Preparing polyaluminum chloride (PAC) solution correctly ensures optimal water treatment performance and prevents costly chemical waste. This guide provides proven methods for mixing PAC solutions that deliver consistent results.
Poor PAC preparation wastes 30-50% of chemical investment through degradation or incomplete dissolution. For plants treating 10,000 m³/day, improper preparation can waste $20,000+ annually.
Key Benefits of Correct Preparation:
● Consistent coagulation performance
● 15-30% chemical cost reduction
● Extended equipment life
● Better safety compliance
| PAC Form | Al₂O₃ Content | Best Use |
|---|---|---|
| Powder | 28-31% | Economic, longer storage |
| Liquid | 10-18% | Fast preparation |
| Application | Solution Strength | Typical Dose |
|---|---|---|
| Drinking Water | 5-10% | 10-30 mg/L |
| Wastewater | 10-15% | 50-300 mg/L |
Important: Solutions below 5% degrade quickly. Above 15% becomes too viscous.
Mixing Tank:
● Material: HDPE, PP, or FRP only (never metal)
● Size: 1.5× batch volume
● Features: Sealed lid, drain valve
Mixer:
● Variable speed (40-200 RPM)
● Stainless steel or plastic paddles
Safety Gear (Mandatory):
● Chemical-resistant gloves
● Safety goggles
● Apron and boots
● N95 mask (for powder)
✅ Safe: Polyethylene, Polypropylene, PVC, FRP, Rubber ❌ Never: Carbon steel, Aluminum, Copper, Brass
Formula:
PAC powder (kg) = (Volume × Target %) / Powder % Water (L) = Total volume - Powder weight
Quick Reference (30% PAC powder to 100L):
| Target % | Powder (kg) | Water (L) | Ratio |
|---|---|---|---|
| 5% | 17 | 83 | 1:5 |
| 10% | 33 | 67 | 1:2 |
| 15% | 50 | 50 | 1:1 |
● Fill tank with 60-70% of water
● Temperature: 15-25°C optimal
● pH: 6.5-8.5 preferred
● Critical: Always add PAC to water, never reverse!
| Tank Size | Speed | Time |
|---|---|---|
| <100L | 100-150 RPM | 30-45 min |
| 100-500L | 80-120 RPM | 45-60 min |
| >500L | 60-100 RPM | 60-90 min |
● Wear full PPE
● Pour along vortex edge slowly
● Small batches: 2-3 kg every 2-3 min
● Never dump all at once
Continue mixing 30-60 minutes after all powder added.
Complete Dissolution Signs:
● Clear to pale yellow
● No visible particles
● Uniform color
● Slightly viscous
● Add remaining 30-40% water
● Mix 10-15 more minutes
● Verify pH (should be 3.5-5.0)
● Concentration and date
● "Use within 24 hours"
● Safety warning: Corrosive
For better stability:
1. Heat water to 60-75°C
2. Add PAC gradually while mixing
3. Maintain temperature 20-30 minutes
4. Cool to room temperature before use
Benefits: 30% faster, better performance
Drawback: Requires cooling time
Formula: C₁ × V₁ = C₂ × V₂
Example: 18% PAC to 10% (100L total)
V₁ = (10 × 100) / 18 = 55.6L concentrate Water = 44.4L
Steps:
1. Measure concentrate
2. Add to tank, start mixing
3. Slowly add water
4. Mix 15 minutes
| Form | Storage | Max Life | Recommended |
|---|---|---|---|
| Powder | Cool, dry | 18-24 months | Check date |
| Solution | Room temp | 48-72 hours | 24 hours |
| Liquid concentrate | Cool, sealed | 12 months | 6-12 months |
Container: Sealed, opaque, corrosion-resistant
Temperature: 10-20°C (avoid <5°C or >30°C)
Location: Dark, ventilated area
Degradation Signs:
● Dark brown color
● Sediment or cloudiness
● Poor floc in jar test → Discard and prepare fresh
DO:
● ✅ Add PAC to water
● ✅ Wear full PPE
● ✅ Work in ventilated area
● ✅ Keep containers sealed
DON'T:
● ❌ Mix with other chemicals
● ❌ Use without PPE
● ❌ Store near heat
Skin: Rinse 15 min, remove clothing
Eyes: Rinse 15 min, seek medical help immediately
Spill: Neutralize with soda ash, absorb, dispose properly
1. Fill 6 beakers with sample water
2. Add different PAC doses (10-60 mg/L)
3. Rapid mix: 200 RPM, 1 min
4. Slow mix: 30 RPM, 15 min
5. Settle: 20-30 min
6. Measure turbidity, select optimal dose
Daily Checks:
● Visual inspection
● pH verification (3.5-5.0)
● Performance consistency
→ Water too cold or added too fast
Fix: Heat water to 20-25°C, add slowly
→ Over 48 hours old or contaminated
Fix: Prepare fresh batch
→ Degraded solution or wrong dose
Fix: Use within 24 hours, perform jar test
→ Overdosing or pH issue
Fix: Reduce dose 10-20%, adjust pH to 6.5-7.5
1. Prepare Daily BatchesCalculate actual consumption, avoid waste → Saves 10-20% on chemicals
2. Use Right ConcentrationMatch to your dosing equipment → Better accuracy, less waste
3. Calibrate Equipment MonthlyCheck pump accuracy with bucket test → Prevents 5-15% overdose
4. Buy Quality PACHigh basicity (75-85%) uses less product → Lower total cost despite higher price
5. Store ProperlyCool (10-15°C), sealed, dark → Extends usable life
Q: Can I store solution for a week?
A: No. Use within 24 hours for best results. Max 48 hours refrigerated.
Q: Powder or liquid PAC?
A: Powder: cheaper, longer storage. Liquid: faster prep, no dust.
Q: Why does solution gel?
A: Too concentrated (>15%) or too cold (<5°C). Use correct concentration, store at room temp.
Q: Can I use tap water?
A: Yes, if hardness <100 mg/L and chlorine <0.5 mg/L.
Q: How to know if solution is bad?
A: Dark color, sediment, or poor jar test results. Prepare fresh.
Q: Mix with other chemicals?
A: Never during preparation. Add chemicals separately in treatment process.
✅ Always add PAC to water
✅ Use within 24 hours
✅ Mix 30-60 minutes
✅ Wear full PPE
✅ Store properly (cool, dark, sealed)
✅ Perform jar tests regularly
Results with Proper Preparation:
● 15-30% cost reduction
● Consistent water quality
● Extended equipment life
● Better safety compliance
Tairan Chemical supplies premium polyaluminum chloride worldwide.
Our Products:
● High basicity PAC (≥75%)
● Drinking water & industrial grades
● Powder and liquid forms
● Full technical support
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