How to ensure the use effect of polymeric ferric sulfate at low temperature in winter

Winter Application Technology of Polyferric Sulfate (PFS) in Water Treatment: PFS hydrolyzes to form polymeric hydroxyl complexes that remove pollutants. However, low winter temperatures impair its effectiveness through three mechanisms: slowing hydrolysis rates (resulting in poor floc formation), reducing water molecule activity (decreasing particle collisions), and affecting dissolution efficiency (increasing turbidity). These challenges require targeted solutions to address the issues of "slow hydrolysis, difficult coagulation, and poor dissolution".

Optimize dissolution process: As PFS solubility decreases at low temperatures, implement "temperature-controlled dissolution with staged stirring". Maintain water temperature between 20-30°C (avoid exceeding 40°C to prevent decomposition), prepare mother liquor at 10%-15% concentration. First add half the water volume and stir for 3-5 minutes, then gradually add PFS while stirring. Supplement with remaining water and continue stirring for 15-20 minutes. If temperature cannot be raised, extend stirring time to over 30 minutes, followed by 3-4 hours of maturation of the mother liquor.

Adjust the dosing parameters: Increase the dosage by 10%-30% above the normal temperature baseline (determined through pilot testing). Apply the "segmented dosing + uniform stirring" method: first add 60%-70% of the solution and stir at 100-150 r/min for 1-2 minutes; then add the remaining dosage and stir at 50-80 r/min for 3-5 minutes.

Optimize the reaction environment: Adjust pH to 6.0-9.0. Add lime milk or sodium hydroxide for acidic conditions, and dilute sulfuric acid for alkaline conditions. If possible, raise the water temperature above 15℃; otherwise, extend the reaction and settling time to 60-90 minutes. When water turbidity is low or pollutants are minimal, add 0.1-0.3mg/L polyacrylamide (PAM).

Standard storage and transportation: Store liquid PFS in a cool, dry, and sealed PFS storage room. Keep solid PFS dry. Liquid PFS must not freeze below-5℃. Thoroughly mix and test after thawing. Transport using insulated vehicles. Always mix before and after transportation of liquid PFS. Unload promptly upon arrival.