Commonly Used Flocculant Types
1. Polyaluminum Chloride (PAC)
Highly efficient flocculation and rapid sedimentation, suitable for removing phosphates, suspended solids, and some heavy metals. Widely used in municipal and industrial wastewater.
2. Polyacrylamide (PAM)
Categories include anionic, cationic, and nonionic types. They are targeted at high turbidity and high COD wastewater, enhancing floc strength and improving sedimentation efficiency.
3. Iron Salts (Ferric Chloride, Ferrous Sulfate)
Form dense precipitates, effectively removing heavy metals and color, and are commonly used for heavy metal-contaminated wastewater.
4. Aluminum Salts (Aluminum Sulfate)
Suitable for acidic wastewater, they offer excellent coagulant effects, but residual aluminum ions should be considered.
Instructions
1. Dissolution and Preparation
Solid flocculants must first be prepared into a 5%-10% solution (PAM should be stirred for at least 30 minutes to fully dissolve) to prevent clumping.
2. Dosage Control
Determine the optimal dosage based on water quality tests and evenly add it to the reaction tank using a metering pump. 3. Mixing Reaction
After addition, the agent and wastewater must be stirred rapidly to thoroughly mix, followed by gentle stirring to promote floc formation.
4. Sedimentation and Separation
After the flocs settle, the sludge is separated in a sedimentation tank or flotation equipment, and the supernatant is sent to subsequent treatment stages.
Notes
The pH of the water affects the flocculation effect (for example, PAC has an optimal pH of 6-9, while iron salts are suitable for pH 4-11), so it must be adjusted in advance.
Sludge must be properly handled to avoid secondary contamination.
Rational selection of flocculants and optimized dosing procedures can significantly improve wastewater treatment efficiency.
