1. Solution Preparation
Dissolve ferrous sulfate in clean water to prepare 5%–10% aqueous solution before dosing; prepare freshly as its solution oxidizes quickly and loses efficacy overnight.
2. Dosing Dosage by Wastewater Type
(1)Printing & Dyeing Wastewater (Decolorization & COD removal)
Adjust wastewater pH to 8.5–10 with lime first.
Dosage: 500–1200 mg/L (0.5–1.2 kg ferrous sulfate per ton of wastewater). Ferric hydroxide flocs form to adsorb pigment and suspended solids for sedimentation.
Dosage: 500–1200 mg/L (0.5–1.2 kg ferrous sulfate per ton of wastewater). Ferric hydroxide flocs form to adsorb pigment and suspended solids for sedimentation.
(2)Municipal Sewage (Phosphorus removal after biochemical treatment)
Optimal pH range:7.0–8.0.
Dosage:80–200 mg/L (0.08–0.2 kg per ton water). It reacts with phosphate to form ferric phosphate precipitate to reduce total phosphorus.
(3)Tap Water Pretreatment (Turbidity & residual chlorine removal)
Dosage:20–50 mg/L, cooperate with a small amount of lime for coagulation and sedimentation of colloids and impurities.
3. Operating Process
(1)Fully stir raw material in dissolving tank for 5–10 minutes until complete dissolution.
(2)Pump the prepared solution into coagulation tank or rear end of aeration tank.
(3)Add a small amount of anionic PAM to accelerate floc precipitation and avoid sludge floating.
4. Important Notes
(1)Never store prepared solution overnight due to easy oxidation.
(2)Increase dosage by 15%–30% under low ambient temperature for stable flocculation effect.
(3)Lumpy ferrous sulfate after damp can be crushed and dissolved normally without performance loss.