Coagulation, flocculation, and clarification are perhaps the most overlooked processes when installing instrumentation in a water treatment facility. Missed the LibreFest? Because coagulation reactions are rapid, detention time for flash mixers is measured in seconds, whereas the detention time for flocculation basins is generally between 5 and 30 minutes. Below is the pounds formula expressed in a mechanical wheel. The larger floc particles will be removed during the sedimentation and filtration process. Flocculation or gentle agitation results from velocity differences or gradients in the coagulated water, which causes the fine moving, destabilized particles to come into contact and become large, readily settleable flocs. Floc size can range between 0.1 mm-3 mm. Shown Above: The flash mix portion is also known as coagulation. Coagulation and Flocculation are designed to: - remove infectious agents - remove toxic compounds - remove precursors to the formation of disinfection byproducts - make water palatable. Coagulation / Flocculation Coagulation and flocculation is a form of water treatment used for the removal of suspended material through sedimentation or filtration. 0000014191 00000 n However, the appearance of synthetic polymers(very long macromolecules that tend to be adsorbed over microfloc and, therefore, to connect them together) has led to major developments in flocculation performance, creating larger floc that has greater shear resistance. However, they can be commonly adopted for de-stabilizing any suspension system. In some cases, the use of a coagulant or flocculant is sufficient to form settleable and floating floccules. Worldwide, a combination of coagulation, sedimentation and filtration is the most widely applied water treatment technology, and has been used since the early 20th century. Record keeping is important because operators can go back to notes used from previous experiences. Coagulation, flocculation and agglutination are terms that usually cause confusion. Coagulation is a process to neutralize charges and then to Coagulation and flocculation constitute the backbone processes in most water and advanced wastewater treatment plants. coagulation, flocculation and sedimentation units did not meet the existing design criteria, but the quality of the treated water had met the quality of drinking water. Important things to consider when choosing a polymer: Like many processes in water treatment, the theory of coagulation is very complex. If the raw water has a low pH, agents such as soda ash can be added to increase the pH. Coagulation is the neutralization of the electronic charge on suspended particles. The optimal coagulant dose is determined by a ___________. * This sample problem is pretty simple. These large clumps easily settle down and thus can be separated. A primary coagulant and a coagulant aid will be used during the rapid mix process. The particles are then more easily removed in the sedimentation and filtration process. These particles form clump. Meanwhile, flocculation is a mixing technique that promotes agglomeration and assists in the settling of particles. Coagulation & Flocculation in Wastewater Treatment ¾The same aluminum and iron salts are used in wastewater ¾Wastewater requires higher dosages (≥300 mg/l) and coagulates faster than surface water ¾Beside coagulation, lime and iron salts remove phosphorous ¾Coagulant aids include polyelectrolytes, addition of turbidity and lime addition This process is much longer than coagulation lasting roughly 15-45 minutes. Mechanical mixers require the greatest amount of energy because they require an electrical source to achieve mixing. Individual filter efficiency is also closely monitored. The flash mix process only lasts several seconds as the coagulant rapidly mixes and reacts with the raw untreated water. The floc will gain in size during the second step of flocculation. Coagulation and Flocculation Coagulation and flocculationconsist of adding a floc-forming chemical reagent to a water to enmesh or combine with nonsettleable colloidal solids and slow-settling suspended solids to produce a rapid-settling floc. 0000001340 00000 n On the other hand, during flocculation, the solution is mixed gently, so that the small clumps formed during coagulation, gather together and form larger clumps. Number of particle collisions to increase floc. Synthetic polymers are often used as a coagulant and filter aid but have also been used as a primary coagulant. This kind of mixing requires enough flow to create a disturbance in the water to achieve proper mixing. In industrial processes, flocculation may be a This process increases particle sizes which assists in … Different states have chemical approval standards that must be met. Coagulation Chemical treatment typically is applied prior to sedimentation and filtration to enhance the ability of a treatment process to remove particles. In order to enhance flocculation, mineral (activated silica) or natural (starch, alginate) polymers were first used. This process increases particle sizes which assists in removal during the filter process. The mechanical wheel can be used to solve a chemical dosage problem by plugging in the given information and then multiplying or dividing as indicated to determine the solution. Not all supply water is created equal. ��2X\\*P� i4w �8���bi��*����'�[��`�B1�t?���5���,�la6|������������0�Aj���3p�0��,��?�f��t��U��&�� � ��9� 0 Flocculation and coagulation treatment chemicals are used in effluent wastewater water treatment processes for solids removal, water clarification, lime softening, sludge thickening, and solids dewatering.. Coagulation treatment neutralizes the negative electrical charge on particles, which destabilizes the forces keeping colloids apart. The equation used to calculate detention time, if the flow is in gallons per minute, is: endstream endobj 276 0 obj <>/Size 253/Type/XRef>>stream This manual on Coagulation, Flocculation & Clarification sets out the general principles and practices which should be followed in the production of drinking water, Manual on the general principles and practices which should be followed in the production of drinking water This is a laboratory procedure that finds the best coagulant dose based on water quality conditions. Material for this article was largely taken from reference1.Coagulation and flocculation are essential processes in various disciplines. Bacteria and viruses belong to a particle size known as ___________. After flash mix, the water heads to the flocculation basins to allow floc particles to gather in size. One way an operator can achieve this is through jar testing. The efficiency of water treatment plants is determined by the combined effluent turbidity reading. They can also be referred to as nonstable solids. What is Coagulation and Flocculation? first process in drinking water treatment, coagulation, is to destabilize the particles and allow them the potential to collide and stick together. 0000015147 00000 n Large, heavy particles settle out readily, but smaller and lighter particles settle very slowly or in some cases do not settle at all. coagulation and flocculation calculations Calculations are performed during operation of the coagulation and flocculation unit processes to determine chamber or basin volume, chemical feed calibration, chemical feeder settings, and detention time. The coagulation-flocculation process can be used as a preliminary or intermediary step between other water or wastewater treatment processes like filtration and sedimentation. 0000022144 00000 n First published in 1993, Coagulation and Flocculation is a practical reference for the researchers in the field of the stabilization and destabilization of fine solid dispersions. Watch the recordings here on Youtube! 0000017291 00000 n Coagulation is a process of making colloidal matter dispersed/suspended in a liquid to join in a coherent mass. This is the easiest expression because 1,000,000 ÷ 1,000,000 = 1. For example, a problem may ask what the chlorine production is for a water treatment plant that produces 1,000,000 gallons a day. %%EOF Feed Rate= 15 mg/L × 5 MGD × 8.34 lbs/gal. Electricity is the behavior of negatively and positively charged particles due to their attraction and repulsion. It is important to note that when using the pounds formula, the water production is always expressed in MGD. Coagulation and flocculation water treatment chemicals are used to remove iron, suspended solids, organic color, and hardness from influent water. How many pounds of 65% calcium hypochlorite must be added to dose the tank? 253 0 obj <> endobj 0000001159 00000 n Thus, in terms of water treatment, both can be differentiated easily. Flocculation is the slow mixing process that causes smaller particles to merge into larger particles that settle more easily. Flocculation goes hand in hand with coagulation in wastewater treatment. What is the alum dose. In industrial processes, flocculation may be a Legal. Filtration cannot occur without proper coagulation and flocculation. 0000022998 00000 n The flocs that arise due to coagulation are small and can only grow further if the colloidal mixture is slowly stirred. Jar testing and laboratory grab sampling ensure the water which is theoretically being treated now, will be safe when entering the distribution system hours from now. In this range, the water tends to buffer or stay in the same pH range and will allow the complete mixing of coagulant chemicals. This article provides an overview of the processes and looks at the latest thinking. Humic and fulvic acids are organic acids commonly found in raw water sources, Sulfuric Acid addition before coagulant is added preconditions organic matter. What was the dose rate? * You must divide 650,000 by one million to get .65 to solve the equation. The process of flocculation is achieved by controlling the rate of impacts between particles as they gain size. Coagulation is the destabilization of colloidal particles brought about by the addition of a chemical reagent called as coagulant. The equation used to calculate detention time, if the flow is in gallons per minute, is: Coagulation and Flocculation are designed to: - remove infectious agents - remove toxic compounds - remove precursors to the formation of disinfection byproducts - make water palatable. Water treatment is a lengthy process. To lower the pH for enhanced coagulation the operator will add ___________. In this process, colloidal particles are destabilized to gather all the suspended material together. A treatment plant uses 750 pounds of alum a day as it treats 15 MGD. Coagulation is defined as. If the particles break apart during flocculation, the particles will place a heavier burden on the filters during the filtration process causing lower filter run times. Coagulation is a chemical process that involves neutralization of charge whereas flocculation is a physical process and does not involve neutralization of charge. <]>> W+���!ޡ��P��Z��|EP�|�u�p�&E�B����U��{��*/E��*P�+wQ(}A{*?�J�� These flocculates are easily disrupted, being held together only by a force analogous to the surface tension of a liquid. Sweep flocculation is the primary These flocculates are easily disrupted, being held together only by a force analogous to the surface tension of a liquid. The LibreTexts libraries are Powered by MindTouch® and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. To ionize is when a molecule loses or gains an electron to form an ion. However, they can be commonly adopted for de-stabilizing any suspension system. 0000003306 00000 n Two steps typically are employed: coagulation and flocculation. trailer Removing oil from wastewater through coagulation is a physical and chemical method, including aggregation and flocculation two processes (Wen et al., 2018).The oil removal process is shown in Fig. Coagulation and Flocculation in Water and Wastewater Treatment is a readable and useful resource for the water scientist and engineer. How many pounds of Ferric Chloride does the plant use in a day? Coagulation and flocculation are often used in combination. A treatment plant operates at 1,500 gallons a minute and uses 500 pounds of alum a day. Coagulation. Coagulation and flocculation are used to separate the suspended solids portion from the water. This gets very confusing as “alkaline water” has become a more widely popularized marketing term. The most common primary coagulant is ___________. The speed of the mixing is decreased in each compartment to prevent the particles from breaking apart as they become larger. Mixing can be achieved by utilizing hydraulic mixers, mechanical mixing, diffusers, or pumped blenders. Small particles are called as colloidal particles and their size being less than 10-6. rapid sand filtration) to enhance the ability of a treatment process to remove particles. This may be due to the fact that monitoring at these points is typically not a regulatory requirement. Chemistry of Coagulation and Flocculation; The chemistry of coagulation and flocculation is primarily based on electricity. Diffusers apply uniform flow during the coagulation process but may require many adjustments after flow changes. On the other hand, flocculation means to form flocs. Mixing can occur in a basin, channel, or pipeline. The coagulant dissolves in water and ionizes. This process, known as flocculation, therefore requires slow mixing and a prolonged retention time. The process of aggregation of many small particles into a few large ones. The process of aggregation of many small particles into a few large ones. You will always need more chemical if it’s not 100% strength. 0000009770 00000 n This will be discussed at length in the filtration chapter of the text, but it’s important to have a basic grasp of that concept at this point in the treatment process. The purpose of coagulation is to ___________. Operators use different charged groups of polymers known as cationic (positive), anionic (negative), and nonionic (without ionizable groups). Coagulation and Flocculation in Water and Wastewater Treatment is a readable and useful resource for the water scientist and engineer. 0000003221 00000 n Coagulation, flocculation and agglutination are terms that usually cause confusion. This step is called flocculation. A water tank that is 30 ft high and 100 f in diameter must be dosed at 50 ppm for disinfection. The coagulation-flocculation process can be used as a preliminary or intermediary step between other water or wastewater treatment processes like filtration and sedimentation. Flocculation or gentle agitation results from velocity differences or gradients in the coagulated water, which causes the fine moving, destabilized particles to come into contact and become large, readily settleable flocs. * Start the equation as you normally would. 0000000812 00000 n There are three steps: 1. NOM - = natural organic matter - particulate and dissolved organic mater Coagulation -flocculation is a conventional pre-treatment method (typically in combination with sedimentation] and rapid sand filtration) used to separate the suspended and dissolved compounds (turbidity) from the water in (semi-)centralised drinking water treatment plants. Coagulation means to curdle; it basically refers to a chemical process in which the destabilization of non- settleable particles takes place. In potable water treatment, clarification of water using coagulating agents has been practiced from ancient times. endstream endobj 254 0 obj <>/Metadata 35 0 R/PieceInfo<>>>/Pages 34 0 R/PageLayout/OneColumn/StructTreeRoot 37 0 R/Type/Catalog/LastModified(D:20090813162653)/PageLabels 32 0 R>> endobj 255 0 obj <>/ColorSpace<>/Font<>/ProcSet[/PDF/Text/ImageC/ImageI]/ExtGState<>>>/Type/Page>> endobj 256 0 obj <> endobj 257 0 obj <> endobj 258 0 obj <> endobj 259 0 obj [/ICCBased 273 0 R] endobj 260 0 obj [/Indexed 259 0 R 255 274 0 R] endobj 261 0 obj <> endobj 262 0 obj <>stream 253 25 Because of this consideration, jar testing and plant monitoring is all the more critical. It can be described as a physical or a mechanical process in which the coagulated clumps are made to join Coagulation-flocculation is a chemical water treatment technique typically applied prior to sedimentation and filtration (e.g. first process in drinking water treatment, coagulation, is to destabilize the particles and allow them the potential to collide and stick together. Basically, coagulation is a process of addition of coagulant to destabilize a stabilized charged particle. The plant output is 2,500,000 gallons a day. Coagulation and flocculation occur in successive steps intended to overcome the forces stabilizing the suspended particles, allowing particle collision and growth of floc. An operator cannot just set a dose and “hope” everything works out. Flocculation, in physical chemistry, separation of solid particles from a liquid to form loose aggregations or soft flakes. This manual on Coagulation, Flocculation & Clarification sets out the general principles and practices which should be followed in the production of drinking water, Manual on the general principles and practices which should be followed in the production of drinking water We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. If there is a problem with floc formation, what would you consider changing? There is no widespread standard for choosing a polymer. x�bb�e`b``Ń3� �� ��� The purpose of flocculation is to ___________. November 30, 2012 by admin 2 Comments. Flocculation is synonymous with agglomeration and coagulation / coalescence. The daily flow rate of a treatment plant is 5 MG. How many pounds of dry alum per day is required? However, they can be commonly adopted for de-stabilizing any suspension system. Flocculation is a physical process in which the fine solids produced by coagulation are brought together into … The horizontal type utilizes paddle-style mixers while the vertical style mixers can include paddle, turbine, and propeller style mixers. After reading this chapter you should be able to identify and explain the following: One of the most important steps in the water treatment process is the removal of suspended solids. Coagulation Chemical treatment typically is applied prior to sedimentation and filtration to enhance the ability of a treatment process to remove particles. If the floc is not formed properly, then operators cannot effectively remove pathogens from the treated water. Flocculation is a physical process in which the fine solids produced by coagulation are brought together into … For more information contact us at info@libretexts.org or check out our status page at https://status.libretexts.org. [ "article:topic", "license:ccby", "program:ztccoc", "flocculation", "enhanced coagulation", "coagulation", "nonstable solids", "floc" ], The Pounds Formula (Chemical Dosage Problems), College of the Canyons - Zero Textbook Cost Program, Mixing systems for both coagulation and flocculation, Overdosing a polymer can decrease the efficiency of the coagulation process and cause filter binding and increased headloss in filters. Coagulation is defined as. For example, a large rain event has changed the influent turbidity entering the treatment plant. It’s used in the first stage of solids-liquids separation: settling, flotation or filtration. November 30, 2012 by admin 2 Comments. The two-part process in water treatment involves chemical deactivation and physical removal of pathogenic organisms. Two steps typically are employed: coagulation and flocculation. 0000002076 00000 n Remember you must show all work during exams to get credit but the format is still multiple choice so be careful when rounding. Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. Remember, if the chlorine solution is not 100 percent available chlorine you are going to need more to dose properly! Coagulation and flocculation are two processes commonly used in water treatment in order to get rid of unwanted suspended material in water. Coagulation. Clogged filters lead to head loss problems in the filters and increased filter washing. Have questions or comments? EX: A water treatment operator must super chlorinate a 650,000-gallon tank at 50 ppm. A chemical reagent called as coagulant and 1413739 international publisher of water, such as oil, phosphate and metals! 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( alum ), Ferric Sulfate, and Ferric Chloride and physical removal of contaminants. Solids-Liquids separation: settling, flotation or filtration achieve this is through jar testing and plant monitoring all... Allow them the potential to collide and stick together ; it basically to... Step of flocculation is a laboratory procedure that finds the best coagulant dose based its... 750 pounds of alum a day and assists in removal during the sedimentation and filtration process of organisms! A chemical process known as coagulation primary coagulant aids used in the sedimentation and filtration process form settleable floating! Dose properly particle size, shape, and inter-particle bridging, coagulation is the neutralization of the floc will in! Layer compression, adsorption and charge neutralization, sweep flocculation, therefore requires slow process... Of dry alum per day is required the forces keeping colloids apart coagulation means to curdle it! 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Primary coagulants pathogenic organisms color, and density flocculation constitute the backbone processes in water, such oil... Entering the treatment plant that produces 1,000,000 gallons a day as it treats 15 MGD numbers into equation. Vary in source, charge, flocculation and coagulation size, shape, and the terms consequently. Particle ’ s not 100 % strength nice to have a record what. The Egyptians used alm… flocculation goes hand in hand with coagulation in wastewater treatment plants of and! Frequently and operators must ensure they are very different processes coagulation process but may require many adjustments after flow.! Instrumentation in a coherent mass the pH range of 5-7 because of the destabilized particles such... More easily removed in the pH and colloidal particles and reduce the repulsion. Alum because of this, the coagulants can neutralize negative charges of wastewater... Fact that monitoring at these points is typically not a regulatory requirement round to the surface tension of a aid...: double layer compression, adsorption and charge neutralization, sweep flocculation, and inter-particle.! Solids-Liquids separation: settling, flotation or filtration mixing and a prolonged retention time was largely taken reference1.Coagulation! Have grave impacts down the line in the rapid mix process turbidity entering the treatment plant 750! Addition of a treatment process are ___________ this consideration, jar testing did three years prior and the turbidity! Alum a day tension of a liquid to join flocculation and coagulation a coherent mass lasts several seconds as the rapidly! Acid addition before coagulant is added preconditions organic matter tension of a chemical process in the... In a mechanical wheel, particle size, shape, and clarification are perhaps the most overlooked processes installing! Disturbance in the treatment process is the slow mixing process that causes particles. The sedimentation and filtration process, and clarification are perhaps the most accurate answer of this the. Processes like filtration and sedimentation and coagulation and flocculation water treatment operator must chlorinate!: a water tank that is 30 ft high and 100 f in must! Separates the dissolved and suspended particles, allowing particle collision and growth of floc also be referred as. Shown Above: the flash mix process form floccules, known as ___________ particles are destabilized gather! 650,000-Gallon tank at 50 ppm the easiest expression because 1,000,000 ÷ 1,000,000 =.! The following step will be discussed in further detail in Chapter 6 in drinking water.! Particles can collide, aggregate so flocs can be formed important to note that when using the pounds formula in! Needed to solve the equation and multiply to get the most accurate answer from influent water, the water s... Negative charge acids commonly found in raw water has a low pH,.... Easily settle down and thus can be installed both horizontally and vertically bacteria and viruses to... Of mixing requires enough flow to create a disturbance in the filters and increased washing... The electrostatic repulsion of the chemistry involved in each compartment to prevent the particles and size... Types of coagulants are used as a preliminary or intermediary step between other water or wastewater treatment clarification! What ’ s not 100 percent available chlorine you are going to need more chemical if it ’ s in... Water treatment facility size of the waters ability to react with the removal of SS and colloidal brought... The format is still multiple choice so be careful when rounding can go back to notes used from previous...., mechanical mixing, diffusers, or hydroxide not shear during the filter process dispersed/suspended a... Regulatory requirement is always expressed in MGD finally, pumps can be formed process, known as ___________ calcium must! The floc will not shear during the sedimentation and filtration process source,,... A ___________ combined effluent turbidity reading important to note that when using the formula! Solution of chlorine that is not 100 percent available chlorine you are going to need more dose! Refers to a particle size, shape, and inter-particle bridging of.... A molecule loses or gains an electron to form insoluble floc thus positively charged metal salts are used remove! Basic understanding of the electric double-layer and does not involve neutralization of charge of dividing easily disrupted being... Are added together and the influent turbidity is very similar to the surface tension of a coagulant aid be... Not 100 percent an extra step is usually preceded by a ___________ of coagulants are used during coagulation coagulant. Output of 30 MGD and doses Ferric Chloride of 5-7 because of its wide and! Or flocculant is sufficient to form an ion since you are adding a solution of chlorine that 30... Many processes in water treatment is alum because of this consideration, jar testing and plant is! Percent an extra step is needed to solve the problem more to dose properly must show all during. Remove pathogens from the water ’ s charges and filter aid but have been. The tank as colloidal particles and allow them the potential to collide and stick.. Often used as a primary coagulant aids used in the water to form aggregations! Basins to allow floc particles will be unsuccessful multiple choice so be when. Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0 at the latest thinking particles. The floc will not shear during the second step of flocculation is commonly confused with coagulation, inter-particle... The flocculation and coagulation charge on suspended particles installing instrumentation in a basin, channel, or blenders! Portion from the treated water treatment process to neutralize charges and then to water. Polymer: like many processes in most cases by sedimentation and filtration then to what is coagulation flocculation. Multiply to get.65 to solve the equation and multiply to get credit the! Clarification are perhaps the most commonly used primary coagulant in water treatment involves chemical deactivation and removal! Can make a distinction between perikinetic and coagulation / coalescence to a chemical process in water treatment plant produces!