Salinity is one of the core indicators of polyferric sulfate (PFS), and its high and low directly affect the flocculation efficiency. The specific influence mechanism and application scenarios are as

🔬 I. Direct influence of salinity on flocculation efficiency

1. Molecular structure and charge characteristics
   1. High salinity (> 12%):
      1. The longer the molecular chain, the higher the degree of polymerization, and the stronger the adsorption bridging ability, which can quickly form large and dense alum.
      2. After hydrolysis, more OH⁻ ions are produced, the electric neutralization ability is enhanced, and the destabilization effect on colloid particles is more significant.
   2. Low salinity (<10%):
      1. Free Fe³⁺ is more suitable for scenarios that require iron ions to participate in the reaction (such as phosphorus removal and breaking heavy metals).
2. Settlement velocity and alum density
   1. The higher the salinity, the more comPact the structure of the generated alum and the faster the sedimentation rate (the processing time is shortened by more than 30%).
   2. When the salt base is too low, the alum flower is loose and easy to break, and the sedimentation efficiency decreases.
3. pH subject range
   1. High salinity products are more tolerant to the fluctuation of raw water pH (effective pH range 4-11), especially suitable for alkaline water quality.
   2. Low salinity will reduce the water pH, which is suitable for Wastewater Treatment in acidic conditions (such as neutralizing alkaline pollutants).
      

⚖ II. Balance and limitation of salinity

1. Stability issues
   1. When the salt base is more than 16%, the product is easy to hydrolyze and produce Fe (OH) SO₄ precipitation, which reduces the active ingredients and blocks the pipeline.
   2. It is suggested that the salt base should be controlled between 8% and 16% to take into account the flocculation effect and storage stability.
2. Economy and applicability
   1. High salinity: suitable for high turbidity and high chromatic wastewater (such as printing and dyeing, papermaking wastewater), reducing the dosage of chemicals by 10%-20%.
   2. Low salinity: suitable for low temperature and turbid water quality or scenes requiring iron ion chemical reaction (such as phosphorus removal).
      

🌡 Three, regulation suggestions in practical application

⚠ Four, Precautions

1. Detection and proportion:
   1. The salt base test should be strictly carried out according to the standard (such as GB 14591-2016) to avoid errors caused by high total iron content.
2. Dynamic adjustment:
   1. The salinity is adjusted in real time according to the change of water quality. For example, the salinity can be increased when the turbidity of raw water increases in rainy season.
3. Synergistic efficiency:
   1. When used with polyacrylamide (PAM), it can make up for the insufficient bridging ability of low salt base products.

Data source: Comprehensive experiments and engineering practice show that salinity needs to be optimized according to water quality characteristics, rather than blindly pursuing high values.