressed on the same product basis:

For example, suppose a trial uses:

• Water flow: 100 m³/h
• Selected product dose: 2 mg/L
• Prepared solution concentration: 2 g/L

The required solution flow is 100 × 2 ÷ 2 = 100 L/h.

6. Common Problems to Investigate

These observations guide troubleshooting; they do not identify a single cause by themselves. Change one variable at a time and compare the results with a recorded baseline.

7. Selecting PAC and PAM with Bluwat Chemicals

Bluwat Chemicals offers PAC coagulants and Blufloc polyacrylamide flocculants for water treatment and solid-liquid separation applications.

When discussing product selection, share the information that defines your treatment problem: wastewater source, flow rate, pH, suspended solids, current chemicals and doses, separation equipment, and the result you need to improve. Photos or videos of jar tests can provide useful supporting context alongside measured results.

Evaluate the treatment program on clarified-water quality, solids handling and total operating requirements. Chemical price per tonne alone does not show how a product will perform in your plant.

Frequently Asked Questions