Polyacrylamide dry powder or emulsion should not be used directly. It needs to be diluted with water in a certain ratio and completely dissolved before use.
The water used for dissolving polyacrylamide should be clean tap water, not wastewater. Room temperature water is sufficient; usually, heating is not necessary.
Weigh the needed polyacrylamide dry powder or emulsion. The dissolution ratio is typically 0.1–0.3%, meaning 1–3 kg of polyacrylamide dry powder or emulsion per ton of water.
A dissolution tank or pool with a stirring device at 60–200 revolutions per minute is required. The dissolution tank and stirring device should not be made of iron, as iron ions can cause product degradation.
Stirring time is 40–60 minutes. The dissolved solution should be a transparent and colorless viscous liquid.
Start by adding a certain amount of water to the dissolution tank or pool. When the water covers the bottom stirring blades, begin stirring. While continuing to add water, slowly and evenly add the measured agent to the water. Note: Adding the agent too quickly may cause clumping.
The dosage of polyacrylamide is determined by factors such as impurity concentration, production process, wastewater properties, and pH value. There is no fixed dosage, and different industries can only refer to which type of product to use. The recommended examples of polyacrylamide dosage below are for reference purposes:
Recommended concentration for sludge dewatering is 0.2%, with a dissolution and stirring time of 50 minutes.
Prior to use, a small-scale test is recommended to determine the ratio. Use 100 ml of wastewater sample and inject 0.5 ml of the solution each time. Continuously stir, observe flocculation effects, speed, clarity of the supernatant, sedimentation, and determine the dosage.
For paper mills, chemical wastewater, sewage treatment plants, and coal washery, the dosage of solid dry powder is 10–20 g/ton of wastewater.
Recommended concentration for coagulation and sedimentation in wastewater treatment is 0.1%.
Stir for 40 minutes, with a speed of 40–60 revolutions per minute.
Prior to use, a small-scale test is recommended to determine the ratio. Use 100 ml of wastewater sample and inject 0.5 ml of the solution each time. Continuously stir, observe flocculation effects, speed, clarity of the supernatant, sedimentation, and determine the dosage.
For steel plants, dyeing factories, electroplating plants, coal washery, and paper mills as dispersants, the dosage of solid dry powder per ton of wastewater is 5–10 g.
Recommended concentration is 0.1%, with a dissolution time of around 50 minutes. The usage method is the same as anionic polyacrylamide.
The choice between anionic and cationic polyacrylamide depends on slurry characteristics. Small-scale tests should be conducted on different slurry types in various regions to select the appropriate polyacrylamide product. Currently, most slurry treatments use anionic polyacrylamide. Based on long-term experimental summaries, the hydrolysis degree of anionic polyacrylamide suitable for slurry treatment is between 25% and 40%, with a molecular weight of 12–18 million. This achieves effective sludge flocculation.
