Flocculation is used to enhance ___________. 0000014541 00000 n These large clumps easily settle down and thus can be separated. Sweep flocculation is the primary Coagulation and flocculation separates the dissolved and suspended particles from the water by application of chemicals. As in the case of the coagulant, the optimum treatment level required will be determined by flocculation tests (designated ja… 0000009770 00000 n Electricity is the behavior of negatively and positively charged particles due to their attraction and repulsion. However, they can be commonly adopted for de-stabilizing any suspension system. Coagulation is defined as. The process of flocculation is achieved by controlling the rate of impacts between particles as they gain size. The flocs that arise due to coagulation are small and can only grow further if the colloidal mixture is slowly stirred. Coagulation, flocculation, and clarification are perhaps the most overlooked processes when installing instrumentation in a water treatment facility. This process increases particle sizes which assists in removal during the filter process. The purpose of coagulation is to ___________. <]>> This step is called flocculation. 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. 0000010160 00000 n 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. For example, a treatment plant will produce 2 MG a day. The influencing factors of oil wastewater treatment by coagulation/flocculation have also been summarized in-depth, like dosage, pH, etc. * Start the equation as you normally would. Flocculation and coagulation is a chemical cleaning treatment for the waste water generally undertaken before the sedimentation process thus aiding in enhancing the process to remove particles from the water. The two-part process in water treatment involves chemical deactivation and physical removal of pathogenic organisms. Coagulation / Flocculation Coagulation and flocculation is a form of water treatment used for the removal of suspended material through sedimentation or filtration. Sweep flocculation is the primary The addition of chlorine can effect polymer effectiveness, As with any chemical, there is a dosage limit, Humic and fulvic molecules separate better with lower pH. However, they can be commonly adopted for de-stabilizing any suspension system. Have questions or comments? Missed the LibreFest? The speed of the mixing is decreased in each compartment to prevent the particles from breaking apart as they become larger. In industrial processes, flocculation may be a The shape and size of a flocculation basin is determined by the type of mixing used and the adjacent structures such as the sedimentation basins. 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. xref A treatment plant uses 750 pounds of alum a day as it treats 15 MGD. The flash mix process only lasts several seconds as the coagulant rapidly mixes and reacts with the raw untreated water. Filtration cannot occur without proper coagulation and flocculation. Coagulation is a process to neutralize charges and then to Since you are adding a solution of chlorine that is not 100 percent an extra step is needed to solve the problem. The coagulation-flocculation processes facilitate the removal of SS and colloidal particles. Humic and fulvic acids are organic acids commonly found in raw water sources, Sulfuric Acid addition before coagulant is added preconditions organic matter. 0000022998 00000 n Correct application of coagulation and flocculation depends upon these factors. Chemistry of Coagulation and Flocculation; The chemistry of coagulation and flocculation is primarily based on electricity. 277 0 obj <>stream These particles form clump. 0000014904 00000 n The function of a flocculation basin is to ___________. The floc is subsequently removed in most cases by sedimentation. Insoluble is something that will not dissolve. 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. This kind of mixing requires enough flow to create a disturbance in the water to achieve proper mixing. The aim of coagulation is to destabilise a colloidal solution, so that polluting matter can bunch together to form floccules. In general, two types of coagulants are used during coagulation. Coagulation is the destabilization of colloidal particles brought about by the addition of a chemical reagent called as coagulant. The efficiency of water treatment plants is determined by the combined effluent turbidity reading. The coagulant dissolves in water and ionizes. Coagulation and flocculation are an essential part of drinking water treatment as well as wastewater treatment. Flocculation basins are usually split into 3 compartments. A treatment plant operates at 1,500 gallons a minute and uses 500 pounds of alum a day. %PDF-1.4 %���� Mechanical mixers require the greatest amount of energy because they require an electrical source to achieve mixing. The coagulation-flocculation processes facilitate the removal of SS and colloidal particles. Coagulation is the destabilization of colloidal particles brought about by the addition of a chemical reagent called as coagulant. Flocculents, such as polyelectrolytes (PE), can be added to improve the flocculation … What is Coagulation and Flocculation? Floc size can range between 0.1 mm-3 mm. For example, a problem may ask what the chlorine production is for a water treatment plant that produces 1,000,000 gallons a day. Basically, coagulation is a process of addition of coagulant to destabilize a stabilized charged particle. In some cases, the use of a coagulant or flocculant is sufficient to form settleable and floating floccules. W+���!ޡ��P��Z��|EP�|�u�p�&E�B����U��{��*/E��*P�+wQ(}A{*?�J�� Flocculation is synonymous with agglomeration and coagulation / coalescence. 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 Thus, in terms of water treatment, both can be differentiated easily. Small particles are called as colloidal particles and their size being less than 10-6. Enhanced coagulation occurs at a lower pH. Coagulation and Flocculation are designed to: - remove infectious agents - remove toxic compounds - remove precursors to the formation of disinfection byproducts - make water palatable. 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. Coagulation and Flocculation in Water and Wastewater Treatment is a readable and useful resource for the water scientist and engineer. Coagulation and flocculation Suspended particles cannot be removed completely by plain settling. ��W�(B�+�̒+��A�J�"(J��V��+|�jUh���|�2$T�n���TQ�5�{]fɽB|��^QrAB��O)Ȩ)C�� Coagulation is a chemical process that involves neutralization of charge whereas flocculation is a physical process and does not involve neutralization of charge. What was the dose rate? The larger floc particles will be removed during the sedimentation and filtration process. 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 0000002691 00000 n It is important to note that when using the pounds formula, the water production is always expressed in MGD. How many pounds of Ferric Chloride does the plant use in a day? Coagulation occurs very quickly in the rapid mix or flash mix process. Two steps typically are employed: coagulation and flocculation. Remember you must show all work during exams to get credit but the format is still multiple choice so be careful when rounding. The daily flow rate of a treatment plant is 5 MG. How many pounds of dry alum per day is required? The particles are then more easily removed in the sedimentation and filtration process. Synthetic polymers are often used as a coagulant and filter aid but have also been used as a primary coagulant. The colloidal surfaces are negative thus positively charged metal salts are used as primary coagulants. The equation used to calculate detention time, if the flow is in gallons per minute, is: first process in drinking water treatment, coagulation, is to destabilize the particles and allow them the potential to collide and stick together. 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. The most commonly used primary coagulant in water treatment is Alum because of its wide availability and affordability. In wastewater treatment these clarification aids help with the removal of other contaminants such as oil, phosphate and heavy metals. Alkalinity is the water’s ability to neutralize an acid based on its makeup of carbonate, bicarbonate, or hydroxide. Coagulation is a process to neutralize charges and then to Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. x�b```b``y������� ̀ �@1V����9����ٲ(׳T� B%#��B-�ש�ɤ8���j��0'�]Rࠕ�B{���m��r�d��us1�kY�c~����L water treatment - coagulation-flocculation general ... Coagulation and flocculation are two processes commonly used in water treatment in order to get rid of unwanted suspended material in water. Coagulation. In this range, the water tends to buffer or stay in the same pH range and will allow the complete mixing of coagulant chemicals. The physical removal of pathogens is accomplished in several steps. 253 25 Water treatment is a lengthy process. endstream endobj 276 0 obj <>/Size 253/Type/XRef>>stream Two steps typically are employed: coagulation and flocculation. 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. 0000015069 00000 n Coagulation and Flocculation are designed to: - remove infectious agents - remove toxic compounds - remove precursors to the formation of disinfection byproducts - make water palatable. Next, you will need to make an adjustment based on chlorine strength. Plug the numbers into the equation and multiply to get your answer. As an operator, you should have a basic understanding of the chemistry involved in each process. Hopefully, the operations staff from three years ago noted changes in coagulant dose, mixing speeds, chlorine demand, and other significant plant changes. 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. Because of this, the sedimentation step is usually preceded by a chemical process known as coagulation. Finally, pumps can be used to push coagulant into water flow. Shown Above: The flash mix portion is also known as coagulation. Diffusers apply uniform flow during the coagulation process but may require many adjustments after flow changes. How many pounds of 65% calcium hypochlorite must be added to dose the tank? Coagulation is a process of making colloidal matter dispersed/suspended in a liquid to join in a coherent mass. How much chlorine must the operator add? Coagulation, flocculation and agglutination are terms that usually cause confusion. What is the alum dose. trailer These flocculates are easily disrupted, being held together only by a force analogous to the surface tension of a liquid. After coagulation the destabilized particles can collide, aggregate so flocs can be formed. 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. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Coagulation and flocculation 14.1 Introduction Coagulation and flocculation provide the water treat-ment process by which finely divided suspended and colloidal matter in the water is made to agglomerate and form flocs. Of settable floc aggregation of many small particles into flocculation and coagulation few large ones downstream processes such soda! First stage of solids-liquids separation: settling, flotation or filtration on the other,... 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