PAC Powder vs PAC Liquid: A Detailed Comparison of Two Forms of Poly Aluminium Chloride
PAC Powder vs PAC Liquid: A Detailed Comparison of Two Forms of Poly Aluminium Chloride
TL;DR: PAC powder (28–32% Al₂O₃) and PAC liquid (10–11% Al₂O₃) share the same coagulant active ingredient, so performance is equivalent when dosed correctly by Al₂O₃ content. PAC powder saves 60–70% on transport costs, has a 12–24 month shelf life, and is suitable for remote areas and long-term storage. PAC liquid is ready for direct pumping, requires no dissolution, and is ideal for large plants with high automation and continuous operation. The choice depends on plant scale, infrastructure, and logistics costs.
The Problem: PAC Powder or PAC Liquid — Which is the Optimal Coagulation Solution?
PAC (Poly Aluminium Chloride, CAS 1327-41-9) is the most widely used inorganic coagulant in drinking water treatment and industrial wastewater treatment. However, PAC exists in two forms — powder and liquid — with a fundamental difference in Al₂O₃ content: powder reaches 28–32% while liquid is only 10–11%. Many plants struggle to choose between these two forms because each has distinct advantages in cost, operation, and logistics. PAC powder is approximately 3 times more concentrated than PAC liquid, significantly reducing transport and storage costs, but it requires investment in a dissolution system and generates dust during preparation. PAC liquid is ready for immediate use, suitable for automated lines, but its larger volume leads to higher logistics costs and a shorter shelf life. Choosing the wrong PAC form can result in operating costs 20–30% higher than the optimal level.
Detailed Comparison Table: PAC Powder vs PAC Liquid
| Criteria | PAC Powder | PAC Liquid |
|---|---|---|
| Al₂O₃ Content | 28–32% | 10–11% |
| Form | Dry powder | Liquid solution |
| Ready to use | No — requires dissolution | Yes — direct pumping |
| Storage volume (for same Al₂O₃) | Low (approx. 3x concentrated) | High (diluted) |
| Transport cost / unit Al₂O₃ | Low | High |
| Shelf life | 12–24 months | 6–12 months |
| Storage temperature | No special requirements | Above −5°C (avoid freezing) |
| Dosing system | Requires dissolution tank + mixer | Simple: pump from storage tank |
| Operational risks | PAC dust (respiratory irritation) | Leaks, spills, corrosion |
| System complexity | Higher | Lower |
| Suitability for automation | Moderate | High |
| Suitability for remote / hard-to-reach areas | High (concentrated, long storage) | Low |
| Purchase price / ton | Higher | Lower |
| Price / kg Al₂O₃ | Lower | Higher |
Coagulation Performance: Is There a Difference?
When dosed at the same Al₂O₃ content, PAC powder and PAC liquid from the same manufacturer deliver identical coagulation efficiency — because the active coagulant is the same (pre-hydrolyzed aluminum polymers with the formula [Al₂(OH)ₙCl₆₋ₙ]ₘ). This is the most important point to understand: the difference lies not in coagulation quality but in logistics, operational, and storage costs. In practice, performance may vary due to: incomplete dissolution of PAC powder leading to uneven concentration, errors in preparing the solution from powder, or degradation of PAC liquid during prolonged storage. With PAC powder, the correct preparation procedure is key — slowly add powder to water (never pour water onto powder), stir for 15–30 minutes at moderate speed, with a solution concentration of 5–15% w/v. If the procedure is followed, the coagulation performance of the two forms is equivalent.
Economic Analysis: The True Operating Cost
| Factor | PAC Powder | PAC Liquid |
|---|---|---|
| Purchase price (FOB, USD/MT) | $380–480 (30% Al₂O₃) | ~$150–250 (10–11% Al₂O₃) |
| Price/kg Al₂O₃ | ~$1.27–1.60/kg | ~$1.36–2.27/kg |
| Transport volume (for 1 ton Al₂O₃) | ~3.3 tons powder | ~10 tons liquid |
| Preparation equipment cost | Requires initial investment | Not required |
| Preparation labor cost | Yes (preparation time) | No (direct pumping) |
Calculated on the same Al₂O₃ unit, PAC powder is 15–30% cheaper to purchase. For the same ton of Al₂O₃, you only need to transport 3.3 tons of PAC powder instead of 10 tons of PAC liquid — saving 60–70% on transport costs. However, PAC powder requires an initial investment in a dissolution tank and mixing system, along with daily labor costs for preparation. PAC liquid, though more expensive per Al₂O₃ unit, requires no preparation equipment, reduces labor costs, and is suitable for high-automation systems. Conclusion: large systems near the supply source should choose PAC liquid; small systems in remote areas should choose PAC powder.
Frequently Asked Questions (FAQ)
1. Do PAC powder and PAC liquid have different coagulation efficiency?
When used at the same Al₂O₃ content, coagulation efficiency is identical because the active ingredient is the same pre-hydrolyzed aluminum polymers. Differences in practice mainly arise from the dissolution process and storage conditions.
2. When should I choose PAC powder?
PAC powder is suitable for small systems, remote areas, islands, where transport costs are high and long-term storage (12–24 months) is needed. It is also suitable when the plant already has a dissolution system.
3. When should I choose PAC liquid?
PAC liquid is suitable for large water treatment plants (>10,000 m³/day), near the supply source, with high automation and a desire for simple operation without dust generation.
4. How to properly dissolve PAC powder?
Fill the tank with clean water to 80% of the final volume, start the mixer before adding powder, add powder slowly (do not dump the entire bag at once), stir for 15–30 minutes, then add water to the final volume. Preparation concentration: 5–15% w/v. Let it settle for 10 minutes before pumping.
5. How long can PAC liquid be stored?
PAC liquid has a shelf life of 6–12 months. It must be stored in HDPE or composite tanks, avoiding temperatures below −5°C (risk of freezing/crystallization). Do not use carbon steel tanks due to its mildly corrosive nature (pH ~3.5–4.5).
6. How do transport costs differ?
PAC powder saves 60–70% on transport costs compared to PAC liquid for the same Al₂O₃ content. For 1 ton of Al₂O₃, you need 3.3 tons of powder versus 10 tons of liquid.
7. Are there occupational safety risks with PAC powder?
Yes. PAC powder generates dust during preparation — causing respiratory irritation, requiring PPE (mask, gloves, goggles). Additionally, incomplete dissolution can cause pump blockages and sediment buildup.
Recommendation Table by Operating Conditions
| Condition | Recommendation |
|---|---|
| Large water plant (>10,000 m³/day), near supply source | PAC liquid |
| Small system, remote areas, islands | PAC powder |
| Need for long-term storage, high transport costs | PAC powder |
| High automation system | PAC liquid |
| No existing dissolution system | PAC liquid |
| Limited initial investment budget | PAC powder (gradual investment) |
Loc Thien — PAC Solutions for Every System
Loc Thien supplies both PAC powder (30–31% Al₂O₃, 25kg bags, Jumbo bags) and PAC liquid (10–17% Al₂O₃, tanks/bulk) with full COA and MSDS per shipment. Products are ZDHC certified for the textile dyeing industry and meet QCVN 01:2009/BYT for domestic drinking water. Loc Thien’s technical team offers free jar-test support and advises on the optimal PAC form and grade based on each plant’s specific water source, equipment system, and operating budget. Delivery is available directly to locations in Ho Chi Minh City, Binh Duong, Dong Nai, and industrial parks nationwide.
Contact now: 📞 0979 891 929 for consultation and the best quotation for your needs.
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References: Hychron (2026), Yiwei Putai, Yuncang Chemical, Dusit Chemicals (2026).