Charge on hydrolysis products and precipitation of metal hydroxides are both controlled by pH. Also compute the daily requirement of alum. Epic Machines Recommended for you A post-treatment alkali dose of 4.7 mg/L was required in this instance (total dose 8.1 mg/L). A higher than the optimum dose of coagulant thus results in less turbidity removal. Chemical coagulants are added to water to facilitate bonding among particulates that are widely used to … an optimal dosage of coagulant, which generally is calculated by means of the “Jar Test,” working under a uniform condition of turbidity. Different coagulants also have an optimum pH range over which they are effective and pH buffering may be required depending on the coagulant and water chemistry. The least turbid sample should correspond to the optimal coagulant dosage chosen in step 10. Addition of caustic soda at 3.4 mg/L was necessary to achieve a coagulation pH of 6.9. Using the given data, calculate the optimal pH, coagulant dose, and the theoretical amount of alkalinity that would be consumed at the optimal dose. At higher dosa-ges of the coagulant … A laboratory experiment called the jar test is generally used for the periodic determination of the optimal dose. the minimum amount required to give acceptable clarification). The optimum coagulant dose was found to be lower than that for aluminium sulphate. Use the concentration of coagulant chosen in steps 10 and 11 and alter the dosage of lime or coagulant aid. The optimal pH ranges for coagulation with aluminum and ferric salts are 5 to 7 and 5 to 8, respectively. Optimum dose definition at Dictionary.com, a free online dictionary with pronunciation, synonyms and translation. DETERMINATION OF THE OPTIMUM COAGULANT DOSE (ALUMINIUM SULPHATE) IN THE WATER TREATMENT PLANT OF ATHENS IN GALATSI FACILITIES DURING THE SUMMER PERIOD Introduction Turbidity is one of the important physical parameters of water that representing the amount of suspended solids, (Kawamura, 2000; Daneshvar, 2009). Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube. Coagulation dosage is one of the most important factors that have been considered to determine the optimum condition for the performance of coagulants in coagulation and flocculation. The criteria thus obtained from a bench jar test are the quality of resultant floc and the clarity of the supernatant liquid after settling. The amount of waste water that passes for 4 hours is 18000 liters. Characteristics of the treated water for each coagulant option determined from WaterQual are given in Table 3. 2 and 3, with the corresponding amounts of R 2 and MSE shown in Table 4. (Yukselen and Gregory 2004 ). Common criteria include supernatant turbidity after settling, and filtrationthrough filter papers. When the issue of the coagulant dosage is solved, the optimum pH range for coagulation is also a undergoing topic. The SCD measures the net surface charge of the particles and shows a streaming current value of 0 when the charges are neutralized (cationic coagulants neutralize the anionic colloids). Ferric sulphate is available as a commercial water treatment coagulant in the form of an anhydrous material that may be transported and stored in wooden barrels. How to dose coagulant? Therefore, it is significant to determine the optimum dosage to minimize the dosing cost and sludge … Enhanced coagulation occurs at a lower pH. 6 Most Satisfying Modern Forestry Machines and Technology Tools That Are At Another Level 9 - Duration: 11:10. The optimum coagulant dosage in a coagulation process is pH dependent and should be established based on an on-site jar or pilot testing for the site-specific conditions of a given application. It’s important to refer to the technical data sheets of the product. As evidenced with Fig. The addition of acid is used to achieve the proper pH unlike sweep treatment were the operator overdoses the coagulant to achieve the correct pH range. Coagulation is an essential part of drinking water treatment process. The students conducted various jar tests with UV254 to determine which chemical combination would produce the best finished water quality results. 1. Determination of Optimum pHfor Optimum Coagulant Dose Rapid mix 1-3 min (at 80 rpm) Slow mix 30 min (at 10-20 rpm) Settle for 20 min Turbidity of supernatant Optimum coagulant dosage determined in part A as-is pH adjust pH5 adjust pH6 adjust pH8 W/ H2SO4 NaOH 29. Essentially, insufficient dosage or overdosing would result in the poor performance in flocculation. However the turbidity values change temporarily on the water, affecting the effectiveness of this process, due to each turbidity value may need a different coagulant dose [2]. Depending on the type of coagulant used, the dosage will vary. In coagulation, coagulant dosage for a given source water should be determined based on jar test and/or pilot testing. It is used to agglomerate suspended solids together into larger bodies. At this dosage the lowest measured concentration of the residual dye was Ck = 16 mg/dm 3 at pH 4.5. An automated device for determining the coagulant dose is the Streaming Current Detector (SCD). 3 , turbidity removal is maximum at an optimized dose of alum 0.25 g/l and when the dose is increased turbidity tends to reappear due to charge reversal. The model has also achieved reasonable accuracy in predicting the amount of the residual aluminum of the treated water with an R 2 of 0.93 and a MSE of 0.37 mg L −1.. The hydrolysis products possess a positive charge at pH values below iso-electric point of the metal hydroxide. At this value (0), the coagulant dose can be said to be optimum. Coagulation dose is one of the most important factors to consider in determining the optimum condition for the performance of coagulants in coagulation and flocculation. Keywords: Turbidity, Optimum dose, Poly Aluminum Chloride (PACL), pH. In model 2, The results of the optimum coagulant dose obtained, by using model 2, are shown in Figs. Will the natural alkalinity of water be sufficient to satisfy reaction with alum? At a smaller dosage of the coagulant 0.5 mg Al/mg dye the efficiency of coagulation dropped in the whole examined pH range by 20% on average, in comparison with the optimal dosage 1.0 mg Al/mg dye. The jar test may be briefly described as follows: A series of samples of water are placed on a special multiple stirrer and the samples, typically 800 ml in 1-litre beakers (or jars), are dosed with a range of coagulant, e.g. Coagulation is an primary process of any kind of water treatment plant, that process must be performed using with cost effective and commonly used coagulants. Look it up now! The evaluation of optimum coagulant type, dosage and pH using the jar test procedure may be carried out on the basis of a wide variety of criteria; the applicability of each dependent on the particular circumstances and the processes used after coagulation. Optimum pH for the coagulation operation obtained through traditional methods and RSM was 7.6. The raw tannery effluent was bluish-black in colour, mildly basic in nature, with high COD 4000mg/l and turbidity in the range 700NTU, was diluted and dosed with organic coagulants, AloeVera, MoringaOleifera and Cactus (O.ficus-indica).. The enhanced coagulation process is used to remove natural organic matter by adjusting the pH and coagulant dose to remove the greatest amount of suspended matter during the treatment process. The goal of the lab was to determine the optimum coagulation dosage for alum and possibly soda ash for this water source. Determination of the optimum dose of such a coagulant is of particular significance. A ‘Stable colloidal particle’ is a colloidal particle that remains as a separate entity in the water, i.e. Coagulation is a chemical process in which a chemical compound, a “coagulant”, is added to the water, in order to destabilize the suspended particles and promote creation of flocs. The dosage range of a coagulant will vary depending on site water chemistry. We are using CFS(coagulant-flocculant-sorbent(PACL)) who have 10-11% Al 2 O 3 or 20-23% w/w PACL, SG = 1.18 50% basicity and 10,5% w/w Cl. Optimum coagulant dose: 12.5 mg/L The coagulant dose with the lowest residual turbidity will be the optimum coagulant dose . BTJCM (Civil/Environmental) (OP) 3 Oct 18 08:05. Essentially, insufficient dosage or overdosing would result in poor performance in flocculation. Charge neutralisation in water can occur very rapidly therefore mixing is important for effective treatment of turbid water. At pH values above 7, the removal performance of aluminum-based coagulants drops markedly. The optimal dosage of the coagulant was 1.0 mg Al/mg dye. the coagulant dose really depends on the required treatment extent and the purpose of treatment. Through RSM optimization, the optimum dose for alum was 7 mg/l and for polymer was 0.004 mg/l. Polymers also reinforce flocs . determine the optimal pH and dosage, the activity of natural coagulant, followed by the real effluent from tannery waste. 15 COAGULANT AIDS Other substances than coagulants used: - Clay minerals - Silicates -Polymers Polymers are often either anionic or cationic to aid coagulation. The data sheets will mention the density as well as the percentage of alum (or other) in each product. In adsorption/charge neutralization, it is found that excessive dosage results in charge reversal and a negative effect on process performance. Usually in electrical double-layer suppression, there is little or no dependence on coagulant dosage after the minimum/optimum dosage. Post-filtration pH adjustment may be necessary to optimize corrosion control and comply with other … General and 7 most commonly used coagulants in water treatment plant is under: 1.Alum (aluminum sulfate), Al 2 (SO 4) 3. Hi I have a problem with coagulant-flocculant-sorbent dosing. optimal coagulant dose for a particular raw water. Optimum operation conditions were: an organic load of 25% of the total dose, total coagulants dose of 10 ppm, pH of 6 with an estimation of high turbidity value of 100 NTU. The turbidity value is proportional to the amount of colloid and suspended solids in water that cannot be deposited in usual ways. Flocculation aids water treatment 16 4/7/2014 . Knowledge of the product used allows a refinement of coagulant dosage calculations. This allows the operator, or an automated control device, to make the necessary coagulant feed adjustments in order to continuously maintain the optimum dosage. Ferric sulphate. in a dispersed state. Feed water pH should be adjusted to the appropriate range prior to coagulant addition. Generally the floc formed by the reaction of copperas and lime is feathery and fragile, but has a high specific gravity. A high dose, in addition to adding costs, can cause the sediment to remain in the filtrate, a dangerous condition according to the standards, while a sub-adequate dose of coagulants can result in the re-ducing the required quality and acceptable performance of the coagulation process. The dose of lime required is approximately 0.27 mg/L to react with 1.0 mg/L of copperas. A plot of turbidity against coagulant dose gives an indication of the optimum dosage (i.e. It was observed that the optimum dose for alum obtained through the traditional method was 12 mg/l, while the value for polymer was set constant at 0.020 mg/l. 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