Role and Selection Considerations of Nonionic Flocculants

Nonionic flocculants are water-soluble polymer or polyelectrolyte compounds. Due to the presence of a certain number of polar groups in their molecular chains, they can adsorb suspended solid particles in water, creating bridges between particles or neutralizing charges to aggregate particles into larger flocs. Therefore, they can accelerate the sedimentation of suspended particles in the solution, significantly speeding up clarification and promoting filtration. So, what are the roles and selection considerations of nonionic flocculants? This article will introduce them.

Mechanism of Action of Nonionic Flocculants

Nonionic flocculants are polymer compounds, with molecules formed by long chains of identical basic units. These molecules form structures composed of macromolecules in water that can adsorb tiny particles in water, forming flocs. Nonionic flocculants mainly act in the following two ways:

Adsorption

The molecular structure of nonionic flocculants can adsorb tiny particles in water, fixing them in place. Through intermolecular forces, an attractive force forms between the particles, and the particles can be collected at a point through flow or centrifugal operations to improve treatment effect and efficiency.

Flocculation

When there are enough molecules in nonionic flocculants, they form macromolecular structures that can adsorb most tiny particles in water, creating interactions between particles. These particles gradually combine to form larger particles, which eventually precipitate or get filtered out.

Selection Considerations for Nonionic Flocculants

• The impact of climate change (temperature) on the selection of flocculants.

  
  

• Selecting the molecular weight of the flocculant based on the required floc size in the treatment process.

  
  

• The hydrolysis degree of the flocculant must be selected through experimentation.

  
  

• Floc strength can be improved by increasing the molecular weight of the nonionic flocculant.

  
  

• The flocculant must be fully mixed and dissolved with the sludge before treatment.

  
  

• The selection of flocculants must fully consider process and equipment requirements.

Nonionic flocculants can accelerate the sedimentation of suspended particles in liquids, significantly speeding up clarity and promoting filtration. They are primarily used in the flocculation and sedimentation of various industrial wastewaters, such as paper and pulp wastewater, mining and metal refining wastewater, and wastewater from steel and stone processing plants.

In summary, nonionic flocculants are widely used chemical agents in the field of water treatment. Their main role is to flocculate and aggregate tiny particles suspended in water to purify water quality. Different application scenarios require the selection of appropriate nonionic flocculants and corresponding treatment processes to achieve better results.