Enter the calcium (Ca) and magnesium (Mg) values from your soil test report. We accomplish this by using the ratio on below equation. 2 Water Softening 1. How does the lime-softening process work? is generally in the range of 20 to 60 ppm. Calculations are presented for daily chemical requirements and solids production rates. Sketch a drawing of a typical lime softening facility, identifying processes and points of chemical addition in the appropriate order for each of the following: 1. Calculate how much lime and soda ash are required to soften a raw water with a total hardness = 215 mg/L (as CaCO_{3}) or 2.15 10^{3} . e use lime softening extensively in certain areas of Florida and have been for over 70 years. However its . Also there are logical choices and numerous equations used in calculating chemical dosages for lime soda water softening . Chemicals normally used are lime (calcium hydroxide, Ca(OH) . . Limitation of Soda Lime Process: Lime soda softening cannot produce a water at completely free of hardness because of the solubility (little) of CaCO3 and Mg(OH)2. All these units together make the lime softener a complicated unit operation. Hence, the net flow per softener is 65 m3/hour. The lime softening reaction is relatively slow, and will continue downstream of the clarifier, exceeding the solubility of calcium carbonate in the clarified water. Lime-soda ash softening is assumed to be capable of reducing calcium and magnesium to empirically determined 11practical limits11 of 0.6 - 0.8 meq/1 and 0.2 meq/1, respectively. The block flow diagram of a typical lime softener is depicted in Fig - 1. In both calculation methods, lime and soda ash dosages depends on carbonate and non-carbonate hardness in the water. Ecodyne can customize the basic Reactivator-Clarifier design to accommodate cold lime or warm lime operation as required for TSS hardness, alkalinity and silica removal. In many communities lime softening processes do . A. First, determine your calcium:magnesium ratio. the two stage excess lime softening process, if concentrations are known or can be calculated for CO2, calcium carbonate hardness, calcium noncarbonate hardness, magnesium carbonate hardness, and magnesium noncarbonate hardness, using design values for excess lime concentration and lower limit of residual magnesium hardness. Hardness definition: A. Hardness is the term often used to characterize a water that : Dose form a foam or lather well and cause soap scum Ca2+ + (Soap)- Ca(Soap) 2 (s) This increase the amount of soap needed for washing cause scaling on pipes and hot boilers. jerry2363 (Chemical) (OP) 4 Jan 07 01:06. cub3bead, happy new year. Ion-Exchange Softening is a common household water softening method that uses salt (sodium chloride or potassium chloride) to soften water. In Salbukh water treatment plant, silica. Determination of lime and soda ash dose requirements for water softening Removal of CH with Lime Feed Only 6 Removal of Noncarbonate Hardness with Lime and . Now calculate the amount of lime needed to precipitate all alkalinity in these small water samples. Lime-enhanced softening can also be used to remove arsenic from water. Enter ppm Ca. Options for on-site erection depending on location and site access are also available. Lime softening has been proven to remove a wide variety of contaminants including tannins, arsenic, barium, lead, nickel, cadmium, chromium and other metals. The warm lime softening process operates in the temperature range of 120-140F (49-60C). Determination of the bicarbonate concentration in moles per liter (alkalinity is assumed to be in the bicarbonate form since the pH is 7.94). Multiply the number of people in your family times 70 (gallons of water used per day, national average). During lime softening process calcium and magnesium are precipitated. 1 pg. calculations, 1400 lbs/MG of lime should be used. Profile B. There is also information about three lime soda water softening process alternatives (two stage excess lime water softening, split treatment, and selective calcium removal), along with calculation of the dosages needed for lime, soda ash, and carbon dioxide. Welcome to Iowa Publications Online - Iowa Publications Online 2 pg. Softening was tried using lime as the sole flocculating agent and using lime with ferric sulfate as a conjunctive coagulant. 3 3 61 1 1 [ ] 305 6.1 10 / 50 1000 61 HCO . Softening James Norberg Follow this and additional works at:https://commons.und.edu/theses . Produced specifically for water treatment operator training, this new video illustrates and explains lime softening processes, chemistry, and feed calculations. Lime soda water softening is the subject of this e-book. According to Wang (), recarbonation is defined as "(a) the process of introducing carbon dioxide, CO 2, as a final stage in the lime-soda ash softening process in order to convert carbonates to bicarbonates and thereby stabilize the solution against precipitation of carbonates, (b) the diffusion of carbon dioxide gas through liquid to replace the carbon dioxide gas removed by the addition of . Program pre-calculations49 Calculate CO 2 . Cold lime softening, also known as Clark's process, is used to reduce the hardness, alkalinity, silica, and other constituents of raw water. . 7 pg. 85% of that amount is added to the first sample, 100% is added to the 2nd sample and 115% is added to the 3rd sample. All Answers (4) Sodium hydroxide (NaOH) (caustic soda) may be utilized for chemical precipitation. The purity of lime is 70% and soda is BS% Ca(HCO 3) = 30.2 , Mg(HCO 3) = 20.8 ,CaCI 2 = 28.1 ,MgCl 2 = 8.78, CaSO 4 = 35, MgSO 4 = 6.7 . softening can be achieved by adding lime in the form of limewater, ca (oh)2, which, in a carbonatation reaction with co2, forms calcium carbonate precipitate, reacts next with multivalent cations to remove carbonate hardness, then reacts with anions to replace the non-carbonate hardness due to multivalent cations with non-carbonate hardness due Sodium aluminate has a special advantage as a coagulant in lime-soda softening since unlike most other coagulants it is alkaline and also contributes to the softening reactions', particularly in reducing magnesium. Slaked Lime Ca(OH) 2 Base - Other Typically 2.0%. Stricter drinking water regulations for arsenic have increased the need for this treatment. Enter ppm Mg. Lime sludges cannot be returned to the Silica content in brackish water. In the lime-softening process, the pH of the water being treated is raised sufficiently to precipitate calcium carbonate and, if necessary, magnesium hydroxide. Lime softening was abandoned on the premise that the effective hardness removal did not warrant So the amount of water flow in each individual will be 130 / 2 =65 m3/hour. Calculation explanations 3.1.1. Fig -1 The FilmTec NF270 nanofiltration membrane, for example, offers low salt rejection, low energy consumption, and stable performance after repetitive cleaning. Is 220 PPM hard water? cause valves to stick due to the formation of calcium carbonate crystals Prices can vary, but for the following calculations, the prices used include $510/dry ton for caustic soda, $130.50/ton for quicklime as delivered and $153.10/ton for hydrated lime as . Carbon dioxide and carbonate hardness (calcium and Magnesium bicarbonate) are complexed by lime. Explain with chemical equations and calculate the amount of lime and soda needed for softening 1,00,000 litres of water containing the following: HCl = 7.3 mg/L, Al 2 (SO 4) 3 = 34.2 mg/L ; MgCl 2 = 9.5 mg/L ; NaCl = 29.25 mg/L Purity of lime is 90% and that of soda 98%. Lime softening, the most widely used precipitation process, serves well to illus- trate the importance of four key variables in precipitation: (1) solubility, (2) par- ticle charge, (3) temperature, and (4) time. Lime is used to remove carbonate harness, and both . pH Adjustment/Coagulation - Hydrated lime is widely used to adjust the pH of water to prepare it for further treatment. Calculate the quantity of the pure lime and soda required for softening of 1,00,000 litres of water containing the following impurities in ppm. This process is used for the following purposes: CALCULATIONS OF LIME AND SODA ASH CONCENTRATIONS REQUIRED FORWATER SOFTENING. Percent lime Required by Specification Depth in Inches Soil Density Total Pounds Applied per Square Yard (This field will be populated automatically) CO2 + H2O = H2CO3 H2CO3 + CaCO3 = Ca (HCO3)2 Cold Lime Softening Lime softening accomplished at ambient temperatures is referred to as cold lime softening. criteria for softening facilities. This article first covers how gravity clarifiers work, some of the chemicals used in clarification, proper chemical feeding procedures, and clarifier equipment designs. Lime Softening 1 Lime Softening . Multiply the answer by your water hardness in grains per gallon (to convert mg/l or ppm to grains, divide by 17.1). Chemical requirement and product composition for lime-soda softening is usually calculated using the bar diagram method and its variations (3,5). Therefore, they are more effectively removed by warm lime softening than by cold lime softening. concentration of raw water is about 30 ppm. The chemicals increase the pH of the water so that calcium carbonate, lime, leaves the solution and crystallizes on the fine sand in the form of rock-hard balls, the pellets. Alkalinity to be added to the water (mg/ L) = total alkalinity required (mg/ L) - (minus) alkalinity present in the water (mg/ L) much lime (the source of alkalinity) must be added. Lime sludges are dense and will tend to settle, however, it is recommended that 10 mgL-1 of an alumina coagulant be added to capture the lime fines. Spreadsheets for Lime Soda Water Softening Calculations There are logical choices (e.g. Allowing the plant to run for 22 hours, and leaving 2 spare hours for regeneration of the cation exchange resin, the output between . It should be stressed that the coagulant is present only to capture the lime fines and not to coagulate raw water turbidity. The solubilities of calcium, magnesium, and silica are reduced by increased temperature. Determine/calculate the mg/L lime required by using a proportion that relates bicarbonate alkalinity to . High concentration of silica causes. Hardness causes problems with the water such as scaling in pipes and excessive usage of soap. The normal pH of water is between 6.5-8.5. softening process to take place. Calculation for Sizing a Water Softener. The chief operator at the plant reduced the lime feed to save money. We normally tolerate a final total hardness on the . It's just a simple spread sheet showing # of hydrated lime and Magox to be used with a varying alkalinty and Mg content of the raw water. With the conversion calculators you can convert the units that are most commonly used. This aids in the preparation of water for direct cooling tower makeup or as a first-stage treatment followed by ion exchange for boiler makeup or RO Reject recycle. How does the lime-softening process work? Supply water and chemicals (caustic soda, lime wash or sodium carbonate) are injected into the bottom of the reactor and mixed intensively. Using either flocculating and softening regime, only about half of the orig inal 260 mg/1 of hardness was removed. Yes. Spreadsheets for Lime Soda Water Softening Calculations There are logical choices (e.g. When hydrated lime, Ca (OH)2, is added to the water being treated, the following reactions occur: CO2 + Ca (OH)2 = CaCO3 + H2O Ca (HCO3)2 + Ca (OH)2 = 2CaCO3 + 2H2O Lime soda softening is the subject of this course, which includes coverage of calculating the different types of hardness in a water sample from lab analysis results, conversions among different units for hardness, information about three lime soda water softening process alternatives (two stage excess lime water softening, split treatment, and lime softening. The normal pH of water is between 6.5-8.5. There might be more economical ways to soften your water without generating a mountain of lime sludge. Calculator Net acidity = potential acidity + existing acidity * The factor 1.02 is used to stoichiometrically convert units of sulfuric acid (H 2 SO 4) to units of calcium carbonate (CaCO 3) A minimum safety factor of 1.5 should be used due to its advantages: produces less sludge than lime, or lime-soda ash processes. chemistry of lime soda process the amount of lime required in (meq/l) = carbon dioxide (meq/l) + carbonate hardness (meq/l) + magnesium ion (meq/l) + 1.25 (meq/l) the amount of soda ash required in (meq/l) = noncarbonate hardness (meq/l). Straight lime Your Ca:Mg ratio is. Revise if necessary. Water will stop at nothing to find equilibrium.so when it's hungry for calcium, it will aggressively look for it. membrane fouling in the reverse osmosis units. treatment process necessary for softening this water is the excess lime process. In small systems, lime softening is typically practiced by adding Effective use of coagulants helps remove silica in the softening process. Calculators. With these calculators you can calculate Anglo-American units to the standards units (SI-units). Lime softening produces large volumes of a mixture of calcium carbonate and magnesium hydroxide in a very finely divided white precipitate which may also contain some organic matter flocculated out of the raw water. If iron is present, add 5 grains for every ppm (mg/l) of iron (iron MUST be . Lime Softeners. 9. . In the lime-softening process, the pH of the water being treated is raised sufficiently to precipitate calcium carbonate and, if necessary, magnesium hydroxide. Volume Step 1: Enter Starting Water Profile Step 5: View Resulting Water Profile Step 3: View Mash pH Distilled water Mash pH (from chart) If your water report gives Sulfate as Sulfur (SO 4-S) such as a Ward Lab's report, multiply by that by 3 to get SO 4 Chalk In small systems, lime softening is typically practiced by adding hydrated