PAM Jar Test: Step-by-Step Procedure

The jar test is the industry standard for determining optimal PAM dosage before full-scale deployment. A 30-minute lab test can save you thousands in wasted chemical and prevent treatment failures. Skip it and you are guessing — and guessing wrong costs real money. We have seen plants running at 3× optimal dosage because nobody ran a jar test when they switched suppliers. We have also seen plants under-dosing by 50% and wondering why their thickener overflow is cloudy.

This guide walks you through the exact procedure we use in our own lab when customers send us wastewater samples. We test 5-8 PAM grades at 4-6 dosages each — that is 20-48 data points per sample. You do not need to go that deep for routine optimization, but the principles are the same.

Why Jar Testing Matters

Every wastewater is unique. Optimal PAM dosage depends on at least six variables that change with season, production, and raw material:

• Turbidity level: 1-1,000+ NTU — a 100× range that changes optimal dosage by 10-50×
• Particle size distribution: Fine clay particles (<1 micron) need higher MW PAM than coarse silt (10-100 microns)
• pH: PAM charge changes with pH. Anionic PAM loses charge below pH 5; cationic PAM loses charge above pH 9
• Temperature: Cold water (5-10°C) needs 20-30% more PAM than warm water (25-35°C)
• Coagulant type and dosage: PAM works with coagulant, not instead of it. Wrong coagulant dose makes PAM ineffective
• Ionic strength: High-salinity water collapses anionic PAM chains, reducing bridging efficiency by 30-60%

Guessing dosage wastes money. A 30-minute jar test gives you optimal dosage with 90%+ accuracy. For a plant consuming 10 tons of PAM per month at $1,500/ton, a 20% dosage reduction from jar testing saves $3,000/month — $36,000/year.

Our nonionic PAM for mineral processing is engineered for exactly this use case, with batch-level quality control from our Zhengzhou facility.

Equipment Needed

You do not need a sophisticated lab. Most of this equipment is standard in any water treatment plant or mining operation:

Preparing the PAM Stock Solution

This step is where most people make mistakes. Improperly prepared PAM solution gives misleading jar test results — you think the PAM is not working when actually the solution was not properly dissolved.

1. Weigh accurately: 1.0g PAM powder on a scale (±0.05g)
2. Use clean water: Tap water or deionized water at 20-25°C. Do not use process water — it may contain ions that affect dissolution
3. Add powder to water, not water to powder: Pour 1L of water into a beaker first, then slowly sprinkle PAM powder onto the surface while stirring gently. Adding water to powder creates lumps that never dissolve
4. Stir gently: 100-150 rpm for 60-90 minutes. Do not use high-shear mixing — it breaks polymer chains
5. Rest: Let solution rest for 30 minutes after stirring. This allows remaining lumps to fully hydrate
6. Check: Solution should be clear and viscous (like thin syrup). If lumpy or cloudy, stir another 30 minutes
7. Use within 4 hours: PAM solution degrades — prepare fresh for each test session

This 0.1% stock solution means 1 mL added to 1L of wastewater = 1 ppm dosage. Easy math for dosing.

Step-by-Step Jar Test Procedure

Step 1: Characterize Your Wastewater (5 minutes)

Before testing, measure baseline parameters. These determine which PAM type and dosage range to test:

• pH (determines anionic vs cationic PAM)
• Temperature (affects dissolution and flocculation rate)
• Turbidity in NTU (determines dosage range)
• Visual appearance (color, odor, particle size estimate)

Step 2: Set Up Test Jars (2 minutes)

• Fill 6 beakers with 1L of wastewater each — use the same sample batch
• If using coagulant (alum, ferric chloride), add the same dose to all jars first
• Label jars 1-6 with planned PAM dosage

Step 3: Select Dosage Range

Step 4: Rapid Mix (1 minute)

• Add PAM solution to each jar simultaneously (or as quickly as possible)
• Set mixer to 150-200 rpm
• Mix for 60 seconds — this disperses PAM throughout the sample
• Observe: small flocs (0.5-1 mm) should start forming

Step 5: Slow Mix (5 minutes)

• Reduce speed to 30-50 rpm
• Mix for 5 minutes — this grows flocs to full size
• Observe floc size: target 2-5 mm for settling, 0.5-2 mm for DAF
• Note which jars have the largest, most uniform flocs

Step 6: Settling (10 minutes)

• Stop mixer, remove paddles carefully without disturbing flocs
• Let settle for 10 minutes undisturbed
• Observe settling rate at 2, 5, and 10 minutes
• Note sludge volume at bottom (smaller = better dewatering)

Step 7: Measure and Record

• Carefully pipette supernatant from top 2 cm of each jar
• Measure turbidity (NTU) of each supernatant
• Record: dosage, turbidity, floc size, settling rate, sludge volume
• Calculate % turbidity reduction for each dosage

How to Interpret Results

Common Mistakes to Avoid

• Using old PAM solution: PAM degrades in solution within 4-8 hours. Prepare fresh for each test session
• Mixing too fast during slow mix: Above 60 rpm during slow mix breaks flocs. Use 30-50 rpm
• Not measuring baseline turbidity: You cannot calculate % reduction without a baseline
• Testing only one PAM type: If anionic PAM gives poor results, try cationic before concluding PAM does not work
• Ignoring pH: PAM performance drops sharply outside pH 5-9. Adjust pH before testing if needed
• Using cold water: PAM dissolves poorly below 15°C. Warm make-up water to 20-25°C for dissolution
• Disturbing jars during settling: Even small vibrations re-suspend flocs. Keep jars still during settling

Scaling Up from Jar Test to Full Scale

Jar test results do not translate directly to full-scale dosage — they need adjustment for mixing energy, residence time, and temperature differences:

• Mixing energy: Full-scale systems often have less controlled mixing than jar tests. Add 10-20% to jar test dosage as a starting point
• Temperature: If your process water is colder than your jar test water, add 5-10% per 5°C temperature difference
• Residence time: If your settling tank has less than 30 minutes residence time, add 10-15% to dosage
• Fine-tune on site: Start at jar test dosage + 15%, then adjust based on actual overflow turbidity

Free Jar Testing Service

We perform free jar testing for customers ordering 5+ tons/month. Send us 5-10 liters of your wastewater or sludge sample, and we test with 5-8 PAM grades at 4-6 dosages each. You receive a full report with:

• Turbidity vs dosage curves for each PAM grade tested
• Recommended grade and optimal dosage range
• Cost-per-ton-treated calculation at optimal dosage
• Comparison against your current PAM (if you send a sample)
• Seasonal adjustment recommendations

Our lab in Zhengzhou processes 20-30 customer samples per month. Turnaround: 3-5 business days from sample receipt.

Related Guides

• Dosage calculation — converting jar test results to full-scale
• PAM dissolving method — proper preparation technique
• Charge density explained — how to select anionic vs cationic
• Water treatment dosage guide — application-specific ranges

Need Help with Jar Testing?

Send us a 5-liter sample of your wastewater. We perform jar tests free and provide detailed recommendations with full dosage data: