How Does Flocculation Work in Water Treatment Plant?
- First Stage: Solid Granules Suspended in Wastewater are Negatively Charged. ...
- Second Stage: Mixers Must be Utilized to Stir the Effluent. ...
- Third Stage: A polymer chemical is added to the wastewater after floc begins to develop. ...
- Fourth Stage: After the completion of flocculation, the huge solid masses in the wastewater stream are removed. ...
What do flocculants do in water treatment?
Sep 13, 2021 · Flocculation is the water purification process to remove contaminants from the water. It is the most common process to treat wastewater management, stormwater, and drinking water, making it clean and disinfected to use. The process of flocculation is separating the solution from the sediment and debris mixed in it.
What happens during the process of flocculation?
May 12, 2021 · In water treatment terms, flocculation is the process of encouraging the formation of clumps of solids — or flocs. This is necessary in the removal of solids that are suspended in the water, leading to an easier process of filtration. Flocculants, or flocculation agents, are deployed in the water to create these flocs and to accelerate the process where necessary.
What is added to water to cause flocculation?
Flocculation is the separation of a solution, commonly the removal of sediment from a fluid. The term is derived from floc, which means flakes of material; and when a solution has been flocculated, the sediment has formed into larger aggregated flakes, making them easier to see and remove. This process occurs naturally, or it can also be forced ...
What is difference between flocculation and precipitation?
Jul 31, 2019 · Flocculation is a water treatment process where solids form larger clusters, or flocs, to be removed from water. This process can happen spontaneously, or with the help of chemical agents. It is a common method of stormwater treatment, wastewater treatment, and in the purification of drinking water. One of the requirements for treated water leaving wastewater …
What is the purpose of flocculation?
As with coagulation, the purpose of flocculation is not to directly reduce turbidity or suspended solids, but to prepare the solids for subsequent removal. Flocculation reduces the number of suspended solids particles as smaller particles combine to form larger ones.
What are the effects of flocculation?
During flocculation, gentle mixing accelerates the rate of particle collision, and the destabilized particles are further aggregated and enmeshed into larger precipitates. Flocculation is affected by several parameters, including mixing speeds, mixing intensity, and mixing time.
What is coagulation and flocculation in water treatment?
Coagulation and flocculation are two separate processes, used in succession, to overcome the forces stabilising the suspended particles. While coagulation neutralises the charges on the particles, flocculation enables them to bind together, making them bigger, so that they can be more easily separated from the liquid.
How does flocculation impact water flow rates?
While the flocculation processes usually lead to the soil aggregates formation and hence an easier water penetration and fertilizers delivery to the plant roots, so the dispersion processes may cause blockade of soil pores and thus hinder the water flow and fertilizers transport.Aug 28, 2014
What is floculation in water?
Flocculation is a water treatment process where solids form larger clusters, or flocs, to be removed from water. This process can happen spontaneously, or with the help of chemical agents. It is a common method of stormwater treatment, wastewater treatment, and in the purification of drinking water. One of the requirements for treated water leaving ...
What is the first stage of flocculation?
In the first stage of flocculation, a coagulant like aluminium sulphate is added to the wastewater . The positively charged coagulant molecules neutralize the negatively charged solid particles suspended in the water. Neutralising these particles paves the way for them to flocculate together into a larger mass.
Why is high energy mixing required in wastewater?
The wastewater must be agitated with mixers. High energy mixing is required initially to ensure that the coagulant spreads throughout the water. When flocculation is in progress the mixing energy is reduced to prevent the mass of particles from separating again.
What is chemical dosing?
Chemical dosing, in particular pH dosing, is a common method of wastewater treatment. Regulations require treated wastewater to be in a neutral pH range when discharged into the environment. Our dosing systems can be set-up as in-line or in a recirculating configuration.
What is disinfection in water?
Disinfection is a process that kills off remaining bacteria in wastewater streams. Cleanawater uses a chlorine-based system to achieve a high level of disinfection. This protects workers and the general public from potential health hazards associated with unwanted bacteria in the wastewater system.
How does phosphorus affect water quality?
Phosphorus content must also be limited in wastewater as a release of phosphorus into rivers promotes algae growth.
Why is flocculation so popular?
Coagulation and flocculation processes have become more and more popular due to the increasingly stringent filtration requirements for industrial and municipal water treatment and wastewater treatment facilities levied by the U.S. Environmental Protection Agency (EPA.)
What is a flocculant?
Flocculants are lightweight, medium weight and heavy polymers that cause the destabilized clumps of particles to agglomerate and drop out of the solution, removing them from the filtered water. The weight used depends on the type of particle.
What is coagulation in water treatment?
Coagulation water treatment is the first step in chemical wastewater treatment. Instead of passing over particles that would otherwise slip through the filter and fall too slowly to be trapped as sediment, coagulation clumps them together so they are more easily removed. Most of us know coagulation from anatomy class.
Is alum a good coagulant?
It’s the same principle with wastewater treatment. In coagulation treatment, a harmless chemical such as alum causes all of the particles to give off a positive charge and thus clump together, making them easier to filter. Coagulation is especially useful in removing the chemical phosphorus from water. Yet coagulation water treatment is far ...
How does orthokinetic flocculation work?
Orthokinetic flocculation arises from induced velocity gradients in the liquid. It is here that primary particles are induced to approach close enough together, make contact and progressively form larger agglomerates, or flocs. The principal parameter governing the rate of orthokinetic flocculation is the velocity gradient applied. The degree or extent of flocculation is governed by both applied velocity gradients and time of flocculation. These two parameters influence the rate and extent of particle aggregation and the rate and extent of breakup of these aggregates.
What happens when you add coagulants to water?
When metal coagulants are added to water the metal ions (Al and Fe) hydrolyze rapidly but in a somewhat uncontrolled manner, forming a series of metal hydrolysis species. The efficiency of rapid mixing, the pH, and the coagulant dosage determine which hydrolysis species is effective for treatment.
What are the variables in coagulation?
The efficiency of the coagulation-flocculation process is dependent on many variables. For a particular water these may include: 1 Type of coagulant used 2 Coagulant dosage 3 Final pH 4 Coagulant feed concentration 5 Type and dosage of chemical additives other than primary coagulant (e.g. polymers) 6 Sequence of chemical addition and time lag between dosing points 7 Intensity and duration of mixing at rapid mix stage 8 Type of rapid mix device 9 Velocity gradients applied during flocculation stage 10 Flocculator retention time 11 Type of stirring device used 12 Flocculator geometry.
Why is coagulation important?
Coagulation is also important in several wastewater treatment operations. A common example is chemical phosphorus removal and another, in overloaded wastewatertreatment plants, is the practice of chemically enhancing primary treatment to reduce suspended solids and organic loads from primary clarifiers.
What is the EPA rule for Giardia?
The U.S. EPA surface water treatment rule requires 99.9-percent (3-log) Giardia removal or inactivation, and at least 99-percent (2-log) removal of Cryptosporidium. Adequately designed and operated water treatment plants, with coagulation, flocculation, sedimentation and filtration are assigned a 2.5-log removal credit for Giardia, leaving only 0.5-log inactivation to be achieved by disinfection.
When was alum used in water?
As early as 2000 BC the Egyptians used almonds smeared around vessels to clarify river water. The use of alum as a coagulant by the Romans was mentioned in around 77 AD. By 1757, alum was being used for coagulation in municipal water treatment in England.
What are some examples of coagulation operations?
Coagulation operations can be useful in some cases for the removal of inorganics. Examples of successful applications are copper and mercury reductions from wastewaterplant effluents. Two applications discussed in more detail below are arsenic and fluoride removals in potable water treatment:
What is short circuiting in flocculation?
Short-circuiting occurs when water bypasses the normal flow path through the basin and reaches the outlet in less than the normal detention time. Inlet and outlet turbulence is sometimes the source of floc-destructive energy and short-circuiting in flocculation basins. The system should evaluate the following:
Why do we use baffles in flocculation?
Baffles are used in flocculation basins to direct the movement of water through the basin. Baffling near the basin inlet and outlet improves basin hydraulics and achieves more uniform flow patterns. Systems should consider the following items when evaluating flocculation:
How is turbidity measured?
Turbidity is measured by using light's response to matter. When a light is shined on matter, matter can either reflect or absorb the light. Reflected light bounces off of the matter in many directions, whereas absorbed light gets trapped within. The light that passes through matter is called transmission.
What do students learn about molecules?
Students learn about the basics of molecules and how they interact with each other. They learn about the idea of polar and non-polar molecules and how they act with other fluids and surfaces. Students acquire a conceptual understanding of surfactant molecules and how they work on a molecular level. ...
How are colloids formed?
Colloids are formed when a material, such as fine silt or fine clay, is microscopically suspended throughout another material, in our case, water. Colloidal suspensions have a dispersed phase (the suspended material) and a continuous phase (water). Colloids are difficult to remove from water for several reasons.
What is the chemical formula for aluminum sulfate?
Figure 3. The chemical structure of aluminum sulfate (alum). Aluminum sulfate is a white, solid (powder) with a chemical formula of Al 2 (SO 4) 3.
What are some examples of flocculants?
Examples of ChemTreat flocculants include low-, medium-, and high-molecular weight polymers.
What is a coagulant in water treatment?
Water treatment coagulants are comprised of positively charged molecules that, when added to the water and mixed, accomplish this charge neutralization. Inorganic, organic, or a combination of both coagulant types are typically used to treat water for suspended solids removal. When an inorganic coagulant is added to water containing ...
Is aluminum sulfate a chemical?
It is manufactured as a liquid, and the crystalline form is dehydrated from the liquid. Alum is one of the most commonly used water treatment chemicals in the world.
What is the most widely used class of organic coagulation chemicals?
Polyamine and PolyDADMAC. These are the most widely used classes of organic coagulation chemicals. They function by charge neutralization alone, so there is no advantage to the sweep-floc mechanism. Polyamines will generally treat higher turbidity raw water (approximately >20 NTU) effectively.
Is aluminum chloride the same as alum?
Generally, aluminum chloride works similarly to alum, but is usually more expensive, hazardous, and corrosive. Because of this, it is normally a distant second choice to alum. ChemTreat has aluminum chloride available as a liquid.
What is a sweep floc?
This sweep-floc precipitate readily adsorbs organic materials such as oil and grease. The precipitate generally dewaters to low moisture concentration, making this choice of coagulant particularly well-suited to unit operations that generate hazardous sludge, such as DGF and IGF units in oil refineries. This self-precipitating chemistry is generally significantly more expensive to use than inorganic coagulant chemistry, but it can be economical when sludge removal and disposal costs are factored in.
Is ferric chloride a coagulant?
Ferric chloride is generally the least expensive inorganic coagulant, because it is generated as a waste material from steel-making operations (waste “pickle liquor”). However, it is by far the most corrosive and hazardous inorganic coagulant, and its use is limited to facilities equipped to handle it safely.
