Poly Aluminum Chloride (PAC) is an aluminum-based coagulant that destabilises colloidal particles so they form flocs removable by sedimentation, DAF, or filtration. Its working dose and performance cannot be selected from the product name alone; both should be confirmed by jar testing the actual water.
PAC is used for raw water, process water, and industrial wastewater to help reduce turbidity, TSS, colour, and contaminants carried by solids. Buyers should compare grade, active content, basicity, pH shift, sludge volume, and cost per cubic metre of water meeting the target. Review powder and liquid PAC products, industrial liquid PAC, and the PAC-versus-alum comparison before requesting an evaluation.
Last technically reviewed: 30 July 2026.
Read the specification and release a PAC batch
A PAC specification establishes whether the delivered product matches the approved product; a jar test establishes whether it works on the current water. Both must pass before a batch enters routine use. Colour, trade name, or price per kilogram cannot replace batch identity, active content, basicity, impurities, and application evidence.
SNI 3822:2018 for polyaluminium chloride is listed as current by Indonesia’s National Standardization Agency and specifies quality requirements and test methods for liquid and solid PAC used in water clarification, paper, and cosmetics. The purchase specification must still state the intended grade and duty; a product standard does not establish the process dose for a particular plant.
| Receiving stage | Evidence to check | Release decision |
|---|---|---|
| Before dispatch | Purchase order, technical data sheet, grade, liquid/solid form, package, shelf life, and storage conditions | Hold dispatch when the product or document differs from the technical approval |
| On vehicle arrival | Product name, lot number, quantity, seals, labels, drum/bag/IBC condition, and evidence of leakage or contamination | Quarantine damaged, mislabelled, or untraceable material |
| Lot-document review | Certificate of Analysis, production date, agreed parameters, and current Safety Data Sheet | Compare every result with the contractual acceptance limits; do not use another lot’s CoA |
| Site verification | Representative lot sample; active content, basicity, pH/density, insoluble matter, or other agreed tests within laboratory capability | Accept, hold for confirmation, or reject under the approved quality procedure |
| Application test | Side-by-side jar test against the reference product on the same water | Release when pH, turbidity/TSS, colour, floc, settling/DAF, and sludge targets are met |
| After release | Retained sample, test results, tank number, consumption, dose, and treated-water trend | Trace any performance change to the lot, influent, make-down, dosing, and separation unit |
Decide when the specification and jar test disagree
Treat document conformity and application performance as separate gates. A batch is not automatically suitable because its CoA meets the specification, and one good-looking jar test does not waive a contractual or quality nonconformity. Define the following dispositions before material is transferred to the operating tank.
| Lot-specification result | Application-test result | Defensible disposition |
|---|---|---|
| Pass | Pass | Accept and release under the approved authority; record the lot, destination tank, approved dose, and retained sample |
| Pass | Fail | Hold. Check water representativeness, mixing, active dose, pH/alkalinity, make-down, and reference product; do not hide the failure by increasing dose without a boundary |
| Fail | Pass | Hold or reject under the quality procedure; one application result does not cancel the failed specification parameter |
| Fail | Fail | Quarantine and reject or return after the nonconformity review; prevent transfer into a tank that would contaminate accepted stock |
Before unloading, confirm the tank identity, previous contents, hose and seal compatibility, valve line-up, ullage, and spill route. Complete sampling and release before the batch mixes with operating stock where the quality procedure requires it. After transfer, reconcile the quantity from the weigh ticket or product mass (kg) = measured volume (L) × lot density (kg/L); for active inventory, multiply again by the Al₂O₃ mass fraction on the same basis.
Arithmetic example: 10,000 L of product at a lot density of 1.20 kg/L and 10% Al₂O₃ contains 12,000 kg of product or 1,200 kg of Al₂O₃. This only illustrates normalisation; density, active content, acceptance tolerance, and test method must come from the approved lot documents and purchase specification.
Normalise bids before comparing price. Active Al₂O₃ dose (mg/L) = product dose (mg/L) × Al₂O₃ mass fraction, while product cost per m³ = product dose (mg/L) × price per kg ÷ 1,000. Arithmetic example: 10 mg/L of a product containing 30% Al₂O₃ equals 3.0 mg/L as Al₂O₃. This normalisation does not prove performance; basicity, speciation, impurities, water pH, and mixing can still produce different jar-test responses.
For industrial wastewater, use the liquid-waste source and characterisation map before setting the dose sweep. For the broader definition, mechanism, supply form, and dosing sequence, continue to the PAC guide for water and wastewater treatment. After release, verify make-down strength and pump output; feed hardware can be compared through Watermart dosing pumps.
What is Poly Aluminum Chloride (PAC)?
PAC is a family of aluminium coagulants that has been partially hydrolysed before delivery to the site. The name does not identify one fixed composition: Al₂O₃ content, basicity, liquid or powder form, impurities, and solution properties can differ by grade and manufacturer. Read the technical data sheet and the lot CoA together.
After rapid mixing, positively charged aluminium species help destabilise colloidal particles. Those particles then collide during flocculation and form flocs that a separation unit can remove. The outcome depends on the water chemistry and the process; PAC does not guarantee a lower dose, a wider useful pH range, or less sludge than alum or iron salts.
PAC primarily treats the coagulable fraction. Particle-bound metals, some phosphate, colour, or organic matter may be captured when the chemistry is suitable, but dissolved compounds are not necessarily removed by coagulation alone. The jar test must therefore measure the actual compliance or process parameter, not visual clarity alone.
Use of PACs in Water and Sewage Treatment
PAC is commonly dosed before sedimentation, lamella clarification, DAF, or filtration. In raw water, the duty may be turbidity and colour control. In industrial wastewater, the target may be TSS, a breakable emulsion, precipitable phosphate, or COD associated with particles. Dose and injection point must be established for each stream.
Coagulation does not replace the processes required for dissolved contaminants, free oil, salts, or biological loading. Before selecting PAC, map stream sources, flow, shift-to-shift variation, pH, alkalinity, temperature, conductivity, and discharge-permit parameters. Segregate concentrated or reactive streams when combining them destabilises the main treatment plant.
For drinking-water duties, use only the grade and documentation accepted by the facility’s applicable requirements, then control residuals and finished-water quality. For wastewater duties, include chemical sludge in the cost balance: a dose that works in a beaker must still be mixed, separated, thickened, and disposed of safely.
Advantages of PACs compared to Other Coagulants
A PAC advantage must be demonstrated on the actual water rather than stated as a universal property. One grade may retain useful floc under conditions that challenge a comparison product, while alum or an iron salt may be more economical elsewhere. Compare active dose and the cost of water that passes the agreed target.
| Comparison area | Data to record |
|---|---|
| Treated-water performance | Turbidity/TSS, colour, target parameter, final pH, and any required residual |
| Chemical demand | Product dose, active content, acid/alkali, polymer aid, and make-down water |
| Floc separation | Formation time, floc size and strength, settling or flotation rate, and carryover |
| Sludge | Volume, solids percentage, thickening/dewatering behaviour, and disposal route |
| Operations | Dose stability as influent changes, material compatibility, storage, and operator demand |
| Total cost | Chemical, freight, energy, sludge, downtime, and extra work per m³ of passing water |
Run PAC, alum, iron salts, or other candidates side by side under the same sample and mixing conditions. If jar-test results are close, use a controlled plant trial so pump limitations, contact time, and the separation unit are represented.
How PAC Works in Water Treatment
PAC works through an operating sequence, not as a standalone reaction:
- Characterise. Measure the conditions that affect coagulation and define each performance limit.
- Dose and rapid-mix. Add a measured dose where mixing energy can distribute it before excessive local reaction occurs.
- Coagulate. Aluminium species destabilise colloids through charge neutralisation and, depending on conditions, entrapment in aluminium-hydroxide precipitate.
- Flocculate. Gentler mixing lets particles collide and grow without breaking the floc.
- Separate. Sedimentation, DAF, or filtration removes the floc; the unit must suit its density and strength.
- Verify. Record actual dose, pH, treated-water parameters, carryover, and sludge so a performance change is traceable.
This sequence explains why more chemical does not always improve the result. A failure can originate in an uncalibrated pump, weak rapid mixing, changed pH or alkalinity, an incompatible polymer aid, short flocculation time, or an overloaded separation unit.
Considerations in Using PACs
Set the trial range with jar tests covering both routine water and credible worst-case conditions. Do not change dose from one turbidity reading alone; check pH, alkalinity, temperature, solids loading, colour or the target parameter, and the condition of the floc and separation unit.
Liquid PAC, powder, dilution water, and make-down solution must be compatible with tanks, seals, pipework, and pumps. Follow the product Safety Data Sheet for PPE, spills, skin or eye contact, ventilation, and incompatible materials. Do not assume that every PAC grade has the same concentration or corrosivity.
Verify the plant dose by measuring pump output and tank-volume change. At minimum, trend water flow, pump stroke/frequency, solution strength, daily consumption, pH before and after coagulation, treated water, and sludge production. When performance changes after a new delivery, check the lot identity, concentration, pump calibration, and influent before making a large process adjustment.
Case Study: PAC Usage in Indonesia
This page does not publish identifiable customer-project data, so it does not present anonymous success figures as case evidence. A plant team can produce an auditable case record by documenting one baseline, changing one factor at a time, and agreeing the acceptance criteria before the trial.
| Plant-trial element | Minimum record |
|---|---|
| Baseline | Date/time, water source, flow, pH, temperature, turbidity/TSS, colour or target parameter, and unit status |
| Product | Name, lot, form, Al₂O₃, basicity, make-down strength, and receiving result |
| Trial programme | Product and active dose, injection point, rapid mix, flocculation, polymer aid, and duration |
| Results | Treated water, floc character, carryover, sludge volume/solids, consumption, and pH correction |
| Decision | Pass/fail against each limit, approved operating conditions, and action owner |
Run the comparison during similar influent conditions. When rainfall, production, or a batch discharge cannot be controlled, document the disturbance and repeat the trial before drawing a commercial conclusion.
Conclusion
PAC is a defensible choice when the batch specification can be verified and an application test proves performance on the actual water. The decision should not stop at visual clarity: pH, the target parameter, resilience to influent change, sludge, safety, and total cost all belong in the evaluation.
PT Beta Pramesti Asia supplies liquid and powder PAC for water and wastewater treatment. When contacting the team, provide water analysis, flow, quality target, process diagram, current chemical programme, and jar-test results so the product discussion begins with verifiable process needs.