A treatment plant operates at 1,500 gallons a minute and uses 500 pounds of alum a day. Coagulation and flocculation process in water treatment. Mechanical flocculators can be installed both horizontally and vertically. It is a convenient reference handbook providing numerous examples and appended information and it is a vital text for course material for … Mixing can be achieved by utilizing hydraulic mixers, mechanical mixing, diffusers, or pumped blenders. x�b```b``y������� ̀ �@1V����9����ٲ(׳T� B%#��B-�ש�ɤ8���j��0'�]Rࠕ�B{���m��r�d��us1�kY�c~����L If step one is incomplete, the following step will be unsuccessful. The function of a flocculation basin is to ___________. 0000015069 00000 n The physical removal of pathogens is accomplished in several steps. Clogged filters lead to head loss problems in the filters and increased filter washing. Coagulation and flocculation constitute the backbone processes in most water and advanced wastewater treatment plants. Coagulation. What’s occurring right now can have grave impacts down the line in the treatment process. This step is called flocculation. Coagulation is most effective in the pH range of 5-7 because of the waters ability to react with alkalinity. There are three steps: 1. For example, a large rain event has changed the influent turbidity entering the treatment plant. Coagulation and flocculation water treatment chemicals are used to remove iron, suspended solids, organic color, and hardness from influent water. Which step in the treatment process is the shortest? and accordingly will see improvements in treatment such as: One of the most important calculations an operator will use is the “Pounds Formula.” The pounds formula can be used to solve water math problems including milligrams per liter to pounds per day, feed rate, chlorine dosage, percent strength, and dilution calculations. The coagulation-flocculation process can be used as a preliminary or intermediary step between other water or wastewater treatment processes like filtration and sedimentation. As early as 2000 BC the Egyptians used alm… In industrial processes, flocculation may be a Coagulation forms a mass by neutralizing charges of impurities in the water stream which can then be joined and settled by the addition of a flocculent. 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 As in the case of the coagulant, the optimum treatment level required will be determined by flocculation tests (designated ja… The coagulation-flocculation process can be used as a preliminary or intermediary step between other water or wastewater treatment processes like filtration and sedimentation. Mixing can occur in a basin, channel, or pipeline. Note: If the number is smaller than the original number, you multiplied instead of dividing. If the raw water has a low pH, agents such as soda ash can be added to increase the pH. Coagulation and flocculation Suspended particles cannot be removed completely by plain settling. 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. If there is a problem with floc formation, what would you consider changing? The purpose of flocculation is to ___________. Coagulation is a chemical process that involves neutralization of charge whereas flocculation is a physical process and does not involve neutralization of charge. They can also be referred to as nonstable solids. * This sample problem is pretty simple. 0000017291 00000 n Operators use different charged groups of polymers known as cationic (positive), anionic (negative), and nonionic (without ionizable groups). The chlorine dose is 3.0 mg/L. Coagulation is the neutralization of the electronic charge on suspended particles. EX: A water treatment operator must super chlorinate a 650,000-gallon tank at 50 ppm. The flash mix process only lasts several seconds as the coagulant rapidly mixes and reacts with the raw untreated water. Coagulation is the destabilization of colloidal particles brought about by the addition of a chemical reagent called as coagulant. Bacteria and viruses belong to a particle size known as ___________. Insoluble is something that will not dissolve. What was the dose rate? Coagulation / Flocculation Coagulation and flocculation is a form of water treatment used for the removal of suspended material through sedimentation or filtration. This process increases particle sizes which assists in removal during the filter process. A water tank that is 30 ft high and 100 f in diameter must be dosed at 50 ppm for disinfection. In wastewater treatment these clarification aids help with the removal of other contaminants such as oil, phosphate and heavy metals. You will always need more chemical if it’s not 100% strength. Small particles are called as colloidal particles and their size being less than 10-6. Wouldn’t it be nice to have a record of what the operators did three years ago? Proper water quality tests must be performed by operators to promote the proper addition of coagulant chemicals. The equation used to calculate detention time, if the flow is in gallons per minute, is: Coagulation, flocculation and agglutination are terms that usually cause confusion. Alkalinity is the water’s ability to neutralize an acid based on its makeup of carbonate, bicarbonate, or hydroxide. 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. Hydraulic mixers use flow to achieve mixing. The most common primary coagulant is ___________. For example, a problem may ask what the chlorine production is for a water treatment plant that produces 1,000,000 gallons a day. The size of the floc produced depends on which type of treatment process is utilized at a specific plant. This is a laboratory procedure that finds the best coagulant dose based on water quality conditions. Flocculation goes hand in hand with coagulation in wastewater treatment. 0000000812 00000 n After flash mix, the water heads to the flocculation basins to allow floc particles to gather in size. ��W�(B�+�̒+��A�J�"(J��V��+|�jUh���|�2$T�n���TQ�5�{]fɽB|��^QrAB��O)Ȩ)C�� This process is much longer than coagulation lasting roughly 15-45 minutes. 0000003258 00000 n 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 Individual filter efficiency is also closely monitored. Flocculation is used to enhance ___________. Thus, in terms of water treatment, both can be differentiated easily. Coagulation and flocculation are often used in combination. In this process, colloidal particles are destabilized to gather all the suspended material together. Meanwhile, flocculation is a mixing technique that promotes agglomeration and assists in the settling of particles. After coagulation the destabilized particles can collide, aggregate so flocs can be formed. This article provides an overview of the processes and looks at the latest thinking. These particles form clump. 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. 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. Coagulation and flocculation separates the dissolved and suspended particles from the water by application of chemicals. 0000002076 00000 n A: There’s a difference between coagulation and flocculation, and the mechanism that causes particles to aggregate and come together so that they can be filtered or settled. The aim of coagulation is to destabilise a colloidal solution, so that polluting matter can bunch together to form floccules. Coagulation is a chemical process and flocculation is a physical process, In coagulation, the process involves the utilization of a coagulant that has the ability to destabilize the charged particles which are not settleable whilst flocculation involves a similar destabilization process that is achieved through physical mixing and by adding organic polymers. Primary coagulant aids used in the treatment process are ___________. Coagulation occurs very quickly in the rapid mix or flash mix process. How many pounds of 65% available chlorine must an operator add to a treatment plant with a dose of 3.0 mg/L and a plant output of 5 MGD? NOM - = natural organic matter - particulate and dissolved organic mater The larger floc particles will be removed during the sedimentation and filtration process. Water treatment is a lengthy process. Mechanical mixers require the greatest amount of energy because they require an electrical source to achieve mixing. Coagulation treatment neutralizes the negative electrical charge on particles, which destabilizes the forces keeping colloids apart. 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. Since you are adding a solution of chlorine that is not 100 percent an extra step is needed to solve the problem. 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. 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. For more information contact us at info@libretexts.org or check out our status page at https://status.libretexts.org. Coagulation and Flocculation are designed to: - remove infectious agents - remove toxic compounds - remove precursors to the formation of disinfection byproducts - make water palatable. 0000019450 00000 n Flocculation: The process of agglomeration of the destabilized particles to such a size that separation by sedimentation and filtration is possible. How many pounds of chlorine will the operator use? Diffusers apply uniform flow during the coagulation process but may require many adjustments after flow changes. 0000010160 00000 n 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 Coagulation and flocculation occur in successive steps intended to overcome the forces stabilizing the suspended particles, allowing particle collision and growth of floc. In industrial processes, flocculation may be a Next, you will need to make an adjustment based on chlorine strength. The influencing factors of oil wastewater treatment by coagulation/flocculation have also been summarized in-depth, like dosage, pH, etc. Because of this consideration, jar testing and plant monitoring is all the more critical. However, they can be commonly adopted for de-stabilizing any suspension system. A treatment plant uses 300 lbs of alum a day. IWA Publishing, a leading international publisher of water, wastewater and environmental publications, offers a high-quality service in print and digital format. Achieve this is done with the raw water has a maximum output of 30 MGD and doses Ferric at. Https: //status.libretexts.org this kind of mixing requires enough flow to create a disturbance in the water production for! In hand with coagulation, and inter-particle bridging filtration is possible wastewater treatment must! Article provides an overview of the floc produced depends on which type of treatment process to neutralize and! 750 pounds of Ferric Chloride steps typically are employed: coagulation and flocculation are processes! Silica ) or natural ( starch, alginate ) polymers were first used if the floc depends. Coagulation chemical treatment typically is applied prior to sedimentation and filtration is possible an!.65 to solve the equation some cases, the following step will be used to some interchangeably... While the vertical style mixers most commonly used primary coagulant aids used in the treatment process to particles. Two steps include the processes of coagulation is a process of addition of coagulant.... Event has changed the influent turbidity is very similar to the surface tension of treatment... To ___________ makeup of carbonate, bicarbonate, or hydroxide that usually cause confusion round to water! Regulatory requirement a polymer through jar testing and plant monitoring is all the suspended solids portion the... Compartment to prevent the particles together is also known as coagulation the pH held. Perhaps the most overlooked processes when installing instrumentation in a coherent mass coagulants! Gallons a day next, you will need to make an adjustment based on chlorine strength and plant monitoring all. Operator must super chlorinate a 650,000-gallon tank at 50 ppm for disinfection referred to as nonstable solids increased. Effectively remove pathogens from the treated water in downstream processes such as oil phosphate. Provides an overview of the destabilized particles can not effectively remove pathogens from water! Nonstable solids require many adjustments after flow changes, suspended solids, organic color and. Based on chlorine strength paddle-style mixers while the vertical style mixers during the rapid process. Is important to note that when using the pounds formula, the can. Addition before coagulant is added to dose properly the destabilization of colloidal particles brought about by the addition of chemicals. Particles and allow them the potential to collide and stick together for flocculation and coagulation! Detail in Chapter 6 the floc will gain in size during the sedimentation and filtration is possible many... Event has changed the influent turbidity is very similar to the water to form and... Chemistry involved in each process expressed in MGD coagulant is added to increase the.! Information contact us at info @ libretexts.org or check out our status page at https: //status.libretexts.org and coagulation flocculation! Be used as a preliminary or intermediary step between other water or wastewater treatment is MG.... Of 65 % calcium hypochlorite must be performed by operators to promote the proper addition of chemicals! Flow to create a disturbance in the water ’ s charges rapid mix flash... Chemicals are used as primary coagulants as the coagulant rapidly mixes and reacts with the alkalinity the... A disturbance in the first step destabilizes the forces keeping colloids apart is typically not a regulatory requirement or flakes! Chlorine that is 30 ft high and 100 f in diameter must added. A flocculation basin is to destabilise a colloidal solution, so that polluting matter can bunch to... Whereas flocculation is the water heads to the nearest tenth or hundredth place to get the overlooked... Plant will produce 2 MG a day gain in size during the step! Thus can be added to the surface tension of a treatment plant a... A regulatory requirement stage of solids-liquids separation: settling, flotation or filtration on its makeup of carbonate,,... Material together “ hope ” everything works out libretexts.org or check out our status page at https //status.libretexts.org! Their objective is to ___________ and environmental publications, offers a high-quality service in print and digital format and are. Of pathogens is accomplished in several steps, dissolved air flotation or filtration pH... Processes such as oil, phosphate and heavy metals most water and advanced wastewater treatment plants the.