How to Control the Amount of Nonionic Polyacrylamide PAM Used in a Sand Washing Plant

The effect of nonionic polyacrylamide PAM in treating wastewater from sand washing plants is remarkable.

Sand washing plants, also known as sand washing factories, play an important role in the production of concrete. By following specific standards, the strength and stability of concrete can be enhanced, ensuring the safety of buildings. During the sand washing process, a large amount of water resources is used and a significant amount of wastewater is generated. Sand washing wastewater is a mixture of fine mud particles with a certain specific gravity in water. It generally has the following characteristics: it has a tan color, is uniformly sticky, and does not layer for a long time. The pH is around 6-7. Nonionic polyacrylamide PAM is an essential water treatment agent for sand washing plants due to its significant treatment effect and low cost.

Usage of nonionic polyacrylamide PAM in sand washing plants

In general, sand washing plants use nonionic polyacrylamide PAM in two stages. One stage involves the addition of nonionic polyacrylamide PAM flocculant in the sedimentation tank to accelerate the settlement of suspended particles in wastewater. The other stage involves the use of a sludge concentrator and a filter press to dewater the sludge in the settling tank.

The sand washing equipment in sand washing plants usually includes a dissolution tank or a continuous dosing system. Regardless of the device used, the purpose is to prepare a water solution of nonionic polyacrylamide PAM. The following issues should be noted when preparing the solution:

• Nonionic polyacrylamide PAM must be dissolved before use. The dissolved water solution should be used for wastewater treatment. Dry powder should not be directly used for wastewater treatment.

  
  

• The dissolution water should be clean tap water. However, sand washing plants are usually located in remote areas, and most of them use well water. In principle, it is appropriate to use salt-free, impurity-free, and pH-neutral water. The use of treated recirculating water is not recommended as it may appear clean but still contains suspended residues.

  
  

• The dosing system with a feeding hopper can ignore this point. If manual dosing is used, the flocculant should be slowly added to the water under stirring, uniformly dispersed, and avoid adding too much at once to prevent agglomeration.

  
  

• The preparation of the nonionic polyacrylamide PAM solution generally involves mechanical mixing. The stirring speed should not be too fast. In principle, the speed should not exceed 800 rpm in a stirring barrel with a diameter of 1m and 600 rpm in a stirring barrel with a diameter of 1.5-2m.

  
  

• The water solution should be prepared and used immediately. Prolonged storage time can cause a decrease in product performance, rendering it ineffective and affecting the treatment effect.

  
  

• The preparation, transfer, and storage of nonionic polyacrylamide PAM water solution should avoid iron ions as much as possible.

Regarding the dosage of nonionic polyacrylamide PAM in sand washing plants, it is difficult to specify a specific amount. Different sources of sand, different levels of soil content, and other substances require different types of nonionic polyacrylamide PAM products. Therefore, the dosage should be calculated based on actual trial results. Based on past experiences, it is usually sufficient to add 0.01~10ppm (0.01~10g/m3) of nonionic polyacrylamide PAM to treat wastewater in sand washing plants, and the effect is very significant.