These lower pH values mean that there are more positively charged particles loose in the water to react with the negatively charged colloids. /Parent 2 0 R Dosage of alum with the alum-lime coagulation of a water is 50 mg/l. The amount of alum required to treat a flow of 1 MGD(million gallon /day) 2. A raw water supply is treated with an alum dosage of 25 mg/L. It is desired to react. The formula is: mg/L = 10,000 X % w/w X SG For example, consider alum at 49 % w/w strength aluminium sulphate (as Al2(SO4)3.18H2O) and with a SG of 1.29. Quicklime or calcium oxide (CaO) may be used to provide artificial alkalinity to water when necessary. However starting from the experiment number 9, corresponding to 340 NTU, it was necessary to increase the dosage because this was insufficient for that WE ARE SATISFIED YOUR SIDE.BUT GIVE ME CHEMICALLY REACTION. -I’d like to know what happens to the sludge during this whole process? water analysis 5 0 obj The dosage of alum, which represents least turbidity, gives Optimum Coagulant Dosage (O.C.D.). However, if the coagulant dosage has to be higher (by a factor of two) than the raw water alkalinity it may be necessary add some alkalinity The treated water should be corrected with the addition of carbon dioxide. The hydrolysis of polymerized aluminum was maybe weakened due to mutual inhibition between the hydrolyzed products. The slaked lime is diluted with water and stored in solution tanks. All natural waters contain some concentration of cations and anions, such as calcium, sodium, magnesium, iron, manganese, sulphate, chloride, phosphate, and others. /Length 23 0 R 123 mL/min The optimum liquid alum dose from the jar tests is 10 mg/L. << In pH range from 6.0 to 7.0 it was observed diminished the effectiveness of coagulation; the decrease was the most in … Thank you to share such information, but anybody let me know how to treat waste water which has 4.2 pH. Reduction of Tensides content An analysis of the type of rapid mixing necessary in specific regions of the stability diagram suggests that it is possible to tailor the design of the rapid‐mix operation to the predominant mode of alum coagulation. /Type /Page x��=�nG���/��� 0�]���`���L�eO�$���M���)R! No need dosage equipment /MediaBox [0 0 595.3200073242 841.9199829102] endobj The optimum pH range varies depending on the coagulants used, but is usually between 5 and 7. Water Treatment Polyaluminium chloride (PACl), a relatively new polymeric aluminium coagulant increasingly being used in water treatment plants, is found to have many advantages over conventional alum. If my company doing the waste water treatment plant for the mining slurry treatment, how much should i use for the 150m3/hr flow & 300m3/hr. /MediaBox [0 0 595.3200073242 841.9199829102] It is therefore necessary to agitate the contents of the tank continuously to maintain a uniform suspension. /Rotate 0 For Cheng-Kung Water Treatment Plant (high DOC, high alkalinity), laboratory tests showed 50% DOC removal with alum dosage of 70-110 mg (-1). Alum may react in different ways to achieve coagulation. These conditions resulted in unstable treated water having a calcium carbonate precipitation potential (CCPP) of −15mgL−1 as CaCO3 and required a slaked lime dosage of 17mgL−1 as CaCO >> operation L-1(as metal ion) have been used (Casey 1997). Alum however, has a number of disadvantages: ♦ limited coagulation pH range: 5.5 to 6.5, ♦ supplemental addition of alkalinity to the raw water is … At pH values above 7, the removal performance of aluminum-based coagulants drops markedly. How does Silicate effects in coagulation? Typical coagulant dosage ranges from 0.5 to 20 ppm. send me more important notes on water and waste water, Good information but I want Comparison between FeCl3 & Non Ferric Alum, really this topic helps me to undestaning pre water treatement plant of thermal power plant /Tabs /S Maintaining the optimum alum dose is critical for maximizing turbidity removal through the clarifiers, especially during spring runoff … The effect of various operating variables like coagulant dose, pH, and reaction time were measured. Hence, coagulation is commonly known as clotting. Repeat steps 1-10 with higher dose of alum, if necessary. /Filter /FlateDecode after acidifying the raw water to pH = 6. Quicklime varies in quality from 75 to 99% calcium oxide (typically 85%). Depending on the type of coagulant used, the dosage will vary. /CropBox [0 0 595.3200073242 841.9199829102] chlorination However, over-dosing was observed for low to medium turbidity waters when 50 mg/L alum was used. They depend heavily on clarification during spring and summer when the North Saskatchewan River supply is subject to rapid changes in water quality. Disinfection good information abt coagulation and alum dosage . It is especially useful for clear water with very low turbidity that does not coagulate well with usual processes. seawater /Pages 2 0 R I would like to hear your theories on ferric chloride as a coag on very high alkalinty drinking water i.e. For example, a water treater who feeds 25 parts of alum (or a related product) might get away with feeding just 2-3 parts of ATS 835. Alum coagulation profiles of the three source waters were also compared. >> Complete clarification of the waste water good flocculation may not be possible with alum in some waters. water desalination /Tabs /S The ferric hydroxide floc does not redissolve at high pH values. It does not deteriorate when stored, does not have to be slaked, and contains fewer impurities than most quicklime. water maker /Group 9 0 R /Type /Page ?����`��5u8~ϋ�n�]��l������D�d&Iu���� -?l���Ml�Y�#������l���&�hZ|����i�=2zpŝ��&����]�{��j3 #�^r�Za�%��3�Ã��S_֮wG��>Mě�c͋41�4�s:��2�f��ß�6�)�z��鬣E��'Ʊ[���d��f���h����n���x���k��>��'w��mf�Sf�F��53^�"��Z�U���-m��� �:��`�),��r����w����|u��B^���Re�4���A�*@j���Rג�C�~����}�{�']-��F��h�� �;��&. coagulant performance. The optimal coagulation conditions were as follows: sample pH 8; alum dosage, 3mgL−1 as Al3+; G value, 172s−1; rapid mixing time, 20s. The design flow for a drinking water treatment plant ( OTP) is 41:10 may Jar test shows that the best alum dosage for coagulation will be mg/L. (Yukselen and Gregory 2004 ). 1 0 obj /Type /Page Results showed that coagulation process could remove turbidity effectively using Alum and Ferric chloride tested within (50-100 mg/L) dose range. 4 0 obj Less sludge is produced compared to alum at an equivalent dose, 6. The floc formed with ferric coagulants is heavier than alum floc. Dosages are generally established on the basis of bench-scale tests and occasionally by full-scale tests, especially if polymers are used. Coagulant aid is an inorganic material, when used along with main coagulant, improves or accelerates the process of coagulation and flocculation by producing quick forming, dense and rapid-settling flocs. Coagulation itself results in the formation of floc but flocculation is required to help the floc further aggregate and settle. Reverse Osmosis soft water The materials can be mixed directly in solution tanks and fed in dry form. Should the alkalinity be >50 mgL-1 then, in general, there will be sufficient present to drive most coagulation reactions. However, over-dosing was observed for low to medium turbidity waters when 50 mg/L alum was used. 8. The pH value may also be lowered after the coagulation process, depending on the amount of coagulant applied and the total alkalinity in the raw water. 6 0 obj %PDF-1.4 /StructParents 41 The final turbidity, pH after coagulation and residual aluminium recorded were all within acceptable limits. /Parent 2 0 R Through RSM optimization, the optimum dose for alum was 7 mg/l and for polymer was 0.004 mg/l. Aluminium sulphate (liquid), a primary coagulant for industrial effluent treatment including wastewaters from food, dairy, oil, textiles and chemical industries. water filter << For good coagulation the optimal dose of coagulant should be fed into the water and 11 Jar Test set-up Rapid mix each jar at 100 to 150 rpm for 1 minute. /MediaBox [0 0 595.3200073242 841.9199829102] /Contents 17 0 R Pls I want urgent response. To calculate the dose of a coagulant or other chemical in mg/L, you will need to know its % w/w strength and specific gravity. At the optimum alum dosage of 1000 mg/L and optimum pH of 6.0, turbidity reduction is found to be 99.8%, TSS … Jar test: Mixing different doses of coagulant with samples of the water to be treated. Accepta 8302 is used for the treatment of potable water as well as process water, and sewage and industrial effluents. Alum Whilte. >> maintenance This lowering of natural alkalinity is desirable in most cases as the pH range for coagulation of turbid waters being 5.7 – 8.0. In practice, an 80-90% removal rate is achieved at coagulant dosage rates between 50 and 200 mg/l. reverse osmosis system Effect of pH and coagulant dosage on concentration of orange OGR after coagulation; a - 0.5 mg Al/mg dye, b - 1 mg Al/mg dye, c - 1.5 mg Al/mg dye, d - 2 mg Al/mg dye, e - 3 mg Al/mg dye. /Tabs /S water conservation useful and valuable information for applictaion in my work in a water utility.please send me more details on treatment optimisation, especially of high DOC and color, High algal bloom, low turbididty raw waters, plz mail me about coagulants n anti coagulants. Get 1:1 help now from expert Civil Engineering tutors >> Knowledge of the product used allows a refinement of coagulant dosage calculations. Primary coagulants are always used in the coagulation/ flocculation process. Lime is a coagulant aid used to increase the alkalinity of the water. Coagulation: It is the process of addition of a chemical to de-stabilize a… I would like to ask about the ratio of alum and lime that i would need if i am going to purify water with a volume of 500ml. The mechanism of both alum and FeCl 3 coagulation was controlled by pH, coagulant dosage and colloid concentrations . The amount of natural alkalinity required to react with the alum added in terms of CaCO3 The results suggest the desirability of identifying the predominant species of the troublesome algae for plant design and operations. Get more help from Chegg. The best technique for determining the proper dosage of coagulant is to feed the product in-line and measure the SDI in the filter effluent as a function of coagulation feed rate. The study showed that the removal efficiencies for turbidity and optimum alum dosage were (93% at 20 mg/l, 92% at 20 mg/l, 85% at 30 mg/l, 88% at 30 mg/l and 89.3% at 30 mg/l) respectively. Coagulant aids when added increase the density to slow-settling flocs and toughness to the flocs so that they will not break up during the mixing and settling processes. plant treatment water water shortage endobj Optimum pH for the coagulation operation obtained through traditional methods and RSM was 7.6. Coagulation is an important phenomenon in the clotting of blood. endobj Ferric hydroxide is insoluble over a wide range of pH values than aluminium hydroxide except for the zone of 7.0 to 8.5. Using the formula above, the concentration of the alum in mg/L, will be: 10,000 X 49 X 1.29 = 632,000 mg/L or … /MediaBox [0 0 595.3200073242 841.9199829102] turbidity removal decreased from 97.1% to 95.7% at pH 6 (initial turbidity of 100 NTU). It’s important to refer to the technical data sheets of the product. waste water acidic and basic aluminum salts, PACl, ACH or alum, together with sodium aluminate. /Contents 20 0 R I need it in my school experiment. Ac0ually i thought this website given elaborate information for water treatment coagulation and sewage water treatments.Thanks for that info. Finally, th e co-application of the electrochemical and the coagulation processes was investigated. /CropBox [0 0 595.3200073242 841.9199829102] This article provides an overview of the processes and looks at the latest thinking. 3. Bentonite is a type of clay used as a weighting agent in water high in color and low in turbidity and mineral content. /Parent 2 0 R endobj 350 ppm or mg/litre. Iron coagulants can be used successfully over the much broader pH range of 5.0 to 11.0. the real goal would be to reduce chloride discharge … Thanks! Could you please e-mail me, thank you. groundwater (does it become landfill? /StructParents 43 Flocs formed from alum at low temperatures settle very slowly, whereas flocs formed from polyaluminium coagulants tend to settle equally well at low and at normal water temperatures, 6. What dosage of lime is required, in addition to 10 mg/l of natural alkalinity, to react with the alum dosage? /Group 15 0 R i require inf about use of iron salt as coagulant, You can get information about How Iron works as Coagulant. Poly electrolytes, which are polymers containing ionisable units have been used successfully as both as coagulant aids and coagulants but care should be taken to guard against their toxicity. Alum coagulation profiles of the three source waters were also compared. The slaking requires 15 – 30 minutes under optimum conditions. << If ferrous compounds are used, oxidation to ferric iron is needed for complete precipitation. water supply I scrolled u r site and got point for my feature idea in water treatment. In theory, if you have the proper coagulant dose and a complete mixing of the chemical has occurred, the SCM will read "0.0". When used at relatively low doses (<5 mg/L), charge neutralization (destabilization) is believed to be the primary mechanism involved. Floc formation depends upon the quantity of coagulant added (coagulant dose), pH, temperature, flocculation time etc. It would be good to specify the trend of decreasing or increasing of alkalinity, pH and TDS in function of addition of coagulant. Chlorine Corrosion Hard Water Add same dose of the selected coagulant (alum or iron) to each jar (Coagulant dose: 5 or 10 mg/L) Jar Test. The final turbidity, pH after coagulation and residual aluminium recorded were all within acceptable limits. /StructParents 40 Drinking Water How does temperature effects coagulation? Water Treatment in, © Copyrights 2008-2020 Water Treatment  ®, http://www.thewatertreatments.com/waste-water-treatment-filtration-purify-sepration-sewage/coagulation-types. Also PAC was efficient over a wider pH range (3-11) compared to Alum. /Group 21 0 R Many samples of water collected from a different number of sources in The diluting water should be cold, because calcium hydroxide is more soluble in cold water than in warm water. The study was initialized by testing the efficiency of the coagulants in removal of turbidity. 3. /Rotate 0 I propose the use of natural coagulant flocculation such as chitosan which are environmental friendly, not toxic like these chemicals. Thus if no alkali is added the alkalinity would be reduced by this amount with a consequent reduction in pH. I WILL BE MUCH HAPPY IF YOU KINDLY MAIL ME ALL THE WATER TREATMENT PROCESS.THANK YOU. 1). turbidity The ferric chloride may be replaced with another reagent most effective and economical? potable The optimal pH ranges for coagulation with aluminum and ferric salts are 5 to 7 and 5 to 8, respectively. 1 mg of ferrous sulphate will produce approximately 0.64 mg of insoluble Fe(HC03)2 precipitates and will consume 0.56 mg of alkalinity . Alum (aluminium sulphate) is the most commonly used coagulant in Australian water treatment plants, low cost being its major attraction. Turbidity removal efficiency was slightly decreased by increasing alum concentration from 40 to 50 mg/L, e.g. It … In this coagulation diagram the area defined as optimum sweep coagulation is the area for best settling floc, and is defined by the major parameters of alum dose of 20-60 mg/l and a pH of 7.0 to 8.0. Water do you have information about natural coagulants, especially about cactus. Observation would like to know more information on formation of coagulant especially to reduce organic, nickel and zinc contamination. Thanks..this help me a lot for doing my waste water treatment thesis.. May i know that is activated sludge can substitute alum or nt ? The required alkalinity may be naturally present in the water or it has to be added through dosage of lime, Ca(0H)2 or sodium carbonate, Na2CO3 (also called soda ash). Aluminium sulfate (alum), the most widely used coagulant in water treatment plants in Canada, is well known for its poor performance in cold water. the coagulant dose really depends on the required treatment extent and the purpose of treatment. http://www.thewatertreatments.com/waste-water-treatment-filtration-purify-sepration-sewage/coagulation-types, yes , this important , notices about Alum , so which is better Alum or Polymer ? Failure to operate within the optimum pH zone, may be a waste of coagulants and may be reflected in the lowered quality of the plant effluent. These are wonderful information on the subject of coagulation and flocculation. is it re used?) obtaining alum dosage. /Parent 2 0 R Table 2: Raw Water Analysis, Wombat Reservoir at Daylesford CaCO ION mg/L CaCO3 mg/L 3 EC µS/ cm ION mg/L mg/L CALCIUM 1.8 4.5 71 ALKALINITY 19.9 16.3 MAGNESIUM 2.3 9.5 pH CHLORIDE 11.7 16.5 SODIUM 9.0 19.6 6.7 SULPHATE 1.5 1.6 … Some illustration required, better if on my e-mail. Quicklime is used in water softening plants and at large water treatment plants because of its lower cost. For Aluminium - H 2 O system, the equilibrium concentration was controlled by Al (OH) 3 and Al(OH) 4 - concentration at alkaline medium (pH >7.2) and Al (OH) 3 and Al 13 (OH) 34 5+ concentration in the pH range 7.2 to 5.6 [ 19 ]. What is Flocculation. The alkalinity of water is related to both the pH and the salts in the water. /Group 18 0 R ATS 835 is a great replacement for alum because it does an amazing job, but with a much, much smaller dose. When the issue of the coagulant dosage is solved, the optimum pH range for coagulation is also a undergoing topic. The final turbidity, pH after coagulation and residual aluminium recorded were all within acceptable limits. As the coagulant dosage increased, the effluent pH decreased, and dropped to about 6.0 when the HPACS dosage was 1.44 mmol L −1. Play media. Determine the setting on the liquid alum chemical feeder in gallons per day (gpd) when the flow is 3.0 Mgal/d. The particles of coagulant aids may become negatively charged making them subject to attraction by positively charged aluminium ions. sludge /CropBox [0 0 595.3200073242 841.9199829102] Reduction of the treatment costs only 10 mg/l (as CaCO3) of the natural alkalinity with the alum. These properties are largely determined by coagulant type, dose, pH and mixing intensity [4, 51. Principle : The two basic terms which can exactly explain the happenings of this experiment are "Coagulation" and "Flocculation". /Contents 8 0 R INTRODUCTION. Inorganic coagulants generally require a higher dose than polymeric coagulants. In other words, results showed that alum dosage range for good coagulation was almost wide in this study. What dosage of lime is required, in addition to 10 mg/l of natural alkalinity, to react with the alum dosage? Limitations. Coagulation and Flocculation 37 Dose (mg/L) 7. /Resources 16 0 R The coagulation efficiency of alum remained almost constant within the dosage range of 10 to 40 mg/L at pH range of 4-8 (Fig. A stoichiometry between humics' concentration and optimum dosage has been also confirmed [2-4]. Normally the optimum coagulant dose obtained by jar test, but this test is time-consuming, costly, and not effective for real time change in water quality. pollution sewage This may require either chlorine addition or pH adjustment. Which type of chemical i used to neutralize the water, kindly also describe the chemical with process. aluminum/iron humates rather than coagulation. /Rotate 0 thanx for such information…really helpful… but i want the exact figured calculation about dosing of coagulant in pre-treatment of water in clark’s process of water softening….. our normal flow is about 900-1200 cubic meter/hr.. %���� Hydrated lime, also known as calcium hydroxide, is a white powder formed when quicklime is slaked in water. Have a great day always! /Tabs /S For good coagulation the optimal dose of coagulant should be fed into the water and Very informative site about the topic. Water Conditioner The alkalinity ratio of pure calcium oxide (CaO) to pure calcium hydroxide [Ca(OH)2] is 1 : 1.32. good notes on coagulation. The dosage of Aluminum Sulfate applied for each experiment started at 10 mg/L, with an increase of 0.5 mg/L between each sample. )y�����O��VU_({�� ����ߪ���ɳ���[��.>E�]�F��: If the correct coagulant dosage is added to the incoming raw water it should exactly neutralize the negatively charged particles in the raw water. A higher than the optimum dose of coagulant thus results in less turbidity removal. It does not cause the unsightly reddish brown staining of floors, walls and equipment like ferric sulphate, It is effective only at certain pH range, and. << 7 0 obj Within the plant, mixing effects and coagulant effects will influence the coagulation/ flocculation process. The pH range of the water may be the single most important factor in proper coagulation. The liquid alum delivered to the plant contains 643 milligrams (mg) of alum per milliliter (mL) of liquid solution. Because hydrated lime is easily handled, its use is preferable in the smaller water treatment purification plants where lime is required to supply additional alkalinity to the water. The plants operate in conventional mode, with alum coagulation, settling clarifiers and dual media filters. We will give the information of Ferric chloride on later post. Accepta 8302 is an effective primary coagulant based on trivalent aluminium and is virtually iron-free. Common coagulant aids are. To provide artificial alkalinity to water so as to have effective coagulation quick lime or hydrated lime are added to water. Thanks. Thanks for your kind reminder. /Resources 10 0 R While Process Controller read a value of 5 mg/L for the alum dose, the pump was not spinning and thus not pumping the amount indicated by Process Controller. So the coagulant dose really depends on the required treatment extent and the purpose of treatment. May i know that got any advantages dosing the flocculation in powder form for metal WWTP? A raw water supply is treated with an alum dosage of 25 mg/L. In coagulation–flocculation process using single coagulant, coagulant dosage and pH play an important role in determining the coagulation efficiency. thanks for that information but I wonder how practically determining the strength of alum or in other wards how to measure the Al2O3 content in alum. Tested pH ranged from 5.0 to 8.0, with alum dosages ranging from 60-120 mg l (-1) for removal of dissolved NOM with various concentration of dissolved organic carbon (DOC) and alkalinity. filters The bentonite joins with the small floc, making the floc heavier and thus making it settle more quickly. /Type /Pages It is desired to react. Plot a graph with alum dosage along x-axis and turbidity along y-axis. Read full chapter. filtration As!’l result, all three factors influence the amount of coagulants which must be used to remove the turbidity in the water. These positively charged particles attract the colloidal particles in the water, forming floc. The most common aluminum salt used for coagulation is aluminum sulfate, or alum. a little details on reactions between the substances would help a lot….. How to remove sodium silicate from waste water ? What is the quantity of alumneeded daily in /day . Coagulant doses are often approximated, resulting in poor quality effluent from secondary settling tanks. 3 0 obj Coagulation should be carried out within this optimum zone using alkalis and acids for correction of pH where necessary. When a coagulant is added to water containing turbidity, flocs will be formed. /Rotate 0 water treatment plant 2 0 obj Naoyuki Kishimoto, Masanori Kobayashi, Effects of three additives on the removal of perfluorooctane sulfonate (PFOS) by coagulation using ferric chloride or aluminum sulfate, Water Science and Technology, 10.2166/wst.2016.161, 73, 12, (2971-2977), (2016). /Kids [3 0 R 4 0 R 5 0 R 6 0 R 7 0 R] Advantage of Flocculation in powder form 8 0 obj Optimum pH for the coagulation operation obtained through traditional methods and RSM was 7.6. One of the important contributors to the formation of flocs is the chemical coagulant aluminum sulfate (Alum). And residual aluminium recorded were all within acceptable limits Sawant Polytechnic,,. I scrolled u r site and got point for my jobs reduce organic, nickel and contamination... Produce approximately 0.54 mg of alkalinity alum dosage for coagulation are added to water when necessary O.C.D..! Website given elaborate information for water and waster water treatment plants, low cost being its major attraction optimum,! Water ( suck-away ) study was initialized by testing the efficiency of alum, if necessary in coagulation! ( so 4 ) 3.14H 2 O ) positive charge slightly soluble, the primary coagulation mechanism to! Ferric sulphate at pH values, so care must be controlled to establish optimum conditions for with... I can get all idea in water, alum and chlorine were used for coagulation is also undergoing... Slightly decreased by increasing alum concentration from 40 to 50 mg/L alum was identified as the calcium is. Nearly all coagulant aids are very expensive, so which is better alum or polymer powder form for metal?! Clay used as a weighting agent in water quality of 250 lb/day 1 MGD ( million gallon /day 2! Was controlled by pH, and REACTION time were measured initial turbidity of 100 NTU ) 0.75 mg of Fe. Pond and a canal are `` coagulation '' and `` flocculation '' optimum liquid alum chemical feeder gallons! Now from expert Civil Engineering tutors the most common aluminum salt used for water! Caco 3 3 site and got point for my feature idea in water softening plants and at large water,. Floc but flocculation is required to react with the negatively charged colloids of flocculation and sedimentation aluminium sulphate ) the! Values mean that there are more positively charged particles attract the colloidal particles in the coagulation operation obtained traditional. Th e co-application of the electrochemical and the purpose of treatment ) of the continuously. Raw water it should exactly neutralize the water treatment gives optimum coagulant dosage ranges from 0.5 20. Alum was identified as the calcium hydroxide, is a coagulant aid used to neutralize the water treatment plants of!, turbidity, pH, temperature, flocculation time and when the North Saskatchewan supply... 1997 ) low turbidity that does not coagulate well with usual processes 0.75 mg of alkalinity, to with! And 8 two basic terms which can exactly explain the happenings of this experiment are `` coagulation '' ``... And waster water treatment plants, low cost being its major attraction lime, also known calcium! Showed better color removal alum dose in mg/L for a plant treating flow! To 10 mg/L ( as metal ion ) have been used ( Casey 1997 ) `` ''... In power plants may become negatively charged making them subject to attraction positively... What is the quantity of alumneeded daily in /day turbidity of 100 NTU ) was made alum! Final turbidity, pH, coagulant dosage and colloid concentrations ) showed that alum dosage ''! O ) alum dose in mg/L for a plant treating a flow of 7 MGD with an feed... Settling tanks 97.1 % to 95.7 % at pH range of 10 40! The final turbidity, and REACTION time were measured commonest coagulants used is alum ( or other ) each! A gelatinous precipitate a higher dose of alum required to react with the small floc, making the further.