Ferrous Sulfate (FeSO₄) in Wastewater Treatment

Ferrous sulfate (FeSO₄) is a cost-effective coagulant widely used in industrial and municipal wastewater treatment. It excels in flocculation, reduction, and decolorization. This guide explains its features, working principles, optimal conditions, and practical uses to help businesses improve efficiency and cut costs.

 

Three Core Functions of Ferrous Sulfate

① Flocculation & Sedimentation Ferrous sulfate releases ferrous ions (Fe²⁺) that react with suspended particles and colloids, forming dense, fast-settling flocs.

✅ Best paired with: Polyacrylamide (PAM) for enhanced flocculation. Ideal for pretreatment stages.

② Reduction: Removing Heavy Metals & Oxidants Fe²⁺ acts as a reducing agent, neutralizing toxic oxidants like hexavalent chromium (Cr⁶⁺), permanganate, and nitrite.

✅ Works for:

• Industrial wastewater with heavy metals (Cr, Cu, Ni).
• Wastewater containing oxidants (e.g., permanganate).

③ Decolorization: Ideal for Dye Wastewater Ferrous sulfate breaks down color-causing compounds in wastewater from textile, dyeing, and paper industries.

✅ Boost effect: Combine with PAM for better color removal.

 

Types of Ferrous Sulfate

Type	Appearance	Features	Applications
Heptahydrate (Green Vitriol)	Green crystals	High water content, dissolves easily	General wastewater treatment
Anhydrous	White powder	Low moisture, stable storage	Facilities needing dry, stable storage

 

✅ Heptahydrate: Most common due to low cost.

✅ Anhydrous: Preferred for humidity-sensitive environments.

Optimal Usage Conditions

• pH Range: ✅ Best: pH 8–9 (alkaline). ❌ Avoid: pH <6 (weak flocculation) or pH >9 (higher dosage needed).
• Dosing Method: Dilute before adding to improve reaction efficiency.

 

Ferrous Sulfate vs. Other Coagulants

Coagulant	pH Range	Key Uses	Pros	Cons
Ferrous Sulfate	8–9	Flocculation, reduction, decolorization	Low cost, fast settling, good decolorization	Poor performance in acidic pH; absorbs moisture
PAC	5–8	Turbidity/organic removal	Broad pH suitability (municipal)	Weak phosphorus removal
PFS	4–11	Phosphorus removal, flocculation	Wide pH range, strong phosphorus removal	Higher cost
Aluminum Sulfate	5–8	Drinking water treatment	Safe for potable water	Poor performance in cold water

 

✅ Usage Tips:

• Municipal wastewater: PAC or ferrous sulfate.
• Phosphorus removal: PFS.
• Dye wastewater: Ferrous sulfate + PAM.

 

Economic & Environmental Benefits

• Cost-Effective: Cheaper than PAC/PFS.
• Less Sludge: Reduces sludge volume, lowering disposal costs.
• Eco-Friendly: Minimizes chemical residues compared to organic coagulants.

 

When to Choose Ferrous Sulfate?

✅ Pick Ferrous Sulfate If:

• Budget-friendly solutions are needed.
• Wastewater is alkaline (pH 8–9).
• Heavy metal removal or decolorization is required.

By matching ferrous sulfate to specific needs, businesses can improve treatment efficiency, reduce costs, and meet environmental standards.

Need help optimizing your wastewater treatment? Contact us for expert guidance!