Flocculants in Industrial Water Treatment: PAC vs PAM

Flocculation is the controlled aggregation of fine suspended solids into larger settleable or filterable flocs. Two chemical families dominate: inorganic coagulants (PAC) and organic polymeric flocculants (PAM).

PAC (Polyaluminium Chloride)

PAC is a pre-hydrolyzed aluminium salt. Key advantages:

• Fast charge neutralization at neutral to slightly acidic pH (6.5–8.5)
• Lower sludge volume than alum
• Typical dose: 10–50 mg/L as Al2O3 equivalent

Basicity ranges from 40–90%. Higher basicity grades work better in cold water and higher pH.

PAM (Polyacrylamide)

PAM is a high-molecular-weight (1–20 million Da) polymer used as a secondary flocculant or primary flocculant for organic-rich streams.

• Anionic PAM: Best for positively charged particles (mineral, paper); works at neutral to alkaline pH.
• Cationic PAM: Best for negatively charged organics (sewage sludge, food effluent).
• Non-ionic PAM: Effective where pH fluctuates widely.

Jar Test Protocol

1. Add PAC at 60–100 rpm for 1 min (rapid mix)
2. Reduce to 20–30 rpm for 10–15 min (slow mix)
3. Settle 20 min; measure turbidity and zeta potential
4. Add PAM (0.5–5 mg/L) if floc is small or slow-settling

HMEChem supplies PAC (basicity 70–90%) and a full range of anionic/cationic PAM grades.