PAC 31% is a powdered coagulant commonly used in industrial wastewater treatment: it helps neutralize colloids, create flocs, and reduce turbidity/color before sedimentation or filtration.
Poly Aluminium Chloride (PAC)CAS 1327-41-9, Al₂O₃ approximately 30-31% Based on batch COA. Loc Thien provides B2B powder PAC with COA/MSDS upon request — pricing on request, no retail sales.
- Jar test before filling the system. — The “standard” dosage is for reference only, depending on the specific wastewater source.
- PAC 31% powder (Al₂O₃ ~30–31%, CAS 1327-41-9) must be mixed to the correct concentration and added at the point of rapid stirring.
- B2B Purchase / COA: PAC Tenor 31% at Loc Thien Hotline: (+84) 979 891 929.
This article is for ETP/Waste Treatment Plant operations engineers and chemical procurement teams: focus Application of PAC 31% in wastewater treatmentThe COA specifications include parameters to read, mixing instructions, reference dosage, and a safety checklist. All dosage figures are technical suggestions—you need to verify them with a jar test using the plant's actual wastewater.
What is PAC 31% in wastewater treatment?
CAP (Poly Aluminium Chloride / Poly Aluminum Chloride) is an inorganic polymer aluminum salt, with the general formula... [Al₂(OH)ₙCl₆₋ₙ]ₘCommon powders contain approximately Al₂O₃. 28-32%The content below focuses on... PAC 31% For wastewater coagulation and related works.
In wastewater treatment, PAC is usually added at the stage... Coagulation – Flocculation (after adjusting pH if necessary) to reduce turbidity, color, SS, and some colloidal COD before sedimentation/filtration. PAC does not replace biological or oxidation treatment when organic load is high.
Definition & basic phase: What is PAC chemical – how to prepare it?Comparison of alum: When to use alum, and when to use PAC?.
Specifications to check
Before finalizing the 31% PAC lot for ETP, compare the COA with operational requirements (don't just look at the "31%" label). The specifications below are common commercial-technical frameworks; actual values vary depending on the manufacturer's lot.
| Targets | Reference level for PAC powder: 31% | Operating Notes |
|---|---|---|
| Name / alias | Poly Aluminum Chloride · PAC | CAS 1327-41-9 |
| Al₂O₃ | ~30–31% (usually ≥28–32% depending on grade) | Convert the dose to the actual % Al₂O₃ based on the COA. |
| Form | Powder (lemon yellow / white depending on the variety) | Unlike liquid PAC, which contains approximately 10–17% Al₂O₃. |
| Basicity | Typically ~40–90% by grade | Effect of pH range and flocculation rate |
| Solubility / Insolubility | Dissolves well in water; low residue | Mix in suitable HDPE/stainless steel containers. |
| Bao bì | Usually 25 kg/bag | Keep dry to prevent clumping. |
| B2B documents | COA by batch · MSDS/SDS | Requirements before project delivery |
PAC powder 31% vs. PAC liquid: Concentrated Al₂O₃ powder is compact and requires pre-mixing before dosing; liquid is more convenient for metering pumps but is more difficult to transport/contain in tanks. Many factories choose 31% powder for ETP due to its flexible inventory; highly automated plants may prioritize liquid — the decision depends on the pump, tank, and dosing frequency.
PAC application rate of 31% by industry.
PAC 31% is present in most XLNT schemes with a coagulation step. Below are common B2B application groups in Vietnam (industrial parks, private factories).
- Textile dyeing/finishing: Reduce turbidity, color, and SS before or after color treatment steps; often combined with a settling polymer. Jar testing is required when changing dyes/seasons.
- Paper & packaging: Fine-fiber flocculant, high turbidity; monitor pH and COD loading to avoid overdose and wet sludge formation.
- Food – Beverages – Preparation: Remove grease/SS/organic colloids during pretreatment; do not replace mechanical grease separators when grease loads are very high.
- Domestic/Industrial Park Wastewater: The process involves settling the water in a coagulation-sedimentation tank to stabilize the biological input or meet discharge standards (depending on the applicable Vietnamese National Technical Regulation).
- Water supply / surface water (reference): PAC is also used for water supply; for drinking water, the appropriate grade and documentation must be selected—separate from the ETP technical grade.
- Aquaculture / ponds (support): Made domestically; incorrect dosage can harm the organism — individual technical advice is required, do not copy ETP dosage.
PAC 31% is effective in control. pH, dosing point, stirring, and polymer support.Variable discharge sources → repeat jar-test, do not lock in one dose all year.
Brief coagulation mechanism
Positively charged aluminum polymers neutralize negatively charged colloids (turbidity, color, humus, etc.); particles clump together into flocs, resulting in better settling/flotation. Over-stirring breaks the flocs; under-stirring prevents the PAC from dispersing. A pH deviation from the appropriate range leads to unnecessary dose increases — the dosage table below is for reference only. refer.
Instructions for mixing and administering PAC powder.
- Prepare clean water (do not use wastewater to dilute the stock solution) and suitable HDPE/stainless steel containers; PPE according to MSDS.
- Pour Water into the bucket first.Then, gradually sprinkle in the PAC powder—pour and stir at the same time. Do not pour in all at once to avoid clumping.
- Popular stock mix 5-10% (W/W or according to internal SOP conversion). For example: ~1 kg of powder in ~9 L of water for a ~10% solution — adjust according to factory procedure.
- Stir until homogeneous (a few minutes to ~10 minutes depending on the equipment); allow any insoluble sediment to settle before pumping.
- Acupuncture rapid mixThen, stir slowly to create a flocculation; use a dosing pump to maintain a stable dose.
- When changing batch/COA or waste source: repeat jar-test, do not keep the old setpoint.
Liquid PAC (if used in parallel at the plant) can be added directly or slightly diluted — do not confuse the ratio with 31% powder because the % Al₂O₃ is different.
Reference dose and jar-test
The unit below is g/m³ of wastewater (or mg/L equivalent) For powdered PAC, the concentration is directional. Concentrated wastewater may have a much higher concentration; clean surface water may have a significantly lower concentration.
| Application / Source | Reference dosage of PAC powder | Note |
|---|---|---|
| Surface water / water supply (reference) | ~1–15 g/m³ | Depending on turbidity; suitable grade for domestic water supply. |
| Domestic wastewater / mixed light industrial wastewater | ~10–50 g/m³ | Polymer combination when cotton is fine |
| Textile dyeing (medium-high color intensity/SS) | ~30–150 g/m³ | Jar-test by batch color; pre-treatment may be required. |
| Paper, high-load food | ~50–200+ g/m³ | Overdose → wastes chemicals + wet sludge |
| Adjustments after jar-test | ± according to the test level | Choose the dose that achieves low opacity and firm cotton; do not select the default highest dose. |
Jar-test suggestions (lab): 4–6 cups of identical wastewater → add gradually increasing doses → stir quickly and briefly → stir slowly to create floc → settle → measure turbidity/observe floc and sludge volume. Record pH before and after. Multiply the results to the actual flow rate and monitor for 1–2 cycles before locking the setpoint.
Disclaimer: The above content is a technical reference document for procurement and operations. No A plant operation SOP or commitment to meeting emission standards is required. All dosages and diagrams must be the responsibility of the operating unit after actual testing.
PAC 31% and aluminum sulfate
Aluminum sulfate is inexpensive and familiar, but it is often more pH-sensitive and can generate more sludge in some sources. PAC polymers typically flocculate faster and have a wider pH range depending on the basicity. There is no "PAC always wins" answer: strongly acidic wastewater, specific loads, or cost constraints may make alum a viable option. Detailed comparison: PAC or aluminum sulfate?
Safety and storage
- Read the MSDS/SDS before opening the package; wear gloves, goggles, and a dust mask when mixing the powder.
- Avoid inhaling dust; if contact with skin/eyes occurs: rinse with clean water as directed in the MSDS, seek medical attention if necessary.
- Store in a dry, well-ventilated place, avoiding moisture to prevent clumping; stack bags on pallets, away from incompatible chemicals as recommended by the manufacturer.
- Do not mix with other chemicals in the same mixing tank — follow the addition order of the ETP scheme (pH → coagulation → polymer…).
- Dispose of packaging and residue in accordance with applicable internal/legal environmental regulations.
For textile and dyeing factories: see PAC for textile dyeing wastewater treatment.
Top Q&A
What is PAC 31% and what is its CAS value?
PAC 31% is a powdered polyaluminum chloride containing approximately 30–31% Al₂O₃ according to the COA. Common CAS number: 1327-41-9. English Alias: polyaluminium chloride / polyaluminum chloride.
How does PAC 31% powder differ from PAC liquid?
Powdered PAC has a higher percentage of Al₂O₃, is packaged in bags (usually 25 kg), and requires stock solution before dosing. Liquid PAC typically contains ~10–17% Al₂O₃, is convenient for dosing, but has a different conversion ratio. Do not use the same "mg/L" for both forms without converting to Al₂O₃.
Why is a jar test necessary before adding PAC to the system?
Wastewater quality varies depending on the production batch, pH, and SS. Jar-test helps select the appropriate dosage, avoiding underdosing (cloudy water) or overdosing (waste chemicals, excessive sludge, and pH deviation). The old setpoint may be inaccurate after changing raw materials.
How does pH affect coagulation using PAC?
A pH outside the optimal range reduces flocculation efficiency or necessitates an increased dosage. Many ETPs adjust the pH before the flocculation step. The optimal range depends on the basicity of the PAC batch and the waste composition—confirmed by testing, not a rigid number for every plant.
Should aluminum sulfate be replaced with PAC 31% immediately?
Only after jar testing and assessment of sludge, pH, and total cost (chemicals + sludge treatment) should this be considered. PAC is generally strong in flocculation speed and pH range, but alum is still suitable for some sources. See the PAC-alum comparison article on the site to choose the right approach.
When buying PAC (Private Partnership) at 31% B2B, what kind of COA/MSDS is needed?
Request a batch COA (Al₂O₃, moisture/insoluble content, basicity if available) and MSDS/SDS before or with shipment. Loc Thien provides PAC 31% on-request for factories/industrial parks — see PAC Tenor 31% or PAC Viet Tri 31%Hotline: (+84) 979 891 929.
Can PAC replace cationic/anionic polymers?
They are not a complete replacement. PAC primarily coagulates (neutralizes electrical charge); polymers usually aid in sedimentation/create larger flocs. Many schemes use PAC followed by polymer sequentially. The polymer dosage also requires a separate jar test.
Is 31% PAC needed for wastewater treatment? Please provide the flow rate, wastewater characteristics (pH, SS, industry), and expected volume to Loc Thien for grade and COA/MSDS consultation.
· Chinese PAC Tenor 31% (25 kg/bag)
· PAC Viet Tri 31%
Hotline: (+84) 979 891 929
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