What is Flocculation?

Flocculation is the accumulation of colloidal particles known as flocs which form visible suspended particles from submicroscopic microflocs that have collided with each other to produce larger visible flocs known as pinflocs. 

What are Flocculants?

Flocculants are substances that promote the clumping of particles used in the treating of wastewater. Flocculant water treatment is useful in separating solid harmful particles in water. 

Flocculation vs Coagulation

Often, the confusion is between the terms flocculation and coagulation. Let us debunk the confusion, now that we know the definition of flocculation. Coagulation is the step where colloidal particles are destabilized, which can be an intermediary step before flocculation assembles the destabilized colloidal particles into aggregates. The destabilization happens because of the addition of chemical reagents to water suspensions where the dispersed colloidal particles are then assembled into microflocs.  Recently, we penned articles on water management in Australia. The focus was on water management techniques and challenges and best practices. This article on flocculation and flocculant solutions serves to cement Global Road Technology’s role in actively contributing to conversations supporting water management in Australia. The following questions are answered in the article:

  • What is the principle of flocculant chemicals?
  • Where is flocculation applied?
  • Who are the flocculant suppliers in Australia?
  • Which are the best practice water management products from GRT? 

What is the principle of flocculant chemicals?

The empirical Schulze-Hardy rule, states “hydrophobic colloids are flocculated most efficiently by ions of the opposite charge type and high charge number.” That is, a negative colloid is coagulated (destabilized) by a positive ion or vice-versa. The greater the valency of coagulating/flocculating ion, the greater will be the coagulating power to cause precipitation, according to the Schulze-Hardy rule. 

  • Coagulation of a negative colloid, the flocculating power is in the order: 

Al3+ > Mg2+ > Na+

  • Coagulation of a positive colloid, the flocculating power is in the order:

 [Fe(CN)6]4- > [PO4]3- > [SO4]2- > Cl-

Coagulation or flocculating power is inversely proportional to coagulation/flocculation value.

Flocculants consist of multivalent positively charged cations such as aluminium or magnesium. Flocculants also consist of multivalent negatively charged anions such as sulphate and chloride. Ionically charged polymers can also be used as dewatering flocculant chemicals with different ranges of polymer size and charge properties. Presence of flocculants, influence the arrangement of the colloidal particles which attract each other and join up into larger groups. Flocculant chemicals, promote flocculation by causing colloids and other suspended particles to aggregate in liquid which can be easily removed by sedimentation and/or filtration.  

Where is flocculation applied? 

There are many different types of applications for flocculation. In everyday life, dirt and other suspended solids must be removed for drinking water before it can be treated for the bacteria it may contain. There are different types of flocculants and examples are vinegar, gelatin and aluminium sulfate. For water management applications such water purification aluminium sulfate is given the name, alum. It is used to clarify water by neutralizing the electrical double layer surrounding very fine suspended particles. This allows them to flocculate and after flocculation, the particles will be large enough to settle. Depending on the chemistry of the treatment, the agglomerated particles may sink, float, or become large enough to be filtered. The net result is cleaner water leaving the treatment process and lower turbidity is likely. Flocculants are also used in the mining industry for dewatering the surface and underground mines, which reduces the sludge volume. High molecular weight, water-soluble polymer flocculants enable much larger aggregates to form, leading to much higher mass throughputs, as well as the potential to greatly reduce thickener diameters.  These additives are mostly used in filtration, sedimentation, and flotation to speed up the solid-liquid separation process. Cationic products are common in wastewater treatment, but higher molecular weights are more accessible for anionics, and the copolymers of acrylamide and acrylates are popular in the mining industry. 

GRT’s water management products

GRT’s water management applications focus on two key elements – water quality and quantity. Saving water through high tech dust control products has long been the focus of the company. This commitment to managing water has expanded into the creation of cutting-edge technologies to directly save water and to improve stored or retained water quality. 

The GRT water clarification range consists of three concentrate products that are safe, easy to handle, fast acting and are cost effective. GRT:CC is a concentrated coagulant, used to clarify water contaminated with finely suspended clays in dams and sedimentation basins. It is also used for removal of nutrients such as phosphate from water and fluoride from industrial wastewater. Works well in conjunction with GRT: Liquid-Floc which is a premium flocculation product utilizing long-chain polymer (LCP) technology to clarify water by capturing suspended particles and dropping them out of suspensions. Finally, GRT: Floc-Bloc is a solidified flocculation agent simply placed on the inlets to sediment basins or outlets to watercourses to allow the clarification of water through flocculation.  

GRT: Dam Sealer is ideal for the agricultural and resource sectors, this granular product is a specifically formulated, complex matrix of soluble and insoluble polymers at the forefront of dam repair technology. It expands quickly to many times and plugs holes to fix leaks and fissures, which cause small currents of water. The secondary polymer then expands to form a gel-blocking layer, whereby GRT: Dam Sealer effectively relines the treated surface with a durable waterproof coating 25 to 50 mm thick.

Water management – for life!

Water is a precious resource. Managing water resources is already one of the key environmental challenges facing the world today and this challenge will become more critical over the coming decades as we are forced to balance water priorities across potable requirements, industry, agriculture, and ecological demands. Along with our dust and erosion control products, GRT’s range of direct water management technologies are focused on improving and conserving this precious resource. 

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