Floculants are used in a wide variety of industries to help remove suspended substances in water. In this article, we examine in detail their role in wastewater treatment, what they are, what they are used for and how they work. We will also explain how flocculants differ from coagulants, another common class of wastewater treatment chemicals.
First;
What is Flocculation?
Flocculation is the separation of a solution, usually the removal of sediment from a liquid. The word is derived from floc, meaning grain; and when a solution is flocculated, the precipitate forms into larger aggregated particles, making them easier to see and remove. This process occurs naturally or can be done using flocculants and/or physical processes.
What is a Flocculant?
Floculants are substances that support the agglomeration of fine particles in a solution, forming a floc, then bringing them to the surface (flotation) or settling them to the bottom (sedimentation). In this way, the clumped substances can be separated from the liquid more easily. In our country, it is also known as polyelectrolyte, polyacrylamide and purification chemical.
Floculants can be organic or inorganic. In addition, it can be in various charges, charge densities, molecular weights and forms.
Organic polymeric flocculants are most widely used today due to their ability to promote flocculation with a relatively low dosage. However, their lack of biodegradability and the resulting dispersion of potentially harmful monomers in water resources causes the focus to shift to more environmentally friendly biopolymers. The main problem with biopolymers is that they have a shorter shelf life and require higher dosages than organic polymeric flocculants. To combat this, combined solutions are being developed in which synthetic polymers are grafted onto natural polymers to create specialized flocculants for water treatment that provide the optimum benefits of both.
What Are Flocculants Used For?
Basically, flocculants are primarily used in the wastewater treatment industry in the removal of solids, purification of water, softening of lime, thickening of sludge and dehydration of solids. In addition, flocculants are used in many different sectors, from construction companies to earth sciences and biotechnology, from automotive factories to textile dye houses.
Water may contain colloidal solids such as clay particles, bacteria, plankton, decaying plant material, or other organic matter; The use of coagulation and flocculation to purify water dates back to B.C., when ancient Egyptians used almonds rubbed around containers to purify river water. It has been an active practice since the 2000s.
Flocculation, which causes sedimentation, is used both in the treatment of drinking water and in the treatment of sewage, rainwater and industrial wastewater. For this reason, flocculants are mostly known as water treatment plant chemicals.
How Do Flocculants Work?
Floculants can be applied alone or in combination with coagulants, depending on the charge and chemical composition of the separated solution.
Coagulants work by disrupting the balance of particles in a stable solution, causing them to clump together and binding them together by flocculants. Flocculants combine particles into flocs, which are then separated from the solution when they settle to the bottom as precipitates or rise to the surface.
The appropriate combination of organic or inorganic coagulants and flocculants will depend on the type of substances removed from the water as well as the separation method used by the water treatment plant (i.e. sedimentation or flotation, etc.).
Which is the Best Flocculant?
In fact, rather than the best flocculant, it is necessary to determine the most suitable flocculant for the water to be flocculated (purified). There are methods such as jar test and measuring tape test to determine the most suitable flocculant, and these studies are provided free of charge by NCC to all its stakeholders.
What are the Differences Between Flocculants and Coagulants?
Although both coagulation and flocculation are common processes used in treating and purifying water, they are actually very different.
Coagulation is a chemical process in which the chemical properties of the solution are changed to promote coagulation. Coagulation means clotting. Coagulants are salts that generally break down to release positive or negative charges. Flocculation is a physical process that causes particles to clump together, forming first a cloud and then a precipitate. Flocculants are generally polymers that enable particles to break down into increasingly larger particles or flocs. While physical agitation or other techniques are often required to promote flocculation, coagulation can occur as soon as the coagulant is added to the solution, without any physical treatment.