PAM for Textile Wastewater: Dosage Guide

Textile wastewater is notoriously difficult to treat — it contains dyes, surfactants, heavy metals, and suspended fibers. Polyacrylamide is one of the few chemicals that works reliably across the wide pH and chemical composition range of textile effluent. Here is how to select the right PAM grade and dosage for your textile mill.

Textile Wastewater Characteristics

Why PAM Works for Textile Wastewater

Textile wastewater contains both organic (dyes, surfactants) and inorganic (suspended fiber, salts) contaminants. Most flocculants work well in one pH range but fail in another. PAM is unique because it works across the entire pH spectrum:

• In alkaline conditions (pH 9-12) — APAM works through bridging, unaffected by high pH
• In neutral conditions (pH 6-8) — CPAM works through charge neutralization
• In acidic conditions (pH 3-5) — NPAM (nonionic) works through pure bridging, unaffected by low pH

This flexibility makes PAM ideal for mills that process multiple fiber types and dye classes, where wastewater pH varies throughout the day.

We supply our cationic PAM retention aid specifically formulated for this application — tested and proven at scale.

Reactive Dye Wastewater (Alkaline, pH 10-12)

Reactive dyes are applied in alkaline conditions. The wastewater is highly alkaline, contains excess dye, salt, and alkali. Most cationic flocculants (like ferric chloride) precipitate in this pH range and become ineffective.

Use APAM with 15-25M molecular weight and 25-35% hydrolysis. The anionic charge is unaffected by high pH. Dosage: 2-8 ppm depending on dye concentration and suspended solids.

Typical performance: TSS reduction from 200-500 ppm to <50 ppm, color reduction 60-80%, turbidity <10 NTU.

Acid Dye Wastewater (Acidic, pH 3-5)

Acid dyes are applied in acidic conditions with sulfuric acid or acetic acid. The wastewater is strongly acidic, contains metal ions (from mordants), and suspended fiber. In this pH range, both APAM and CPAM lose effectiveness because surface charges collapse.

Use NPAM (nonionic polyacrylamide) with 8-12M molecular weight. Nonionic PAM works through pure polymer bridging, independent of pH. Dosage: 3-10 ppm.

Typical performance: TSS reduction 70-90%, color reduction 40-60%, turbidity <20 NTU. Note: color reduction is lower in acidic conditions because dyes remain dissolved. Pre-treatment with pH adjustment (to neutral) improves color removal.

Pigment Printing Wastewater (Neutral, pH 6-8)

Pigment printing uses binders (starch, acrylics) and pigments suspended in water. The wastewater is neutral to slightly alkaline, contains suspended pigments and binder particles (negatively charged).

Use CPAM with 30-50% charge density and 10-15M molecular weight. The positive charge neutralizes pigment particles; the polymer bridges them into large flocs. Dosage: 2-6 ppm.

Typical performance: TSS reduction 80-95%, turbidity <5 NTU, clear supernatant suitable for reuse.

Sizing and Finishing Wastewater

Sizing wastewater contains starch, oils, waxes, and synthetic binders. These are mostly organic and negatively charged. Use CPAM with 40-60% charge density to handle the high organic load. Dosage: 3-8 ppm.

For oily sizing wastewater, pre-treatment with an oil-water separator is recommended before PAM dosing. This reduces the organic load and improves PAM efficiency.

Combined Wastewater (Mixed pH and Contaminants)

Many mills combine wastewater from multiple processes — dyeing, printing, finishing, washing. The combined stream has variable pH (5-9), mixed contaminants, and unpredictable composition.

For combined wastewater, use CPAM with 30-50% charge density. This is a compromise that works reasonably well across the pH range. Alternatively, add pH adjustment (lime or acid) to bring the wastewater to neutral (pH 6-8) before PAM dosing — this improves performance significantly.

Dosage: 3-10 ppm depending on composition. Always run jar tests with your actual wastewater to optimize.

Jar Testing for Textile Wastewater

Textile wastewater composition varies by mill, process, and season. Jar testing is essential:

1. Collect wastewater samples from each process (dyeing, printing, finishing)
2. Measure pH, TSS, color (ADMI units), and conductivity
3. Prepare 0.1% PAM solutions of different types (APAM, CPAM, NPAM)
4. Add PAM at 1, 2, 5, 10 ppm increments to each sample
5. Observe floc formation, settling speed, and supernatant clarity
6. Measure final TSS and color of supernatant
7. Select the PAM type and dose that achieves target clarity at lowest cost

Our Textile-Grade PAM

At our Zhengzhou factory, we produce all three PAM types for textile applications:

• APAM for alkaline wastewater: 12-25M MW, 20-35% hydrolysis
• CPAM for neutral/mixed wastewater: 10-15M MW, 30-60% charge density
• NPAM for acidic wastewater: 8-12M MW, 0% charge (nonionic)

All grades meet our standard specs: solid content ≥92%, dissolution time ≤90 minutes, residual monomer ≤0.05%. We also supply emulsion formats for mills that cannot wait 60-90 minutes for powder dissolution.

Case Study: Indian Textile Mill

A large textile mill in Gujarat was struggling with wastewater treatment. They were using ferric chloride as the primary flocculant, but performance was inconsistent — some days the effluent was clear, other days it was turbid. The problem: their wastewater pH varied from 4 to 11 depending on which processes were running.

We recommended a three-stage approach:

1. pH adjustment to neutral (6-8) using lime
2. CPAM dosing at 3-5 ppm
3. Settling in a clarifier

Results after 1 month:

• Effluent TSS: consistently <30 ppm (previously 50-200 ppm)
• Color: reduced 70-80% (previously 40-50%)
• Turbidity: <5 NTU (previously 20-50 NTU)
• Chemical cost: reduced 20% (CPAM is cheaper than ferric chloride on a per-ton basis)

Get the Right PAM for Your Textile Mill

Send us your wastewater analysis (pH, TSS, color, conductivity, process types) and we will recommend the optimal PAM type and dosage within 24 hours. Free samples available for jar testing.

WhatsApp: +86 150-0381-8598 | Request a quote

Related Guides

• PAM water treatment
• Cationic PAM wholesale
• Electroplating wastewater

Get a Quote

Our factory in Zhengzhou produces 100,000 tons/year of PAM across 18+ grades. MOQ 500kg, delivery 7-10 days standard. Contact us for pricing and free sample:

• WhatsApp: +86 150-0381-8598
• Email: info@chinapolyacrylamide.com